TSR2
Page 56
By Night. Vertical photography at heights between 500 and 1,200ft is required. (But see also paragraph 53.)
General. Automatic control of exposure is desirable, particularly for low-level cameras. Camera magazines must be easily and rapidly removed after a sortie and must be capable of fitment in, and be removable from, cameras in situ. Means must be provided to protect camera installations including radar equipment using photographic materials against nuclear radiation when the aircraft is on the ground ready for flight, and at all altitudes.
Line Scan Reconaissance. Line scan reconnaissance is required capable of acquiring by day or by night, from any altitude between 200 and 1,000 feet, video signals which, when related to a receiving and display system on the ground will produce a picture of sufficient clarity to disclose the presence of a single vehicle of 3-ton truck dimensions. When flying at 1,000ft the picture coverage of the ground beneath the aircraft is to be continuous along track, and include at least ½nm on either side of track. At heights between. 200 and 1,000 feet, the widest possible picture coverage is required within the definition limits specified.
Direct transmission between the aircraft and a ground station of the line scan signals, with the aircraft’s DR position at 4nm intervals is required. Air Staff Requirement No. OR.2153 specifies the ground station which will be used in conjunction with the airborne equipment. The use of an airborne relay located over friendly territory will be acceptable if this is necessary to achieve the required range of at least 110nm. This communication system is to be as free as possible from interception and interference.
The airborne transmitter, together with recording equipment capable of storing line scan signals acquired over at least 50nm of track, is to be developed as an integral part of the line scan installation. The equipment must be capable of transmitting a picture irrespective of aircraft heading, and adjustment of directional aerials (if such are required) is to be automatic. Adjustment of the main equipment is also to be fully automatic and the visual head is to operate over the widest practicable range of photographic conditions without resort to manual adjustment in the air.
Providing the performance of line scan at night is adequate, the Air Staff are prepared to accept this as fulfilling the night PR requirement.
Radar Reconaissance. The Army’s requirement for tactical radar reconnaissance calls for the best possible resolution and is to incorporate Moving Target Indication (MTI). An all-weather capability from medium altitude (but without MTI) is also required. A facility for instantaneous or delayed transmission of radar reconnaissance information to a ground station is highly desirable, and a method of integrating this with the similar line scan requirement should be attempted.
Data Recording. Automatic recording of data essential for all phases of reconnaissance interpretation is required. DR position at least is to be readily available for first phase interpretation of film or radar reconnaissance records.
Automatic Flight Control Facilities
An automatic flight control system (AFCS) is required, which at the discretion of the pilot will provide either automatic control of the aircraft or flight director instructions, or both, during the following manoeuvres.
Approach and landing using an instrument landing system and suitable radio altimeter. All selections to be made by the pilot.
Maintenance of track and mean true altitude over the ground as selected by the navigator. The pilot is to have overriding control of aircraft height. (See paragraph (f) and (g) below.)
Bombing – selections to be made by the pilot or navigator according to the bombing system being used.
Turn on to and hold any heading selected by the pilot or navigator. It is desirable that the pilot or navigator should be able to preselect this manoeuvre at least 20 seconds before initiating it.
Turn left or right, regardless of the heading selected on the pilot’s or navigator’s display, at a rate determined by the deflection of the pilot’s control.
Maintenance of any barometric or true height and/or Mach number as selected by the pilot.
Descend or climb at any rate of change of true height selected by the pilot. It is highly desirable that the aircraft should level out automatically at any height pre-selected by the pilot, and that director steering instructions should be provided to assist him when manually levelling out at a predetermined height.
Maintenance of flight conditions for maximum range.
The AFCS is required to operate at the lowest practicable altitude. The pilot is to have overriding authority under all circumstances. Attention should be given to means of preventing the inadvertent operation of one mode of the weapon system when any other mode is selected.
Pilot’s Display
To enable the pilot to fly the aircraft manually, and to monitor its progress during automatic flight, he must be provided with a situation display of the following information in a form that is easily appreciated. This must include, on the main instrument display, an indication in flight director form, of the nature of the commands being transmitted to the controls by the autopilot.
Aerodynamic data comprising attitude, heading, speed and height. This may be displayed by a presentation based on the Instrument System OR.946.
Manoeuvring data in the form of flight director signals both on the instruments in sub-para, (a) above, and also on a collimated windscreen display which must include an artificial horizon. The director signals are to cover the following range of manoeuvres :
Take-off.
Maintenance of track and altitude during cruise.
Climb and descent to preselected heights.
Attack.
Approach and landing.
[Issue 2: ‘windscreen’ replaced by ‘head up’ and approach and landing part deleted.]
Director and information display fed from the terrain clearance system to enable the pilot to take the best tactical path in pitch to avoid high ground or to monitor the AFCS performing the same task.
[Issue 2: changed to enabling pilot to follow ground contours.]
Standby instruments are required to meet the safety requirements in para. 61 below.
A navigation display based on the concept of OR.946 (including Instrument Landing mode), plus a topographic display giving progress along track, or base position, in addition to aircraft heading. This display should be fed from any of the navigation aids at will.
[Issue 2: topographic display replaced by moving map display.]
For rocket firing the pilot is to have suitable sighting and aiming data provided by the forward radar and flight director in the head up windscreen display.
[Issue 2: para 59 deleted, covered under HUD.]
Navigator’s Display
The navigator is to be given a clear display showing continuously the aircraft’s position accurately in a form that will enable him to follow closely a pre-planned track, and maintain the correct heading right up to the moment of weapon release. The display must, however, enable the navigator to regain track after unplanned departures therefrom. When D.R. position is displayed it must be possible to correct it quickly and accurately from visual or other fixes.
The still-air range remaining, under the following preselected conditions is to be displayed:-
Assuming the present conditions of flight are maintained.
Assuming that optimum range conditions of flight will be adopted as quickly as possible.
[Issue 2: replaced by flight time remaining display assuming economic cruise.]
Safety Measures
The AFCS must not accelerate the aircraft so as to incapacitate the crew, stall the aircraft or exceed its load factor.
After any single failure within the main electrical generating system the aircraft must be capable of completing its mission without loss of the use of subsystems. After any two failures in the main electrical generating system, or after any single failure within the navigation, armament, reconnaissance or flight control subsystems, sufficient power and services mus
t be available for the crew to be able to complete the sortie. To do this they must have the following minimum facilities:-
Sufficient control of the aircraft to allow for return from the most distant point on any sortie.
DR information to enable the aircraft to arrive sufficiently near to base to obtain air traffic control assistance by R/T. Where the nature of the failure so demands DR information should be available from an air data system with manually-set wind.
An adequate display of:-
Heading - this should be at least a stand-by directional gyro with magnetic monitoring.
Attitude.
Speed.
Height.
[Issue 2: added para – In the terrain following mode, no single failure is to endanger the aircraft. If after one failure has occurred, the terrain following facility is still being employed, no second failure is to endanger the aircraft.]
No single failure in the bomb release system must cause inadvertent release of the weapon(s), neither should a failure prevent the weapon(s) from being jettisoned if necessary.
OPERATIONAL EQUIPMENT
Counter Measure Equipment
The aircraft will carry such electronic countermeasures as may be dictated by the nature of the opposing weapon systems in the theatre concerned. These counter measures cannot be precisely specified until the feasibility of future developments has been assessed, but at least a passive warning receiver system is required, providing visual and aural warning of attack from any direction, and capable of automatic triggering of any of the countermeasures listed below. This equipment is to weigh not more than 50lb. nor exceed 1 cubic foot in volume. It is to be fitted permanently in the airframe.
Other countermeasures will be developed as part of the ECM programme and will be the subject of ORs of more general application. The extent to which they are required will depend upon the operational environment. One, or a combination of the following is to be allowed for in the design of the aircraft :
Between 6 and 12 rocket propelled radar and infra-red decoys, which may be about 44 inches in length, 3 inches in diameter and weigh approximately 30lb each and would fly forwards and upwards from the aircraft.
24 cartridges of explosively launched very rapidly blooming Window.
One of a series of noise jammers, or a deception jammer, designed to confuse specific radar systems. Their aerial system will require, as far as possible, a view all round the aircraft and may comprise several interchangeable units.
[Issue 2: changed (b) to ‘a method of launching window’.] [AL1: deleted all of (c) noise/deception jammers.]
In order to permit the carriage of these countermeasures adequate provision of weight, space, power and cooling is to be made, which should not be less than 350lb, 8 cubic feet and 5KW. This power demand need not be covered by reserve aircraft generating capacity, and in the event of a power failure it is accepted that the countermeasures will be switched off. Carriage in the weapon-bay with the least limitation of the weapon load is acceptable. If carried in an external pod some loss of performance will be accepted. In either case the installation is to be self-contained.
Communication Equipment
The following communication equipment is required :
Two-way voice communication with the ground up to the maximum radius of action of the aircraft at all altitudes. The equipment is to have not less than 24 channels and is to be controllable by either crew member. The necessary ground equipment is to be developed concurrently to Air Staff Requirement No. OR.2109.
[Issue 2: need for control by either crew member deleted.]
Multi-channel UHF derived from the equipment developed to Air Staff Requirement No. OR.3502. An audible channel annunciator is required.
[Issue 2: added new sub-para covering standby UHF operated from aircraft emergency electrical supply.]
Intercommunication equipment operating independently of (a) and (b) above.
[AL2: added VHF.]
Identification Equipment
Provision is to be made for the installation of IFF Mark 12.
[Issue 2: replaced by IFF Mk 10.]
Flight Refuelling Positioning Equipment
A system is required which will allow the aircraft to home on to a tanker from at least 100nm down to a minimum which will enable contact to be established in conditions of ½nm visibility. The Air Staff consider that full advantage should be taken of the possibility of adapting the forward radar to provide this facility. The ‘Buddy’ tanker fit is to incorporate a suitable transponder beacon.
[AL4: buddy tanker fit deleted.]
CREW STATIONS
Crew Composition
The crew will consist of a pilot and a navigator.
Crew Stations - General
The crew are to be provided as far as possible with an environment which will enable effective accomplishment of their duties during high speed low altitude flight. The maximum degree of comfort is essential and it must be possible to carry out all duties without moving from the seats.
The crew must have good view at all times. There is to be:-
For the pilot a real downward view of 18°. Limited deterioration of view in any forward direction must not reduce the real downward view below a critical value of 11°. (The real downward view is the view forward and downward measured from the horizontal over the nose with the aircraft in its approach configuration, at instrument approach speed on a 3° glide path).
Adequate sideways and forward view for the pilot and navigator to gather and correlate information to ensure accurate track holding.
A downward view for one of the crew members approximately equal to the area being covered by the vertical cameras.
[Issue 2: sub-para (c) replaced by: In the reconnaissance role the forward and downward view for the navigator is to be sufficient for tracking and operation of the vertical cameras.]
Heating and Ventilation
It is essential to provide an adequate air supply for cooling and heating. The crew are to be protected against heat and cold at low altitude in the event of failure of the cabin conditioning. It is essential that adequate means are provided to ensure proper ventilation and cooling of the crew space while the aircraft is on the ground with engines stopped, and when taxying.
The mean cabin air temperature is to be automatically controlled throughout flight between reasonable limits of any value selected by the crew between +15°C and +35°C. The aim should be to achieve limits of the order of ± 2°C. Under the conditions chosen by the crew, the temperature at the hottest and coldest points of the crew station should be as constant as possible and ideally should not differ by more than 5°C.
Pressurisation
A cabin pressurisation system is required. The system is to have a single differential pressure only of 5lb per square inch.
The rate of change of pressure should be kept to the minimum during descent. If possible this rate should not exceed 1lb. per square inch per minute for normal descent. For tactical descents it is acceptable to fly at low altitude with negative differential pressure in order to obtain a reasonably low rate of change of pressure.
ANTI-ICING/MISTING
Windscreen and Transparencies
Good view is essential at all times with no optical distortion where sighting of armament is involved. Means are to be provided, to be effective throughout the full sortie, to prevent the windscreen or transparencies, including camera windows, from icing or misting up, or becoming obscured by precipitation or insects. The rain removal system should be capable of clearing an area sufficient to give an adequate view for approach and landing in heavy rain, and to see straight ahead in cruising flight in moderate rain. The system is to be effective against dust, dirt and insects during taxying and take-off. A blast air/aerodynamic system is required.
Engine
An ice warning detector is required. Adequate engine and intake anti-icing is required for half the duration of the aircraft.
FUEL SYSTEM
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It is essential that the fuel system should be simple and, so far as possible, automatic in operation. The pilot must not be distracted by having to pay attention to fuel management.
The aircraft is to operate with AVTAG, AVTUR or AVCAT fuel without the need for engine adjustments. The aircraft performance is to be based on the use of AVTAG. The Air Staff wish to be informed of the penalties in performance or design imposed by AVTAG.
[Issue 2: performance to be based on AVTUR.]
Refuelling
Provision is to be made for flight refuelling at a rate of not less than 300gal/minute. It is to be possible to refuel all tanks in this way. It is desirable that flight refuelling should be carried out through the same system as ground refuelling. Ground refuelling is normally to be by a pressure fuelling system but the alternative of open line refuelling is required.
[Issue 2: open line refuelling deleted.]
It is to be possible to flight refuel from a ‘V’ Class tanker aircraft. Additionally a ‘Buddy’ type refuelling capability is required. The system must be designed to permit easy conversion of the basic aircraft to the tanker role and vice versa. Conversion under squadron servicing conditions is not to exceed 6 hours. The off loading capability of the ‘Buddy’ tanker, compatible with its own requirements, is to be not less than 300gal per minute.
[AL4: buddy refuelling deleted.]
Fuel Monitoring System
A fuel flow-meter is required, and space provision is to be made for the installation of a combined range, endurance and fuel remaining computer. Air Staff Requirement No. OR.998 defines this system.