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Contents:
Pegasus (PHM-1): The Patrol Hydrofoil Ship 101
By Lieutenant Commander E. H. Ashburn, U. S. Navy On Board a Sailing Ship 107 By Ken Berents
Engineering Readiness Shot in the Arm:
The Propulsion Examining Board 108
By Commander Richard L. Madouse, U. S. Navy The Rigid Airship in the Sea Control Mission 112 By Commander Ben B. Levitt, U. S. Navy (Retired)
Pegasus (PHM-1): The Patrol Hydrofoil
By Lieutenant Commander E. H. Ashburn, U. S. Navy, Prospective Commanding Officer, Pegasus (PHM-1)
The cruise missile-launching fast pa- tr°l Boat (fpb) burst upon the naval scene with the successful "Styx”-armed Komar” attack on the Eilat in 1967. Slnce that October day, fpb craft, their Missiles, and tactics have matured and stained a sophistication which permits successful engagement of major naval utces in narrow seas and littoral waters, he improved FPB command and con- tr°l systems (some with data links) and rapid reaction, fire-control systems mag- n'fy effectiveness while maintaining good survivability. The development and proliferation of missile boats in the w°rld’s navies make them a threat which no naval power can ignore.
FPBs are extremely capable, but they have disadvantages. Chief among these 15 a Sea State limitation. In the commonly occurring Sea State 5 (8-12 foot Waves), crew and equipment effectiveness rs low, particularly at speeds above 8 or 10 knots. This shortcoming, however, has been eliminated with the introduc- r*°n of the fully-submerged-foil hydro- 01 ship. And, the patrol combatant missile [hydrofoil] (PHM), at 235 metric tQns, is the first combatant ship to apply rhe fully-submerged hydrofoil solution to the missile boat Sea State problem.
The Pegasus (PHM-i), proceeding rou- tlnely at high speeds in Sea State 5, ^presents a new era in FPB warfare. Wlth a ride quality akin to a high-speed rail train, the foilborne PHM is a weapons platform which operates with great efficiency and comfort in an aroused sea.
Good foilborne ride quality is an essential combat characteristic but represents only one of the two modes of hydrofoil operation. Of equal importance is the ship’s hullborne ride quality which more nearly approximates a destroyer-sized ship’s, owing to the damping effect of the large submerged foil surfaces. The Pegasus possesses sea-keeping ability, combat power, and speed heretofore possible only in much larger ships.
The patrol hydrofoil was developed to meet a 1969 CinCSouth operational requirement to counter the missile boat threat in the Mediterranean Sea. The requirement was expanded by NATO to include a response capability to the Soviet major combatant threat throughout the NATO area. The NATO Naval Armaments Group (NNAG) determined the feasibility of a guided-missile-armed fast
131.2 feet 28.2 feet
Length Beam Draft
Hullborne (foils retracted) 6.2 feet Hullborne (foils extended) 23.2 feet Foilborne (nominal) 8.8 feet
Displacement Speed Hullborne Foilborne Propulsion Hullborne Foilborne Crew
40.0 m 8.6 m
1.9 m 7.1 m 2.7 m
231 long tons 235 metric tons 12 knots
in excess of 40 knots
2 diesels with 2 waterjets 1 gas turbine with waterjet 21
OUTBOARD PROFILE
COW’*"
BOEING AEROSPACE
patrol boat to meet the threat, and selected the fully-submerged-foil hydrofoil craft as the most suitable solution. The resulting mission statement for the PHM is to: "Operate offensively against major surface combatants and other surface craft by utilizing surface-to-surface missile systems and secondary armament and to conduct surveillance, screening, and special operations.”
In November 1972, Germany, Italy, and the United States signed a Memorandum of Understanding in which the three nations agreed to share the nonrecurring costs of design of the PHM. The United States agreed to construct the lead ship; each nation, however, will bear the construction costs of its own ships. The remaining NATO nations, which maintained observer status in the development program, may elect to participate fully in the PHM program at any time. Because the NATO PHM is a common design, the ship is constructed to metric standards. Equipments were selected from each participating nation to lessen the imbalance of payments. Combat system variants were accommodated in the design.
Factors which influenced the NNAG selection of the hydrofoil over displacement hulls included payload fraction, as well as speed and seaworthiness. The lower drag and consequent lower power requirement of the hydrofoil result in a lighter power plant and higher payload factor. This increased payload may include more fuel for longer endurance or more systems payload. In the U. S. PHM variant, the Navy opted for endurance; whereas, the variant destined for the Federal Republic of Germany will carry the heavier command and control system installed in the German Navy’s Type 143-class missile-equipped fast patrol boats.
The Pegasus is armed with eight Harpoon missiles in cannister launchers, the Oto Melara-designed 76mm./62 caliber dual-purpose gun, and small arms. Air defense measures consist of the 76-mm. gun, which is designated the Mk 75 Mod 1, and rapid blooming off-board chaff (RBOC) launchers. The primary ship’s sensor, and heart of the combat system, is the Netherlands Hollandse Signaalapparaten (HSA) WM-28 fire control system, designated the Mk 94 in the U. S. Navy. Mated to this system, is the Mk XII IFF (identification friend or foe). Follow-on U. S. PHMs may be equipped with an adapted copy of the Mk 94 manufactured by the Sperry Company and designated the Mk 92. The gun and Mk 92 GFCS (gunfire control system) will also see service in the U. S. FFG-7- class frigates. ’
The PHM combat system’s level of automation is such that one man, unassisted, can simultaneously engage air and surface targets with gun and missile respectively. Because the PHM can employ full combat power at lesser conditions of readiness, the ship can operate for extended periods in high threat environments without crew fatigue problems. General quarters stations add little to the condition III fighting capability. At general quarters, the presence of a second fire control operator permits splitting air and surface assignments, and loaders are stationed to replenish the gun after expenditure of its initial 80
founds. Command and control capabil- icy is also increased by strengthening bridge and CIC watches.
The Mk 75 gun is primarily an air- defense weapon. It has a more rapid rate °b fire than the venerable 3 in./50 caliber and its rounds travel at higher velocities. Several projectile fuses are available, including an IR (infrared) version which is effective against aircraft and patrol boats.
In low speed patrol scenarios, oppos- mg fpb forces often do not detect each
other until the dispositions are quite olose and inside minimum missile range. Small radar cross section, land mass masking, electronic silence, etc., all act to shorten detection ranges. In such an environment, a gun battle is likely to er>sue in which the PHM will be favored ecause the Mk 75 outranges any poten- ttal opposing patrol boat gun.
The Mk 75 has a water-cooled barrel; hence, there is never a "hot gun,” irrespective of the rate or number of rounds fifed. The safety of this feature and gun reliability to date have made it a favorite w'fh those charged with its operation and maintenance.
The Mk 92 GFCS possesses excellent mdirect NGFS (naval gunfire support) capability. This feature would find usefulness in several mission areas despite fhe fact that it controls but a three-inch Weapon.
The PHM is equipped with an automatic classification esm (electronic warfare support measures) set for missile Earning and over-the-horizon targeting °f enemy surface units. The communications capability consists of HF (high frequency) secure teletype and UHF (ultra-high frequency) voice transceivers and includes a SatCom (satellite communications) mode.
The phm’s size is an integral element °f the combat system and is tactically exploited. Like all FPB’s, the PHM, in the low speed patrol mode, presents a small, ambiguous target, which is difficult to <fetect and equally difficult to classify. Even the radiation of her commercial Italian-manufactured navigation radar is Uridamaging in many environments.
The Pegasus is designed with a high degree of engineering redundancy. Mobility is provided by three independent Propulsion trains. Normal hullborne
HYDROFOIL SYSTEMS
Inspection of the illustrations reveals that the primary difference between surface-piercing foil and fully-submerged foil systems occurs at the penetration of the air/water interface. The lifting wing-structure part of the V-foil operates partially in water with the remainder protruding into the air. Conversely, the lifting surface is completely submerged in the Pegasus-type hydrofoil. This difference results in a dramatic difference in sea-keeping ability, ride quality, maneuverability, and complexity.
The V-foil surface piercing design has been in use for the past 70 years and is used intensively in passenger ferry service (and in some military service) around the world. The surface-piercing hydrofoils are simple, require no attitude controls, and the boat is self-stabilizing. Simply stated, the faster the boat travels, the higher it rises above the water; and, should the boat roll, the increased submerged area of the low-side foil generates additional lift on that side, returning the boat to level. However, when passing through waves at high speeds, the rapid wetting and unwetting of the foil causes a series of lift pulses which result in severe vibrations. Consequently, the boat must slow, and the end result is a craft of little more sea-keeping ability than a conventional displacement hull. Simplicity, smooth water speed, and high payload fraction are the principle advantages of the surface-piercing hydrofoil boat.
The fully-submerged foil is not subjected to the lift-pulse situation because no portion of the lifting wing is ever unwetted. When the ship lists or rolls, there is no automatic restoring force generated as in the surface penetrating foil. Therefore, an attitude control system is necessary and consists of acoustic altimeters, gyros, accelerometers, and hydraulically operated flaps (ailerons) on the foils. This control system provides flying stability, and its presence makes possible two important additional features. First, the ship will bank in turns with turn rates exceeding those of many aircraft. This coordinated turn yields a maneuverability greater than any other ocean-going craft. Personnel and equipment are unaffected by the banked turn and, in fact, are often unable to detect the turning motion. The other feature of this attitude system is the enhancement of high Sea State ride quality. The simple analog computer associated with the system adapts to the sea condition and permits the ship to negotiate extremely large waves and swells by ‘‘platforming’’ them. The control system actions result in varying the flying altitude such that the ship rises only enough to clear a crest then lowers only enough to prevent unwetting a foil. This motion is barely perceptible inside the ship.
This control system technology is derived from the aircraft autopilot and has matured over a 15-year period. Most of the components are variations of their aerospace counterparts and share their high reliability. This technology and reliability have been proven on U.S. military and civilian hydrofoils. The submerged foil system and its controls have been developed primarily in the United States, thus placing the NATO PHM far ahead of any other world hydrofoil.
propulsion is generated by two German MTU 8V331TC8O 670 h.p. diesels which drive independent waterjet propulsors equipped with steering nozzles and reversing buckets. Augmenting hull- borne propulsion and providing foil- borne power is an lm 2500 gas turbine which drives a two-stage, axial flow, 90,000 g.p.m. waterjet pump. The water supply for the foilborne system is drawn up through the hollow after struts, accelerated through the pump, and expelled from the transom. Direct throttle control of each propulsion unit is available below decks at the enclosed operating station (EOS) and on the bridge. A hydraulically-powered bow thruster is provided to assist in mooring. Ship service electric power is supplied by two gas-turbine-driven 400 Hertz generators. Either generator is capable of supplying the ship’s total electrical combat load requirements by a substantial margin. The ship’s hullborne and foilborne mobility are little affected by generator casualties because all control functions are powered by 28-volt battery banks
charged by the propulsion diesel engines. Five salt water cooling pumps are installed but only two are required for normal operations. Foilborne hydraulic systems are 100% redundant, and hydraulic pumps are 200% redundant. The portable damage control pump and the pumps and motors of the bilge system, the chilled water system, and the lube oil system are interchangeable. The examples go on, but it suffices to note that the maintenance of mobility is the least of the PHM operator’s concerns.
All propulsion, auxiliary, and hotel service systems are started, operated, and secured by the one-man operating watch in the EOS. A second watchstander performs logging duties and patrols the normally unmanned machinery spaces.
All machinery spaces are protected by a Halon 1301 automatic fire extinguishing system.
The PHM hull is constructed of high strength, corrosion-resistant 5456 aluminum alloy. The hull exterior is painted; the interior is unpainted and sheathed with decorative paneling in the manned spaces. To conserve weight, the shell plating thickness varies throughout the hull. However, the hull girder remains extremely rigid to resist the stresses of foilborne operations. The hull shape is a compromise; the fine bow promotes good hullborne performance, while the square stern and hard chine minimize high-speed drag during transition to the foilborne mode. The hull contains nine watertight compartments with machinery spaces occupying the after three. These spaces are insulated from the manned compartments by considerable soundproofing to overcome the noise problem common to small high-performance ships. The platform deck, which extends from frame 9 to 25 (one meter frame spacing), forms the tank tops for the four fuel tanks. The hull contains living, messing, and berth- lng spaces. The riveted aluminum deckhouse contains the combat systems spaces and equipment and the captain’s cabin.
The struts and foils are welded and heat-treated 17-4PH unpainted stainless steel. The size and strength of the strut ar>d foil assemblies necessary to support the Pegasus yield the collateral advantage °f object impact resistance. A foilborne PHm should not be damaged by striking a horizontally floating log as large as 20 ‘nches in diameter. The large after foils support 68% of the ship’s weight; the forward foil supports 32%. All foils are equipped with flaps for attitude control—the after flaps (ailerons) maintain r°h control; and the forward flap (elevator) controls depth. The forward strut rotates in response to the degree of hanked turn to maintain coordination between roll angle and turn rate. While rhe ship operates at all times with struts ar>d foils extended—for added stability and controllability—these surfaces can he rapidly retracted for shallow water °peration and for maintenance.
The Pegasus is an all-waterjet-propel- led ship with no screws or rudders. In rhe foils retracted mode, hullborne directional control is maintained by steerable waterjet nozzles and fixed skegs at rhe stern. With foils extended, the large heel-like struts produce a directional rrgidity which reduces the waterjet nozzle directional effectiveness. Responsiveness is restored by selecting the "strut Peering” mode which causes the forward strut to rotate in response to helm commands. Thus, the strut and nozzles combine to produce steering moments f°re and aft for excellent maneuverabil- *ry. The two independent diesels and Waterjets permit opposing thrust for a twisting” effect. With bow thruster assistance, the ship moves handily in and °ut of tight moorings.
Since the after foil tips extend beyond the ship’s side, the ship cannot moor to a flat pier face. The PHM must moor to a barge, an arrangement of camels, or a pontoon section. The Pegasus does occasionally moor at piers-end where the after foil protrudes beyond the end of the pier. However, fore and aft positioning is critical, and this mooring requires a nice bit of seamanship.
The absence of a blade rudder when the foils are retracted requires a change in maneuvering methods. Applying a burst of power followed by a coast with the rudder controlling direction is ineffective with no rudder. Directional control of the PHM is maintained in the coasting condition by putting the helm over and applying a pulse of ahead or astern thrust. The bow thruster is not effective when the ship’s speed is greater than 2 or 3 knots.
Hullborne ship maneuvers are directed by the standard helm commands. All operating personnel wear intercom headsets which facilitate reliable, low noise communications. Automatic logging is accomplished by tape recording the maneuvering circuit.
The Pegasus receives stores and fuel on port or starboard by the normal alongside underway replenishment method. Stores are taken at a station on the 01 level at the mast, and fuel is taken on the main deck at the after part of the deck house. Modified close-in rigs are used with manila highline/spanline. Replenishment is conducted at normal fleet replenishment speed in order to obtain optimum stability augmentation from the foils and flaps. The forward strut, acting as a rudder, provides exceptional directional control due to its massive area. The foil-augmented stability and rudder authority of the PHM give her the capability to replenish safely in higher Sea States than is possible for other 200-ton ships.
Transition from hullborne to foil- borne operation is a simple procedure. The automatic control system (ACS) is turned on and a flying height is selected; the gas turbine is started and a power setting selected; the ship then accelerates, takes off, and establishes steady state. The diesels are supplied with cooling water and may be idled or secured as desired when foilborne. Helm commands vary somewhat from the hullborne condition. For example, the helmsman is ordered to: "Come left at 5° per second and steady on new course 180.” The helmsman rolls the ship with the helm wheel until the ordered yaw rate is established; the banked turn is maintained until the helmsman rolls out on the new course. A "heading hold” circuit is provided to lock-in a compass course. The helmsman is thus freed to assist the OOD with contact evaluation, lookout, and navigational duties. The helmsmen are senior enlisted personnel who receive extensive watch officer training. The helmsman’s duties foilborne are similar to those of a JOOD (or perhaps a copilot).
The PHM navigation suite is similar to that installed in most surface ships, although there are some differences in procedures generated by the platform and equipment capabilities and limitations. The basic sensors consist of navigation or fire control radar video, high- accuracy electromagnetic log, gyro compass, Omega, depth sounder, and dead reckoning tracer (DRT). The PL-41E compass is actually a highly-accurate inertial system which reads out a continuous digital latitude/longitude display as well as course and speed. The Omega also displays latitude and longitude and requires no special charts or other conversion procedures.
Foilborne navigation varies significantly from standard methods. The PHM generally transits to operating areas at speeds well in excess of 40 knots. Mission requirements often route these transits through coastal waters and heavy traffic areas. (For example the Pegasus transited from Seattle to San Diego in 36 hours.) Maintaining a good navigational track over the long term is difficult. The ship travels more than two miles between fixes, and the rapidly changing terrain makes radar and visual identification tenuous.
The procedure evolved (reinvented!) in the Pegasus to gain near real-time information is to use the DRT as a position keeper. The DRT "bug” shining through the nautical chart is updated by fixes to maintain the ship’s position. The precision of the procedure is based on the high accuracy of the log and compass; the success is a function of personnel skills. Because there is no
real-time information on the bridge- other than a radar repeater—the OOD and helmsman are in continuous intercom communications with the navigation station at the DRT. The OOD has an annotated lap chart for verification and identification purposes. It must be emphasized that excellence of foilborne navigation is essential to phm operations. During the first year of operations, the Pegasus steamed over 13,000 miles, of which 33% was at speeds in excess of 40 knots.
The PHM is a minimum-manned ship: four officers and 17 enlisted crewmen. This manning level is sufficient to operate the ship; however, the numbers are quite inadequate to properly maintain the profusion of equipment. The maintenance concept, therefore, follows that most recently used by the U. S. PGs in the Mediterranean. A mobile logistic support group (MLSG) is constituted which contains the principle maintenance assets for the PHM squadron. The MLSG presently operates from six SeaLand-type vans and can support two PHMs. The one officer and 28 enlisted men would eventually be absorbed by the PHM support ship, designated the
AGHS. Although the MLSG performs tender services for the ships, the organizational relationship between the MLSG and the ships is more closely meshed than other tender/ship situations.
The ship’s minimum manning levels result in significant degradations of readiness when a crewman is temporarily lost, e.g. emergency leave, binnacle list, etc. To compensate for this problem, MLSG personnel are trained to fill personnel gaps, thus maintaining the PHM’s full capability. Furthermore, the extensive cross-training required for the PHM crew tends to minimize the impact of personnel losses. The MLSG also augments the security and damage control forces when the PHM is in port.
The repair of PHM equipment is accomplished by modular change-out as much as possible. The MLSG or a depot repairs these modules. All electronic equipment, controls, and systems in the ship have built-in test functions to isolate casualties to the "card” level without test equipment. Thus, test equipment weight and space are saved in the ship. The MLSG is fully equipped with support equipment for more detailed analysis and sub-unit repair.
The PHM lead ship, Pegasus, was launched on 9 November 1974, at the Boeing Marine Systems Company in Renton, Washington. In February, 1975, the ship began an intensive series of tests and trials to verify performance and contractual compliance. From the first voyage, the contractor’s trials crew con- 1 sisted of 50% Navymen from the precommissioning unit. As the weeks passed, the sailors of the precommissioning unit replaced all contractor personnel with the exception of the licensed ship’s master.
The early involvement of the Navy crew was necessitated by the precepts of DoD directive 5000.1, "Fly-before-buy.” Prior to acceptance by the Navy and a production decision for more PHMs, the Pegasus was required to prove that she could perform the missions for which she was designed. This operational eval- , uation (OpEval) is performed under fleet operational conditions while the ship is operated and maintained by the Navy crew without contractor involvement. Should the Pegasus’ performance \ result in a favorable production decision, the Navy’s plans call for an additional five PHMs.
The PHM is a surface attack weapon system which is particularly useful in choke points and in bad weather and low visibility conditions. Consequently the ship is optimized for the barrier , interdiction, search, and surveillance tasks. To give PHM the formidability for these tasks, a new marriage of marine and aircraft technologies has been realized. (
The PHM is the first U. S. surface ship class to attempt the combination of the technological initiatives of the NATO nations. The melding of a high per-
formance platform and a rapid reaction combat system has a synergistic effect. The result produces unanticipated capability; for instance, the Pegasus has demonstrated more antiaircraft defensibility than was predicted. As these unpredicted abilities are discovered and explored, the PHM will likely experience a broadening of her mission areas. Mine warfare and cover-and-deception missions suggest themselves as fertile areas for phm application.
Between the performance envelopes
of displacement ships and aircraft lies the PHM; she shares many of the strengths and some of the weaknesses of each. Applying and exploiting the PHM performance zone in existing scenarios suggests refined tactics. For instance, the tactician will observe that in the allweather surface surveillance role a marriage of PHM and patrol aircraft assets can magnify results. Both PHM and patrol aircraft are cost effective for this mission when their respective optimum design points are exploited—i.e., a large area intermittent coverage complemented by continuous detailed surveillance of interesting or threatening contacts.
The PHM brings to the fleet a new capability which is an extension of the displacement hull ship. More important, the Pegasus class is a precursor of a new type of surface navy—a navy equipped with larger multimission hydrofoils, surface effect ships, and other high performance, high technology combat/ platform systems.
It is the darkest part of the night, and a West German naval cadet is fast asleep to his hammock after a hard day work- lr>g and studying on board the sailing ship Gorch Pock.
Suddenly, a squall comes up and a horn blows, signaling all hands on deck.
Imagine, going aloft in the middle of the night, working your way out on a steel yardarm on rigging no thicker than a man’s big toe, pitching and rolling 100-feet above a raging sea, to furl sails.
"To work the deck is not difficult,” says 20-year-old cadet Richard Seifert.
But to work the sails is.” Pointing to bis arm, he smiles, saying in halting English, "It builds muscles.”
In five to six minutes, the 280-man crew can set all 23 of the 293-foot, three-masted bark’s sails.
On a stormy night, especially in winter, the officers have no second thoughts about sending the crew, many no more than boys, aloft. It’s all part of their training.
Like many of the other tall ships still ,n use, the Gorch Pock’s mission is to tram first-class officers and petty officers. While experience on a training ship does not teach a crew the technique of utodern warfare, it does build character and teach respect and knowledge of the sea.
Some 7,000 sail trainees have gone on to serve the German Navy since the Gorch Pock, named after a German poet’s pseudonym, first sailed in 1958.
"We are not here for show, nor to race, nor to say you are a man because you were on a sailing ship,” says training officer Lieutenant Commander Uwe Schneidewind, a veteran of 21 years at sea. "We are one of the stages a young man must pass in his navy career. We want to show the cadets what teamwork is.”
If a trainee works through the night, whether unfurling the sails or standing a boring two-hour watch, he is still expected to rise at 0630, eat breakfast, scrub the ship, and be ready for morning classes. Sleep is secondary.
And once the cadet leaves his hammock, he cannot return to its comforts until the night. All hammocks are stowed away at 0630. The only place to catch a nap is on the hardwood deck. The space he sleeps in with 20 or more men is also used for eating and for classes.
The German officers realize that the ship is not only the sailors’ home, but also their universe, and to avoid the loneliness that often affects crewmen, they keep them busy.
That’s why the ship is cleaned two, sometimes three times a day. When the cadets are studying, the 80-man permanent crew, much of it composed of draftees, is kept busy working, rearranging the rigging, painting, and chipping. The schedule makes the little free time they get precious.
"Sometimes the work is hard,” admits 25-year-old Klaus Dieter, a petty officer and the ship’s carpenter. "But never mind, you only remember the good times.”
The thrill of sailing, plus the adventure of traveling to foreign ports, draws many of the permanent crewmen to the Gorch Pock.
"You go to sea to be in a port,” says 20-year-old Hans Haemmerling, a medical assistant. "The ports where we’ve been are more exciting than the sea,” adds 19-year-old Fred Demby, a crewman responsible for maintaining the masts. "One of the aims of this ship,” says Lieutenant Commander Schneidewind, "is to see how other people live.”
Since the Gorch Fock has been in commission, she has visited more than 140 ports and traveled 250,000 miles, two- thirds of the time under sail. Recently, she was one of a number of tall ships to take part in the 4 July Operation Sail extravaganza in New York harbor.
During a three-month training cruise, an 18- to 24-year old cadet is expected to undergo 400 hours of classroom study
in seamanship, communications, navigation, and naval emergencies. Classes last for one hour and 45 minutes in the morning and three hours and 15 minutes in the afternoon. And if the studies are interrupted by a port visit, lessons are conducted on the crew’s days off, Saturdays, Sundays, and holidays.
Lieutenant Commander Schneide- wind stresses that these classes are taken seriously. Sometimes, he says, trainees take exams in a buffeting sea, lying flat on their stomachs, feet extended against the nearest bulkhead, while writing on papers a few inches in front of their faces.
Discipline is the key, he says. "We train them much better than a school. I like this job. You can work with young people and force them to do something they are proud of.”
One of the most difficult jobs a cadet must do is to learn to climb the rigging. This phase of his education begins the first day he arrives on board.
"You have to overcome the fear. It’s all you have to do,” says another training officer, Lieutenant Wolfgang
Schramm, who trained on board the Gorch Fock five years ago.
"The first time you don’t feel safe,” says Demby. But, he goes on to say that it takes only two or three days to get into the routine. "Nearly the whole crew likes to climb.” Only one man has died from falling from the Gorch Fork’s
rigging-
For the privilege of being on the Gorch Fock, a trainee receives $380 to $400 a month. If the cadets are to become petty officers, they must serve four years in the navy. For officers, the stay is 12 years.
The age of sail has been referred to as the Era of Iron Men and Wooden Ships. While ships like the Gorch Fock are made of steel instead of wood, and whether they are schoolships or not, the drilling still requires men of iron.
Engineering Readiness Shot in the Arm:
The Propulsion Examining Board
By Commander Richard L. Madouse, U. S. Navy, Served with the Pacific Fleet Propulsion Examining Board (1974-1976); now attending the Naval War College
The advent of the 1200-PSI Propulsion Examining Board (PEB) in November 1972 injected needed adrenalin into the high-pressure engineering plant improvement program and challenged the conventional surface Navy to seriously concern itself with safe propulsion plant operations and sound engineering management. The importance accorded the PEB was reflected in the establishment of the boards on the staffs of Command- ers-in-Chief Pacific and Atlantic fleets, with the senior member reporting directly to the fleet commanders. Through the conduct of light-off examinations (LOE) and operational propulsion plant examinations (OPPE), the Propulsion Examining Boards have been providing their respective fleet commanders with accurate assessments of the material readiness of the 1200-pounders. They have been telling it like it is, and few would choose to underestimate the impact of the boards’ operations.
As the program has expanded to encompass selected high-value, 600-PSI ships, the fleet boards have dropped their initial 1200 PSI designations, and the technical leadership given by the former 1200 PSI Improvement Program now emanates from the Steam Propulsion Plant Improvement Program (PMS-301). Nuclear propulsion examining boards had been functioning on fleet commander staffs prior to the introduction of the examination concept to conventional surface units. Examining procedures employed by both boards are essentially similar. This discourse will focus on the operations of the Pacific Fleet Propulsion Examining Board and will treat only examinations conducted >n the 1200-pound inventory. At this writing the 600-pound program is still ln its early stages with base-line examinations being conducted to provide clearer definition of the course to be followed in the months ahead.
The emergence of the PEB coincided with our Readiness Improvement Program, following relief from the Navy’s burdensome Vietnam commitments. This was the time of rededication to an mvolvement with all the details of sound shipboard material management, details which had been routinely ignored ln the interests of quick deployment turnarounds, throwing more five-inch projectiles into the Vietnam country- S1de, and pursuing a counterproductive attempt at six-section liberty during brief home-port periods. The time was nght for an in-depth examination of our propulsion plants, but few ship drivers Were ready for the shocking consequences.
The "can do” approach almost ruined the destroyer force. External direction of such an engineering readiness degradation was distressing enough; endorse- tuent of the "can do” philosophy by far too many commanding officers only compounded the misery. In defense of the skippers, they probably had little choice. Regrettably, however, this endorsement often represented a crutch to screen-out absence of command involvement and a pronounced weakness ln deck plate knowledge.
We were granted an opportunity for a can do” reassessment in the Pacific Fleet in early 1973 when the first operational propulsion plant examination was conducted. The debacle that ensued prompted the ship’s squadron commander to conclude the board’s critique With the observation that never before *ri his naval career had he been subjected t° such humiliation. "Can do” died a fitting death. Someone had finally told it like it was.
A second unsatisfactory OPPE made it dear that although the PEB was ready to meet the fleet, the reverse was subject to discussion. A three-month moratorium on examinations was imposed in favor of an Assist Visit Program. Each ship in the fleet’s 1200-pound inventory was the recipient of a short visit during which board members provided an introduction to PEB examination methodology, and offered a snapshot assessment in the areas of engineering administration, training, material condition, cleanliness, and preservation. The compilation of results was far from encouraging and served to bring into sharp focus the alarmingly low state of engineering readiness that existed in the immediate post-Vietnam period.
We would have been well advised to forego the Assist Visit Program, for it failed to bring about any improvement in readiness; it only postponed the embarassment. There was some initial shock value, but management levels within and external to the ships visited apparently were united in their reluctance or inability to move out smartly and positively prior to nomination for an actual examination.
With the reinstitution of examinations in May 1973, the Pacific Fleet program officially got under way. It was slow, and it was painful. Complaints were registered that all of the fleet’s 1200-pounders would soon be shut down or under some form of steaming restriction. These fears were a bit premature, and the PacFlt PEB’s tough stand was misread by many as indicative of the program being thoroughly bogged down. In actuality, there was a scheduling problem. The type commander simply was not nominating his ships to the fleet commander, perhaps reluctant to do so in view of the initially high rate of unsatisfactory findings. But the board’s insistence on rigid application of fleet standards eventually produced handsome dividends.
Despite being attached to the fleet commander’s staff, the PacFlt PEB does not make its home in Makalapa, Hawaii, but rather at the San Diego Naval Station. With 68% of all Pacific Fleet 1200-pounders homeported in San Diego, this is the natural base of operations. The ten-member, all-officer board represents a significant level of high pressure engineering and ship driving expertise. The senior member, a captain, has, as a minimum, served as engineer officer of a 1200-PSI ship and as commanding officer of a 1200-pounder. His qualifications are matched by those of the deputy senior member, another captain, and two commanders. Anyone of these four senior officers may function as the senior examiner for a particular examination. Remaining board members consist of four lieutenant commanders, one of whom is an engineering duty only officer, and two lieutenants. A tour of duty as an engineer officer of a 1200- PSI ship is a minimum prerequisite for each of these officers.
The chartered mission of the Propulsion Examining Board is to examine ships to ensure that strict adherence to 1200-PSI propulsion plant readiness standards is maintained and that these plants are operated safely and properly. The board’s examination responsibilities cover four areas:
► Examine the material condition of the propulsion plant to ascertain its state of operational readiness, cleanliness, and preservation.
► Examine engineering personnel assigned to the underway watch bill by means of oral interviews and written examinations to determine their level of plant knowledge.
► Witness and evaluate the conduct of propulsion plant casualty control drills to provide the deck plate performance input to an overall evaluation of the state of training and watch qualification.
► Review and evaluate the ship’s engineering department administration.
An operational examination is more than verifying that most of the main steam leaks are eliminated and the bilges reasonably free of oil. The examination focuses on a totally managed approach to engineering readiness and, as such, demands that emphasis be applied to all parts of the engineering readiness loop.
An OPPE is scheduled within six months after a light-off examination, placing it in the post-overhaul operational workup immediately after the first phase of refresher training. Operational re-certification within 12-15 months is required. For all high-pressure plant ships, except aircraft carriers, the OPPE is completed within three days. An extra day, perhaps two, must be added for carrier examinations.
The board’s meticulous approach is directed toward gaining accurate answers to the following questions:
^ Is the ship adhering to her promulgated procedures?
► Does the engineering department have three qualified watch sections?
► Do all propulsion plant systems and equipments operate properly, or are they merely getting by?
A light-off examination during a ship’s regular overhaul covers about a day-and-a-half and the same areas are addressed with the exception, obviously, of casualty control drills and a hot plant material examination. The specific purpose of the examination is to certify the propulsion plant safe to light off. No torch is placed in a boiler during the LOE.
Since the senior member of the Propulsion Examining Board reports by message directly to the fleet commander-in-chief on the results of each examination, he must arrive at a finding on a particular exam. There are three evaluation categories, defined as follows:
► Satisfactory—Ready for Unrestricted Operations (or for Light-Off): Minor deficiencies may exist which reduce the effectiveness of the propulsion plant, however the deficiencies do not appreciably affect the ship’s ability to safely steam and conduct operations appropriate to her mission and/or maintenance status. Essentially, a Satisfactory finding means a clean bill of health for the ship’s engineers until the subsequent re-certification.
► Conditionally Satisfactory—Operational
Limitations Recommended: Deficiencies
exist which are of such significance that authorization to continue propulsion plant operations should be subject to specific limitations. The examination message report will identify these deficiencies (or aggregate of deficiencies) that require corrective action to attain a satisfactory evaluation and will recommend specific operational limitations. A ship that has received a Conditionally Satisfactory evaluation has not passed the examination. There may indeed be many significant deficiencies that preclude the ship from performing unrestricted engineering operations, or only a very few clear-cut deficiencies that frustrate a satisfactory evaluation and correction of these could well be certified by someone other than the PEB. The senior examiner must recommend whether or not a re-examination is required. And, a follow-on look by the board is not automatic, but in the vast majority of cases will occur.
► Unsatisfactory—Not Certified for Propulsion Plant Operations: Deficiencies exist which are of such significance that propulsion plant operations are considered unsafe. The examination message report will identify each deficiency (or aggregate of deficiencies) which contributed to the finding. A finding of Unsatisfactory requires the suspension of propulsion operations. A plan of corrective action addressing those major deficiencies that prompted the finding is required from the type commander. This plan must address correction of any restrictive material or training items called out in the message report prior to granting permission to relight fires in any boilers. Following resumption of hot plant operations, specific alongside training may be necessary before returning to an underway status. A reexamination by the PEB is required following such a finding.
The PEB examination concept in the Pacific Fleet is at a critical juncture. The effort is now in high gear despite the fact that, at this writing, four ships in the 1200-pound inventory have yet to be exposed to the board. Overall material conditions have substantially improved, yet a disappointing number of Unsatisfactory findings continue to be adjudged. At the three-year point, when one would expect the positive dividends of the program to place the PEB out of business in another two years, the need is greater than ever to keep applying the pressure.
Regrettably, there are those who would prefer the program to go away. Fortunately, the membership in this club is relatively small. The thinking among this group is that it was far more comfortable inspecting each other the "way we’ve always done,” with "Yes- No” check-off lists and a nice pat on the back, avoiding the unpleasant mention of unpleasant details. What we didn’t need was this board descending on us and then reporting by message to the fleet commander on the actual conditions observed.
Perhaps this same nucleus of negative concern gave birth to the phrase "PEB standards.” No commanding officer or squadron commander who professes a dedication to the principles of good engineering practice should ever endorse this phrase. There are no PEB standards. The PEB is performing a function which was directed by the Chief of Naval Operations because the type commanders themselves were not doing the job, and is doing nothing more than measuring readiness of the fleet against standards that have been long established by the CNO and the Chief of Naval Material.
There is a clear realization that all ships have not marched out smartly to attain the desired level of engineering readiness. But there is an equally clear understanding of reasonable progress that should have been made in ships of a particular class and age.
Our 1200-pound carriers were very reluctant to join the program. The unsafe propulsion space conditions observed in early carrier examinations bordered on criminal. For some reason carrier sailors seemed possessed with their "bigness,” convinced that their unique problems are so big as to defy effective management. This feeling was certainly conveyed by carrier engineers on numerous examinations. Since oil on the deck plates, 1200-pound steam leaks, inoperative safety devices, and operating machinery outside design parameters and with grossly contaminated lube oil were accepted as routine, seasoned officer and senior enlisted engineers, who should have known better, simply failed to recognize how far they lagged the rest of the fleet. It is no secret that the Propulsion Examining Board had to resort to a double standard in the interest of completing previous carrier examinations, foregoing the walkoff—the PEB debarks before the examination is completed because conditions are in an obvious unsatisfactory state—that would have occurred if similar conditions were identified in a destroyer. Fortunately, a healthy engineering operational awareness has emerged in the carrier community, and recent shipyard light-off examinations have indicated that these plants can be granted the same positive starting point as our destroyers.
Ship age and class notwithstanding, the broad fleet visibility afforded the PEB quickly puts propulsion housekeeping in
proper perspective. When tender care and feeding has been the order of the day, the results will be obvious. Conversely, if the disaster "did happen on your watch,” the message will be unmistakably clear.
The upgrading of material conditions has not been matched by a correspond- *ng improvement in deck-plate training. Personnel stability haunts us, and we persist to be our own worst enemies in distributing people. Ships are not scheduled at sea specifically for engineering training. Too many commanding officers fail to seize the opportunity to light-off their plants periodically during in-port periods for hot-plant training. People come and go during all phases of the operational cycle. Quality of training suffers badly. The change of watch syndrome sends ships back to square one. Too frequently, the end result is a training debacle at OPPE time.
Two recommendations are offered tvith regard to examination evaluation categories:
► Eliminate the Conditionally Satisfactory finding and return to the SAT/UNSAT approach. The introduction of this gray area finding has done much to impede program progress. The connotation of Conditionally Satisfactory is that "you’re almost there.” In most cases this is far from the truth. The operators tend to view the finding as a victory, and the type commander has been guilty of professing the Conditionally Satisfactory level to be his goal for many ships. "Let’s get him Conditionally Satisfactory and then we can deploy him,” has been the recurring theme. Too many ships have deployed in that category and have remained in this uncertified twilight zone for many months prior to the scheduling of a ^-examination.
►With a return to the SAT/UNSAT category of findings, then we should reword the peb charter to redefine the Unsatisfactory finding. The automatic propulsion plant shutdown, the requirement for permission to light-off, and the formation of an extensive plan of action prior to resuming underway operations should be abandoned in favor of an approach that would allow the PEB senior examiner to make whatever operational restriction recommendations he feels are warranted on a particular examination. The present definition of an Unsatisfactory finding is too rigid. Some of the stigma of such a finding should also be removed. The senior examiner who adjudged the finding is also in the best position to recommend the appropriate get-well course of action.
What does the Pacific Fleet examination track record reveal? As of 1 April 1976, the PEB has adjudged nine Unsatisfactory findings on light-off examinations. Only two of these occurred since 1 January 1975, indicating that shipyards and ships’ force have profited from lessons learned. Thirty-seven Unsatisfactory findings have been adjudged on operational propulsion plant examinations. Sixteen of these occurred since 1 January 1975, and four during the first three months of 1976. The same heartening percentage improvement on LOEs is not evident on OPPE results. Of 68 ships on the PacFlt 1200-pound roster, nine claimed the distinction of attaining a Satisfactory OPPE finding on the first try. In addition to realizing a great deal of well-deserved self-satisfaction, these nine ships shattered the ridiculous illusion that the examination was designed not to be passed.
The PacFlt PEB consistently has taken a firm stand and never backed away from fleet standards. If it appears to some that the board’s position in recent months has hardened, then perhaps consideration should be given to the increased level of board members’ expertise in performing their job, and to the understandable disappointment over ships that "peak” for the examination then silently slip away from the pier, and to the equally disappointing absence of progress noted on some follow-on examinations. There is no joy when a ship fails. It only means more travel and more work for the board on a re-exam. PEB members share in the satisfaction experienced by a team of engineers knowing they have put it all together.
Hopefully, the fear associated with the PEB that dominated the scene for an extended period, precluding timely nomination for examination and clouding pre-exam assessments, is gone. It is time to ensure that each ship is nominated for examination in accordance with the provisions of the OpNav Charter, and, where re-examinations are required, that they be scheduled on a priority basis, again as required by the OpNav Charter. Each ship rates its turn at bat and being granted an unrestricted steaming certification on a punctual basis. There is no valid reason why the PEB senior examiner’s message report should have to "tell it like it is” in response to some of the lies that were told and secrets that were kept prior to the board’s visit. This only places the ship’s skipper between a rock and a hard place and brands the PEB as the bad guy.
From the standpoint of the PEB itself, it should not matter what the causes are for a lowered condition of readiness. It is the responsibility of the type commander and the fleet commander to determine these underlying reasons. The practice of inferring that the PEB is some kind of a bogeyman, administering some sort of an inquisition, should be put aside. Whatever pressures have been brought to bear on type commanders and on ships has not been generated by the PEB. The pressures have been generated within the ships themselves and by echelons of commands above them.
Examinations administered by Propulsion Examining Boards in the Atlantic and Pacific fleets still constitute the solid foundation of the Steam Propulsion Plant Improvement Program. The examination concept is meaningful because it’s unique. It addresses details; it stresses basics; it demands that we take our own engineering readiness standards seriously; and there is follow-up action. The effect of the program on the deck plates is definitely positive and represents the best friend the working engineer has seen in many years. It would be difficult indeed to not get a very positive feeling about the program when one sees first-hand the refreshing starting point our engineers now have well in advance of the final day of regular overhaul. They simply had very little going for them prior to the PEB concept.
The examination effort is clearly in consonance with one of our most important goals: to vigorously upgrade material readiness. This all-Navy evolution deserves the sustained support of all levels of command until such time as substantially higher levels of engineering material and training readiness dictate otherwise.
There is a current revival of interest, both in the United States and in Europe, in the use of lighter-than-aircraft (LTA) as a commercial cargo hauler or as a passenger aircraft. This has been motivated by the search for a vehicle that could haul bulk freight with the minimum expenditure of energy; that is, achieve the maximum value of ton-miles of cargo moved for each BTU of fuel consumed. At the same time, a vehicle is being sought that minimizes the emission of pollutants and is environmentally acceptable. The large rigid airship looks very promising under both of these criteria. Only economic feasibility remains to be demonstrated.
Accordingly, it seems an appropriate time to reexamine the possible applications of rigid airships in today’s Navy. Lighter-than-air has been an integral part of Naval Aviation during much of its history, although it was often considered as a stepchild, or worse. Nonrigid airships (blimps) were used during the period between World War I and World War II and had a distinguished record as convoy escorts in World War II. They were continued in use in ASW and AEW roles until the early 1960s.
There have been no large rigid airships in the U. S. Navy, however, since the loss of the USS Macon (ZR-5) in February 1935, although the USS Los Angeles (ZR-3) remained in inactive service for a few more years. Is it possible that a vehicle type that has not seen operational service in 40 years could once more be gainfully employed in our modern Navy?
Any discussion of the use of airships in military operations must first address the question of the vulnerability of these large vehicles. This has always been a foremost argument against the military use of airships, both rigid and non-rigid. It should be remembered, however, that the military rigid airship evolved during World War I as a bombing platform designed to operate against formidable opposition, and at that time the lifting gas used was highly flammable hydrogen! The airship eventually lost the battle to become a first-line bomber or dreadnought of the skies, and has never since been considered seriously as a combat vehicle. Current technology has not reversed this decision but has contributed to the improvement in expected survivability when the airship is used in military support roles such as cargo transport or in other possible missions to be suggested.
From a technical aspect, the large rigid airship could probably sustain hits from a number of air-to-air missiles or surface-to-air missiles without serious consequences. In this respect it is much more survivable than a C-5A, for example, where a single missile hit would normally be catastrophic. Damage control is feasible in a rigid airship since all of the structure and the gas cells are accessible to repair parties in flight. Even more important is the fact that the airship can be equipped with a very credible self-defense capability. This could consist of early warning and fire control radar, anti-air and anti-missile missiles, ESM (electronic warfare support measures) equipment and a variety of ECM (electronic countermeasures) suitable to the threat.
In spite of this capability to sustain damage, to conduct in-flight repair, and to provide for its own self-defense, prudent military operation would not permit the airship to be used in situations that were beyond its limited combat capabilities. In short, the answer to achieving acceptable levels of survivability lies in employing the airship in missions for which it is particularly suited, and in tactical environments for which it has been designed. In this regard the vulnerability aspects of a rigid airship are no different than a C-5A, a B-52 bomber, a CV, or a large surface troop transport. Each of these vehicles must be operated in a tactical environment for which it has been designed if an acceptable level of survivability is to be attained.
Aside from its role as a cargo carrier and troop transport, the military applications of the large rigid airship seem most appropriate to the missions of the Navy. The over-water (and over-ice) environment has traditionally been most suitable for airship operations. It should also be noted that the airship is basically a low-altitude vehicle. It can be operated with best efficiency at altitudes below 10,000 feet. These inherent characteristics cause the military roles of the rigid airship to gravitate toward the recognized Navy missions. The evolving mission of sea control appears to be most suited to the capabilities of the large rigid airship. This mission is perceived as the capability to gain control of the sea in any designated area of the world, including the surface, air, and subsurface domains, and to deny the use of such an area to enemy forces.
The sea control mission requires, as a prime necessity, the capability to conduct surveillance of wide areas of the open ocean. This capability must include surveillance of the ocean surface, the air (and perhaps space), and the subsurface if the entire threat spectrum is to be covered. It is in this role of ocean surveillance that the large rigid airship is best suited and in which its military effectiveness might best be applied.
Surface surveillance is a relatively straightforward task that has become increasingly important, as the size and military effectiveness of Soviet surface forces continues to grow at a geometric
rate. The large rigid airship is ideally suited to conduct surface surveillance because of its size and shape. Using the lrr>mense sides of the airship, a phased array radar could be designed of unprecedented power and performance capabil- “y- This would permit the airship to 'Maintain surface surveillance over extremely large ocean areas. The airship ba'ght also be used as a platform for
surface surveillance sensors other than conventional radar as the tactical situation might warrant. Such sensors include infrared (IR), ESM, HF/DF, and over-the-horizon radar.
The effectiveness of the airship’s surface surveillance capability might be further enhanced if suitable classification or intelligence of detected targets is available. This would permit the airship to assume an offensive role by firing air-to-surface missiles at targets identified as unfriendly. Alternatively, the airship might launch its own aircraft to classify and attack detected targets. The use of aircraft might also be considered when the tactical situation indicates that the use of the airship’s high-powered surveillance radar would not be prudent due to the high threat level. In this case the airship would assume a condition of electromagnetic emission control (EMCON), and aircraft would be launched to conduct surveillance of the assigned area. In this situation the airship would still function as an airborne command and control post to receive and assess the surveillance information as it is transmitted from its aircraft. The parallel to surface aircraft carrier operations is obvious.
Use of the large rigid airship as an aircraft carrier was a U. S. Navy development that was an integral part of the Akron's and Macon's capabilities. Both of these airships were designed to carry a complement of five (then) modern reconnaissance aircraft, and routinely launched and recovered them in fleet exercises. This capability could certainly be extended to include current fixed- wing carrier aircraft and, perhaps, remotely-piloted vehicles (RPVs) and helicopters as well.
In the air surveillance task the airship would continue to act as a platform for very high-performance radar (and other sensors). Against manned enemy aircraft the rigid airship might also be used as an offensive weapon system in addition to its surveillance role. Air-to-air missiles could be launched against detected targets at stand-off ranges approaching the detection range of the radar. Or interceptor aircraft might be launched and vectored to conduct the kill with their own air-to-air missiles.
The large rigid airship would provide a multiple capability against the cruise missile submarine threat. The airship offers a capability to accomplish underwater detection of the submarine— this is discussed further in regard to subsurface surveillance. It also can contribute to the denial of targeting intelligence to enemy reconnaissance efforts. Additionally, the air surveillance capability of the rigid airship permits it to detect the cruise missile after it has been launched. This allows early warning of an attack to be given to the threatened forces and alerting of their area and point defense units. The airship might also take an active part in defense against the cruise missile by launching appropriate intercepting missiles, or vectoring CAP (combat air patrol) aircraft to an intercept position. Electronic warfare measures could also be directed against the cruise missile from the airship platform.
The air surveillance capabilities of the rigid airship could also play a vital strategic role. In this mission the airship would provide early warning of manned bomber attack in the same manner that Navy and Air Force radar pickets were used for many years. In fact, the last squadron of Navy non-rigid airships (ZPG-3Ws) was designed to perform this mission. The rigid airship would be vastly superior to both the blimps and the fixed-wing aircraft due to its much
longer endurance and improved radar performance.
The rigid airship would also provide a means for detection and early warning of ballistic missiles fired from submarines. The air surveillance capability of the rigid airship would provide for a significant improvement in available early warning time to CONUS defensive forces. Further, if the airship can also conduct suitable subsurface surveillance, it provides a platform for launching counterweapons against both the firing submarine and the missiles during their boost phases. The ballistic missile is most vulnerable to attack during the boost phase where its speed is low, exoatmospheric conditions do not apply, and a large IR signature is available to an intercepting weapon. It would also be feasible to design a rigid airship to detect submarine-launched ballistic missiles in their mid-course trajectory, and to launch suitable interceptor missiles.
Underwater surveillance is the third domain in which the rigid airship could contribute to accomplishment of the sea control mission. In this role the airship could be employed in several ways. It could be used to emplace and monitor large fields of moored sonar buoys in specific ocean areas where it is desired to establish a high level of underwater surveillance. The airship would monitor the buoy fields, classify and correlate detections, and vector ASW forces to accomplish localizations and attacks against threat submarines.
These ASW support forces might take the form of ASW aircraft operated from the airship itself. The airship would be capable of recovering and replacing surveillance buoys that fail, are damaged, or drift from their desired positions. Maintenance facilities could be carried aboard the airship.
The rigid airship might be operated entirely as an ASW aircraft carrier (CVS) in order to accomplish the underwater surveillance role. In this mode the ASW aircraft would employ their own surveillance sensors in open ocean search. The airship would launch and recover the aircraft, provide facilities for maintenance and stores, and function as the command and control center for the search, localization, and attack operations. Since the dedicated ASW aircraft carrier has been replaced the CV concept,
the rigid airship ASW aircraft carrier could provide a means of returning to a single mission ASW carrier, and without the need for accompanying destroyers or underway replenishment groups, h would again provide the Navy with a capability to conduct offensive ASW operations in the open ocean as opposed to the basically defensive posture associated with the CV concept. This hunter-killer type of operation proved to be very effective in the attrition of German submarines during World War II.
Another mode in which the rigid airship could be employed for underwa- i ter surveillance would be as a platform to tow horizontal linear passive sonar ' arrays. Such arrays could be designed with an extremely large aperture, essentially to the limits of the environment. Improved performance would result further from the fact that the interfering radiated noise of the towing ship would j be eliminated. The resulting performance characteristics in terms of sweep rate should greatly exceed any other type of available platform-passive sonar system. The airship, once again, could carry its own ASW aircraft to localize and attack detections that are made, or it could vector other ASW forces to the , scene.
The use of towed array systems with rigid airships seems especially suited to the task of maintaining surveillance on Soviet ballistic missile submarines. Cou- ■ pling this capability with a boost phase intercept system, as indicated above in the discussion of air surveillance applications, would result in a particularly effective employment of the rigid airship’s attributes.
Finally, the airship appears to be eminently suited to perform command and , control tasks, either in conjunction with a specific surveillance role, or as an airborne mobile command and control post. In this latter task the airship would serve as the central command post and j the operational control center for a designated sector of open ocean. The airship is large enough to house the most sophisticated communication equipment, computers and ancillary software, analysis and display equipment suitable for a major fleet command. The mobility of the airship would permit the area commander to remain literally "on top’ of the situation in his assigned sector.