Dynamic Testing

Because of the need to test the compatibility of the ejection seat with an actual representative cockpit section, Martin-Baker designed and built a special high-speed test facility.
A level site was chosen alongside a main runway. A concrete foundation one metre deep was constructed with steel anchor bolts moulded in place. Steel sleepers (ties) were bolted to the concrete foundation, the whole process being carefully surveyed to ensure accurate alignment. Continuously welded bullhead section rails were then laid at a 30inch (762mm) gauge and were ground in-situ using a specially designed laser alignment fixture. The rail was pretensioned to eliminate distorsion due to the fluctuations in ambient temperature. The result is a 6,000 ft (1829 meters) long track which is straight within a tolerance of 0.010 ins (0.254mm) over 125 ft (38.1 metres). This accuracy is essential to minimise horizontal and vertical vehicle loads when travelling at high speed. The test vehicle and pusher rocket are mounted on the track by means of slippers which fit around the rail section permitting only horizontal motion along the track. The fuselage is mounted on a standard base to simplify the interfacing of the different fuselages with the track. The test cockpit is fully representative of the subject aircraft and sub systems such as a canopy jettison and interseat sequencing systems are installed as on the actual aircraft. A fully representative seat and clothed instrumented dummy are also installed.

The test fuselage is propelled by a solid rocket powered pusher sled which is coupled to the standard base on which the fuselage is mounted. The test speed is varied depending on the number of rockets fitted to the pusher. For high-speed tests, with large test fuselages, up to fifteen main motors will be used. These motors develop a combined thrust of 112800lbs for 2.25 seconds and accelerate the test vehicle to over 600knots. Smaller sustained motors then fire to maintain the selected ejection speed for approximately one second. During this cruise portion of the test, the ejection seat is electrically initiated by a track-side signal, the canopy removal and ejection being filmed by on-board and track-side cameras. Telemetry data is also sent from the seat and dummy to a recording station alongside the track.
This data shows accelerations in all axes throughout the entire ejection, parachute opening and descent to touchdown. High speed photosonic 16mm cameras, mounted on the sled, within the cockpit, fixed alongside the track and hand-held, provide a multiple high definition record of all events. The films and data are analysed by a highly experienced team of test engineers to ensure that the ejection has met the established criteria. Tests are conducted at various speeds for each aircraft type to ensure the correct functioning of the complete escape system. This high speed test facility is UK, US and NATO approved, and has been used to quality the escape systems of the: Panavia Tornado, AMD/BA Alpha Jet, AMD/BA Mirage F1B, Grumman EA6B Prowler (4 seats), Aermacchi 339, CASA 101 Aviojet, Locheed Martin TF-104 Starfighter, IAI Kfir, IAI Lavi, SAAB JAS 39 and many others.This valuable facility is also used for ejection seat research using a specially fabricated test vehicle.

The Human Engineering Department

The Human Engineering Department provides all the services required to undertake the entire range of MIL-HBDK-1472 requirements.
The specialist engineers undertake all work associated with aircrew to seat interface, flight clothing compatibility and life support system integration. Other facilities also allow for the evaluation of parachute descent procedures, and post ejection survival in both land and sea operating environments. Trial installations and cockpit mapping functions are also carried out by the department. An extensive range of flight equipment in the various sizes is held within the department together with examples of most survival equipment.