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y/STOL Close Air Support >n the U. S. Marine Corps 113
% Colonel Stanley P. Lewis,
C- S. Marine Corps
The Eyes of the Fleet 117
By Thomas A. Guarino and Charles F. Muller, Jr.
VS, The Enemy Has Been Found and the Enemy is Us 120 By Lieutenant Commander Stephen L. Chappell,
S. Navy
The F-18 123
By Captain Hank L. Halleland, U. S. Navy (Ret.)
UTTAS: The Helicopter of the 1980s? 128
By Mark Lambert
The S-3A Viking 131
By Commander Rasario Rausa, U. S. Naval Reserve (TAR)
Fiber Optics and Naval Aviation 133
By William M. Powers
V/STOL Close Air Support in the U. S. Marine Corps
By Colonel Stanley P. Lewis, U. S. Marine CorpSj Project Manager, V/STOL Weapon ^sterns Project, Naval Air Systems
Command
■Aviation occupies a particularly prominent position among the support- lng arms available to the Marine ground Commander whose task it is to seize and efend an objective area. The Corps’ first Use °f aviation as a supporting arm was n Nicaragua in the late Twenties. World War II enabled the Marines to Perfect an operational close air support octrine which is the parent of today’s lv'sion/wing team organization. At Peaces like Peleliu, Marine close air sup- P°rt aircraft operated from small carriers and off coral airstrips within sight of the yrpported Marine rifle companies. In
orea, the gap between the aviators and ground Marines began to widen as new tactical aircraft which required longer runways entered service.
The Vietnam conflict saw Marine A-4s at Chu Lai supporting Marine regiments near the DMZ. The speed of the jets Cnabled them to cover the 150-mile dis- tar)ce in 30 minutes, but that was often to° late to meet the urgent need of a Sr°Und commander in contact with the enemy. Furthermore, the geographical SeParation of the Marine divisions and
wings, discounting the helicopters, made the "air-ground team” concept of the past a practical impossibility. The jet pilots and their commanders at the major air bases were simply too far removed from their ground counterparts to build the mutual confidence and to affect the personal coordination that we know as teamwork.
Adequate close air support was in fact furnished, but the cost was great in jets airborne around the clock on air loiter or, more often, on questionable 7th Air Force "preplanned” missions against "suspected enemy positions.” There were no benefits of air-ground teamwork at the unit level, where it really counted. The problem of close air support in the jet age had been approached in the best way possible, but it was evident at Headquarters Marine Corps that there had to be a better way in the future, for reasons of both economics and effectiveness.
A high performance V/STOL (vertical or short take-off and landing) aircraft, capable of operating under basing conditions similar to those of World War II propeller-driven planes but survivable over the modern battlefield, seemed to offer the best solution. The only such aircraft in the world was the British- made Hawker Siddeley Harrier. Small, fast, extremely maneuverable, and smokeless, it met the pilots’ need for survivability. It could operate off roads, grass, or bombed-out airfields with A-4-like range and payload in its primary short takeoff mode. It could even take off vertically like a helicopter from a clean, hard surface, with a reduced but useful payload. The Harrier had entered service with the Royal Air Force (RAF) in 1969. The Marine Corps, spurred on by two visionaries, Major General Keith McCutcheon and Colonel Thomas H. Miller, received its first Harriers, designated AV-8As, for service in the Fleet Marine Forces in 1971.
The AV-8A is a single-engine, transonic, turbofan aircraft. Fan and turbine air is exhausted through four rotatable nozzles rather than out a tailpipe. In forward flight, the engine thrust is directed aft. The pilot can also vector the thrust with a nozzle control lever to the
vertical for hover, 18° forward of the vertical for braking, or to any intermediate position. Control of aircraft attitude in jet-borne flight is accomplished through a reaction control system exhausting engine bleed air at the wing- tips, nose, and tail. The aircraft has the combat thrust-to-weight ratio of a fighter using full afterburner but at a specific fuel consumption comparable to that of other attack aircraft. Five ordnance stations and two 30-mm. guns enable it to carry all standard close air support weapons. Weapons delivery accuracy is enhanced by a roll-stabilized sight and exceptionally responsive handling qualities. Ferry range is over 1,400 nautical miles with external tanks, and more with air refueling.
Common legend pictures the AV-8A as a short-range, lightly-armed toy. In reality, it is a powerful, agile combat aircraft with a more than adequate ordnance load and excellent "legs.” The AV-8A’s detractors are generally those least familiar with its capabilities and record.
The Harrier was not immediately accepted. The Marines’ Deputy Chief of Staff (Air), Major General Homer D. Hill, in testimony before the Senate Armed Services Committee in 1971, stated the problem well:
"Many responsible leaders of our country believe that the long-range future holds a great deal for the Harrier-type aircraft. They state that v/STOL technology is not the problem that hinders the introduction of this new capability into our aviation forces. The real problem is a shortage in operational concepts and operational experience in using V/STOL aircraft. The way to overcome this shortage is to put good V/STOL aircraft in the hands of the troops. The Marine Corps Harrier program proposes to do just that.”
A series of operational tests of the AV-8A’s sortie rate capability, close air support responsiveness, shipboard compatibility, command and control, and weapons delivery effectiveness formally established its technical worth. These tests, and an increasingly complex series of fleet exercises, resulted in the development and validation of the very operational concepts that Major General Hill had identified as short-falls.
The Marine Corps’ operational doctrine for V/STOL close air support identifies three distinct phases in an amphibious operation. Phase I features the use of sea bases, sea platforms, and austere forward sites ashore. Aircraft carriers or amphibious assault ships—LPHs and LHAs—can serve equally well as sea bases. The sea base furnishes all-weather operational capability and intermediate level maintenance support. Sea platform5 may be any decks capable of handling CH-46 or CH-53 helicopters. AV-8AS are
spotted in a sea loiter mode, armed and fueled, on call for immediate strike when needed. The forward sites ashore likewise furnish alert sites for on-call AV-8As which return to their sea bases for rearming, refueling, and maintenance.
Phase II includes the establishment of v/STol facilities ashore, where AV-8As can be rearmed, refueled, and can receive sSuadron level maintenance. The Harriers are staged from the facilities to forward sites as needed. Intermediate level maintenance activity remains at the sea base.
Phase III sees full support for the Harriers established ashore as the amphibious operation progresses. A V/STOL main base, with about 1,500 feet of runway, handles the heavier maintenance loads with satellite facilities sustaining daily operations and forward Sltes furnishing responsive ground alert, fmst and complexity of logistic support are minimized by basing plans which disperse the aircraft only to the extent needed to meet operational requirements.
it is worth noting that the entire c°ncept is user-oriented. The Marines Vlew close air support in the same way m which they view tanks, mortars, and artillery. Tactical air, specifically close air Support, must be integrated into the 8r°und scheme of maneuver as one of ground commander’s supporting arms. As Major General Hill told the enate Armed Services Committee:
"Phis system is consumer-oriented in that it is designed to be responsive to the needs of the ground force as °Pposed to a producer-oriented system ... It is not a case of Marine aviation telling that ground commander what he is going to get and When he is going to get it. Our whole Purpose in life is to support that ground commander with the assets that have been integrated into and are 0rganic to the Marine air-ground
team.”
Th
e v/STOL concept of close air support P'tornizes this Marine philosophy. It t d CCS av-8A squadrons on board the s and LHAs with the battalions they ^ PP°rt. Ashore, they are based tens, not Undreds, of miles from the ground °°ps. With v/STOL aircraft, Marine
close air support is now once again as closely integrated physically as it has been doctrinally since the 1920s. It is a true supporting arm, not an individual weapon system on temporary loan to the ground forces.
This user-oriented, physically integrated V/STOL close air support force is also close to the ground commander in command and control. An AV-8A ground loitering at a forward site can be launched in standard fashion by the direct air support center, or can be assigned in direct support of an infantry unit to be launched as needed by its commander. This latter direct mode of support uses the VHF/FM capability of the Harrier to give response times which have been nothing short of amazing in fleet exercises. Similar response can be obtained from conventional jets in air loiter only by direct assignment of a succession of airborne aircraft, at greatly increased cost in fuel consumption, inventory, and attendant logistic factors.
The operational flexibility inherent in the AV-8A aircraft and the three-phase, multi-level operational concept require appropriately structured squadrons. A Harrier squadron is organized so that it can operate as an entity or can be deployed in detachments. Each 20-plane squadron contains an independently deployable unit detachment (IDUD) of six to eight aircraft. These detachments can operate with their own limited intermediate maintenance, operations, and organizational maintenance crews. A good example was Lieutenant Colonel Robert E. O’Dare’s six-Harrier detachment which deployed to the Mediterranean for six months on the USS Guam (LPH-9) as part of a Marine Amphibious Unit of the Sixth Fleet. The parent squadron, VMA-513, meantime deployed to the Far East with the remaining 14 AV-8AS.
Each squadron is also outfitted to support a "dependent” six-plane detachment which can operate separately from the parent squadron for a limited time only. This three-level AV-8A support concept—parent squadron, independent and dependent detachments—is more costly than a 20-plane conventional jet squadron. However, a 20-plane A-4M squadron would not offer the basing flexibility, sortie rate, and close air support response that the Harriers do.
Over the past five years, the Marine Corps and the Naval Air Systems Command have learned more and more about support of a V/STOL force and its concept of operations. There is little doubt that savings in maintenance men and ground support equipment can be realized in the AV-8A squadrons. For instance, the worth of the dependent detachment requirement is under scrutiny. Simplifications in the AV-sA weapon system itself since purchase of the original lot and Americanization of components have reduced the maintenance load. Initial deployment of the Harrier was undertaken off-the-shelf without the integrated logistic and manpower support planning that normally accompanies an aircraft development and procurement program. For this reason, the squadrons were intentionally made "fat” so that the concept would not fail by accidental neglect of some unknown support requirement. Some readjustments have been made, and there are clear indications that future V/STOL organizations will be considerably more streamlined than are today’s Harrier squadrons.
The Marines’ V/STOL close air support concept has been closely identified with the Corps’ amphibious role. As Frank Uhlig, Jr., editor of the U. S. Naval Institute’s Naval Review, noted in the June 1976 Marine Corps Gazette:
"The scarcity of carriers, the heavy demand for their services, and the small likelihood of having friendly air bases near where the Marines would wish to make an assault landing suggest how important it would be to have V/STOL attack and fighter planes in the assault force.”
But the v/STOL concept of close air support offers payoffs in other scenarios as well. In a continental war, AV-8As can be dispersed to reduce basing vulnerability while still providing full support. They can operate when conventional jet bases have been rendered inoperative. Harriers can generate an extremely high sortie rate when needed, and have a productive flight time to combat time rate ratio two to four times that of conventional jets. If sophisticated air request and control nets are jammed or break down, the AV-8AS are close enough to the fighting to be controlled in the
same manner as artillery.
The Marines’ three tactical AV-8A squadrons and the RAF squadrons have demonstrated all these operational advantages of V/STOL over the past five years. Some important additional capabilities have appeared along the way. The AV-8A’s two 30-mm. guns, lead computing gunsight, Sidewinder missiles with expanded acquisition mode, high thrust-to-weight ratio, and its ability to vector its thrust in forward flight (VIFF) make it a very creditable air-to-air combat machine. It is used routinely and effectively by the British in primary interdiction and reconnaissance roles. The AV-8A has also performed in a variety of sea control roles with the U. S. Navy during the Interim Sea Control Ship tests, operating in situations where no other jet aircraft could operate. This year, VMA-231 is scheduled to make the first Harrier deployment on board a cv, the USS Franklin D. Roosevelt (CV-42).
The next step in V/STOL close air support for the Marines is a natural one. In the mid-1980s the light attack force will become all-V/STOL with the introduction of the AV-8B advanced Harrier. Ordnance load or range will be roughly double that of the AV-8A. It will have a highly accurate weapons delivery system and carry the finest close air support precision guided munitions available. The Navy’s heavily committed aircraft carriers will no longer be required for sea basing of any portion of the Marines’ light attack force during amphibious operations. The AV-8B will be able to fly to Europe without air refueling, taking off from a 1,500-foot road segment and landing in a parking lot, ready for any contingency. It will strike an objective area or furnish limited air defense from great distances from the decks of amphibious ships. The Marine ground forces, ready to fight anywhere in the world, will know that they will have responsive V/STOL close air support wherever they go.
The writer is admittedly a V/STOL advocate, but only after 20-years’ experience flying every attack aircraft type in the Marine Corps’ inventory. Operating the old AD Skyraider was an experience in vulnerability and slow response. The FJ-4BS and A-4s were fine attack aircraft, but the "air-ground team” was far more visible in the Marine Corps Gazette than it was in the Fleet Marine Force. Command of an A-6A squadron in Vietnam was an education in the value of allweather close air support. But the experience of commanding an AV-8A squadron on board an LPH and in the maneuver area with the supported battalions, meeting with the commanders we supported, our troops and pilots knowing the ground troops and unit leaders, was memorable. If only our A-6 squadron had had V/STOL airplanes in Vietnam! Combat effectiveness and mission completion in radar beacon close air support missions would probably have doubled as a result of personal contact and teamwork between aircrews and infantry.
Perhaps someday the Marines will have an all-weather attack V/STOL aircraft, and a fighter, too. When that day arrives, today’s integrated Marine air- ground team of AV-ss, helicopters, and ground forces will be joined by the rest of the aviation community, freed from miles of concrete runway, catapults, arresting gear, and precious carrier space. An all-V/STOL tactical air capability will not be developed by the Marine Corps acting alone, but must be born within the larger framework of Naval Aviation. It will not be an overnight process, nor should it be. The path of the future for Naval Aviation lies in V/STOL for many of the same reasons which drove the Marine Corps to V/STOL close air support. Remote siting of air vehicles on hundreds of small platforms and short runways at sea offers significant advantages to a Navy under increasing pressure to exert control of the seas with limited assets. The tremendous investment of today’s fleet in conventional aircraft at sea cannot and should not be discarded. A change to V/STOL in the Navy must be gradual, as it has been in the Marine Corps. The AV-8B advanced Harrier may be the first V/STOL aircraft to see service in both branches of Naval Aviation, since it builds upon an area of existing expertise within the Department of the Navy inventory and offers significant increases in operational capability. If this happens, the technical and conceptual groundwork laid by the Marine V/STOL close air support community will have been the forerunner of an evolutionary process effecting the entire fleet.
The philosophy of close air support in the Marine Corps has not changed since the 1920s. Only the execution of this philosophy has varied as equipment has changed. Today’s Harrier and tomorrow’s AV-8B have brought the Corps full circle in the integration of aviation as a supporting arm. The U. S. Marine Corps V/STOL force is the only tactical aviation asset in America’s inventory that can literally deploy anywhere, no matter what facilities are available. The engineering achievement of the airframe and engine manufacturers and the vision of a few military leaders have opened the door to a new era in Naval Aviation-
The AV-8B advanced Harrier, shown here in mock-up, will give the Marines an all-V/STOL light attack force in the mid-1980s.
MCDONNELL
The Eyes of the Fleet
% Thomas A. Guarino, Vice President arid Director of Navy Programs, and Charles F. Muller, Jr., Program Manager for Israeli E-2C Procurement, Grumman Aerospace Corporation
The concept of airborne early warn- *ng (AEW) for naval fleets was formulated before the start of World War II. Scout aircraft, such as the OS-2U Kingfisher, were used as the "eyes of the fleet” even before the tactical deployment of radar. During World War II, cfie carrier-based fighter aircraft, such as the Wildcat, Hellcat, and Corsair, as well as the shore-based, multi-engine Coronado and Catalina seaplanes, proved the fleet with airborne early warn- mg- As the war drew to a close and the and-based, random kamikazi air strike cAreat developed, the need was made ev‘dent for longer range detection of airborne threats beyond the range of ^hipborne radar and the physical sight 'nutations of airborne crews. The evo- ution of radar as the primary detection evice of AEW began with the fitting of cAe APS-20 radar to the Grumman torpedo bomber, the Avenger, in December 1945, and the first active AEW squadron, vC-2, was formed in 1948, outfitted with 'fie modified TBM-3W Avengers.
In 1957; the first dedicated AEW airCraft, the Grumman WF-2 Tracer, made \v aPPearance. Known in the fleet as the 'fly Fudd, the Tracer carries a massive a'rfc>il-shaped radar scanner above its Uselage. The Tracer’s APS-82 radar was sPecifically designed for AEW application and provides the two AEW operators ^"h a video presentation which enables trianual grease pencil tracking and voice target reporting. The WF-2S were subse- fluently redesignated the E-iBs and are CUrrently scheduled to make their thir- '^nth last deployment this year on ' e Uss Franklin D. Roosevelt (CV-42).
The naval tactical data system (NTDS) c°ncept, which provides a task force /’'nmander with comprehensive infor- atI°n on the disposition of all ships "A aircraft in his area so he can effectively control and deploy his force, requires an AEW aircraft with expanded detection, tracking, and reporting capability. Thus, in 1955, an operation requirement was promulgated for an airborne tactical data system (ATDS) that would detect, identify, and track airborne and surface targets by means of radar; compute, display, and transmit command data for the control of interceptors; and compute, display, and transmit tactical data to NTDS. The aircraft developed to meet this operational requirement was the Grumman E-2A Hawkeye, originally designated W2F-1.
The first E-2A contract was let by the Navy in March 1957, and the first flight of an E-2A was accomplished in October I960. The E-2A’s APS-96 radar, designed and built by General Electric, provides the necessary performance in the presence of radar returns from heavy seas (i.e., radar clutter) to permit for the first time automatic detection and tracking of targets. Still another first for the E-2A was automatic height determination of airborne targets overwater.
The E-2A’s first two deployments were in 1965 on the attack carriers Kitty Hawk (CVA-63) and Ranger (CVA-61) in operations in the Gulf of Tonkin. These early deployments to Vietnam waters, as well as subsequent deployments, indicated the developing expanded role of the AEW/ATDS aircraft in fleet operations. In addition to its normal AEW mission, the E-2A played important roles in missions such as PIRAZ (positive identification radar advisory zone) wherein returning carrier-based strike aircraft were required to over-fly a designated picket ship for positive identification and recognition before proceeding to the carrier. Search and rescue missions, always primary missions for AEW aircraft, took on new dimensions in
Vietnam, both overland and overwater. The Hawkeye permitted improved, extended UHF radio communications between distant surface stations through the use of its UHF relay capability.
Perhaps the most significant E-2 mission to develop in Southeast Asia was that of strike control. The Super Fudd, as the Hawkeye is sometimes known, is capable of tracking cooperating targets overland using IFF (identification friend or foe) radar. This feature, as well as the ability to enter fixed geographical locations on the video display, permits an E-2 operator to plot the path of the strike aircraft around known surface-to-air missile (SAM) sites and any other manmade or natural hazards and to ensure that the air space of neighboring countries is not violated. This flight path information is transmitted to the strike aircraft in the form of command data (i.e., heading, range to turnpoint, etc.) via voice communications or in digital messages using data link.
These early deployments also uncovered restrictions in the use of the E-2A. The CP-588 central computer, for example, was a hard-wired, drum memory digital computer necessitating hardware modification everytime the tactical program required changing, no matter how small the program change. In fact, the computer and its program were inflexible. In 1967, the first E-2A was fitted with a software programmable, core memory, dual processor, general purpose digital computer, manufactured by Litton Industries. Several other operational and reliability improvements were incorporated into the avionics system during the modification of the aircraft by the Naval Air Rework Facility at NAS North Island, San Diego, California. The modified E-2A was redesignated E-2B, and the modification program was completed in November 1971. During the
A lone VAW-133 E-2C returns to the USS Saratoga's deck after a night mission over the Mediterranean.
early E-2B deployments a unique fleetwide reliability demonstration of the new OA-8206 computer programmer was conducted by the Navy at all E-2 facilities, both ashore and afloat. More than 12,300 hours of computer operation were accrued during the eight-month demonstration test and the reliability of the computer was found to be 30% higher than its specified requirement.
During the early 1960s military planners realized that limited war situations involving naval operations close to coastlines required radar detection of low flying targets overland. As a result, in 1964, the Navy contracted for the development of an overland radar which would permit manual detection and tracking of low flying aircraft immersed in land clutter (i.e., radar returns from land terrain). Flight testing of the experimental APS-in overland radar began in a modified E-2A in June 1965. During the two years of development flight testing, the APS-m radar, in a manual mode, demonstrated the capability to detect and track airborne targets overland to a sufficient degree to warrant further development of overland radar.
The overall system reliability and maintainability of the E-2A was found to be insufficient to maintain the round- the-clock AEW coverage desired for operations in the Gulf of Tonkin. A three-fold increase in reliability was required to meet the taxing flight schedule for the four aircraft AEW squadrons.
To meet the operational fleet’s needs, the Naval Air Systems Command contracted in June 1968 for a new Hawkeye aircraft, subsequently designated E-2C, which would include an overland radar detection capability, a four-fold increase in reliability, and a substantial reduction in required maintenance for each hour of aircraft flight. The requirement for a passive detection capability was added to the program the following year. This passive detection capability would augment the active system, radar and IFF, and would for the first time permit concurrent detection, location, and identification of emitting friendly or enemy radars by a single operator.
Like its predecessors, the E-2C is a twin engine, high wing, carrier-based aircraft. Its most identifying features are a 24-foot rotating pancake-like antenna mounted above the fuselage and the four vertical stabilizers in the tail section. The flight crew consists of a pilot, copilot, and three AEW operators. Ten thousand pounds of electronic equipment is carried within the pressurized hull which is cooled by a large Garrett air conditioning system.
The "eyes of the hawk” are the active detection systems comprised of the APS- 120 radar, the production version of the APS-ili overland radar; the OL-93 radar detector processor (RDP) which prepares the radar’s signals for processing in the central computer; the APX-76 IFF interrogator, the radar which asks the ques-- tion friend or foe; and the OL-76 IFF detector processor which does to the IFF signals what the RDP does to the radar signals.
The ALR-59 passive detection system (PDS), developed and manufactured by Litton Amecom, constitutes the "hawk’s ears.” This system detects electronic emissions from radars at distances from in-close to long range. The received signals are examined by the PDS to determine the characteristics of the emissions (such as pulse width, frequency, scan rate, etc.) for comparison with a file of known emitter characteristics. When a match is made the AEW operator is informed of the identity of the radar and its possible platform. Direction of arrival (bearing) information is also supplied to the operator who can then correlate this information with range and bearing information from the active sensors for positive location of the emitter. If the active detection systems are not employed, as in the case of EMCON (emission control) conditions, passive triangulation techniques can be used to obtain emitter location.
The "hawk’s brain” is the OL-77 central computer. The arithmetic and memory section of the central computer, built by the Data System Division of Litton Industries, is common to the
E-2B, only the interface devices have been changed to operate with the new avionics systems of the E-2C. The central computer accepts target information from the radar and IFF detection systems and then processes, stores, tracks, associates, and correlates this target information for display to the AEW operators in the form of target location (i.e., range, bearing and height); identification (i.e., friend or foe, air, surface or sub-surface): and target velocity (i.e., course and speed). In addition to supplying the AEW operators with target information, the central computer calculates intercept information and prepares this command data in digital message format for transmission to assigned interceptors, such as the F-4 and F-i4 aircraft via UHF data link 4A. The computer also prepares target information in digital message format for transmittal to cooperating NTDS ships via UHF and/or HF data link 11. The computer can accept target information from other NTDS and/or ATDS units, and process and display this received target data to the AEW operators.
Hazeltine’s APA-172 control indicator group, operator’s console, provides the man-machine interface through which the AEW operators can "talk” to the avionics system. These identical consoles are located amidships in the E-2C—one each for the combat information center officer (CICO), air control officer (ACO), and the radar operator (RO). The consoles comprise a 10-inch diameter video symbology main display, a five-foeh square alphanumeric auxiliary display an operator’s alphanumeric keyboard, and various switches and controls f°r presentation selection and adjustment- The main display, essentially a plaf1’ position indicator (PPI), shows target- track information that permits the operators to read the tactical situation in the form of raw video, processed video, and/ or target symbology with a velocity
vector (showing course and speed of the target). The auxiliary display permits the operator to read-out in alphanumerics target information such as range, bear- In8> course, speed, altitude, etc. The auxiliary display also shows the mode of operation the crewman has selected. The alphanumeric keyboard enables the operator to communicate with the central computer, to obtain information stored °r calculated in the computer, and to display that information on his console.
The tactical navigation system is comprised of the Litton ASN-92 CAINS (carrier aircraft inertial navigation sys- tern), the General Precision APN-153 Doppler radar, and the Conrac air data computer. The CAINS is also used on the
S-3A Viking, F-14 Tomcat, and the A-6E intruder. CAINS is aligned prior to each night with information supplied by the shiP’s inertial navigation system (SINS) jla data link or a hard-wired connection, rhe sins is inoperative, the CAINS can e Signed in-flight using inputs from ’Te Doppler radar. The E-2C’s navigation system is one of the most accurate sys- ^ms in use today and provides the awkeye with the ability to control lnterceptors with pin-point accuracy.
Communications between the task 0rce> airborne interceptors, and strike aircraft are provided through the use of |W° HF and five UHF Collins radio sets.
addition to voice communications, 1 e E-2C can talk to the carrier (NTDS) or other e-2s (ATDS) via UHF and/or HF ata Dnk 11, in clear or scrambled mesSages. The five UHF radios permit voice atld data link communications with a j^ultiple number of cooperating air- 0rr>e interceptors and strike aircraft, as as search and rescue aircraft, anti- toarine warfare aircraft, and numer- °us other special purpose aircraft.
be in-flight performance monitor fvt) system permits the operators to SSess continually the readiness of the avionic equipment while in flight. e use of built-in test equipment *n the IFPM system allows the a^ect‘on of faults within the system the isolation of these faults to a eapons replaceable assembly (i.e., black °x) for immediate replacement on ren t° the carrier. IFPM information is Ouf a'e<^ 'n the English language read- on the auxiliary display at the oper- r s console. The IFPM system played
an important role during a recent fleet exercise in the Mediterranean Sea, wherein a single E-2C aircraft flew nine double cycle consecutive sorties, 26.8 flight hours, all launched in full system capability (FSC) status.
The versatile avionic shop test (VAST) is used as the primary means for supporting the E-2C. VAST is a programmed automatic test set used for troubleshooting, repairing, and checking out of weapon replaceable assemblies (WRA), shop replaceable assemblies (SRA) within the WRA, and sub-shop replaceable assemblies (SSRA) within the SRA. Repairs are made down to the component part level. VAST, being the Navy’s universal test equipment, is used on the F-i4s and S-3As.
The first production E-2C was delivered to Carrier Airborne Early Warning Wing Twelve (CAEWW-12) at NAS, Norfolk, Virginia, in June 1973. Wing 12 is comprised of one training squadron and six AEW squadrons and recently underwent the transition from E-lBs and E-2Bs to an all E-2C force. VAW-123, one of Wing 12’s squadrons, made the first E-2C deployment on board an attack carrier, the USS Saratoga (CVA-60), from September 1974 to March 1975, in the Mediterranean Sea with the Sixth Fleet. The Commander of the Sixth Fleet made the following comment in a message to the Chief of Naval Operations:
"There is no doubt the E-2C represents an order of magnitude improvement over its forerunners. It is proving to have capabilities and reliability never before achieved in carrier AEW aircraft, and by its demonstrated dependability, it has won the confidence of the operators. Increasingly, the ship and Wing have come to depend on the E-2C Hummer and to integrate it into significant contributing roles in every major mission of the Ship/Wing Team.”
During the six-month period, October 1975 through March 1976, the average aircraft utilization of the E-2C was the highest of all carrier-based aircraft in the fleet while maintaining one of the highest operational readiness averages and one of the lowest expenditures of maintenance per hour of flight.
The second deployment of the E-2C was completed by VAW-125 on board the
USS John F. Kennedy (CV-67). In addition to the Hawkeye, the JFK’s aircraft complement included two other new aircraft, the F-14 and the S-3A. The deployment represented the first tactical marriage of the F-14 and the E-2C wherein a two-way data link has been established for transmission of target data both ways—AEW to interceptor and interceptor to AEW. This enhancing feature of the E-2C/F-14 team further extends the total AEW coverage for the fleet. During a National Week exercise the E-2C/F-14 team detected, intercepted, and "de-
The E-2C operator’s displays, the AN/APA-172 control indicator group, and the view of the tactical display provide the link between the operators and the AEW system. The E-2C equipment pictured here is part of the training facilities of the Fleet Specialized Operational Training Group, Atlantic.
stroyed” all airborne threats from the opposing forces.
To further improve the Hawkeye’s detection and tracking capabilities in the near land and overland environment, the Navy funded a study in 1971 of an advanced radar processing system (ARPS) which would provide automatic radar detection and tracking of low flying airborne targets overland with the same dependability as the E-2C currently does overwater. ARPS would also include antijam features to reduce the effect of an enemy employing electronic countermeasures against the E-2C. ARPS employs the technique of digital doppler filtering to remove the undesirable land clutter returns which accompanies the true target radar return signal. Doppler filtering was studied earlier by Grumman in 1966 and led to the fabrication of a limited capability experimental model of an overland processor. The Navy funded a limited flight test program for this experimental processor during 1968-1969- These flight tests demonstrated the feasibility of digital doppler filtering.
In 1972, the Navy awarded a contract for the fabrication and flight test of a full capability overland processor with anti-jam features. The first flight of the General Electric-built ARPS was accomplished in January 1974. Navy Preliminary Evaluation (NPE) is now underway. The first E-2C containing a production ARPS, designated the APS-125, will be delivered to the Navy in December.
Current Navy planning calls for an all E-2C fleet by the mid 1980s. The planning also includes the retrofit of ARPS into all E-2C aircraft, which will provide the Navy with a fleet of AEW aircraft that performs as well overland as it does over water.
International interest in the E-2C as a land-based AEW aircraft has been expressed by the United Kingdom, Japan, Israel, and Iran. In fact, Israel signed a letter of acceptance for four E-2C ARPS aircraft and associated support equipment, spares, documentation, and training in February of this year.
Increased flight endurance for the Hawkeye can be accomplished by pr0' viding "wet wings”—putting fuel in the outer panels of wings beyond the wingfold mechanism. Other improvements such as extended radar range, expanded PDS coverage, and even longer flighf endurance through inflight refueling and external wing-mounted drop tanks can be accomplished within the growth capability of the basic E-2C weapon system.
The Navy’s AEW capability has grown during the past 40 years from visual search and voice radio relay of the Vought OS-2U Kingfisher to the automatic detection and tracking of targets overland and data link reporting of the E-2C Hawkeye.
This saga starts in the training command: A starry-eyed Wings of Gold candidate arrives at VT-i (Training Squadron One), hoping for jets, as probably 90-95% do. A big, rugged allAmerican pilot welcomes him aboard and says among other things; "If you cannot hold your flight grades up, you won’t get jets and we will send you to props.” The candidate thinks to himself, "not me; and besides, Navy pilots are Navy pilots, regardless of what they fly.”
That’s what he wants to believe. As he sits around the ready room, however, he begins to notice an interesting phenomenon. When the instructor who is asked what he flew in the fleet answers fighters or attack aircraft in Vietnam, he draws a crowd. As his stories begin to pour forth, the instructor’s hands begin to move as he talks of yet unfamiliar terms—yo-yo, scissors, Thach Weave— and of SAM missiles and MiGs.
Another instructor, when asked of his
experience, may reply VS (air anti-sub marine squadron). Generally such 3 reply is mumbled. No one seems t0 gravitate to this instructor, for wh3c exciting aviation terms can he use' DIFAR, LOFAR, MAD, RADAR? When W3S the last time a VS pilot sank an enen1) submarine? It’s not that VS pilots m^e bad instructors, for the training cot*1 mand is full of outstanding VS, ^ (transport), and vp (patrol) backgrouf1 instructors. There is, however, no gl°r'
our
arc
and °Ur fiable of the fulfilled fly-boy lscuss the real world.
or aura of heroism attached to their fields of Naval Aviation and the young candidate begins to think, rightly or Wrongly, that if he wants to associate with the elite of Naval Aviation he has t0 be a fighter or attack pilot.
Then the dreaded day comes, the day when he is told he is going to props.
tells himself and his classmates that he chose props, and they all then 8° to the club for a beer. A second phenomenon now developes. Those of ls classmates who were selected for jets now sit together and begin to fly with tlr hands and talk of someday bagging 1Gs- Those chosen for props sit at an°ther table and listen, then talk of sports, for no one has taught them to a k Vs. The next day they all depart VT-i and head for advance training and ulti- mate,y their squadron—for this saga it is a VS squadron.
Over the ensuing months and years ” guy comes to realize that VS pilots outstanding pilots and every bit as Professional as jet pilots. He finds "late th°0rners>” pilots who given another ee or four months in the training . utmand could have become outstand- esf *Ct P^ots- Tic finds pilots who, hon- to-God, did have the grades to go to
i tS Tut instead chose VS for its chal- *enge.
^ Challenge? How did our candidate th °Ut aT°ut the challenge of ASW in a6 tra>ning command? Well, he was tng the few who were lucky enough wh n<^ an *nstructor who when asked at he flew did not mumble VS but , °udly said: «j £ew vs jt js carrjer. Das^d • i
airplane used to hunt subma- ■ the instructor told of the real Ses°nal reward and satisfaction of being 10ut t0 look for a submarine, U.S. or 0c m a thousand square miles of n an<f finding that submarine. He syst*° Use bis knowledge of his weapon 0m> °f submarine tactics, of ocean- getaphy> and had to meld his crew to- Orcjermt0 a cohesive working unit in •j. t0 find this "unseen enemy.” f,0r'Je> the instructor told him, there is Pets^ am°ur 'n vs> but there is a deep alb °nal sense of satisfaction. And, in an Wii] , War> the instructor said, VS too beroe3VC *tS moments °f glory and its Us ^nd, on this happy ending, let
Some VS pilots did find their way to VA and VF and then to war. War is hell—it’s challenging, exciting, scary, and the saving of lives is rewarding. But during the shore-based phase, many of these former VS pilots found it extremely boring, day after day, to hurl themselves at the ground in rocket and bomb practice. And to stay in attack or fighters, awaiting a war that seems to occur on the average once every 9.5 years, does not seem designed to keep one’s interest. Thus, many pilots returned to VS and, more importantly, to their jet aircraft.
A carrier jet and the challenge of VS are, in this pilot’s mind, the ultimate marriage. The S-3A Viking is a magnifi- cient plane to fly and, from an avionics package standpoint, the most sophisticated airplane in the fleet today
But lo, what is happening? Why does the VS jet have to have two pilots instead of one? Could the rumors be true that the "old guard” still believes VS pilots are not as good as fighter and attack pilots, and therefore two pilots are required in the S-3A to watch out for each other? Maybe the "old VA/VF guard” in Washington still believes it; but why, apparently, does the "old VS guard?” Snatches of conversations can be heard at VS parties, VS clubs, VS ready rooms, and VS meetings, emanating not from the junior pilots, but from many of the seniors: Why should we have only one pilot? We always had two and it worked great. Why do VS pilots need to fly formation or aerobatics or perform in-flight refueling? And finally, you hear, "If I hadn’t a pilot in my right seat I might have flown into the water or made a gear up pass, etc, etc.”
Well, let’s see if some of the myths can be put to rest. We had two pilots in S-2 Trackers because there were two sets of controls, and, more importantly, we were told we would have two pilots. Many VS squadrons flew good formation, but it was not really a necessity on a CVS. Now it is. VS is now on a CV, not a CVS. The mixed-jet VFR (visual flight rules) holding pattern is in effect, and "ZIP Lip” (radio silence) makes it mandatory that the VS pilots know how to fly good formation professionally and safely. As for aerobatics, the S-2 was a Model T compared to the S-3, and the S-3 is fully capable of performing aerobatics. It is a swept wing, high performance, high altitude jet, and the pilot must understand his plane and be able to fly it
to its limits. Most importantly, the S-3 will operate in an environment where Soviet ships carry SAM-3 missiles and the pilot had better be able to conduct evasive actions. Also, the S-3 can carry an extensive variety of weapons, including rockets, bombs, and torpedoes. Some day, someone is going to order the S-3 to carry and deliver non-ASW weapons, and that is not the time to learn aerobatics and weapons delivery techniques.
Regarding in-flight refueling (IFR), the S-3 can range from the ship three times as far as the S-2 and, because of its relative low fuel consumption, is placed in the top of the CV recovery stack. Add a couple of bolters and a wave off, and all of a sudden the S-3 pilot had better know all about IFR. This is not just a possibility, it is a reality. It has already happened.
Finally, in reference to the "I was saved because I had a pilot in the right seat theory,” I can not honestly believe that there are VS pilots who felt safer in a down low ASW situation because they had a pilot in the right seat. If the copilot was doing his ASW thing by keeping reams of records, tactically running the problem, operating the ASN-30, and using his Mk 6 plotting board, then, as a safety observer, he was about as useless as teats on a boar hog. It is fact that every S-2 that flew into the water had a pilot in the right seat. When the S-2 came back to the ship, did we really need a copilot to read the check list, watch the instruments, get the hook- down, and inform the pilot that he had a red ball and was low? The answer is NO! Any competent man could perform in this capacity of a safety observer, and, in the case of the S-3, we have a group of real professionals called NFOs (naval flight officers) who could perform admirably as safety observers.
Does it not bother any of the "old S-2 guard” to know, that in spite of your 3,000-4,000 hours, your 250-350 carrier landings, and your years of aviation experience, that once you and other S-3 pilots fly to the ship for initial CQs (carrier qualifications) in VS-41, you must fly with a safety observer instructor? After all these years must we still be considered less than equal? In the training command, VF and VA RAGs (replacement air groups), ensigns are allowed to
into wings of radar, MAD, FLIR, and ESM. Let me assure you that word has gotten back to the training command: "any ensign pilot who volunteers for the S-3 is a fool.”
Then there is a theory being espoused in the higher echelons of the VS community that a young pilot who sits m the right seat of the S-3, as the nonacoustic operator, will be a better left seat pilot because he will have learned ASW and watched the pilot perform. I must most strongly disagree with this. For those pilots now in the right seat will not stay in the Navy—many are already out. They did not spend 18 grueling months in the training command earning their coveted "Wings of Gold” to become radar operators, as their contemporaries fly off into the sky in their F-14S and A-6S with their NFOS.
If the VS right-seat theory is valid, it should be valid for all aircraft. The Navy could save millions of dollars by closing down the NFO pipeline. If the F-14 RI° could be an ensign pilot, he would learn all there is to know about air intercept) then would be much more effective when he moved to the pilot’s seat. The
fly to the ship by themselves, but not so with vs—commanders, let alone ensigns, must still be chaperoned.
Finally, what about these ensigns coming to VS out of the jet pipeline? Many of them requested VS because they were told that the S-3 was a fun and challenging airplane to fly. But now they know better, for a first tour pilot will be lucky if he gets 200 hours in the left seat. Their wings of gold have turned same could be said for A-6s, F-4s, etc. The VA/VF community, however, would not stand still for this and rightfully s0’ but VS does.
We have come full circle. For it is not now the instructors in the training command, but the ensigns in the flee1’ wjio, when asked what they fly, murnble VS and long to fly a jet with the elite-
It is true, in VS, the enemy has bee*1 found, and the enemy is us.
Two separate hearings were conducted by the Senate Subcommittee on Government Operations to review the proposed F-i8 program and determine if that program was being conducted in accordance with government procedures. Additional formal hearings were held by the House and Senate Armed Services Committees, their Research and development and Tactical Airpower Subcommittees, and by numerous congressional staffs. As the bill came closer t0 the floor, pressures continued to ruount. The Navy position was sue- einctly put forth by the Chief of Naval operations in his 8 July 1975 letter to ^he Chairman of the Senate Armed Serv- lces Committee:
■ ■ • The Navy’s most pressing tactical air Problem today is assuring maintenance of an ^luate fighter force level. We have begun the job with the F-14. The F-14 is un- eclualled in its capability to perform the duty’s fighter missions, but is expensive to acf}uire and operate, and our buying power is J rinking. While we might now be able to afford the acquisition of enough F-14’s to fill e fighter force levels, we are faced with 'gh follow-on operating and support costs. I elteve the F-18 is a clear demonstration of avy dedication to making the most of our hmited funds.
hz its cost class, the F-18 provides unsurpassed capability to perform the Navy’s Jlgpter and attack missions. It can augment actively the F-14 in fighter missions, and J r some missions, specifically those requiring maneuverability and agility, the F-18 is S°mewhat better than the F-14.
T?or attack missions, we believe the F-18 ^ 1 provide an excellent replacement for the 7 Ught attack plane. It will be signifi- “»tly m°re capable than the A-7, notably in f ability to get to the target, deliver its tio-S’ aHt^escaPe' in an attack configura- and U retain &00^ fighter performance . arrftament, thereby achieving a credible el/-escort capability.
The F-18 will replace those F-4’s not replaced by F-14’s, and all A-l’s with one airframe-engine platform, a most important consideration in optimizing use of limited space aboard aircraft carriers. The cascade effect of this simplification will be felt throughout the Naval Establishment, in terms of reduced cost for personnel, training, support equipment, intermediate and depot facilities, overhaul, spares and repair parts. . ..
. .. acquisition of the F-18 is in the best interests of the Navy and I believe, in the best interests of the United States. It is affordable. In conjunction with the F-14, it meets our operational requirements at lowest cost. . . .
The Commandant of the Marine Corps in his 23 September 1975 letter to the four committees stated:
... We are in agreement with the Navy’s concept for developing two F-18 variants, fighter and attack. Although the Marine Corps’ requirement for a V/STOL Light Attack Aircraft precludes our current interest in the attack version of the F-18, the fighter variant configuration must possess three essential weapons system capabilities to meet our requirements for a multi-purpose fighter. These systems capabilities are: (1) All-weather Sparrow missile system; (2) 8-10 mil iron bomb delivery system; and (3) Laser/Electrical-Optical (EO) guided air- to-ground delivery systems. . . .
. . . I am in full agreement that the F-18 will be an adequate replacement for the aging F-4 inventory. It is essential that we proceed now with the F-18 to assure force level maintenance and modernization of our multi-mission fighter forces during the 1980’s. . . .
Finally, the Navy proposal to commence full-scale F-18 development was approved by all of the required congressional committees and then the Congress itself. Life was breathed into a program that will provide an efficient and effective multi-mission strike-fighter for the Navy and Marine Corps through the year 2000.
While there is risk associated with the development of any new aircraft program, the chance aspects of the F-18 program have been reduced by the availability of a data base more complete than any other program has had in the Navy’s aircraft development history. The F-18 is based on the proven technology of the YF-17, the aircraft not selected by the Air Force in its light-weight fighter competition.
The changes from the YF-17 concentrated on meeting carrier suitability and Navy and Marine Corps mission requirements. For carrier suitability, wing area was increased by 12%, thereby improving low-speed handling characteristics, including catapult and arresting capabilities; the landing gear was redesigned; and, the fuselage was strengthened to take the carrier loads. Navy mission requirements necessitated the addition of a Sparrow missile capability and all-weather avionics. Range and performance needs dictated additional internal fuel and an increase in engine thrust. These changes were made while retaining the basic aerodynamic shape of the aircraft and the basic design of the prototype engine. By combining the flight data accumulated on the YF-17 with existing carrier aircraft data, the Navy and McDonnell Douglas/North- rop/General Electric team has come up with a low-cost airplane that meets the Navy’s and Marine Corps’ availability and mission requirements and is eminently suitable for carrier operations.
In order to understand more fully the F-18 and how it fits into Navy and Marine planning, a more detailed description of the design is required. In general, the F-18 is a single place, twin tail, twin engine, high performance fighter/attack aircraft. Its size is between the F-4’s and A-7’s; it has a new multi-mode radar, carries ordnance on nine stores stations, and is powered by two 16,000 pound thrust class engines.
The General Electric F-404 engine is a direct derivative of the GE Yj-ioi engine which flew so successfully in the YF-17 prototype program. To all outward appearances the F-404 engine is the same as the YJ-ioi; there is 90% commonality between the two engines. The bypass ratio was increased from .2 to .34; the turbine inlet temperature was increased 50°; the diameter of the engine was increased 0.9 inch; and the afterburner area was increased. These modifications provided the needed increase in thrust while retaining the design-to-cost objectives of mechanical simplicity and a minimum number of parts, resulting in reduced costs and higher reliability. The engines are started by an onboard auxiliary power unit which is also used for full ground checkout of all aircraft systems requiring electrical power, hydraulic power, fuel pressure, or cooling air. This feature significantly reduces the requirement for external power sources of any kind. The F-404 engine development program will run for 58 months and will include every conceivable type of testing. The first production unit is scheduled to be delivered in 1980.
At this point, the basic tenets of the F-18 fighter design philosophy should be defined. Simply, incorporate all of the mission-essential features; then trade the mission-desirable features against one another and against cost to define the optimum affordable aircraft.
Crew size is one of many fighter aircraft design parameters that affect capability, together with such factors as engine thrust-to-weight ratio, radar range, number and characteristics of air-to-air missiles, etc. Other factors being equal, a second crew member can increase combat capability, as can a longer-range radar or missile. In a tight-budget environment, no aircraft design can afford to include all the capabilities that technology makes possible.
Just one design generation ago, a two-man crew for an air-superiority fighter could be considered essential. Radar presentations were raw video, requiring frame-to-frame correlation by the operator. Typical pilot workload permitted a single pilot to devote no more than 20% to 30% of his time to monitoring a search radar display. In those circumstances, addition of a second crewman permitted at least an eight-fold gain in the rate of data accumulation for detection of threats.
More modern technology, with automatic track memory and digitally-generated, clutter-free displays, reduces the detection range disadvantage of the single pilot to less than 10%. That slight disadvantage can be overcome by increased radar power, at appreciably less cost than building an aircraft to accommodate a second crew member. Computer-generated displays also minimize or negate the advantage of a second crew member in an ECM (electronic countermeasures) environment.
Flight tests on an F-i8-type cockpit design indicated that:
"The entire ACM mission can be flown with the pilot’s hands on the throttle and control stick [HOTAS]. All necessary information is displayed on the HUD [head-up display], so there is no need for the pilot to look inside the cockpit. The auto acquisition modes of the radar provide almost immediate ranging and positional data. Weapons envelope information is provided immediately so that accurate weapons employment is possible within seconds after conversion.”
Reducing pilot workload to allow efficient one-man operation dictated integration and concentration of displays and controls up front within easy reach and vision. By use of current state-of- the-art multiplex techniques, complete fighter and attack capability is provided in a smaller size cockpit than in present fleet aircraft. The primary flight instrument is the head-up display. Two CRTs (cathode ray tubes), one on the right and one on the left, provide a synthetic radar scope and a multi-mode display for control of armament, moding, built-in test and display of EO (electro optical) weapon sensor information. The synthetic radar display provides an uncluttered view of radar information with a memory so that it does not have to be watched constantly. These CRTs are identical, offering redundancy and a reduced logistics requirement.
An up-front control panel in the middle of the instrument panel allows all communication, navigation, and identification (CNI) functions to be selected and controlled by either hand. The fighter configuration has a horizontal situation indicator and an EW (early warning) display located below the up-front CNI control. The attack configuration has a moving map display with the electronic navigation and EW information superimposed over the map.
The airborne weapon control system is made up of a multimode radar, fot- ward looking infrared radar (FLIR), and a laser spot tracker (LST). The radar, with only a slightly different signal processor for the fighter and attack variants, provides a number of ways for detecting and acquiring airborne targets and guiding Sparrow missiles to designated targets. This same radar also provides air to ground ranging and mapping information in the attack modes of operation-
Recent combat experience shows that air to ground runs against defended targets call for a maximum of two passes to get the job done. This feature requires a guided weapon capability, and accordingly the F-18 is equipped to carry an LST pod and a FLIR tracker sensor. This increased capability and improved delivery accuracy will make the F-18 more formidable than any other light-attack, carrier-based aircraft.
The F-i8’s armament load is carried on nine stores stations. The primary air-to- air armament is carried on four dedicated stations—Sidewinders mounted on each wing tip for optimum sensor angle and low drag carriage; Sparrows on each of the lower "corners” of the fuselage. A M6i, 20-mm. multi-barrel cannon >s mounted in the fuselage ahead of the cockpit. The inboard wing stations and the centerline station can carry either external fuel tanks or a range of conventional or guided air-to-ground weapons- The outboard wing stations are used for additional ordnance carriage, and wing pylons are interchangeable. F°r attack flexibility, the FLIR and LST pods are designed for carriage on the Sparro"' stations.
A key factor in the success of the F-18 will be the attainment of reliability much higher than that found in aircraft currently in the fleet. This reliability improvement will be accomplished by 3 deliberate program with several critic3
KEY
I Radome
2 Flat-dish radar antenna
3 Radar equipment
4 M-61 20mm cannon
5 Gun-gas purging inlet
4 Retractable flight-refuelling probe
7 Front pressure bulkhead
8 Cabin pressurisation valve
9 Frameless windscreen, hinges forward for instrument access
10 Head-up display
11 Upward-hingeing canopy
12 Canopy jack
13 Lightweight ejection seat
14 Avionics compartments
15 Liquid-oxygen container
16 Forward-retracting twin nose- wheels
17 Fuselage forebody strakes/w/ng- root extensions, graphite-composite material
18 Navigation lights
19 Boundary-layer slot
20 Boundary-layer splitter plate
21 Fixed-geometry air inlet
22 Air inlet duct
23 Environmental system equipment bay
24 Aft-retracting mainwheel leg
25 Fuselage bag-type fuel tanks 24 Wing integral fuel tanks
27 Multi-spar light-alloy wing structure
28 Wing-root pin-joint fittings
29 Wing-fold hinge line
30 Fold actuator
31 Inboard pylon attachment fitting
32 Outboard pylon attachment fitting
33 Leading-edge manoeuvre flaps
34 Leading-edge actuators
35 Trailing-edge flaps 34 Flap actuators
37 Drooping ailerons
38 Aileron jacks, electrically signalled
39 Flap and aileron leading-edge "drooping shrouds"
40 Graphite-composite skin on honeycomb core material
41 Aluminium-alloy twin fin structures
42 Rudder actuator
43 Collision beacon
44 Tail warning radar antenna
45 Airbrake and actuator
44 All-moving independently acting tailplane surfaces
47 Tailplane actuator
4® Deck arresting hook
4f General Electric F404 afterburning powerplant
50 Fully variable exhaust nozzles
51 Engine access doors, graphite composite
52 Airframe-mounted accessory drive gearbox (2)
53 Airborne auxiliary power unit
54 AIM-7F Sparrow III air-to-air missile
55 AIM-9L Sidewinder air-to-air missile
54 Wingtip missile adapter shoe
steps. The initial key step is designing into each piece of equipment the specific reliability needed to meet the overall requirements. For the first time, with the F-18 program, detailed design guidelines for reliability will be issued to all designers, suppliers of equipment, and prime contractors.
Beginning as early as the conceptual phase of the procurement cycle, the designer must emphasize simplicity in design, keeping to a minimum the use of high-risk advanced concepts and parts whose reliability "track records” as yet lack the test of time. Equally important is a stringent derating policy for parts and materials which assures that electrical, mechanical, and thermal stresses on the parts in the product are substantially below their design limits.
In addition, redundancy, alternate, and degraded backup modes of operation, and fail-safe concepts will be emphasized to minimize the number of single parts whose failure can cause mission failure or crew loss, and to single out those which are unavoidable as candidates for higher reliability requirements, tighter parts screening, and additional subassembly-level testing.
Finally, reliability experts have been made an integral part of the F-is team to: (1) aid the designers; (2) stay in touch with how the designers are doing; and (3) review the designs to insure that the needed reliability has been designed-in. The design reviews will treat reliability as an equal to performance, cost, and schedule. These same stringent guidelines and requirements are being written into all procurement specifications for subcontracted equipment. Demonstrations of reliability will be performed both in the laboratory and in flight to validate that reliability objectives have been achieved.
Good maintainability starts with designed-in high reliability. The longer equipment works without failure, the less maintenance must be done. But, equipment won’t last forever, so maintainability, like reliability, must be designed in.
The F-18 maintenance concept allows for rapid fault isolation and location, quick access to the equipment, and then easy removal and replacement.
The F-i8’s built-in test (bit) capability covers 98% of the contract-or-fur- nished avionics and many of the consumables. A caution light gives a warning and the pilot can call up on the multi-mode display a BIT monitor which indicates what has failed. On the ground, the ground crew checks the BIT status panel in the nose wheel well for more detailed indication of the fault and its location. The piece of equipment will then have a fail flag indication, confirming its failure.
A consumables panel is also a part of the design. This will give a go/no-g0 indication of various liquid levels, including engine oil, hydraulic fluid, oxygen, radar coolant, Sidewinder nitrogen, and auxiliary power unit and oil. This feature allows a quick check of a panel rather than opening numerous doors to check gauges, thereby reducing servicing time.
■>
|
AIM-9 3001b | 2350 lb | 2500 lb | 500 lb | 2400 lb | 500 lb | 2500 lb | 2350 lb | AIM-9 3001b |
Sidewinder Only | Sparrow or Sidewinder or Ordnance |
| Sparrow or LST Pod | 300 gal Tank or Ordnance | Sparrow or FLIR Pod | 300 gal Tank or Ordnance | Sparrow or Sidewinder or Ordnance | Sidewinder Only |
The F-18’s armament capability is 13,700 poutids and a 20-mm. cannon.
To enhance maintainability, the avi-
°kvious twin
Pror
redu,
Action measures, which significantly
fijeCC t^le probability of catastrophic ’ explosions, and massive fuel leaks,
are of le.
°nics equipment is secured with special lock rachets which require no special tools or lockwire. In addition, only 11 connections are necessary for engine removal and replacement.
Since direct maintenance manhours per flight hour (DMMH/FH) is a parameter that is used to measure the maintenance required on an aircraft, any reductions have a direct relationship to tmproved logistics and cost savings.
oese F-18 improvements and low MMH/FH will require fewer personnel for maintenance and support, alleviating space problems in the carrier, training of personnel, and lowering the operating c°sts of the aircraft.
Other maintainability features are the ^tuck-access doors and the convenience getting to the equipment. All major ®Suipment can be reached from the deck evel without the use of work stands. Recent Southeast Asia and Middle ast experience has clearly pointed out e necessity for improving the surviv- a tlity of tactical aircraft in both the ghter and attack roles. In the F-18 this 'mprovement comes in two ways: de- ^gned-in survivability and aircraft per- mrmance.
fe ^as'c aircraft design has inherent arures which contribute to surviv- uity. its sma[] s;ze ancj smokeless en- Slnes make it harder to see, and there- j°re difficult to track and hit. It has a w radar cross section and design fea- tUJes are being considered which will Uce its infrared signature. There is redundancy in the dual engines, vertical tails, multi-sparred con- • Uction of the wings, and the multiple path provisions throughout the cture. Essential components are lo- j-ated well toward the center of the ]. Se age structure and all exposed fuel ncs and the fuel tanks are self-sealing. Pecific survivability concepts and lncorporated in the design. The use Css flammable hydraulic fluids and su lncorP°ration of a fire detection and tain reSS*°n system further help to sus- dan! t^*e a'rcraflt’s combat capability after lie ^as ^een sustained. The hydrau- ajtatld flight control systems feature t;a^fnate operating modes which essen- y eliminate single-point total control
failures. This partial list of survivability design techniques, coupled with the electronic countermeasures provisions and the inherent maneuverability of the F-18, illustrates the improved survivability of the F-18 design.
The agility built into the F-18 also enhances its survivability in the target area. Today, fighter capability in attack aircraft is virtually nonexistent and attack capability in fighters is marginal at best. The F-18 fighter design, however, offers an excellent attack capability and retains many of the sensors. The attack version of the F-18, the A-is, retains the Sidewinder and gun, and has the same performance as the fighter after it delivers its air-to-ground ordnance. The agility feature of the F-18 design not only enhances its survivability in the target area, but also provides the operational commander a wide degree of flexibility in his planning for operations. He has the potential of launching an all-fighter air wing if operational conditions dictate air superiority as first priority in a heavily defended target area. After establishing air superiority he then can configure his F-iss for sustained air-to-ground operations.
The fighter configuration, with air- to-air missiles and the internal gun, has excellent capabilities using intermediate power and can achieve a thrust to weight ratio of over one using combat power. The radar detects targets at ranges which allow the use of the full capability of the missiles carried, a feature which is retained by the F-18 in its attack configuration. The outstanding maneuvering capability is demonstrated in that, while the F-18 completes a 360° constant speed turn, the F-4J completes only three-fourths of the turn with almost twice the turn radius.
In the attack configuration the F-18 has full capability for the complete range of conventional, laser/EO-guided, and anti-radiation weapons. The bombing accuracy is better than current carrier- based systems, allowing a high probability of destroying the target on the first pass. Again, the agility of the F-18 is graphically depicted compared to the A-7. Both loaded and unloaded, the F-18 is significantly better.
Since the F-is is replacing both the F-4 and A-7 and its fighter and attack configurations are approximately 96% common, naval logistic and operational planners will enjoy more flexibility in their planning than is available with current operational aircraft. For an example of the benefits of this commonality, there are 12,500 and 8,000 support items required for the F-4 and A-7 and only 3,600-4,800 listed items for the F-18. This, together with the reduction in the number of types of aircraft on board the carrier, will have a multiplier effect on reducing the planning effort and the support costs associated with outfitting our operational forces.
In summary, the F-is naval strike fighter program makes sense to the Nation in spite of all the controversy over its birth. It puts a weapon system into the inventory which will meet and excel over the air-to-air and the ground defenses through the 1980s. It permits the replacement of two types of aircraft with one. It simplifies the heavily-taxed logistics support systems of each air wing and the aviation community. And, perhaps most important, it will permit Naval Aviation to continue doing its job with equipment that is second to none.
UTTAS: The Helicopter of the 1980s?
By Mark Lambert, International Editor, Flight International
Around Christmas or early in 1977 we should know which helicopter will succeed the Army’s legendary Huey into the 1980s. And soon after we may learn if the Navy likes the Army’s choice enough to buy the same basic aircraft. The project name at the moment is UTTAS, Utility Tactical Transport Aircraft System, and it has been going through its development since the beginning of the 1970s. More than 10,000 Hueys were made by Bell Helicopter, largely under the stimulus of the Vietnam War in which the helicopter played a leading role. UTTAS is an effort to improve on the Huey, but is also an important factor in keeping technology moving forward through the inevitable trough which is following the Vietnam helicopter boom.
Thus, of the major U. S. helicopter manufacturers, Boeing Vertol and Sikorsky were selected to manufacture the competitive UTTAS helicopters which are now being flown in competition with each other by the U. S. Army. The selection was made in August 1972, after all the main manufacturers had submitted competitive design studies. Five months earlier, General Electric had received a U. S. Army contract to develop its GE12 advanced turboshaft engine as the 1,500 S.h.p. T700-GE-700 for the UTTAS program. In June 1973, Bell Helicopter and Hughes were in turn commissioned to manufacture prototypes of their Advanced Attack Helicopters (AAH). Two other projects, the Advanced Scout Helicopter and the Heavy Lift Helicopter (HLH) have been abandoned, though Boeing Vertol completed considerable risk-reducing engineering and test work on the main components of the HLH.
One other helicopter fits into the overall development picture, namely, the Light Airborne Multi-Purpose System (LAMPS) by means of which the U. S. Navy plans to give destroyers a powerful airborne extension to their defensive armory. While the Kaman SH-2F Sea Sprite, LAMPS Mkl, is doing an interim LAMPS job for Navy destroyers and escorts, a suitably modified UTTAS is an obvious candidate as an ultimate successor—LAMPS Mk3.
Once in production UTTAS will not be a cheap machine. It is powered by a pair of 1,500 s.h.p. engines, compared with the Huey’s single engine of around 2,000 h.p. But it will have compensations. It has been designed to meet very stringent targets for reliability, maintainability, and efficiency so that its cost of ownership should be as good as that of any other helicopter available.
But as the competing UTTAS prototypes, Sikorsky’s YUH-60A and Boeing’s YUH-61A, undergo their exhaustive Army evaluation, both in tactical trials at Forts Rucker and Campbell and in pure flight testing at the Army Aviation Engineering Flight Activity at Edwards Air Force Base, $2.5 billion worth of orders hang in the balance—the Army wants 1,100 UTTAS helicopters.
If you designed a new helicopter now, you would expect it to look pretty much like UTTAS, but it is remarkable that the innovations of UTTAS were inspired by the Army some six years ago. Superficially, a helicopter—even when you call it a utility tactical transport aircraft system—comes out looking like a helicopter. The break-throughs in the two UTTAS designs are in the machinery, and both Boeing and Sikorsky made major attacks on the helicopter’s traditional complications. The "elbows and wrists” of the fully articulated rotor head had been inescapable till then, but Sikorsky and Boeing found radically simplified solutions. Sikorsky, for example, remained faithful to the fully articulated rotor head, which has separate bearings allowing each blade to twist when changing pitch for control purposes and to flap and drag as the rotor rides out the relative airflow and the changing attitudes. But in UTTAS, Sikorsky adopted a system of soft joints lined with bonded elastomeric compound which could yield without a bearing surface.
Boeing went to Europe and licensed
from Germany’s Messerschmitt-Bolkow-
Blohm (MBB) the once daring rigid titanium head which allows neither drag nor flap movement, only swivelling f°r pitch changing. The suppleness to absorb the shocks of drag and flap movement is molded into the glass-reinforced
plastic blades, which have no metal spats- The Boeing version of the MBB rotor has only 93 parts instead of some 240, is easy to inspect, and needs hardly any maintenance. The blades have an extra smooth finish for high performance, and the nature of the plastic material gives them virtually unlimited life. The relative rigidity of the MBB rotor gives it unusual stability, resistance to trim changes, and immediate, positive response to control- The blades are strong, too. MBB in Germany have run one of their own blades for more than 90 hours after the main spar area had been pierced by a rifle bullet.
Sikorsky based its bladed on an extruded, hollow titanium spar with the aerodynamic blade section molded onto it in plastic. The spar is inflated with gaS and the pressure is registered by a lit^e gauge glass at the blade root, easily visible from the ground during a walk around inspection. Any crack or fault allows the gas to leak away and the l°ss in pressure can be immediately spotte • That is Sikorsky’s blade inspecti°n method (BIM). Rotor vibrations are damped by tuned bifilar weights on the rotor head. A smooth ride without vl bration is comfortable, but it is important for accurate sighting and c° protect sensitive equipment.
criminately.
Both manufacturers have designed
engine-to-rotor transmissions so
P'lots
Both Boeing and Sikorsky have designed completely new hingeless tail rotor systems. Boeing designed the flex-strap rotor in which the blades are attached to the hub by four plastic straps which allow all the necessary movement without any bearings. Sikorsky achieved an equivalent result with lts cross-beam system, in which the blades are mounted in pairs on the ends °f two plastic beams. Neither rotor needs greasing.
Sikorsky’s rotor is mounted on the up-wind” side of the fin and tilted several degrees to the left. It therefore produces some 400 pounds of lift as well as resisting torque. This has saved five feet of fuselage length, says Sikorsky, and lets the pilot easily compensate for large variations in the center of gravity so that the machine can be loaded indistheir that individual sections can easily be removed for repair or inspection; and t"e Army demanded that they show that aA gearboxes can be run for a given time at full power without oil, even after a hit from a 23-mm. round.
Finally, on the rotor and transmission s‘de, the Army demanded that UTTAS should be able to fly with the tail rotor missing, perhaps shot away. Previously that meant curtains, but the airplane- bke tails of both machines are large enough to let them cruise without a tail rotor. The tailplane automatically routes to a near-vertical angle of attack in rhe hover so that it does not respond unnecessarily to rotor downwash. As a °nus, the big tailplane prevents troops madvertently walking into the tail rotor (a traditional helicopter hazard) and acts as a platform on which maintainance ^en can stand to work on the tail rotor. . But there is far more than machinery ln UTTas. The Army laid down some really tough performance specifications, ^hich stretched the state-of-the-art in all Sections. The basic mission is to carry fully-equipped troops into combat Wlth a three-man flight crew—pilot/ c°mrnander, co-pilot/gunner, and gun- ner/crew chief. Two 7.65-mm. machine Suns are positioned at waist-high gunner s windows just to the rear of the ’ seats.
BTtas needs an ample cabin with wide sliding doors, which have to remain safely open at up to 145 knots airspeed. The fuselage is more than 60- feet long. Yet it has to be loaded into the 10-feet-square cross-section of the U. S. Air Force C-130 Hercules and C-141 Starlifter freighters with little more preparation than blade-folding and landing gear telescoping. Six UTTAS have to nestle on the cargo floor of a Lockheed C-5A Galaxy. That was the requirement which, more than any other, dictated the squat outline of UTTAS. It forced designers to accept the technical risk of aerodynamic interference between rotor and fuselage. Only the ill-fated Lockheed Cheyenne had previously carried its rotor so close to its fuselage.
Significantly, the very rigid rotor of the Boeing UTTAS has retained its low position, while the more flexible rotor of the Sikorsky has been raised on a telescopic pylon, but this can be collapsed in minutes for loading into a transport aircraft.
Even tougher than the dimensional restraints of UTTAS were the performance requirements. Helicopters never have been as highly maneuverable as fixed-wing aircraft. Yet the Army required the ability to apply more than 90° of bank, to pull more than 3G, to fly at something approaching zero G, and to roll at 120° a second. In the whole pattern of performance, Sikorsky felt that the toughest was to pull a 1.75G turn during 1,100 feet of forward flight and then to push over into a zero G nose-over. That is part of the maneuverability needed to allow UTTAS to hug the ground at high speed as it approaches a landing zone. Again, all UTTAS performance is referenced to 4,000-feet altitude and a torrid 95° F temperature. UTTAS has to climb to 17,500 feet; it must land on ground sloping at 17°; and it has to
lift a slung load of 7,000 pounds.
All this has to be achieved, says the U. S. Army, for a target selling price per aircraft of $600,000 at 1972 prices. Design to cost procedures were enforced and the contracts carried incentive bonuses and penalties. Sikorsky’s contract for three prototypes and a static test airframe was $61 million: Boeing’s was $91 million. (As it happened, both manufacturers proposed civil derivatives of their UTTAS designs—Boeing the Model 179 and Sikorsky the S-78
[originally the S-70] in two versions.)
Now, the final stage of the Army competition is in full swing. The first Sikorsky prototype flew some weeks ahead of schedule in October 1974 and all three were airborne by the following February. Boeing cut it fine with a first flight in November 1974 and had the third prototype flying in early 1975. Sikorsky completed around 650 hours flying before it delivered its three machines for Army evaluation at Fort Rucker on 20 March this year. They had been carried south from the Stratford, Connecticut, factory in a C-i4i Starlifter. Boeing completed a similar number of hours flying and handed over its prototypes on the same day. Boeing test flying had not been seriously delayed by an accident last November in which a folding maintenance step rubbed against the tail rotor shaft and broke it during a practice engine-off landing. The machine came down in trees, but the crew was uninjured, the fuselage remained true, and the transmissions were not further damaged. The machine was refurbished and completed the test program. The Army will now fly each team of prototypes for between 700 and 800 hours.
In order to get the maximum output from test flying, Sikorsky used its Rapid telemetry station at Stratford. Test measurements were transmitted to the Rapid station and evaluated while the helicopter was still flying. Boeing made use of a similar telemetry installation at Grumman’s flight test base at Calverton, on Long Island. Both manufacturers ran some 1,200 hours on a ground test vehicle. Both machines were fitted with full blind-flying instruments, autopilots, and radio approach aids and are to be qualified for IFR (instrument flight rules) airways flying. Sikorsky has adopted a fluidic autostabilizer in which hydraulic fluid flowing under pressure through a labyrinth of galleries in a block of material replaces the conventional electronics used for stabilization.
Both companies used high-performance management systems in their development programs. Sikorsky set up a "work breakdown structure,” in which each part was allowed to occupy a certain proportion of the overall airframe weight. If the initial design was too heavy it was rejected. If it was too light it might be simplified and allowed to become heavier, but cheaper. The result was that the first airframe weighed in at 10,339 pounds against a target of 10,460 pounds. For UTTAS, all that remains is for the U. S. Army to judge the results.
The Navy, however, now must determine whether either LAMPS version of the UTTAS competitors is suitable for fleet operations; if both are, which one is best; or is there another helicopter which would better fulfill the Navy’s requirements?
The Navy has been watching UTTAS developments closely and both manufacturers have built mock-ups representing the LAMPS configuration fitted with a trailing magnetometer head, torpedo carriers, search radar, and sonobuoy dispensers, plus a folding tail and other provisions for shipboard operation. These have been checked out on the fantail of a Navy destroyer.
Boeing provided its UTTAS with a fairly short-coupled nosewheel landing gear, which fits well on the smaller platforms of ships. Sikorsky fitted its UTTAS with a tailwheel gear which has advantages for Army operational landings in which the tail is allowed to trail along the ground long before the mainwheels touch down. But it has moved the tailwheel well forward in the LAMPS mockup.
Meanwhile, the Navy has issued requests for quotations for the LAMPS Mk3 program and numerous U. S. and foreign helicopter companies have expressed interest in the competition. The U. S. Navy will likely make its helicopter judgment by March 1977.
The S-3A Viking
By Commander Rosario Rausa,
C. S. Naval Reserve (TAR), Editor of Naval Avialion News
dr:
The U. S. Navy’s S-3A Viking represents a giant step forward in the continuing lethal struggle to match wits Wlth modern submarines. It has successfully joined other units dedicated to antisubmarine warfare. Ten squadrons now fly the Viking and three more will functional in 1977. One squadron, Vs-2i, completed the first operational deployment in 1975 on board the Uss John F. Kennedy (CV-67) for a Med- 'terranean deployment.
The Viking is a solid-looking, stale-flying, supersophisticated airborne Weapon system. It uses technology in Ways that Naval Aviation’s forefathers c°uld not have envisioned. Yet, it still requires the maximum skills of extensively trained pilots and crews to extract t^le most from its advanced sensors.
The Viking’s principal mission is to ^xpIoit the offensive antisubmarine war- arc capability of carrier-based aircraft. It Marches, by providing the flight crew 'Vlth a variety of sensors, for submarine and surface threats over huge sea areas, % or night.
The rapidly growing and increasingly Capable Soviet Navy provided the impe- jus for the development of the S-3. The Ussians have 335 submarines, about ^Jo-and-a-half times the U. S. inventory.
any of these are nuclear powered and operate deeper and faster than the subs 15 years ago. Some Soviet nuclear ornarines can travel at speeds in excess of 30 knots.
lo the 1950s and 1960s, the prop- 'ven S-2 Tracker served well, finding tracking many diesel-powered subs. e Grumman-built aircraft have given
o
man service since becoming opera- nal. Now, as a lieutenant commander ^!th nearly 500 Viking hours puts it, ne S-3A can detect and destroy any sub j e Soviets have, even if that sub is °'Vn m the ocean near its crush depth.” Built by the Lockheed-California
Company in association with LTV Aerospace (Vought Systems Division) and Sperry Rand (Univac Federal Systems Division), the S-3 carries a crew of four—pilot, copilot, sensor operator (SENSO), and tactical coordinator (TACCO). It can dash to the hunt at 450 knots, loiter in the target area at a comfortable 160 knots at low altitudes, and, when necessary, make sharp, buffet-free turns while localizing a contact. It can remain aloft for as much as seven-and- a-half hours, although most missions usually last half that time. Its range is about 2,500 miles.
Mounted from the Viking’s moderately swept wings are two high-bypass, turbo-fan engines. Each of these TF34- GE-4oo power plants generates in excess of 9,000 pounds of sea-level static thrust.
The airframe is fortified by two parallel beams which form a keelson running the length of the aircraft. The S-3 can be "hauled” around and sustain 4.1G + or 1.0G —. Unlike most heavily instrumented airplanes, the Viking can be flown through aerobatic, over-the-back maneuvers. In fact, at NAS North Island’s VS-41, where fleet replacement pilot training for the S-3 is conducted, aerobatics are part of the flight syllabus.
The Viking can get down from altitude in a hurry. With speed brakes extended, descent from 35,000 feet to the deck takes only two minutes.
Wing span is nearly 70 feet, although outboard sections of the wings can be folded to facilitate close quarters parking. The vertical stabilizer is huge and enhances the overall impression of simplicity and strength in design. Measuring over two stories high from ground level to its tip, it too can be folded.
Still, it’s the people and systems inside the Viking which count the most. The pilot and copilot operate in the traditional left and right seat arrangement up front. Forward visibility is excellent, and they have easy view of the wing leading
edges and engine nacelles. The extra large windshield affords the pilots full perspective on approaching descents to the carrier. All crew members, incidentally, can eject from the aircraft in an emergency.
Some Viking drivers admit to seat discomfort after several airborne hours in the S-3. A cushion modification is being evaluated and eventually may be incorporated. Overall, however, the flyers agree that the aircrew stations are superior. Unlike the Tracker, the Viking has a control stick, rather than the wheel-type yoke.
From the left seat the pilot in command performs most of the flying. The copilot has a multitude of non-flying related chores which keep him busy. This has led to some understandable dismay on the part of first-tour flyers. They don’t get much stick time, not to mention carrier landings. The copilot’s station, however, was designed so that he could function as a navigator, communicator, and nonacoustic sensor operator, in addition to backing up the pilot. Two squadrons, VS-32 (East Coast) and VS-33 (West Coast), are experimenting with naval flight officers (NFOs) manning the copilots’ stations in half their flight crews. This change will be carefully evaluated before fleet users totally adopt the practice.
The SENSO, normally an aviation ASW operator (AWO), is located behind the pilot and separated from him by a vertical bank of electronic equipment. A pair of cathode ray tubes (CRTs) are situated one atop the other at comfortable eye level. A keyboard for initiating computer commands juts out slightly over his knees.
About two arm’s lengths to the SENSO’s right, the TACCO works behind a similar column of equipment. The TACCO is a naval flight officer. Like the SENSO, he has had at least six months of specialized instruction in addition to regular ASW training.
If the S-3A crew were likened to a football team, the TACCO would be the quarterback. He directs the minute-byminute tactical activities. On an ASW mission the flow of information to the crew is rapid, voluminous, and, to the uninitiated, frighteningly complex. It would seem like all the crew members are trying to get a drink of water from a fire hydrant. Yet there is a disciplined order to their actions as they decipher the myriad CRT displays, punch keys to order data from the various systems, and make the hundreds of mini-decisions characteristic of a mission.
The Viking is the first carrier-based ASW aircraft equipped with a general purpose digital computer—the Univac 1832. It functions along with an intricate battery of acoustic and nonacoustic sensor gear and is the nerve center of the S-3.
Software computer programs for the Univac are divided into three categories—operational, system test, and weapons system support. The first is devoted to solving a broad spectrum of tactical problems. The system test comprises an in-flight and ground maintenance feature. It isolates malfunctioning weapons’ replacement assemblies and signals the operator. This reduces troubleshooting and repair time measurably once the aircraft is back on board the ship or shore base. Weapon system support programs contain pre- and postflight analysis data which ultimately contribute toward building operational tapes. These tapes, literally, constitute a real-time diagrammatic recording of the flight’s track and tactical actions. They can later be replayed and studied in the Tactical Support Center (TSC).
TSCs will eventually be operational at several land stations and on board all carriers. Each will house computerized data banks and support both P-3 Orion and S-3 aircraft. Before a mission, one of the crew members will collect the RD-3/*a tape cartridge from the TSC. It will t>e inserted into the Viking’s digital magnetic tape unit at the outset of the flighc and remain on until shutdown.
These tapes not only record what the Viking does throughout a sub-hunting mission but also provide the program initiate the general purpose digital computer. For example, the TACCO can query the computer for the water tern- perature and salinity content in the area being worked. A full scale of technical data can be projected onto CRT displays >n alfanumerics and/or symbols within seconds. A seemingly unending mass of tactical knowledge, such as sonobuoy dispersal patterns of ordnance loading, is available on demand.
After a flight, tapes can be viewed in the TSC for careful analysis. In a way, these "movies” are like instant replays in the sports world presented in the form °f an electrocardiagram. The tapes can be run at real time or accelerated 60 times that fast for selective observation. Lines, circles, triangles, and various other symbols move, disappear, blossom again—each contributing to a total tac- ttcal picture. The crew can determine tvhere, precisely, it flew, what sonobuoy patterns it dispersed, and where contacts tvere made.
The Viking carries several types of sonobuoys. They are stored in 60 swiss- cheese-like chambers in the lower fuselage area. Torpedoes, bombs, and depth bombs are carried in various combinations in two weapons bays. Mines and special weapons are also in the Viking’s armament inventory. Wing pylons with the BRU-n/A bomb racks installed can accommodate triple ejector racks for lncreased armament loads.
Sonobuoys can be released manually but usually are dropped by computer SIgnal. They are stabilized in flight by vanes which spread out from the top of fhe buoy. Each contains a miniature radio transmitter. Hydrophones suspended below the buoy collect sounds in the water and transmit them to the aircraft.
Interpretation of sonobuoy sounds is, of course, a primary concern for the crew. As one experienced VS-41 instructor asserted, "Success in ASW depends, in large part, on selecting the right sonobuoy pattern for a given situation.” Tacticians are continuously evaluating and modifying patterns just as submarine commanders strive to alter their own tactics and evasive maneuvers.
In a mission’s search phase, buoys may be released from high altitude in a broad pattern. Signals are then observed by the Viking’s Acoustic Data Processor (ADP), which instantly recognizes varying levels of sound and displays information to both the TACCO and SENSO. At the start of the search, the ADP is operated on one or more of its passive modes, storing information on a pair of magnetic memory drums. By comparing signals, the SENSO, hopefully, can narrow the search area. This is a laborious process and demands absolute concentration and a methodical mental evaluation. If a target is found, the passive acoustic classification system is engaged to help in the identifying process. Sonobuoy patterns then might be compressed or reduced in size.
As the Viking closes for the attack, the TACCO may direct release of "active” buoys—those which emit signals and receive echoes from the submarine. The
ADP is switched to what might be called the aggressive mode. The sub is pinpointed and weapons are released.
In the ideal operational scenario the target is unaware it is being pursued during the passive sonobuoy phase. Once the buoys go active, however, the submarine’s sonar operators easily detect the sound and the sub commander orders emergency, evasive maneuvers to elude the threat. Therefore the interval between active buoy dispersal and attack has to be brief.
The above is a simplification of the search, find, and destroy evolution. At VS-41, a sonar operator, who has served in several submarines, expressed respect for his Soviet counterparts. "They are extremely skilled,” he declared. "I don’t think they’re better trained or qualified than we are. But, I do know that they can often pick up the mere splash of a buoy striking the water 1,500 to 2,000 yards away, especially if the sub is running silent.”
In the end, the business of ASW, success or defeat on the high seas,
hinges on the harmony of human and mechanical skills in action. The men in the Vikings must know how to work the systems, manage the knowledge available, and do so expeditiously.
The Viking has a command signal generator (CSG) and an analog tape recorder to help process data and also a completely automated sonobuoy receiver. The CSG uses the S-3 UHF radio transmitters to "command” the active sonobuoys into different modes. Nonacoustic sensors provide even further information and complement the acoustic systems.
The plane’s high resolution radar, the AN/APS 116, was specifically designed to detect small-size surface targets even in high sea states. In addition, the Viking can see through haze and light fog, day or night, with its FLIR (forward looking infrared) scanner, which presents a television-like display, generated solely by the target’s heat, on the CRTs. Surface ships or low-flying aircraft appear in sufficient detail for positive identification.
The FLIR scanner’s exterior sensor unit is mounted in a retractable turret on the plane’s underside. The computer guides it automatically. And, with its wide-angle and zoom features, the scanners continue tracking even after the plane has passed a contact.
Magnetic anomaly detection (MAD) gear has been and continues to be effective in sub hunting. The MAD boom extends directly out the tail section, detects signals, and transmits them to the computer which records the contact’s location and quickly classifies it. Within seconds, after recording at least one other contact location, the general purpose digital computer generates the contact’s track. A "fly-to” (intercept) point appears on the CRT and the crew selects auto-pilot, if not already engaged, directs the computer to take over, and monitors its performance. The Viking automatically banks, levels out on proper course, and continues the search.
The Viking’s electronic counter measures (ECM) equipment is always working. Omni-directional, wing-tip mounted antennae automatically—and continuously—provide bearing information from emitting air or seaborne stations. Data cycles through the computer which searches its software library, analyzes the signals, and then "informs” the crew whether signals emanate from friendly, unknown, or threat targets.
CAINS—carrier aircraft intertial navigation system—combines with doppler gear to solve any navigation problems which occur. The Viking, with its great range capability, often operates alone and at vast distances from the carrier. Since CAINS can be aligned on the carrier or in-flight, the S-3 can operate beyond the range of regular ship or shore- installed navigation aids, heretofore needed to cross-check positions. In the meantime, the Viking is tied in with the carrier and various other ASW units through a data link communications system.
A sonobuoy reference system serves as another form of navigation equipment. By monitoring the buoys’ VHF signal outputs, as the Viking moves through the sky, it can detail the aircraft’s position in relation to the buoys and even determine the actual distance in miles from the buoys.
Crew coordination is, perhaps, an overworked phrase, but, in the S-3, the pilot, copilot, SENSO, and TACCO must be masters at it. The array of on-board equipment and the inherent complications of ASW demand it.
Although the TACCO "runs the show,” he would be over loaded without the ongoing exchange of information with his colleagues. Somewhat surprising, the elevated level of equipment sophistication precludes excess verbal communication between the crew members. They need to concentrate on the gear and must have minimum intercom interruptions. So, they actually talk to
each other through computer-generated
displays and relay their actions visually.
Before the S-3, ASW tacticians were deluged by cumbersome charts and logs, and an army of switches and knobs requiring attention. With the Viking, the same information and much much more is only a few finger manipulations away.
On top of all this, the Viking has adapted to carrier operations with comparative ease.
There are, of course, bugs in the Viking which are being worked out. Every new fleet aircraft has growing pains. But the airframe was designed with adequate growth space so that even more sophisticated electronic equipment can be incorporated as state-of-the-art changes in the years to come.
The skilled professionals who man the Vikings know that they have a first-class antisubmarine aircraft. Now, and through at least the 1980s, the Viking and its crews, working in conjunction with other ASW units, will be able to counter any known and forecast undersea threats.
Situation Normal
All was peaceful in the control tower at the naval air field when suddenly the following transmission was received, "South Tower, this is Whiskey Bravo 23. My oil pressure is reading zero and I have a rough running engine. What should I do?”
Realizing the serious nature of the message, the tower anxiously replied, "What is your altitude and position?”
Answered Whiskey Bravo 23, "I am warming up on the end of Runway 16.”
Lieutenant (j.g.) Bart W. Fordham, USN
{The Naval Institute will pay $25.00 for each anecdote published in the Proceedings.)
Fiber Optics and Naval Aviation
By William M. Powers
The U. S. Navy has begun exploring the operational use of fiber optics technology in a program utilizing an A-7C Corsair II aircraft. Early tests indicate that fiber optics possess several significant advantages over conventional wire cables in the transmission of data signals between avionic components in military a*rcraft.
Since fiber optics bundles, unlike meta be conductors, are immune to electri-
C3l *
1 'nterference and are unaffected by ectronic conduction problems because
The program, dubbed ALOFT (Airborne Light Optical Fiber Technology), tnvolves several Navy commands as well as civilian industry. Testing has included Modifying the navigation and weapons delivery system of an A-7C at the Naval Weapons Center, China Lake, and conducting bombing and rocket-firing demonstrations.
With funding provided by Naval Air Systems Command, the Naval Electron- *cs Laboratory Center (NELC) in San bhego is directing the program based upon its own research done in the fiber °ptics field since 1970. Engineers at N£LC indicate that test flights to date confirm that fiber optics technology is Practical now, and can be improved for 'rdlitary aviation use.
Existing avionic components trans- rnit data signals with electrical pulses, Usually through twisted shielded copper 'Vlre- Fiber optics transmit data with 'ght pulses through bundles of purified fitass fibers and, unlike metal wiring, are j'.rtually immune to electromagnetic, ra- 10 frequency, or electromagnetic-pulse types of interference (EMI, RFI, or EMp), Thus, fiber optic systems are less Susceptible to enemy electronic counter- rueasures (ecm) in a combat environment, or to other types of interference Such as EMI or RFI caused by electrical st°rm, or to EMP phenomenon caused by Unclear blast.
of their favorable dielectrical and wide bandwidth properties, they can be adapted to "multiplexing.” This technique reduces both the number of required signal paths and the complexity of cable connectors. In a conventional A-7 system of copper-shielded wiring linking the aircraft’s tactical computer and various electronic adaptors, 115 signals normally transmitted over 300 wires were instead time-division multiplexed into 13 serial data channels and transmitted via fiber optics. These characteristics result in a dramatic savings in weight and space and improve the performance of any given avionics system.
Conventional copper wires transmit modulated electrical current. When they break, and thus short-circuit, they can create hazards such as fire-starting sparks, electrical shock, and component damage. Fiber optics transmit only light, not current, hence these hazards are eliminated.
After NELC engineers determined the favorable possibilities of using fiber optics in avionic systems, they sought civilian companies to create or modify the hardware necessary for use in a practical aircraft test. In 1975, contracts were let under the sponsorship of the Naval Air Systems Command to the Federal Systems Division of International Business Machines (IBM) and to Vought Systems Division of Ling-Temco-Vought. IBM was to design and build the electro-optic interface for the navigation and weapon delivery system of the A-7. Vought was charged with providing an installation plan and providing ground test facilities for systems hardware evaluation. Naval Weapons Center China Lake provided software, safety of flight verification for the modified A-7 system installation, and flight test facilities.
The ALOFT program was initiated not only to demonstrate that the physical properties of fiber optics technology were suitable for military aviation application, but, of equal or surpassing importance, that the technology could be used in the future to lower overall lifecycle costs. McDonnell Aircraft Company has been contracted to compile ALOFT test data and do an economic analysis. Other studies being conducted at the Naval Postgraduate School will be combined with the McDonnell analysis and NELC’s work to produce a definitive finding in fiber optics’ economic feasibility. Very preliminary conclusions indicate that fiber optics, in fact, will reduce total life-cycle costs.
The Navy has made limited use of fiber optics in the past. A closed circuit television link was once used in a ready room on board the USS Kitty Hawk (CV- 63), and the USS Little Rock (CG-4) has a five-station telephone system utilizing fiber optics.
The A-7 was specifically chosen for a full systems demonstration for three reasons. The system modified with fiber optics could not be related to flight safety; the Corsair’s navigation and weapons delivery system meets this requirement. Second, there are sufficient A-7 aircraft available within the Navy supply system so that assignment of critically needed avionics to ALOFT would not adversely affect the overall A-7
maintenance program. Finally, the A-7 is an aircraft which can be maintained until the fiber optics research program is completed.
In modifying the ASN-91 navigation and weapons delivery system (NWDS) of the test A-7C, as many "off-the-shelf” components made by industry as possible were used in the conversion, lowering costs and simplifying parts procurement.
IBM, tasked with fabricating the hardware for the actual conversion, did not change the basic structure of the "black boxes” involved. It did devise a means to convert electrically-pulsed signals into light—an electro-optic interface. In fact, the installation in the test A-7C could be converted back to a standard configuration in less than one day.
Actual testing of the fiber optic interface lasted more than six months at China Lake. The A-7C flew approximately 100 hours, performing a series of navigation and weapons delivery tests. Tests generally verified that fiber optics could successfully operate in the military environment, up to and including a "worst case” stress situation. Reliability and maintenance potential were considered good. Additional tests will be conducted to compare the performance of shielded cable with fiber optics under known conditions.
During the final phase of the ALOFT program an economic analysis will examine projected production costs, estimated development costs, plus operating and support costs. Based upon reliability and maintainability the analysis will also evaluate mission effectiveness in terms of success and aircraft survivability. If this study produces positive results, the effects on the efficiency of avionics both in military and civilian applications, could be profound and long-reaching.
Fiber optics could be used in a multitude of advanced development systems, such as point-to-point communications interfaces, fly-by-optic control systems, and avionic databus systems.
A databus system utilizing fiber optics in an ASW aircraft, for example, would permit a significant increase in data rate and consequently an increase in tactical performance. ALOFT has already demonstrated that a ten-fold increase in volume is possible, compared to using shielded cable, with little loss of signal intensity.
Fiber optics may also become important because of the composite structures now being used in the manufacture of high-performance aircraft which do not provide the EMI shielding comparable to metallic aircraft skins. A composite structure (made of graphite-epoxy) will not shield avionics against a lightning strike. A lightning strike will follow aircraft wiring, rather than its skin, resulting in massive damage to both avionics and the structure of the aircraft- Since fiber optics are made of glass and are non-conductors, this hazard is minimized.
The need to reduce both the size and weight of avionics, and to increase their efficiency, is becoming vital as new generations of aircraft, such as the F-14 and the F-18, are introduced into service. The solution to this need may well rest in the exciting new field of fiber optics.
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