seat testing

The name Martin-Baker is synonymous around the world with the design and construction of emergency ejection seats. Through half a century of development, today's fully automatic zero-zero rocket assisted ejection seats are a far cry from the basic seat in which Bernard Lynch made the company's first live airborne ejection in July 1946. Amazingly this first ejection was made from the same type of aircraft that Martin-Baker uses as its ejection seat testbed today - the Gloster Meteor. The work completed by the Martin-Baker Meteors since, and the tremendously brave volunteers who conducted the early live test ejections, have saved many thousands of airmen's lives.

Escape from a damaged or uncontrollable aircraft had naturally been at the forefront of pilot's thoughts right from the earliest days of flight. The terrible losses suffered by aircrew on both sides in World War I forcefully highlighted that in future conflicts, an air force's greatest asset - its highly-trained pilots and aircrew - must be offered an effective way of emergency escape, and the most obvious solution was the parachute. During World War I escape by means of parachute had become a regular occurrence from observation balloons and airships. However, pilots of fixed-wing aircraft were generally not afforded such a luxury and were obliged to either attempt to bring their damaged aircraft to earth in a forced-landing or, if the airframe had ignited, jump from their aircraft to face almost certain death to prevent being burned alive. In the inter-war period the parachute was steadily introduced into widespread use for combat aircrew around the world. Using the standard practice of standing up in the cockpit and diving over the side of the aircraft - aiming to miss the trailing-edge of the wing - parachute escape saved many hundreds of lives. As is the case in times of conflict, technological advances allowed the performance of combat aircraft to advance at a startling rate during World War II. In the mid-1930s, the RAF was equipped with biplane fighters such as the Gloster Gladiator, with a maximum speed barely exceeding 250mph.

A decade later the RAF was busy equipping with its first generation of jet fighters capable of speeds in excess of 5OOmph. Experience in air combat had revealed that the 'over-the-side' technique of exiting an aircraft was becoming increasingly difficult and, in a growing number of cases, was proving impossible. Attempting to stand up and dive from a cockpit in a slipstream of over 400mph, with the pilot often under a significant g-loading, was beyond the capabilities of any pilot.

A number of promising schemes were devised during the war to aid emergency exit. In Germany, the deficit of experienced fighter pilots prompted Hans Sander, Focke-Wulf's chief test pilot, to form a small design team to devise an emergency escape system for the company's Fw190 fighter. A forerunner of the successful ejection seats introduced post-war, the system showed great promise, but the timescale and resources needed to introduce the device could not be allocated as Germany's position became increasingly desperate.

Meanwhile, in the UK, the need for such a system was finally rammed home with the death of one of the Royal Aircraft Establishment's (RAE) leading test pilots, Squadron Leader Davie, and the loss of a valuable prototype of what was to become the Gloster Meteor. During a test in January 1944, an emergency was encountered and the pilot attempted the standard abandoning technique. However, the high airspeed caused injury as he leapt over the side of the stricken aircraft, causing him to lose consciousness and therefore make no attempt to open his parachute.

The Air Ministry, after a thorough investigation, concluded that the increasing performance of aircraft, accelerated by the introduction of jet engines, would render conventional emergency escape techniques obsolete, and a new system would have to be devised. The most attractive of these would be by forced ejection of both seat and occupant by explosive charge and, in a far-sighted move, the Ministry of Aircraft Production invited a little known aircraft designer - James Martin - to investigate the practicability of providing fighter aircraft with a means of assisted escape for the pilot. At that time there had been little research into the effects on the human body of a sudden and powerful vertical compressive thrust. To conduct the necessary physiological research, the company devised and built a 16ft vertical test rig in tripod form, with one of the legs encompassing guide rails along which a dummy pilot's seat would travel. The seat was activated by two telescopic tubes driven by an explosive charge. After tests with a dummy, the first live test was made by Bernard Lynch on 24 January 1945, to a height of 4ft Sin. The power of the cartridge was increased steadily until 10ft was reached. However, as the firing mechanism became more powerful, the stress on the human body was reaching intolerable levels. This manifested itself the injury of a technical journalist who was admitted to hospital with crushed spinal vertebrae. To help overcome the problems associated with spinal compression, James Martin acquired a human spine, and tests on this, along with the test rig research, allowed Martin to calculate the design criteria which his new design (and all subsequent ejection seat designs) must follow:

1. The peak acceleration should not exceed 21 'g' and this peak should not be held for longer than 1/1O th of a second.

2. That the rate of rise of 'g' should not be greater than 300 'g' per second.

3. That in sustaining this acceleration, the body should be held in a position to ensure that adjacent spinal vertebrae are square to each other.

To aid the design of the seat and firing mechanism a new 65ft test rig was built. The seat now incorporated a firing handle above the occupant's head to ensure the spine was in the correct alignment and a rearrangement of the footrests. Meanwhile, the company had been allocated a Boulton Paul Defiant for modification, for the commencement of airborne tests. At this time the company was using Oakley Airfield near Thame, Oxfordshire, for its test flying. It was here that the modified Defiant, incorporating structural changes to the rear cockpit (which included the removal of the turret and the fitting of the experimental ejection seat) began its test programme. After successful static test of the seat, loaded with sand bags, on 10 May 1945, the first ejection from an aircraft in flight was made the following day with Bryan Greensted piloting the aircraft. Six further dummy elections  were made from the Defiant at speeds up to 300mph. However, with the initial live test programme on the 65ft rig reaching its conclusion and the concept proved, it was time to look for a new flying testbed that would have more representative performance of the latest RAF combat aircraft.

On 6 November 1945, a modified Meteor F3 (EE416) arrived at Oakley to begin the company's 57 year association with the aircraft Design work had begun on the aircraft the previous September after the Ministry of Aircraft Production decided that it was the type most suited to the task. Fitted with Rolls-Royce Derwent I engines, the forward fuselage section was considerably modified to allow the ejection seat and its associated apparatus to be fitted behind the pilot's cockpit, in what was formerly the ammunition bay. The original seat bulkhead was removed and replaced by a new sloping bulkhead further aft, the rear decking was modified and the floor beams reinforced to withstand the stresses imposed by the ejection gun. On completion of the modifications the aircraft was delivered to Chalgrove airfield, Oxfordshire, which has remained Martin-Baker's main test flying base to this day.

After a static ejection, with the aid of a catch net, was made on 8 June 1946, the first airborne dummy ejection was completed on 24 June at a height of 2,000ft and an indicated speed of 415mph. The initial dummy tests were not a success, as the speed of the airflow caused the parachute to burst with the loss of the seat. To cure the problem, a drogue parachute was incorporated to help slow the seat before the deployment of the main parachute and, after several failures at perfecting the new system, the prototype seat was declared ready for live testing in late July. On 24 July, after two final dummy tests were completed, Bernard Lynch ejected himself from EE416 at 320mph and 8,000ft - and thus became the first person to make a live ejection from an aircraft in the UK. It proved to be landmark event in the history of Martin-Baker, with the whole system working without a glitch and Lynch making a perfect landing. Unlike the automatic seats of today, Lynch, once established in a steady descent beneath the main parachute, had to unfasten his seat harness and push himself clear of the seat, before pulling the ripcord of his own personal parachute, with the seat continuing its descent under the original 'chute.

The   success   of   the   Martin-Baker   system attracted the interest of the US Navy who, following a presentation to them at Martin-Baker's Denham headquarters, ordered one of the experimental seats to be fitted in the rear cockpit of a Douglas A-26 Invader. Thus, the second live ejection from a Martin-Baker seat was made by Lt Furtek, US Navy, on 1 November 1946 over Lake Hurst, Philadelphia. Having proved the concept, Martin-Baker progressed to design its first production seat, the Mk 1, which incorporated a host of improvements identified by the engineers, Lynch and James Martin. The new seat was guided during ejection by four rollers on the seat structure running in a guide rail assembly bolted to the Meteor's structure, the ejection gun being located within the hollow guide rail assembly. Testing of the seat commenced over Chalgrove from EE416 on 19 August 1947, again with Lynch the man in the 'hot seat'. The system worked without problems and the seat was subsequently put into production for installation into the Meteor, Supermarine Attacker, Westland Wyvern, English Electric Canberra and later the Hawker Sea Hawk and de Havilland Venom. EE416 continued its valuable experimental work through the late 1940s and early '50s, racking up some 400 airborne tests in support of the project, including over 20 live test ejections. During this time the company employed a number of other Meteors in support of the project. Meteor Mk 3 EE415 was used as an aerial photographic platform to capture the ejection sequence on film. The ammunition bay was removed and replaced with a forward-angled camera. Flying slightly astern of EE416, the pilot would activate the camera after notification from the test aircraft - however, due to the rapid deceleration of the seat and occupant, only a short sequence could be captured before the subject disappeared from the camera's line of sight. Proving of only marginal use, EE415 was returned to Glosters on the19th October 1949. Two further Meteor F3s (EE338 and EE479) were utilised by Martin-Baker during the late 1940s - the former again for photographic work, and the latter as a ground test rig for ejection trials. Both aircraft were found to be of nominal value and after brief service were returned to the RAE and RAF respectively. Meteor F4 EE519 was also on Martin-Bakers' books for a brief period in 1950-51, but again was found to be surplus to requirements. Approaching the end of its usefulness, EE416 was joined by a Meteor T7 two-seat trainer, WA634. Built in November 1949, the aircraft had a noticeable performance advantage thanks to its Derwent 5 engines, giving it a maximum speed of 585mph. This additional speed would soon prove an advantage in the development of the next generation of seats cleared for use in higher speed ranges. Initial modifications followed along the same lines as for EE416, although this time with the advantage of already being a two-seat design. Modifications included the repositioning of the bulkhead between the two cockpits, strengthening of the floor structure and removal of the flight controls from the rear cockpit. Further modifications were introduced in 1952, when the aircraft returned to Glosters for the fitting of the E.1/44 'high-speed' rear fuselage and tail unit, destined for production Meteor F8s. This configuration was later afforded the designation Meteor T71/2. On return to Martin-Baker in late 1952, the aircraft underwent further modifications before commencing its ejection test career on 31st August 1953.

A number of notable first were achieved by WA634 - including the first live runway ejection, by Sqn Ldr J. S. Fifield at Chalgrove on 3rd September 1955. The Meteor was travelling at 145kts and within six seconds of initiating the ejection sequence, Fifield was safely on the ground, having accomplished an ejection which many people had though impossible. The following month Fifield set a new record at the other end of the scale making a successful ejection at an altitude in excess of 40,000ft.

With the trials starting on the Martin-Baker rocket-assisted ejection seat it was necessary to determine beforehand what effect the rocket blast would have in a confined cockpit space. For this purpose the company obtained the shell of WA686. In an opposite configuration to WA634, the aircraft comprised the forward fuselage of a Meteor Mk 8 combined with the rear fuselage of a T7 and lacked outer wings, engines and part of the tail section.

The aircraft was used for static tests of the rocket-powered seats before the modification of WA634 to begin airborne tests. The first live ejection using a rocket seat was completed by Sqn Ldr Peter Howard in March 1962, who described the ride as 'very smooth'.

After WA634 reached the end of its useful life, its work was continued by another Meteor converted to T71/2 standard, WA638. The aircraft continued as the main flying trials aircraft until December 1977. when it was replaced by a further Mk 7'/2, WL419.

Named Asterix, WL419 has remained in service up to this day and has now been joined by a resurrected WA638, which made its maiden flight after refurbishment on 29th May 2001. Both aircraft have received additional modifications including external strengthening straps along the fuselage sides and a heavy-duty aluminium blast-tank in the rear fuselage to contain ejection seat rocket blast pressure. The pilot himself is seated in a modern Mk 12L(MBA) ejection seat which fires through a new non-MDC bubble canopy. The continuing use of the Meteor is partly due to the superb serviceability of the aircraft and the centrifugal flow Derwent engines which are extremely resistant to bird strikes.

Now in their 57th year of continuous operations with Martin-Baker, the Meteors have a long career in front of them. With only 50 hours or so flying per year, WA638 - as the oldest flying military registered jet aircraft in service in the world - will continue to set new records, and help save more lives for many more years.

Test aircraft

Along with the company's Gloster Meteors, Martin-Baker employed a number of other aircraft types to investigate specific aircraft characteristics or flight envelopes for the development of new systems and seats propulsion system allowing safe ejections at low speeds and low altitudes. With the ultimate aim being clearance for zero-speed zero-height (zero-zero ejections) a number of test vehicles were used. Ground tests were completed on a specially constructed zero-zero launching stand and a specially adapted motor vehicle for low-speed runs before the main air test phase began with low and medium speed ejections from Meteor T7 WA634. However, for higher speed tests an aircraft with greater performance was required. The solution arrived in the shape of Hawker Siddeley's company Hawker Hunter T7 XJ627, which was loaned to Martin-Baker for the duration of the tests. Having received the necessary modifications, the Hunter was used to test the seat in the 500-600 mph speed range. Although no live tests were conducted by the Hunter, dummies of varying weights and statures were fired from the Hunter, eventually clearing the seat for use by all pilots in this speed range. The Hunter was returned to Hawker Siddeley at the completion of the test programme in the mid-1960s.

Concurrent with the development of the rocket seat, James Martin had been placing increasing pressure on the RAF and the government to consider ejection seats for all crew members of the UK's V-bomber force consisting of the Avro Vulcan, Handley Page Victor and Vickers Valiant. In 1960, Martin-Baker carried out tests to demonstrate that safe ejection from aircraft fitted with rearward facing seats was practicable. A specially designed seat was installed in Valiant WP199. A programme of three dummy ejections were carried out, one on the runway during the take-off run (see photo) and two at 200 ft above the airfield at 250 kt and 300 kt respectively. The series of tests was completed by a live ejection by 'Doddy' Hay at 1,000 ft and 250 kt over Chalgrove on 1 July 1960. Despite the success of the world's first live rearward-facing ejection, in front of representatives from the Ministry of Aviation and Bomber Command, the seats were never developed for service aircraft despite the constant protestations by James Martin. He campaigned for their introduction throughout the 1960s and, after a Vulcan crash in 1968, he telephoned Air Chief Marshal Sir Wallace Kyle stating that he was disturbed to hear that the RAF was flying portable crematoriums. Escape systems were again briefly investigated but were subsequently rejected on cost grounds, much to Martin's chagrin.

For development of the Mk 12H rocket assisted ejection seat, Martin-Baker and the RAE modified Canberra WH876 for airborne tests of the new seat.The seat was intended for service in the new generation of BAe/McDonnell Douglas Harriers which entered RAF service as the GR5. The tests were conducted during the 1980s at the MoD's Boscombe Down airfield, and included live airborne ejections of dummies of various configurations and weights.

 

 

 

This aircraft has survived and is presently at RAE Boscombe Down where it is stored outside in a pretty poor state!

(c) Daniel J Marsh (Royal Air Force Year Book 2002)