The second installment of our historical overview of Western military aircraft aircrew escape ('egress') systems, without which modern high altitude flight in fast jet powered military aircraft would simply not be possible. (The image below shows the successful ejection made by a Russian pilot at the very moment his disabled MiG-29 struck the ground at the Paris Air Show in 1989--truly an incredible feat!)
A Brief History of the Development
of Western Aircraft Egress Systems:
(Part Two of Three)
FURTHER REFINEMENT AND IMPROVEMENT OUTSIDE THE UK
Although Germany’s involvement in aircraft egress systems had come to an end with the conclusion of the Second World War, the other early pioneering nation in ejection seat design--Sweden--continued to evolve their indigenous egress system engineering.
With development of the SAAB J32 Lanson interceptor/strike aircraft, a two-seat machine which flew for the first time in 1952, a new requirement arose for an ejectable seat system. This resulted in the 101 pound SAAB Type 3 (Type 32) ejection seat, powered by a two-stage explosive cartridge gun, and featuring the standard pilot-worn back-style personal parachute and seat-stowed survival kit as the in the previous seat (Type 29). Whereas the Type 29 seat had weighed about 66 pounds and was capable of being used at an altitude of 300 feet in level flight, minimum altitude for safe ejection using the SAAB Type 32 seat was reported to be about 150 feet in level flight. The Type 32 seat also featured separate guide rails (as in the Martin-Baker seat design) and a specially shaped parachute canopy; the seat survival kit incorporated a hard-shell container for the first time, instead of a soft-pack, thereby helping reduce acceleration overshoot potential. An inertia reel restraint system was also added, as was a modification from guide rail rollers to slide bars, an innovation that enhanced smoothness of operation. Seat actuation was again initiated by either use of the a face blind or a secondary "grab-loop" situated on the seat between the occupant’s knees.
In 1949 SAAB began studies which would result in the development of an entirely new design for a supersonic, delta-winged interceptor aircraft, capable of speeds in the vicinity of Mach 1.5 to Mach 2, to be designated the SAAB J35 Draken. In view of the rather small cross section selected for the new design so as to insure sufficiently favorable drag characteristics favorable for supersonic flight, the cockpit’s dimensions would have to be carefully considered in development of a suitable ejection seat system. [Interestingly, while the Swedish aeronautical engineers quickly focused on this critical concern--supersonic drag coefficients as related to cross section--their Convair colleagues in the United States who were developing the new delta-winged American interceptors (XF102) initially did not, and it was only after incorporation of Whitcomb’s 'Area Rule' formula that the American delta design achieved a modicum of its anticipated performance capabilities.]
In order to comply with the requirement for a low profile cross-section, it was decided that an entirely new seat would have to be developed. This new seat was again explosive cartridge driven and was installed on the first of the new SAAB J35 Draken delta-winged aircraft, which flew initially in October of 1955. The Type 35 seat featured a back-style parachute, again not integrated to the seat but worn by the pilot, and a seat-pan survival kit of rigid design. The seat was actuated either by the conventional head-blind device or a secondary actuator located on the lower seat, and had a dampening feature built in to help absorb crash-landing forces as well as an adjustable seat pan. Harness and deployment mechanisms were virtually the same as those used on the preceding Type 32 seat, and installation of the seat was made on a slight rearward cant (similar to the 30 degree rearward angle found on the SAAB J29 aircraft).
Sometime later, the SAAB J35 Draken F model was fitted with the new SAAB 35 Draken Rocket Seat Escape System. This new generation egress design replaced the conventional explosive catapult gun with a 5-nozzle cylindrical rocket motor fitted under the seat pan, as in the later Martin-Baker rocket seats. Firing of the 4.4 pound rocket charge was accomplished by generation of pressure in the catapult gun, and total burn time was about 0.2 seconds. While the original (non-rocket) Draken seat weighed about 176 pounds, the new rocket powered version totaled about 222 pounds (this included all components, chutes, kits, etc.), and substantial revisions of the rocket-equipped J35 seat included doing away with the face-blind actuation device in favor of a lower, pan-mounted ejection handle, and installation of automatic leg restraining straps. Additionally, the new rocket powered seat required installation of a new type of drogue for stabilisation control.
Fully automatic in egress sequencing from initial actuation, the rocket system allowed true zero/zero ejection capability for Draken fighter aircrewmen, and the new rocket seat was retrofitted to all earlier J35 Draken models. In 1967 the next generation SAAB J37 Viggen interceptor first flew, and a slightly improved version of the SAAB rocket seat was fitted to it. Understandably, use of the SAAB rocket seat in operational employment has provided much valuable data on the system, which has been constantly improved and evolved by SAAB.
Although the SAAB seat system was not selected for installation on the latest Swedish aircraft design, the JAS39 Gripen (The Martin-Baker Mk.XL system was chosen), there is no question concerning the excellence of Sweden’s past and present contributions to aircrew egress systems development, from its earliest products through the latest (and last). So well engineered and maintained are the now more than 40 year old Drakens, and their internal systems (including the egress system), that in Finland, one nation which uses the Draken, the Finnish Satakunta Air Wing’s Drakens have never had to use the SAAB egress system in an emergency.
Unfortunately, the pioneering research accomplished by SAAB in the field of egress systems from the late 1930s onwards is many times not fully acknowledged or recognized as today’s advances in system technology continue to overshadow previous standards of excellence. For those specialists in this critical area of aviation design, however, the facts peak loudly and eloquently for the engineering capabilities of the SAAB-Scania Aircraft Company, as they shall continue to in the years ahead.
DEVELOPMENT CONTINUES: THE UNITED STATES
Work in the field of military aircraft emergency egress systems in the United States had begun in earnest, as previously referenced, with the revelation of captured German egress documentation painstakingly gathered by the Heinkel Company and the Luftwaffe’s Aviation Medicine branch since before the war. However, a complication in the process which was largely absent in the United Kingdom was the intensely political rivalry which existed between the US Air Force and the US Naval Aviation. Ever since the growing importance of US air power in the war had propelled the US Army Air Force further along on its avowed quest to become a fully separate and equal military service within the War Department, there had been corresponding exacerbation of the existing contest between the Army Air Force and the Navy to gain the upper hand in military aeronautical ascendancy. This intense inter-service struggle to surpass the efforts of the other was strongly in evidence in almost every aspect of operational development as well as in research and experimental areas of investigation. In brief, each service argued that it ought to be given the overall supreme authority to develop the nation’s potentially awesome aeronautical strength.
Nowhere was this rivalry more in evidence than in the field of aeronautical research and development, and both services maintained distinctly separate research and development commands (in 1947 the US Navy’s worst fears were realised when the US Army’s Air Force was granted separate and autonomous peerage within the Defense Department as the US Air Force). The political battles which were continually being waged in the US Congress for funding of military projects were clearly polarised between Air Force and Naval Air Arm proponents in just about every category.
This included ancillary but no less important areas such as air crew life support and egress. Fueled to a significant degree by this antagonistic atmosphere, it is not much of a mystery that egress research and development schools in both services inherently tended to diverge even more sharply from each other. Of further, and undoubtedly greater importance were the diverging performance criteria maintained by each service regarding ejection seat operational parameters. The US Navy insisted that naval aircraft needed a fully developed low-level ejection performance, reflecting safety concerns for the intrinsically hazardous nature of carrier operations. The US Air Force, by contrast, felt that safe ejection capability below 500 feet was unrealistic (not survivable, statistically speaking) and therefore unimportant as a procurement objective. Adding further impetus to this Air Force view was its awareness of the coming importance of the high-altitude interception role, which would increase with escalation of a Cold War hostile penetration treat posed by high and fast flying Soviet intercontinental bombers.
Immediately after the war had ended, the US Navy had shown a great interest in the work being carried out by the Martin-Baker Company on aircraft ejection systems. The US Army Air Force, in contrast, maintained the opinion that the development of ejection seat systems ought properly to be undertaken by American aviation companies in cooperation with the US Army Air Force’s Air Research and Development Command (ARDC) at Wright Field (soon to become the Wright-Patterson AFB Air Development Center). The consequence of this veering away from each other’s inflexible contention was that US Air Force airplanes ultimately were developed with a range of different and proprietary US designed ejection systems, while the US Navy’s aircraft for the most part, initially used systems at least heavily influenced by the English designs and ultimately incorporating specially modified and uniformly adopted Martin-Baker systems after experience with US systems proved not fully suited to low-level ejection requirements (i.e. carrier operations).
As previously mentioned, In October of 1945, US Naval officers J.J. Ide and R.B. Barnes had visited the Martin-Baker works at Denham to investigate the M-B test program and witness ejection seat trials. Subsequent to the visit, and after completing an assessment of suitable types of research equipment intended for ejection seat testing, the US Navy ordered a 105 foot seat testing tower to be installed at the Navy Yard in Philadelphia and for an actual example of the Martin-Baker Mk.I seat for purposes of testing it in a naval aircraft. Less than a year after the installation an initial test shot was undertaken, followed shortly thereafter by the first live seat test (August 1946). From that time forward, over the ensuing few years, a great deal of intensive physiological investigation was accomplished by the US Navy on ejection seat operational parameters and this was further advanced by numerous studies undertaken on Martin-Baker ejection seats installed in a modified Grumman F9F Cougar in 1957. Despite reluctance of the Grumman Company to participate in the tests, the results were quite satisfactory and the US Navy/Martin-Baker bond was further strengthened. The Navy approached the Martin-Baker Company in this matter of fitting a special Martin-Baker seat to replace the Grumman seat in the Cougar with a mind to adopting the English seat for all its carrier-based aircraft. The tests were quite successful and this resulted in the development of the Martin-Baker Mk.V seat specifically for US Navy use, which was widely used in variant applications in the F9F-6, the F-4, the A-6, and several other Navy aircraft. The Mk.V was produced alongside the Mk.IV, but differed in that it (the Mk.V) had been specially strengthened to decellerative G limits well beyond that engineered into the Mk.IV seat (40 Gs vs. 25 Gs). The Navy Mk. IV seat also incorporated a crotch loop pull handle actuator for the first time, as it had been found that in certain instances involving sustained high-G force, a pilot sometimes could not reach his arms above his head to grab the face-blind actuator to eject. The crotch level pull-loop provided ejection actuation capability for both possible scenarios.
Meanwhile, the US Air Force’s Wright Air Development Center was developing a concern, in the mid-1950s, over how to best configure a suitable high-performance ejection system for the latest supersonic members of its new 'Century Series' aircraft. American developed ejection seats had been produced by the North American, Douglas, Republic, Lockheed, Grumman, Weber, Stanley, and Stencil companies, and US Air Force aircraft had come into production in the early 50s with these seats. Most were actuated by arm-rest type triggers and were intended to work with the standard US Air Force back-type personal parachute, but none provided even a vestige of zero/zero capability and few indeed assured a safe ejection below the 500 foot altitude selected by the Air Force originally as the minimum safe low-level performance parameter. Of the many designs in use on Air Force aircraft, the Douglas ESCAPAC seat purportedly had the best reputation and would later almost match Martin-Baker performance standards, statistically speaking (the Douglas ESCAPAC 1A system was originally developed for use in the US Navy's A4 Skyhawk; it proved so effective that the Escapac 1A system served as the developmental basis for a whole collection of successive evolutions of this basic design that ultimately culminated in today's McD/D ACES II system).
One of the reasons the Air Force apparently initially abandoned study of low-level ejection systems was the opinion that extant seat catapult forces generated by systems in use on its planes could not generate the high forces needed to lift the aircrew high enough above the ground to allow full parachute deployment in low level egress situations.. The Air Force maintained that a limit of 22 Gs of vertical acceleration were the human physiological ceiling for safe ejection. Curiously, this figure seems to coincide with the final criteria developed by Germany in its early (WWII) studies of allowable vertical ejection acceleration forces, but it contrasted strongly to the vertical G limits of the Martin-Baker seats being tested at that time (about 32 Gs). Further, with Mach 2+ aircraft such as the Convair F106 Delta Dart under development, another concern expressed itself in how to engineer a high-performance seat that would allow routinely safe supersonic ejection. The development of a whole new generation of post-war, high performance jet aircraft (soon to be known as 'The Century Series'), would spur interest in the swift development of a functionally adequate USAF ejection seat with capability for safe ejection well in excess of the speed of sound.
These problems were soon to be investigated at Edwards Flight Test Center in California, Holloman AFB in New Mexico, and on Hurricane Mesa in Utah, using high speed rocket-powered sleds in a series of ongoing investigations which were ultimately intended to produce what the Air Force termed perhaps too simply the 'Supersonic Seat'.
It was recognized that one likely way of providing the necessary power to successfully meet the demanding parameters of human physiological limits, while simultaneously satisfying the ejection systems physics requirements, was through the use of staged rocket motors incorporated into the seats. In October of 1957 a requirement was specified by the US Air Force for a satisfactory supersonic-rated ejection seat system which would provide high-speed egress as well as adequate and reasonably safe low-level ejection (although this was still suborned to the high speed/high altitude capability requirement).
This was termed the USAF / ICESC (Industry Crew Escape System Committee) program, and a committee of major US aviation firms was jointly established with the Air Force Systems Command to develop the system. Two proposals for a system meeting all requirements were considered, an 'A' proposal and a 'B' proposal. The Convair Company (formerly Consolidated Vultee) was finally given the go-ahead under the aegis of the ICESC to undertake primary project development of its 'B Seat' design proposal, with the Stanley Aviation Company as a partner. The ICESC studies involved over 6 years of intensive testing (1 January 1956 through 30 June 1961) of the Convair / ICESC 'B' Seat System on the high-speed rocket sled tracks at Edwards and Holloman. These rigorous and extensive tests ultimately culminated in the live ejection of volunteer TSgt. James A. Howell from the specially modified Convair F106B (two seater) aircraft at an altitude of 7113 meters and an IAS of 800 kph. The Convair / ICESC 'B' Seat featured a unique, tilt-articulated design which upon actuation would first elevate the seat into a backwards-tilted horizontal plane (with pilot in supine position) above the aircraft’s cockpit, before firing the seat’s rocket motor to blast the occupant clear of the plane. The seat’s appearance was distinctive in that, when deployed, the seat pan’s convex bottom extended beyond the feet of the aircrewman, which were first drawn up tightly towards his chest in a foetal position, so as to protect him from supersonic wind-blast effects.
The 'B Seat' (other slang terms for the seat included the 'Tilt Seat', the 'Rotation Seat', and 'Supersonic Seat') was a strangely appearing design, with twin survival kit components sited bilaterally along the sides of the seat's occupant, and ejection actuator D-ring situated at crotch level. Featuring an integrated shoulder/lap harness, upward rotating 'sugar scoop' foot pans, powered foot retraction spurs, bilateral thigh guards that pulled the knees up towards the chest, aneroid controlled drag and recovery chutes, and two gas operated telescoping stabilisation booms that projected aft on actuation, the seat not only looked strange but certainly must have presented the rider with a unique (possibly) terrifying prospect as he was first shot upwards into the wind at supersonic speed, then slammed back into a supine position before being fired away from his stricken aircraft with a powerful rocket blast. The seat was secured to the rotation frame with 4 explosive bolts that blew just before the rocket fired.
The B Seat ejection sequence was essentially as follows: A pull on the D-ring jettisoned the canopy, tripped the AFCWS (automatic flight control system) disconnect switch, retracted and locked the shoulder harness, retracted the occupant's feet via cable connected power reel spurs, raised the foot pans and elevated the occupant's knees and thigh guards. Feet retraction and canopy jettison safety locks release, allowing further pull on the D-ring, which disconnected the seat actuator and fired the seat's vertical thruster, moving the seat up the rails and out into the slip-stream. At this point the hose disconnect and personal-leads disconnect separated and at the end of the vertical thrust stroke, two rotational thrusters fired, slamming the pilot into a supine (horizontal) position above the aircraft's fuselage. During this rotation, the gas operated stabilisation booms were extended and the four break-away bolts were fired. At this moment the primary escape rocket would fire the seat and occupant away from the aircraft. Two modes of chute deployment provided full deployment in low speed/low altitude mode at three and a half seconds, and full deployment at high speed in four and three quarters seconds. At extremely high altitudes, the pilot would stay with the seat until a safe lower altitude had been regained. The total weight of the seat and occupant, fitted with all normal personal equipment, was a substantial 607 pounds.
Although tested extensively in at least 15 rocket sled tests and 11 test flights (using an F106B two-seater), the single high altitude human 'live-fire' test was accomplished at 22,580 feet and only Mach .77 (at that altitude); flight performance parameters at the time of the test were far in excess of more realistic suboptimal conditions and did not come anywhere near the 'hard corners' of the seat's anticipated performance envelope. Rocket sled tests were exhaustively run on the test track with instrumented dummies at speeds simulating Mach 2.5 at a simulated altitude of 9,700 meters, with satisfactory results. Additionally, 35 human test subject rocket sled runs were reportedly concluded, verifying that ejections up to 900 knots IAS were within the range of human endurance.
As a result of the successful tests, the Convair / ICESC 'B' Seat, or 'Tilt-seat' as it became more commonly known by life support and human factors specialists, was installed in all production block Mach 2+ rated F106A & B aircraft--the most formidable and most high performance of the US Air Force’s vaunted "Century Series" aircraft of the late 50s and 60s--from 1957 through 1959.
Unfortunately, and in spite of the years of exhaustive testing carried out in its development, the Convair / ICESC Tilt-seat did not prove satisfactory in actual Air Force operational use; this was especially true in the less favorable corners of the projected envelope. As might be predicted, the marginally assured low-level, low speed performance of the controversial seat simply did not meet minimal
requirements...especially under anything less than optimal conditions. After several fatalities occurred during F-106 emergency ejections involving use of the Tilt-seat, a decision was made to remove the seat and replace it with a conventional, rocket-powered seat design made by the Weber Corporation. This retrofitting of the Delta Dart with the Weber seat was accomplished in 1963; thereafter, the Weber seat egress system remained in the delta-winged F106 for the rest of its 30 year service life and provided satisfactory high-speed ejection as well as adequate zero/zero capability.
Possibly as a consequence of the ultimate failure of the Air Force’s ICESC supersonic seat program, the decision to use Martin-Baker designed seats in the Air Force version of the McDonnell-Douglas F4 Phantom II was a bit less objectionable in the years to come, and especially owing to its already proven performance. In any event, it is fascinating to speculate on this.
To return to the US Navy’s growing post-war association with the Martin-Baker Company, formerly alluded to, the Navy was by now also investigating the use of rocket engines as a satisfactory means of propelling a seat clear of a stricken naval aircraft without incurring unacceptable ejection injuries in its personnel. Studies conducted with the catapult gun then in use indicated that even significantly enhancing the conventional gun’s charge would not produce the desired Naval requirement for 'dirty' low-level escape. Consequent to this, the Navy authorized the development of a rocket motor capable of being used on existing American egress system seats. A lengthy series of tests were conducted at the China Lake Naval Ordinance Test Station (NOTS, as it was then designated) on its high speed rocket sled track, and this eventually resulted in the production of the RAPEC (Rocket Assisted Personnel Ejection Catapult) system. Tests continued, concurrently, with the Martin-Baker ejection system at the US Naval Flight Test Facility in Patuxent River, Ohio.
By this time, the Douglas and Vought aircraft companies had devised rocket powered seats which were in the research and development phase. Both appeared to be capable of meeting Naval emergency ejection requirements at a lower limit of 150 feet altitude and 150 knots IAS--still not satisfactory parameters for the stringent zero/zero emergency requirements desired by the Navy. At this point, the political nuances of the competing systems manufacturers’ battles to secure Naval procurement contracts intensified considerably, and the result was a compromise in which the Douglas Escapac RAPEC system was selected for use in the Douglas A-4 Skyhawk, while Martin-Baker was selected to provide a uniform system for use in the remainder of US Navy aircraft. This final decision was still complicated further by an exception to the agreement which allowed North American Aviation to provide its own seat for use in the RA-5 (A3J) Vigilante and one other aircraft.
Furthermore, a concurrent program authorized use of the Stanley built RAPEC seat in the Martin P6M jet-powered seaplane patrol bomber, due to inadequacies existing in the aircraft’s original seat system. Subsequent emergency ejections involving an unmodified P6M and a later, RAPEC configured version, confirmed the effectiveness of the new RAPEC system.
In operational use, the Douglas Escapac HS-1 and LS-1 RAPEC seats used in the RA-5 (A3J) and T-2 aircraft proved their effectiveness in several incidents involving successful non-combat egress in the RA-5 (A3J) Vigilante at and above the speed of sound, and during the Vietnam conflict, Douglas HS-1 Escapac RAPEC type seats in the A-5 routinely allowed aircrew to successfully eject above the speed of sound in emergency combat ejections involving that type (25% of the combat RA-5/A3J ejections were undertaken above Mach I).
With the withdrawal of the RA-5 Vigilante from active operational use in the late 1970s, the only American rocket powered open (non-encapsulated) escape system proven in use for successful Mach 1+ recovery, and capable of zero/zero to 700 knots IAS performance, was also retired (this was a North American Aviation design), excluding the special X-15 seat system (also a North American design) and the Stanley/Lockheed S/R-1 system used in the Lockheed SR-71 Blackbird aircraft.
Meanwhile, development in both the US Air Force and the US Navy continued apace as new aircraft with different performance parameters came into service. One type of advanced concept ejection system which found its way into at least two supersonic, multi-engine designs was the fully encapsulated aircrew escape system. A version built by the Stanley company was installed on the Mach 2 Convair B-58 Hustler, a strategic nuclear bomber of amazingly high performance for its time (originally flown in the early 1960s). The 558 pound capsule, which unfortunately had a relatively high failure rate, was designed to provide flotation in the event of a water landing, and upon ejection streamed the half-open recovery parachute for 2 seconds to slow forward speed before reef cutting devices automatically allowed the 41 foot ring-sail type chute to fully open. The B-58 capsule featured upper and lower frontal clam-shell doors, which would close and seal in an emergency. The capsules featured self-contained individual oxygen and pressurisation systems, much like another, later design, engineered by the North American Aviation company and installed in its Mach 3, advanced strategic bomber prototype, the XB-70 Valkyrie. The Valkyrie’s encapsulated system was the only one of its general design to have been fully flight tested and approved prior to completion of the XB-70 aircraft itself. Another system, based upon the ejectable crew cockpit design (which harked back to the original ejectable crew-section concept used in both the WWII era Bachem Ba 349 Natter and Heinkel He-176), was developed for the controversial American TFX swing-wing aircraft. The TFX aircraft, after a prolonged and difficulty-laden initial development which called for its being adopted by both the US Air Force and the US Navy in slightly differing versions, would ultimately outgrow its teething problems and evolve into the excellent US Air Force F-111 Aardvaark fighter-bomber.
Returning, for a moment to the early part of the 1950s, it is interesting to reflect for a moment on the concept of the American downward-firing ejection seat system. In particular, the Lockheed Company, in developing its powerful but lightweight F104 Starfighter in response to requirements provoked by experiences derived from aerial combat in the Korean War, elected to incorporate a downward firing pilot’s ejection system in the unltra-compact crew section of that post early 1950s design. As the inherent hazards of downward ejecting seat configuration are readily apparent, Lockheed’s decision provokes speculation that the official US Air Force’s consensus that ejections below 500 feet were not essentially survivable may have had inordinate impact on this aspect of the Starfighter’s development. There were Lockheed engineers who believed that, owing to the great speeds which the aircraft was designed to fly at, an upward firing system using the existing seat catapult technology would not be able to clear the F104’s tail assembly in supersonic flight. There were certainly also numerous critics of the downward ejection scheme at that time, but the preponderant opinion that successful upward ejection was not absolutely attainable with existing technology managed to sweep these objections aside and work continued using the downward ejecting seat design.
Lockheed, in partly addressing critics of the system, suggested emergency procedures which would partly offset the hazards of egress situations occurring below 500 feet. Among these were the recommendation that in the event of a low-level emergency requiring ejection, the pilot of the Starfighter was to roll the aircraft 90 to 180 degrees or more to either side before ejecting. This would then yield, at least in theory, a horizontal or inverted vertical upwards ejection trajectory for pilot and seat, rather than a vertical descent. The suggestion was more euphemistic than practical, for in situations involving sudden loss of power, hydraulics or flight controls, such a maneuver would be near impossible to achieve. Further, the small cross section of the Starfighter allowed very little room for the crew compartment, and it was determined that there simply was not enough room in the by-then frozen design configuration to re-engineer a cockpit which would allow for installation of a conventional upward firing system without a major (and costly) redesign. Pilots, who could relate to such possibilities as low-level emergency bailout far more readily than could engineers, viewed the downwards firing system with obvious disapprobation.
The Starfighter prototype, as well as all developmental pre-production and initial production models, had the Lockheed downward firing seat installed. Egress was achieved through a large rectangular hatch located directly below the cockpit. In the event of an emergency requiring ejection, the between the knees actuator handle was pulled first, which set off the following sequential events: 1) the cabin was depressurised, and the control stick stowed forward, clear of the seat; 2) the pilot’s parachute harness tightened automatically, just as did the arm restraint net which secured his arms; 3) the pilot’s feet where drawn back into the seat’s footrests through use of cable attached spurs on his boots; 4) the hatch was blown off automatically, and the seat was ejected straight down with a conventional explosive catapult charge. For clear-thinking individuals, unencumbered by the policy constraints of a manufacturer’s cost projections, this system was purely and simply an accident waiting to happen; especially so, in view of the problems that early 1950s high-performance aircraft frequently had with power failure, compressor stalls and flame-outs, and the particular hazards normally implicit in landing and take-off portions of the flight envelope. Although adjudged satisfactory for medium to high altitude use, the original downward firing system was completely useless for low-level emergencies.
Unfortunately, it took the death of a high-profile and very popular flight test pilot to spur a major revision of the Starfighter’s egress design. Capt. Iven C. Kincheloe, blonde, handsome and personable, as well as a highly regarded and high-profile flight test pilot, experienced an in-flight emergency in his production F104A Starfighter in 1958 shortly after takeoff at Edwards AFB in California. His ejection in the Stanley B-1 downward firing seat fitted to his aircraft successfully removed him from the stricken aircraft in a sideways, horizontal plane, as recommended by Lockheed; ironically, however, the aircraft banked and came down shortly after he ejected, exploding in a fireball on the ground which Captain Kincheloe was carried directly into by the ejection trajectory. Kincheloe’s death accomplished what a previous ground-swell of earlier protests had failed to do: shortly afterwards the F104 fleet was grounded, the old B, C, and C-1 seats removed, and quickly retrofitted with a Lockheed designed upward firing seat designated the C-2 Seat.
Incorporation of the new C-2 seat increased aircrew confidence in the new fighter. At a later date (after 1966) the initial Lockheed designed upward firing seat was replaced by an improved upward firing version of the C-2 seat, designated the S/R-2 seat. This seat was reported to offer near zero/zero ejection capability. All European, export, and later generation Starfighter variants had their American upward-firing seat replaced with a Martin Baker Mk.VII series seat specially engineered for the Starfighter, designated the M-B Mk.DQ-7 model. The new Martin-Baker Starfighter seat unexpectedly experienced some initial problems, however, and several German Luftwaffe pilots were killed in Starfighter ejections using M-B Mk.DQ-7 seat. An investigation team was quickly brought into determine the source of the seat failure and found that frequently the pilot’s knees would not clear the forward canopy edge due to the fact that the parachute placement positioned the pilot too far forward. The seat was subsequently modified to address this problem and from then on the Martin-Baker Mk. GQ-7F seat performed quite well in Starfighter emergencies experienced by the German Luftwaffe. The same GQ-7F seat was installed in all export Starfighter seats the Danish Air Force and other NATO countries were taking delivery of and there were no further difficulties. It is indeed well that that was the case, since the F104 remained a demanding machine to fly throughout its long NATO service life owing to the peculiarities of its high wing-loading, high-performance design, and the training dissimilarities between the American west, where European pilots were trained to use the aircraft under typically excellent conditions and the European region with its usually marginal weather.
Among the refinements added to American-made seats of the mid-50s were inertial-locking harnesses and seat-pilot separation mechanisms (the seat-man separator on US Air Force seats consisted of a strap arrangement fitted between the seat and the pilot’s rear seat cushion, or parachute pack, which was sequenced to actuate after ejection had occurred and simultaneous with seat restraint release), after studies indicated that a more positive man-seat separation action was required to get the aircrewman away from the ejected seat. Thigh restraining guards were usually fitted and folded away in the down position until the seat was fired, being raised for use along with the armrest ejection triggers which were a standard American feature. In some cases, leg restraining mechanisms were also fitted, as in the original F-104 Starfighter seats.
In the early 1960s, North American Aviation experimented with a series of lightweight seat systems termed the 'LW' series. This resulted in an LW-1, an LW-2 (developed for the XV-19 experimental aircraft), and a final LW-3 seat that was produced for use in its twin prop driven OV-10A Bronco forward air control / armed reconnaissance plane. The seat was designated the LW-3B model and two were fitted, fore and aft, in the Bronco’s cockpit. Uncharacteristic of the trend at that time, the LW-3B seat featured a seat-mounted pilot personal chute in an unusual configuration. The aircrewman’s parachute was fitted to the side of the seat, housed in an elongated rectangular pack, and the system was capable of near zero/zero performance. In view of the fore and after seating arrangement of the OV-10A, the seats were angled to fire slightly to the side and away from each other, with the rear seat sequenced to eject first in the accustomed manner. The LW-3B type seat was later installed in the experimental prototype VTOL XV-15 tilt-rotor aircraft for flight testing of that machine in a tandem arrangement, and has also been installed more recently in civilian turbo-Mustang (F-51) conversions such as the Cavalier II, where it provides emergency ejection capability in a confined cockpit structure.
The LW-3B seat featured a standard hard-shell seat type survival kit (RSSK 9) under the seat cushion. This was the first American seat to presage the future trend of installing the pilot’s personal parachute on the seat itself (although modern seats feature the chute assembly in the seat’s headrest area, not fitted to the side of the seat as was the case with the LW-3B). Reports of the Bronco system in use indicate it had a satisfactory success rate in combat situations (Vietnam), both for low level and medium level ejection.
It must be noted in passing that although American systems had originated from studies based upon the German escape technology of World War Two, there were several features incorporated in them which were thoughtfully conceived and engineered. One of these was the locking inertia-reel harness, which is to be found on nearly all American manufactured seats produced in the early 1950s (each of the 1950s Century Series fighters featured this device). Another is the life-support quick disconnect block, again incorporated in virtually every system produced by the US in this period. This latter device featured a module, frequently affixed securely to the seat, into which the aircraft and pilot connections were inserted for G-suit, breathing oxygen and communications use. Upon ejection, the aircraft connectors would pull free, leaving the seat-portion attached, from which the pilot’s connections would be released at the time of man-seat separation. Similar systems were not incorporated into Martin-Baker seats until the advent of later M-B Mk.IV models.
Several other systems were investigated that involved a pseudo-podded escape concept. One of these proposals was a design that featured inclusion of the aircraft's canopy as a sort of protective enclosure, with the pilot being drawn upwards into a supine position under it before actuation (this was researched for initial use on the Convair F102 Delta Dagger, but discarded in favor of a conventional Weber rocket seat). The canopy, with the pilot enclosed under it, would then be fired away from the aircraft. This concept was discarded after some initial exploration into its suitability.
Of passing interest is the fact that while the idea of the crew 'escape pod' was not entirely new, having been first actively explored in German designs of the early 40s (notably in the He-176 rocket powered aircraft), its possibilities were being closely studied in the late 40s and early 50s by US aeronautical and egress scientists. While US aircraft engineers subsequently designed several systems that would be incorporated into high performance aircraft of the 50s and 60s, in a curious footnote to this inovation, a little known Humphrey Bogart film titled 'CHAIN LIGHTNING' that came out in 1950 featured the escape pod idea with a central role in the plot (along with a primitive high altitude pressure suit). Although the technology represented was rude and almost laughable, by today's standards and in terms of what we now know about such highly sophisticated systems, the basic concept was amazingly all there. This old Bogy film is worth seeing for this and Hollywood's 1950s pressure suit representation, although the story line itself is considerably dated.
In the early to mid-1950s, a considerably advanced Mach 3.7 high altitude, point/area defense air interceptor aircraft design was proposed by Republic Aviation. This was what came to be known as the XF-103 (USAF Secret Project MX-1787), which never saw production (it was cancelled in 1957), but which took form in a completed full-scale engineering mock-up. This futuristic appearing interceptor featured an unusual 'boot-shaped' crew pod, in which the pilot of the XF-103 could encapsulate and eject downward. Preliminary studies showed the pod to be unusually aerodynamically stable, despite its odd appearance, but the system was never actually tested. The XF-103 pod promised to allow aircrew escape at the upper limits of the aircraft's performance envelope, although data was never released concerning its low altitude, low speed characteristics (presumable very poor, given experience with other downward firing systems in use at the time in similar operating conditions). This concept did, however, pioneer certain parameters shared with later upward firing podded escape systems that would be used successfully in the B-58 Hustler and XB-70 Valkyrie.
One instance of a very satisfactory American escape system having been developed is found in the ejectable crew compartment concept employed in the General Dynamics F-111 Aardvark. Although a controversial design from its very onset, the F-111 (neé TFX), with its swept-wing features and technical innovations, featured an egress system which was one of the most reliable component systems found on the plane. Borrowing from pioneering studies conducted by the Heinkel company and use of the concept in its He-176 rocket-powered airplane of WWII vintage, the General Dynamics Corporation (formerly Convair) incorporated an ejectable crew compartment egress system in the final pre-production TFX prototypes. Although the original prototype had flown using two conventional ejection seats, the ejectable crew compartment became a standard feature of the F-111, and throughout its service life provided Aardvark crews with reliable, safe egress--both in non-combat emergencies as well as in wartime combat situations (Vietnam). As might be imagine, the ejection sequence involved actuation of an explosive disconnect system which separated the crew compartment from the nose section and fired a rocket system which shot the crew section away from the crippled aircraft. A high-speed drogue system then deployed, which in turn actuated a recovery parachute attached to the compartment.
Crew members had the choice of either staying in the capsule until it came down to earth or opening the canopy and manually parachuting from the compartment while it was still descending. Statistically, the success rate of F-111 ejections was remarkably high, testifying to the engineering concept and development underlying the design.
It is worth noting, in passing, that the Bell X-2 rocket research aircraft that was being flight tested in the mid 1950s at the Edwards Flight Test Center in California featured a jettisonable crew compartment. The plane was designed to exceed Mach 2 at a time when such extreme speeds by manned aircraft were still challenging, and as yet unreached, aeronautical objectives beckoning to aviation engineers.
Interestingly, on September 27, 1956, Captain Milburn Apt was flying the 13th test flight of the Bell X-2 when he encountered a particularly severe roll-coupling situation in flight testing at a speed of Mach 3, after beginning a descent from 72,000 feet. So unusual was the situation, and so severe the buffeting which resulted that the decision was made by Apt to eject, and he did do, actuating separation of the entire nose section of the research aircraft which contained the small cockpit. The capsule was designed to be separated, then stabilised by a drogue chute after adequate deceleration had occurred. Once the capsule’s recovery chute had been deployed, the plan was for the occupant to release the canopy, unstrap his harness and manually bail out using the capsule’s seat-type personal parachute.
Documentation of the accident shows that the capsule separation was achieved as planned for and that the drogue system worked as anticipated. Unfortunately, Apt appears to have been disabled through some sort of injury sustained, either in the violent buffeting before ejection occurred or after the capsule separation took place, and was unable to leave the capsule before it plummeted into the desert floor at about 120 mph. The G forces sustained in the impact, estimated to be about 90 G (plus or minus 40 G), resulted in Apt’s death. The Bell X-2’s recovery capsule was not intended to land with the pilot in it, unlike other systems (such as the F-111) in which emergency descents might be survived while still contained within the capsule’s crew compartment. Evidence was found at the site which indicated that Apt had succeeded in jettisoning the capsule’s canopy, and also had been able to release his restraint harness prior to impact, but had not been able to leave the capsule to bail out of it for reasons which are still uncertain.
Although the North American XB-70 supersonic advanced strategic bomber program never progressed beyond the production of two prototypes, the crew escape system that consisted of fully encapsulating individual crew modules was inadvertently put to the test in an unfortunate mid-air accident which destroyed the number two XB-70 prototype (XB-70A-2) on 8 June 1966. As designed, the individual capsule-type crew ejection system allowed for safe ejection from near zero/zero conditions (90 knots IAS, zero altitude) through Mach 3 and its 80,000 feet operating ceiling. Each module consisted of a central seat unit which employed upper and lower clam-shell type doors to cocoon the crew member when the escape system was actuated. Each contained its own environmental support system and allowed for pressurisation and crew oxygen so that in addition to serving as a rocket powered escape vehicle, the capsules could also protect against emergency high-altitude decompression in flight.
A window in the upper clamshell door allowed observation of instruments while the crewman was encapsulated, and provision was made for minimal encapsulated control of the aircraft thusly configured. Ejection sequencing consisted of manual actuation of the arm-rest triggers, immediately whereupon the capsule tilted 20 degrees to the rear before encapsulation by the clam-shell doors was accomplished. Further, the crewman’s heels had to be properly emplaced before the process would begin. After the capsule had closed and sealed, the crewman had to activate a further actuator to jettison the upper and lower fuselage before firing the capsule out and away with its integral rocket motor. Main recovery chute was automatically deployed by a complex barostatic system and capsule descent rate was reported to be about 28 feet per second. Twin, rear projecting booms served to stabilise the capsule during ejection and an inflatable cushion automatically deployed (with a manual inflation option) under the capsule to help the occupant withstand landing forces. The crewman remained within the capsule throughout the entire recovery process, from ejection to landing, and included in the capsule were survival equipment, life-raft and other items. On a water entry, the capsule would remain afloat in an upright position automatically.
The prototype XB-70A-1 and A-2 aircraft undergoing flight testing from 1964 through 1969 were configured with two such crew capsules (pilot & copilot), although the intended production B-70 bomber was to have two additional crew positions in routine operational use.
On 8 June of 1966, during a media fly-by flight of several types of aircraft using GE engines (the XB-70 included), an inadvertent mid-air collision occurred involving a Lockheed F104 Starfighter and the number two XB-70 prototype. The cause of the F104’s veering into the starboard outer wing section of the XB-70 was never to be learned, although the consequence of the collision was the immediate destruction of the Starfighter and the smashing of the two vertical fins of the XB-70, which the F104 slashed through after hitting the bomber’s wingtip.
The XB-70A-2, traveling at about 300 knots IAS, remained in a state of stable horizontal flight for about 16 seconds after the collision before suddenly going into a nose-down roll, with subsequent violent yawing that ended up with the aircraft entering a final, unrecoverable flat-spin before impacting in the desert, 25,000 feet below. The two crew, test pilots White and Cross, immediately upon experiencing the roll over, began to realise that ejection was mandated. Pilot White was successful in ejecting himself by pulling the ring to begin encapsulation, which he estimates he accomplished about 60 seconds after the XB-70A-2 became violently unstable. His copilot, Cross, was apparently unable to do so. It is speculated that possibly G-forces or a head-injury may have prevented him from taking the initial step to initiate ejection. White, meanwhile, caught his arm between the clam-shell closure seals and suffered a dislocated shoulder attempting to free the arm, but managed to get free and was safely lowered to earth in his capsule. Despite the fact that the impact cushion beneath his seat failed to inflate, he survived the 43 G impact, albeit with severe internal injuries that were partly lessened by collapse of the capsule’s internal seat structure.
Cross’s capsule was never ejected, and its remains were recovered in situ at the site where the XB-70A-2 hit the earth in a flat spinning attitude and burned. The incident was thoroughly investigated from all angles, including performance of the life support/escape system, and White’s survival contributed greatly to knowledge of how such an encapsulated escape system could be further engineered to deliver an even higher level of protection. The mere fact of his survival vindicated, at least in part, the integrity of the encapsulation escape system concept.
[A further system utilising an ejectable nose was briefly considered for use in the Lockheed F-104 Starfighter and prototype mockups were actually constructed of such a design, but due to weight and complexities involved, the idea was early-on rejected in favor of a conventional ejection seat system.]
In still other areas of US military flight operations--particularly in the area of flight test--various escape seat systems were developed for special applications. One of these was the North American Aviation escape seat designed for their X-15 high-altitude, Mach 6 rocket research vehicle. The seat employed was designed and extensively tested--again on the Air Force’s rocket sled track at Edwards in California--to allow for escape at extremely high altitude and extreme speed. Considering the performance parameters of the X-15 (maximum altitude of more than 50 miles and maximum speeds exceeding 6 times the speed of sound) the challenge was formidable. Once more, a rocket powered, open-seat design was employed, which would allow recoverable egress up to a speed of Mach 4 in any attitude and any altitude up to 120,000 feet. During ground testing on rocket sleds at Edwards Air Force Base, the seat was demonstrated to give good ground-level escape at speeds as low as 90 knots IAS. A ballistic rocket-type catapult system provided the basic propulsion force, and the seat featured side-mounted folding stabilizing fins and extendible booms that would deploy upon ejection to maintain proper escape attitude during initial boost phase of about 0.5 seconds and subsequent recovery deceleration, until the seat drogue system and main recovery chute could release satisfactorily.
Amazingly, despite many years of often quite dangerous flight testing at the very limits of known aerospace performance parameters for manned vehicles, the X-15 ejection seat system was never needed, and hence no documentation exists as to its actual performance in the event of a genuine flight emergency requiring ejection, as none occurred.
Among the more unusual egress systems developed in the US was the Stanley 'Yankee' System, in which a tractor rocket was integrated to the pilot’s harness which would be fired off to literally haul him out of the aircraft’s cockpit. This system, which was fitted to some aircraft in which it would have been impossible install conventional ejection seats, was in use in the mid 1960s and was fitted to the Douglas A-1D Skyraider, among others. The system provided for aircrew extraction by rocket first, after which a second rocket deployed and spread the pilot’s personal back-style parachute; the Yankee System was successfully employed in a real emergency situation in Vietnam in 1967, when a Skyraider piloted by Maj. J.E. Holler sustained engine failure at low level in combat. It is interesting to note that this system provided true zero/zero capability at a time when no other conventional systems did. The Yankee ejection system proved to be quite a reliable and effective design while in combat use in Vietnam, despite its novel technology.
Still other innovative egress systems under investigation during the Vietnam conflict were the Karmen Aircraft SAVER System, and the Goodyear Aerospace PARD System. The first design consisted of an ejection seat which after deployment functioned like an autogyro. The Karmen Stowable Aircrew Vehicle Escape Rotoseat (SAVER) contained a small turbojet and folding rotors and tailplane, which would allow the pilot to remain airborne and travel about 50 miles at speeds of about 100 knots. Its development was incomplete when the war ended, thereby ending investigation into its possible use in combat aircraft.
The second egress system mentioned above was the Goodyear Pilot Airborne Recovery Device (PARD), and this system featured an unusual balloon-parachute hybrid design (called a BALUTE) which would fill with heated air provided by a small LPG burner above the pilot’s conventional parachute, after ejection in a standard ejection system seat. The heated air would allow the pilot to remain airborne for about 30 minutes, during which time a mid-air recovery attempt could be effected with an aircraft equipped with appropriate snaring apparatus. The system was tested and demonstrated to work successfully in tests performed in Southern California, but again the project was discontinued when America’s Vietnam involvement ended in 1975.
(Next: Part 3, the final installment)