Ejection seats for military aircraft

Abstract: A reclining ejection seat (1) for an aircraft which includes an arm support (7) composed of two parts (8,10) which are moveable fore and aft. A first part (8) carries flying controls (9) and is adjustable for reach. A second part (10) which is adjustable for comfort, locates the elbow of a pilot (11) and supports his forearm. The arm support (7) permits the pilot (11) to maintain adequate control over his arm movements even when the aircraft is carrying out very high speed manoeuvres.

Description: This invention relates to improvement in cockpits for military aircraft and in particular, to improvements which protect the pilot of such an aircraft from the adverse effects of high 'g' forces. It has been found that when an aircraft is carrying out manoeuvres involving forces of more than 8g, the pilot needs to be in almost supine position if he is to remain conscious (even when wearing the conventional 'g' suit). Ejection seats which are moveable from an upright position to a reclining position have been proposed for use in high speed aircraft. See, for example, US 3,981,465. For most flying operations, the pilot selects the upright position. For high-speed manoeuvres, he reclines the seat so that his tolerance to 'g' forces is improved. The inventors have found that whilst in a supine position and under high 'g' conditions, the pilot has appreciable difficulty in controlling his arm movements and, consequentially, operating the manual flying controls. US Patent No. US-A-3 580 636 describes a dual side arm controller for use within the armrests of a seat. The seat is made up of a back portion and an pair of retractable arm rests in which a pair of controllers is formed. This 1970 invention was not concerned with high 'g' problems, it was proposed to overcome the problems of limited space for instruments, seating and controls in modern jet aircraft. Single side arm controllers had been known previously for large commercial jet aircraft, but for linkage complexity reasons it had been virtually impossible to retractably mount the side arm controller in the armrests, which would have allowed the pilot easier access to his seat. The dual side arm controller of this 1970s invention allowed the pilot to control the output of the controller with either hand, and either side arm could be retracted, for seat access, without altering linkage lengths or destroying the function of the controllers. It is an object of this invention to provide an arm support for the pilot so that he can execute the necessary control over the manual flying controls when carrying out high speed manoeuvres. Thus the invention comprises an ejection seat for a pilot of an aircraft including an armrest and control elements built into the armrest characterised in that the armrest is composed of a first part on which are mounted aircraft control levers and a second part for supporting in use a pilot's elbow and forearm wherein the first and second parts may be moved independently of one another relative to the remainder of the seat. Optionally, the armrest may carry aircraft control levers such as the throttle, stick and rudder pedals, all of which may be adjustable for reach. The relative movement of said first and second parts may be controlled by an electric motor. Some embodiments of the invention will now be described, by way of example only, with reference to the drawings of which:- Figure 1(a), (b) and (c) shows three side views of an ejection seat (incorporating an arm support in accordance with the invention) in three different positions of deployment; Figure 2 is a further side view of the ejection seat of Figure 1(a). Figure 1 shows an ejection seat 1 having one pair of guide rails 2 located either side of the seat (only one rail being shown here for clarity), s pyrotechnic ram device 3, an electric motor 4 for rotating the seat about a point x and an ejection gun 5. The Pyrotechnic ram 3 is provided as an additional energy source in order to produce a force to act with the gun 5 on an escape sequence at any instance before, during and after articulation of the seat. The ram 3 works on a ratchet device (not shown) in order to provide anchorage to the ram 3 so enabling a firm reaction during the escape sequence. The locus of the pilots' eye 6 is shown for each of three positions (a), (b) and (c) of the seat 1. Position (a) shows the seat in a fully reclining position at approximately 65° to the vertical, (b) shows the seat rotated through approximately 21° to a more upright, intermediate position, and (c) shows the seat raised on its guide rails 2 without any further rotation from position (b). This last function serves to give adjustment for the full range of aircrew 3%ile to 99%ile to a common eye datum with an external view. Position (a) is chosen by the pilot for maximum 'g' protection when sustaining high 'g' manoeuvres. Whilst in this reclining position, and unable to see through the windshield the pilot deploys a head-down display (not shown) comprising two panels which fold outward away from the pilot's line of sight when not required. The panels display computer generated images of geographical features and data which relate to the area over which the pilot is flying. Methods of generating images suitable for this purpose are described in our co-pending UK Patent Application No. 8912026. When the seat 1 is in its most upright position corresponding to position (c) in Figure 1, the pilot uses a conventional head-up display (not shown). In this position, the pilot is permitted a 20° field of view in elevation through the windshield. The design philosophy of the ejection seat described above with reference to Figures 1 and 2 is a complete departure from the conventional method of raising or lowering the seating platform to achieve a common eye datum, irrespective of the size of pilot. The eye datum is not now considered as critical with the seat reclined and no external view being possible. Furthermore, the need to raise and lower the seat in order to reach and operate controls and the ability for the pilot to rotate his arm about the shoulder are no longer relevant. An anthropometric survey concluded that the pilot's elbow would have to be located into the corner of an armrest so that adequate support for the forearm at very high 'g' values could be provided. The survey also concluded that the armrest should be adjustable fore and aft to accommodate pilots of different size. The range of adjustment within the survey was found to be 66mm of fore and aft movement. The above findings are embodied in the seat of Figure 2. The seat 1 incorporates an arm rest 7 composed of a first part 8 on which are mounted aircraft control levers 9, and a second part 10 which supports the elbow and forearm of a pilot 11. The first and second parts of the arm rest (8,10) can be moved independently of one another relative to the remainder of the seat 1, in a fore and aft direction (as shown by the arrows in Figure 2). The pilot 11 firstly adjusts the second part 10 so that his elbow is comfortably located. Adjustment is achieved by means of an electric motor 12. Next, the pilot 11 adjusts the first part 8 of the arm rest 7 so that he can comfortably reach and operate the controls 9. Adjustment is effected by an electric motor 13. An armrest as described above can provide adequate support for the forearm under high 'g' conditions and thus enable the pilot to operate the manual flying controls with the required accuracy.

Claims: An ejection seat for a pilot of an aircraft including an armrest and control elements built into the armrest characterised in that the armrest (7) is composed of a first part (8) on which are mounted aircraft control levers (9) and a second part (10) for supporting in use a pilot's elbow and forearm and wherein the first and second parts may be moved independently of one another relative to the remainder of the seat (1). An ejection seat according to claim 1 and characterised in that the relative movement of said first and second parts is controlled by an electric motor (12).

Inventors: ASH GEOFFREY JAMES BRITISH AER, VALENTINE TIMOTHY BRITISH AERO, ASH, GEOFFREY JAMES, BRITISH AEROSPACE, VALENTINE, TIMOTHY, BRITISH AEROSPACE
Applicants: BRITISH AEROSPACE, BRITISH AEROSPACE PUBLIC LIMITED COMPANY
Application year: 1991
Main classification: B64D25
IPC codes: B64D25, B64D11