A bugle call resounds throughout the ship followed by the word being passed over the loudspeakers, “Man All Flight Quarter Stations.” There is the familiar beehive of activity throughout the carrier in preparation for the launching of the day’s strike. These activities—carrier aircraft operations—were a daily routine during World War II, and so they are today. Many aspects of these operations and of the equipment aboard today’s carriers, however, would appear strange and unfamiliar to the naval aviator of World War II. The problems involved in modern carrier aviation transcend in magnitude and hazard the problems that were experienced in the past.
World War II
During World War II, naval aviation and carrier operations rapidly came to the front as the primary method of conducting sea warfare. To achieve this rapid advancement and expansion required the all out efforts of the Bureau of Aeronautics and the Bureau of Ships. In a span of a few short war years, a decade or more of research and development was accomplished. Through these efforts, the carrier became one of the outstanding naval developments of all time.
In World War II, flight operations involved only the conventional reciprocating- propeller driven aircraft. These aircraft were relatively light in weight and slow in landing and launching speeds in comparison to the aircraft of today. Without the need for radical new developments, the launching, arresting, and landing equipment were modified and enlarged to meet and fulfill the new wartime requirements. The flight deck personnel operated the equipment under established procedures born of long years of experience. The pattern of operations was firmly established; for the flight deck operated as safely, smoothly, and efficiently as was expected. Most of the problems that arose from wartime around-the-clock operations were solved by changes in technique or procedures.
One of these extensive problems was the continuous night operations encountered in the Navy’s first night carrier, the U.S.S. Independence, during the last six months of 1944. Specially qualified night pilots had to develop new operational techniques. Even with these trained pilots, the flight deck personnel, operating in all weather conditions, were faced with frequent deck crashes. Knowing that a poor landing at night would result in a barrier or more serious crash produced a detrimental psychological effect on the pilots.
The only known or used method of landing aircraft was up the centerline of the ship or flight deck. Now, as it was in World War II, each flight deck is divided into three distinct regions as shown in the illustrations. The after two-fifths of the flight deck is the touchdown or landing area with its arresting wires. The next fifth of the deck is the barrier and barricade region—the emergency arrestment area—in which are erected steel wires and nylon rope webs to prevent an aircraft which missed the arresting wires from rolling on into the third region. This last region or forward end of the flight deck is the parking area. In the parking area, aircraft are serviced or are parked waiting to be struck below to the hangar deck via the elevators.
Since the only method known for landing airplanes on a carrier was up the centerline of the ship, directly toward the barrier and parked areas, there appeared to be no final, or complete solution to some of the operation problems that resulted in serious and crippling crashes with loss of lives and untold millions of dollars in equipment and aircraft; and the loss to the fleet commanders of the availability of aircraft when they were vitally needed in the war effort. One such problem to which no ready solution appeared available was the protection of the flight deck personnel and parked aircraft from rockets or bombs that were jarred loose from the pylons of a landing aircraft and skidded along the deck into the parking area. An additional unsolved danger that threatened the shipboard personnel was the inadvertent triggering of the machine guns from a landing aircraft that sprayed death up the deck. Another major serious problem was the direct result of poor landings or hook bounces which often permitted the landing aircraft to go through or over the barriers and crash into the parking area. These and other problems that could not be solved satisfactorily came to be accepted as operational hazards that were a part of naval aviation.
Post War Trend
Since the war, naval aviation has undergone many radical changes; a new and different era of naval aviation was underway —the “Jet Age.” Aircraft development was not only rapid, but was aimed at the introduction of the new jet-propelled aircraft to the fleet. There were great increases in the aircraft performances which were accompanied by a substantial growth in the size and weight of the carrier aircraft. With the jet aircraft, there was also a very rapid increase in speeds—launching, arresting, cruise, and maximum speeds.
The growth and development of the aircraft carrier did not keep pace with the growth of the modern aircraft. Since the length of the carrier decks could not be extended, the areas for landing and launching aircraft could not be increased to keep pace with requirements imposed by aircraft growth. It became necessary to land the heavier, faster jet aircraft in virtually the same arresting area that was taxed by the propeller-driven aircraft of World War II.
To bring the heavier aircraft with their increased touch-down speeds to an arrested landing, the capacities of the arresting engines have had to be increased many fold. However, to prevent too large an accelerating load from being placed on the aircraft structures, the effective runout—landing roll after the aircraft has engaged the arresting wire—of the arresting gear has been increased to the limit permitted by the landing area; any further increase will decrease the area for parking. Requirements for further increase in runout of the arresting wires are rapidly approaching if higher deceleration stresses on the aircraft and a resultant “beef-up” in the aircraft structures are to be prevented. Thus, the Navy has been faced with the problems of endeavoring to provide on a ship of constant length longer landing and barrier areas, and at the same time to insure increased safety and protection to the operating personnel and equipment during landing operations.
The problems of protection of personnel and equipment during the landing operations with jet aircraft have increased and become more difficult to solve. The problem of emergency arrestment of the jet aircraft with their tricycle landing gear has been indeed great. With jet aircraft there has been a marked increase in barrier crashes. A failure to arrest these aircraft in the barriers has led to an increase in the far more serious type of crash, i.e., the landing aircraft crashing into the parked aircraft and the flight deck servicing crews. The likelihood of this type of crash has been radically reduced, but not eliminated, by the development of two new safety devices.
The Davis barrier, for example, was developed to replace the conventional wire barrier which was an emergency arresting device utilized to stop the propeller-driven aircraft of the past war. This new development was required because World War II wire barriers had a tendency to ride up the nose of the low slung tricycled jet aircraft and smash the cockpit, with a fair chance of the pilot being decapitated. The Davis barrier is actuated when the nose wheel of the aircraft strikes an athwartship nylon strap. Through vertical lift straps attached to the barrier cables lying on the deck, the nylon strap flips the barrier cables that are attached to arresting engines up in front of the airplane’s main landing gear, arresting the aircraft. If the nose wheel cannot be extended due to battle damage, hydraulic failure, or other reasons, the aircraft probably will not actuate the barrier. This has resulted in the landing aircraft’s going into the parking area and causing widespread destruction. Neither this barrier nor any other reasonable one can stop an aircraft that bounces too high and jumps over it.
In an effort to preclude, if possible, or at least reduce, these costly landing accidents, the Bureau of Aeronautics developed a “barricade” to go between the barriers and the parking area, in order to protect primarily the personnel and planes in the bow, secondarily the pilot, and last the landing airplane. The barricade, which has been installed in all but two of the Essex class carriers, is essentially a nylon web wing retardation method of arrestment, i.e., the nylon web wraps around the wings and arrests the airplane. The energy required to bring the airplane to a stop is absorbed by the conventional hydraulic arresting gear engines to which the nylon webbing is attached. Although damage to the airplane was a tertiary consideration in the original design, aircraft have suffered only minor damage in barricade arrestment while not only protecting the bow of the carrier but also safeguarding the pilot as well. In the past nine months, the barricade has successfully arrested errant airplanes on several occasions and prevented what would have otherwise been catastrophic crashes into the parked aircraft. However, like the Davis barrier, the barricade has its functional limitations. The design had to be geared to reasonable engaging speeds, strength, and permissible runout of the gear. Death and destruction have already resulted in one case from an airplane’s flying through the barricade at a speed far in excess of the designed engaging speed. However, through the all-out efforts of the Bureau of Aeronautics, the Fleets, Naval Air Material Center, Naval Air Test Center, the Office of Naval Research, and the concerted effort of industry, the fatal and destructive bow crashes have been greatly reduced in number and probability, but they have not been eliminated. The job, then, was not complete.
Within a few years after World War II, the requirements placed upon the launching and arresting equipment by the advancements in jet aircraft designs far exceeded the existing capabilities of the gear. An accelerated development program was undertaken and a vital race was underway. As soon as new equipment was designed and under manufacture it would rapidly become outmoded. New arresting engines with greatly increased capacities are currently under procurement that will meet the demands now placed upon the arresting equipment by current aircraft developments. The situation for catapulting some of the new jet aircraft and some heavy reciprocating-engined aircraft remained critical. For even before new designed hydraulic catapults with their increased capacity could be installed aboard carrier conversions in 1952, they had become marginal in capacity. In the spring of 1952 at the request of the U. S. Navy, the British Admiralty sent H.M.S. Perseus to Philadelphia to demonstrate the new British designed steam catapult. The modern steam catapult and the armored flight deck were first developed by the British. The successful tests of the steam catapult resulted in the adoption of the basic British designs. The modified British steam catapult under development and manufacture for the carrier conversions programs and for the new CVA- 59 class ships (Forrestal and Saratoga) have sufficient excess capacity to handle the aircraft under procurement and permit a greater flexibility of operations.
In spite of the rapid advancement in the launching and arresting fields, the situation still remained critical. A vital factor has been the space available for aircraft launching and recovery operations. The runways of land based airfields rapidly increased in length in order to accommodate jet aircraft; but the carrier’s flight deck remained fixed in length, and at the same time was required to accomplish now with jet aircraft the same functions it performed in World War II. While these functions were carried out despite the many problems involved, the trend in aircraft design and earlier equipment indicated the need for a new carrier design.
In addition to the space factor, the situation in regard to the protection of personnel and equipment remained serious. As long as the aircraft parking area remained in the projected flight path of the landing aircraft, serious crashes were a possibility. Further, loose bombs and triggering of machine guns still had to be coped with. If carrier operations were to be conducted with new, heavy, high speed jet aircraft, using existing concepts and procedures, the operational hazards and problems associated with naval aviation would increase in scope. Something had to be done to increase the operational flexibility and safety of carrier aviation. The pressure of the situation forced a complete re-examination and re-evaluation of all concepts of carrier operations and of the potentialities of radically new and different types of carriers.
The U.S.S. Forrestal (CVA-59) with its increased deck length and increased number of catapults provided the solution to some of the problems. Only three ships of this class have been authorized. The same operational problems still confronted the Navy in regard to the other carriers in operation and in mothballs.
Courses of Action
One course of action is to accept aircraft whose potential performance is limited by the existing capabilities of the aircraft carriers in operation. Aircraft designers have been forced to compromise in the past to fit the aircraft to the environment of the carriers; but to continue to base aircraft design on the capabilities of the carriers of World War II is unsatisfactory and unsuitable. It is mandatory that the Navy have aircraft whose performance criteria are equal to, or better than, those of land-based aircraft.
Another course of action available is to reduce the aircraft complement to the number that can be accommodated in the hangar. This would eliminate the necessity of barrier and parking areas and, consequently, the costly bow crashes. Further, longer runouts of the landing could be obtained. To keep the bow clear under this plan, landing intervals would probably have to be increased to permit each aircraft to be struck below before the next aircraft lands. The biggest disadvantage of this course of action is the decrease in the carrier’s aircraft complement and the reduction in the task force’s striking power. This course of action is feasible, but the slower landing interval and smaller aircraft complement are not acceptable.
Another course of action is to provide existing flight decks with adequate catapult and arresting capabilities by replacing existing equipment with new catapults and arresting gear of higher capacity. In this case, the hazards and problems associated with landing high-speed jet aircraft straight up a limited deck would have to be accepted. This has been done in the past and is being done now—but the cost in flexibility and safety are rapidly becoming too great.
The fourth and most promising course of action is now under test aboard the U.S.S. Antietam. It is a new carrier deck concept, known as the “Canted Deck.”
The Canted Deck
During a conference with a British Admiralty exchange team in the fall of 1951, the deck layout of the new Forrestal class carrier was under discussion. One of the members of the British team remarked that the extension of the flight deck at the port and starboard sides closely followed a new type of landing area conceived and proposed by Mr. L. Boddington of R.A.E., and Captain D.R.F. Campbell, D.S.C., R.N. The personnel of the Ships Installations Division, Bureau of Aeronautics, under Captain Sheldon W. Brown, U.S.N., recognized this suggestion as having great promise as a possible solution to many of the problems confronting carrier operations.
The proposal was so simple a solution to many carrier aviation problems that individuals remarked, “Why hasn’t somebody thought of this before?” Instead of landing aircraft straight up the centerline of the ship, the British proposal was to land the aircraft diagonally across the deck. This would be accomplished by angling or canting the centerline of the landing area eight or ten degrees to port of the centerline of the ship. Figures in the illustrations show a plan view of the conventional carrier deck of the past and the canted landing area on the same ship.
On the conventional carrier deck, the landings are straight up the deck, and the maximum practicable number of arresting wires and barriers are installed in the ship to provide the greatest possibility of arresting the landing aircraft and to afford maximum protection to personnel and aircraft on the forward part of the flight deck. On Essex class carriers there are thirteen arresting wires, five barriers, and one barricade with a total of twelve arresting engines.
With the canted deck, the great number of arresting wires and barriers are not required. If a pilot fails to engage an arresting wire, he simply takes off and comes around for another pass. Therefore, only six arresting wires are installed in a canted deck landing area. It will be noted that there are provisions for an emergency barricade for jet aircraft and two emergency wire barriers for propeller aircraft. Under normal operations they will not be erected. In the event of a hook mechanism becoming inoperative, the barricade or barriers, as required, will be raised for an emergency arrestment of the aircraft. The weight saved from the radical reduction in the number of arresting wires, barriers, and arresting engines required for the canted deck will more than offset the weight increase due to the extension of the port deck and will at the same time produce a great saving in the cost of flight deck equipment and installations.
Not only will weight and complexity be saved in the carrier, but there is the possibility of reducing the weight and structural complexity of the carrier aircraft. With jet aircraft, the structural strength supplied in order for the aircraft to sustain a Davis barrier crash will no longer be required. With the extra landing area available, longer runouts of arresting wires are permissible, resulting in lower stresses being applied during an arrestment. By utilizing the “power-on” landing and new approach technique, much lower vertical sink speeds should be realized which will result in reduced initial stresses and shock on landing impact and consequently reduced strength requirements in the aircraft.
Since the potentialities of the canted deck concept appeared excellent, preliminary tests were conducted at sea. “Touch and go” landings with various types of aircraft were made straight up the deck on the U.S.S. Wasp in March, 1952, to develop approach techniques and to test out “power-on” landings. With “power-on” landings, approximately 70 to 80 per cent power is maintained on the jet engines until after touch down or until a wire has been engaged. There are definite advantages in using a “power-on” technique in landing swept wing aircraft because of their high angles of attack in the landing attitude. The vertical component of the engine thrust is a significant part of the airplane’s lift and should be maintained until contact with the deck is made if a hard landing is to be avoided. “Power-on” landings are not possible with barriers, barricades, and parked aircraft in front of the landing airplane. However, during the Wasp tests, the use of “power-on” landings with jet propelled aircraft proved not only feasible but appeared to be particularly well-suited to the canted deck concept of carrier landings.
The success of the Wasp tests led to further evaluation. A simulated canted deck was painted on the existing flight deck of the U.S.S. Midway in May, 1952. The arresting wires were removed and the aircraft made “touch and go” landings diagonally across the existing flight deck. Tests were conducted using the “power-on” technique for jet-propelled aircraft. The conventional landing technique in which a pilot “cuts” his throttle after receiving a cut from the landing signal officer, will be required with propeller- driven aircraft. Future tests will firm up the “power-on” and “cut” techniques to be employed with each type of airplane. However, the Midway tests substantiated the operational feasibility of the canted deck and confirmed the results obtained by the British Admiralty in similar tests. Both Fleet and Naval Air Test Center pilots participated in these preliminary tests aboard the Midway. The majority of the pilots and the flight deck crews, as well as the observers, were enthusiastic over the potentialities and implications of the canted deck concept.
Since the Wasp and Midway tests were successful, the decision was made to carry out a full scale test and evaluation of the canted deck concept. To accomplish this, the flight deck of the U.S.S. Antietam was modified in the New York Naval Shipyard during the fall of 1952 to provide the canted deck area. Under the direction of the Bureau of Ships, this project was completed in remarkably short time. The Bureau bent every effort toward making the Antietam available at the earliest practicable date to carry out the tests which are so important to Naval Aviation of the future. The Antietam put to sea in January of this year and the tests have now been conducted aboard her.
Due to the short time available for the conversion, many features that may be incorporated in the canted decks of the future had to be improvised in the Antietam. The basic plan or concept, however, was put into the Antietam conversion. As shown in the illustrations, an angle between the centerline of the ship and canted deck of eight degrees and nine minutes was chosen for the initial tests. It is planned that various angles will be tested during the trials. There were six landing wires installed perpendicular to the axis of the canted deck. The deck sheaves were modified and idler sheaves placed on the forward three wires to cut down on the span and the tendency toward off-center landings. A triangular strip of deck was added to the port side as the forward extension of the landing area. Since the deck extended fifteen feet beyond the elevator, the elevator for these tests was fixed in the up position. In future installations the elevator will be operable. With the additional strip of deck, the landing area on the Antietam became 75 feet by 525 feet, which gives approximately a 20 per cent increase in the usable length of the landing area. A triangular strip of deck was also added to the aft end of the landing area to square off the deck edge with relation to the axis of the canted deck.
The landing signal officer’s platform was not changed. In future conversions, the landing signal officer’s platform will be aligned parallel to the axis of the canted landing area. The current test probably will dictate further modifications to improve the operational capabilities of the deck arrangement and of the concept itself.
There should be little change in shiphandling requirements resulting from the angled landing area during recovery of aircraft. The best condition for the approach and landing of aircraft will be with the relative wind directly down the axis of the canted deck. This can generally be brought about by the proper adjustment of the carrier’s course and speed. Under this condition, and with the aircraft in the groove, the pilot simply maintains his heading along the axis of the canted deck. In so doing, the track of the airplane with respect to the ship will always coincide with the projected axis of the canted deck, regardless of variations in approach speeds. The aircraft, then, will not have to land in a crosswind. It is not mandatory, however, that the wind be down the axis of the landing area. The effect of relative winds from various angles has been tested—down the centerline of the ship, down the centerline of the canted deck, and at small angles to the axis of the canted deck. Pilots indicated that no difficulty was encountered in the approach and touchdown and no unusual or excessive turbulences from the “island” were encountered under any of these wind conditions.
If the surface winds drop below four knots, it will be impossible to obtain a relative wind of 25 knots or greater down the axis of the canted deck. In the worst condition, a dead calm, the relative wind will be down the centerline of the ship. This will give an eight degree crosswind and a heading slightly to the right of the canted deck axis will have to be held in order that the track of the airplane with respect to the ship may be maintained along the axis of the landing area. This should present no difficulty and the new approach should be no more difficult than the approach has been in the past.
The biggest implication of the canted deck to the pilots and to the flight deck personnel is the very substantial improvement in safety of landing operations. No longer does the pilot have to face barriers, barricades, and parked aircraft as he approaches for a landing. With the canted deck, the pilot, failing to engage an arresting wire, has ample room to take-off and go around for another attempt. A missed engagement results in nothing more serious than a simple “touch and go” landing. The disturbing thought that something may go wrong and result in a barrier engagement or a serious crash into the parked aircraft will no longer exist. This is particularly applicable to night carrier landings. The hook bounces or faulty landings that used to result in the clang of the crash alarm should now be just another pass to be improved on in the next landing. The new landing technique will stress a smooth, soft touchdown in which the vertical rate of descent is greatly reduced. The new pilot, or old pilot requalifying, may make several “touch and go” landings to iron out his approach technique and get the feel of the aircraft in the canted deck approach before he is arrested by the landing wires. The safety features of the canted deck have an excellent psychological effect on the pilots; from their point of view, these are vital factors.
The pilot of the landing aircraft is not the only one who benefits by the canted deck, for the flight deck crews—the personnel who park and service the aircraft that have landed, and who are required to be on the forward flight deck—for these men the canted deck is the best carrier innovation in twenty years of operation. No longer will they need to worry about the landing aircraft while they park and service those aircraft which have already been recovered. No longer will they need to keep one eye peeled aft, ready to dive for the nearest exit. The ordnancemen, the fueling detail, the electronics men—all flight deck personnel—will be able to go about their duties with peace of mind during landing operations instead of with a feeling that they are ever in danger from that occasional crash, loose bomb or rocket, or inadvertent triggering of guns that can be so costly to life and material. This applies equally well to the pilot who has taxied forward and is being parked. The maintenance crews also will feel the impact of the implications of the canted deck through reduced deck crashes. This should radically cut down on the man-hours and material which have been required in the past to patch up aircraft damaged in barrier and barricade engagements and in crashes into the parking area.
The Task Force Commander should benefit by the canted deck. In the past, the crashes into the parking area have cost him greatly in striking power, and the cost is usually unanticipated. No longer should his planned air offensives be reduced by landing accidents.
And, far from the carrier at sea, the Bureau of Aeronautics will likewise feel the impact of the canted deck. For the design of the Navy carrier airplane must ever be tailored to the capabilities of the aircraft carrier from which it is to operate. The Navy’s carrier aircraft have traditionally suffered performance penalties because of the inevitable limitations of their floating operating bases. As these limitations are minimized by improvements in the ships, so is combat performance increased by improvements in the airplanes. The canted deck appears to be one of these improvements in the aircraft carrier. The advancements in aircraft performance which have eventuated in recent years seemed headed for retardation as a result of increased costliness of carrier landing accidents. The canted deck seems to be the answer to these accidents and should flash the green light for further aircraft development. These advantages, coupled with the previously discussed weight and material savings and with elimination of costly crashes into the parking area, should pay for canted deck conversions many times over.
The modern aircraft carrier, called upon to operate aircraft which are rapidly growing in weight and performance, requires a difficult balance in launching, landing, and handling capabilities. Her catapults, arresting gear, and airplane elevators, in particular, must be mated to the most demanding of the various types of aircraft which she will operate. Within the limitations of her fixed flight deck length, and within the established ship stability criteria, the provision of adequate equipment for flight operations of advanced aircraft is a serious problem, and one which in many cases leads to a compromise with other ship features which have not heretofore been encroached upon. If the Antietam tests live up to their expectations, great relief in this area should result. Some of our carrier classes which today have reached the limit of their “elasticity” will be born anew for many more useful years of life, and others will be provided a margin of operational capabilities which will permit a most desirable and necessary continuing advancement in naval aircraft performance.
The first six months of canted deck trials aboard the Antietam have been an unqualified success. The increased safety features of the canted deck are best exemplified by the record established so far by the ship. Over four thousand (4000) landings have been made, both night and day, without a barrier or deck crash. Due to the successful demonstration of the improved safety and operational features on the Antietam, the canted deck has been approved for installations aboard present and future carrier conversions.