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Aviation History
1957
1957 - 0694.PDF
700 Mr. M. J. Brennon, B.Sc, M.I.Mech.E., F.R.Ae.S., Saunders- Roe chief designer, and S/L. J. S. Booth, D.F.C., the company's chief test pilot. MIXED-POWER INTERCEPTER . . . to a higher figure As for the turbojet, it cannot have any propul- sive value whatever in the thin outer reaches of the atmosphere to which the rocket must be able to push the aircraft. It is worth recording in this context that the Grumman F11F-1FTiger has already reached 72,000ft on the power of a turbojet alone. It is more than likely that the Saro fighter could exceedthis height by a substantial margin. In fact, if it were allowed to climb at a really steep (and steepening) angle under full thrust itcould doubtless reach a trajectory peak of perhaps 100,000ft. At such heights the wing could not support the aircraft, even atmaximum lift coefficient and peak forward speed, so the aircraft would literally fall out of the sky. The all-rocket Bell X-2, ofcourse, has flown semi-ballistically at 126,000ft, and the North American X-15 is designed to reach heights four times as great. As far as one can determine from the exterior appearance of theaircraft, the new Saro fighter prototype is remarkably conven- tional and straightforward in design. It is usual practice for thefirst officially released photographs of a new aeroplane to be so posed as to reveal little of the wing plan. The shadow in thepicture, however, reveals that the Saro wing is almost an obtuse delta with squared-off tips. By modern standards the wing profileis not particularly thin, and it seems quite orthodox in having a rounded leading edge which should prove beneficial at moderatespeeds. There are no fences, neither is there evidence of abrupt changes in section at the leading edge, like the familiar "dog-tooth"or kinked leading-edge arrangements. As far as can be seen, conical camber is not incorporated either. As is to be expectedwith a high-speed aeroplane of this configuration, there is marked anhedral to introduce a destabilizing element and improve lateralstability at altitude. The exact form of the flaps cannot be determined from thereleased photograph. It is highly likely that the leading edge is hinged and can be depressed for landing, or flying at low airspeeds.The squat fin should prove to be both an efficient structure and an effective surface. No doubt it is full of tailplane controls, for,unlike many high-speed aircraft, the horizontal surface is mounted at the extreme top of the fin in undisturbed air. It would havebeen difficult to attach it in the neighbourhood of the powerplants or to have found accommodation there for the operating jacksand controls. No doubt all control surfaces are fully powered or power-assisted.Hydraulic power for this purpose is probably obtained from a pump driven by the turbojet, but provision must also be madefor maintaining essential hydraulic power at extreme altitude when the turbojet may be unable to function. It is, of course, notyet possible to discuss how this problem has been overcome. In general, the fuselage is of excellent form, conforming with theN.A.C.A. area rule and making the maximum use of the limited interior volume. Behind the fine supersonic nose-cone is thepilot's cockpit with a hinged canopy and a Martin-Baker ejection seat which apparently fires upwards. Most of the space behindthe cockpit is filled with fuel. With substantially axial distribution of a considerable fuel load, a major design problem must have beento achieve proper balance and e.g. position over the whole range of flight speeds from tanks-full to tanks-empty. It remains to beseen whether room has been found for much fuel in the wing. Pressure fuelling is certain, but provision for in-flight refuellingis doubtful. It is also unlikely that the aircraft is intended to be parked with rocket fuel on board. The undercarriage looks particularly neat. All tyres are tinyand are probably tubeless units inflated to very high pressure. The main legs retract inwards into the wing and the nose gear goesforwards. Air brakes are fitted to the rear fuselage and a braking parachute is housed beneath the rear end. Additionally, the firstS.R.53 probably has an anti-spin parachute above, in the visible faired box. There is little possibility of commenting at length upon thepowerplant installation. The rocket is mounted in the bottom of the rear fuselage, no doubt within a steel-skinned fireproof bay.The turbojet is mounted beneath the upper fuselage decking and FLIGHT, 24 May 1957 can obviously be removed from the aircraft by being lifted outvertically through large dorsal doors. Intake position is always a most interesting variable, and no doubt the Saunders-Roe choiceis as good as any. It is noteworthy that the intakes do not seem to be designed to create their own inclined shocks. Responsibility for flight testing of the first machine is vestedin Mr. J. S. Booth, D.F.C., the company's chief test pilot. His assistant is Jack Overbury who joined the firm from the RoyalNavy last November. The first flight took place on May 16 and the aircraft behaved normally and successfully. Unlike aircraftwith acute-delta wings, it can be landed with its nose not par- ticularly high in the air. What exactly is the significance of Saro's beautiful white midget?One must remember that it represents the first stab at a very big problem, and it is no easy task to hit the correct balance betweenthe opposing mistakes of over-caution and trying to accomplish too much at one jump. The mere fact that the present machinehas a flat windscreen indicates that, by modern standards, its maximum speed is not particularly high in the supersonic region,and it is also unlikely to be designed to fly at full thrust at low altitude. Another important factor is that its maximum flightendurance is probably too short to allow the boundary layer really to heat up fully to the temperatures for which we are now design-ing structures. Later machines may be able to fly beyond the main thermal-lag periods and will prove invaluable for advancedairframe research. For the moment, however, one cannot look much beyond the"bird in the hand," the white-painted S.R.53 itself. To a consider- able degree this is not a combat aircraft but a research and develop-ment vehicle, so one should not try to draw too many conclusions from its configuration, size or characteristics. It is, however, amachine capable of undertaking investigations previously beyond the scope of any British aeroplane, and Saro should be justifiedin also expecting it to lead to larger and more advanced machines for operational purposes. In conclusion, the following is an extract from a letter publishedin our "Correspondence" page on March 1. After likening the S.R.53 to the mixed-power Trident 2 (Sud-Aviation 9050) the Lt-Cdr. J. R. S. Overbury, A.R.Ae.S., who joined Saunders- Roe from the Fleet Air Arm six months ago. writer continued: "This raises an interesting possibility, becausethe Trident's makers have announced that its ultimate develop- ment will be pilotless. Is it not equally feasible that the S.R.53could be evolved into an unmanned missile in due course? Such evolution would not only make good sense, but might even beinevitable. For example, it was largely because of the occasional erratic behaviour of pilotless targets that aircraft like the unmannedFirefly U.8 and U.9 and Meteor U.15 and U.16 had .to be produced as targets for missiles at Aberporth and Woomera. Asthey have a cockpit with normal controls, a check pilot can fly them to a safe height, then sit back and fold his arms while themachines are tested under remote control, so offering reasonable certainty that they will not cause abortive missile-launchings insubsequent pilotless flight. "Similarly, there is little doubt that Boeing have discoveredthat the cheapest and best way of perfecting their Bomarc inter- cepter is not by repeated trial and error launchings but by lettinga pilot go along with the guidance system to keep an eye on its functioning. This accounts for the appearance of a Temco-modified B-57 with 17ft of simulated Bomarc on its nose, two or three years after the first firing of this missile. "This B-57 is a device to get the Bomarc guidance system up tothe altitudes where Boeing want to put it through its paces. The next generation of piloted intercepters, such as the S.R.53 series,will be devices to put air-to-air guided missiles in the right posi- tion to ensure destruction of enemy bombers. In short, they willbe "boosters" for a homing warhead, performing the same func- tion as the rocket-motors of a ground-to-air missile, but witha pilot to make sure that the warhead goes in the right direction, until such time as a black box can be made to do the job asefficiently."
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