A Gamble in Air Defence
By E. COISTON SHEPHERD /F only we had known that Russia would keep alive the threat of war during the first six years of the peace, the British . programme of aircraft development would have been differ- ently framed. In 1945 the Service 'chiefs promised themselves a spell of ten years of peace. Statesmen took scientific stock of what might be done with aircraft, and chose a plan which would yield big results at the end of ten years and relatively little in between. That was not unreasonable, for at that time we had the fastest, best-climbing, most manoeuvrable jet fighters in the world. It was also economical, for it meant that research and development might go systematically forward without haste and without the disturbance and expense implicit in putting succes- sive designs into production. The only thing that was wrong with the plan was that it made no provision against Russian intransigence. In consequence the R.A.F. has had to beg bombers from the United States and to try, so far without success, to buy later types of fighters from the United States. The United States Air Force has had to station bombers and their fighter escorts in England, and is now supplementing the force of interceptors charged with the defence of Britain with a wing-75 aircraft— of its own latest fighters. Meanwhile, the R.A.F. is equipped only with improved versions of the aircraft which were in its hands at the end of the war. American reports on the air-fighting in Korea say that the latest American fighters, the Sabres or F.86s, are certainly no better than the Russian-built MiG 15s. For the moment the Sabre is the best we or the Americans-have in squadron service to set against the Russians if they should move in the West.
Our gamble on ten years of peace has evidently run us into danger. That was apparent two years ago when the decision to re-arm was taken. With that decision came orders for a change in the aircraft-development programme. The long-term plan was not abandoned, but intermediate results were demanded quickly. Aircraft are being shown to the public this week at Farnborough which are proof of the brilliant response by designers to the challenge, and others, described simply as research aircraft, suggest other imminent responses. What lies in secret behind them belongs mainly.4o the next stage of progress towards speeds exceeding the speed of sound.
No supersonic aeroplanes are yet ready to be built in quantity for the R.A.F. or, apparently, for the U.S.A.F. Some in the present batch of new fighters can be flown at supersonic speeds (above 720 to 760 m.p.h. according to temperature at sea-level), but in their standard form they are not intended to make regular use of such speeds. They advance performance a step beyond the 660 m.p.h.tf the Sabre, and they probably advance it enough to match whatever the Russians have in preparation to succeed the MiG 15. These fighters are now going into production: They should be flowing into the squadrons before the end of 1953. With them will arrive the new bombers, of which the Valiant four-jet bomber is an outstanding example. These new bombers are the best justification of Britain's original decision to put. ten years of work into her next generation of military aircraft. They are popularly described as 600-m.p.h." bombers. Even if that is a slight exaggeration, they still present any interceptor now flying with a task of the utmost difficulty. It must climb, perhaps 40,000 feet, to make contact, and if its climb is not on the true line of intereeption, it will have little time for pursuit and only a speed margin of 100 m.p.h. to save pursuit from becoming procession. A supersonic fighter is plainly desirable in opposing this class of bomber, especially as these bombers are capable of carrying atomic bombs. It is still to be desired if it is to be used only as an elevated control-tower for the launching of guided missiles of supersonic speeds at the incoming bomber.
Bombers can be expected to lag more and more behind fighters in speed so long as they have to provide'for long flights to their targets and to use existing fuels. Speed, and particularly super- sonic speed, is costly in fuel ;' and present fuels mean weight. A pinch of uranium may some day provide the heat for journeys which now demand the consumption of many tons of oil or spirit. That day seems to be a long way off. Until then the bomber must accept the best compromise it can get between speed, range and military load, and in present circumstances must put range and bomb-load before speed. What the Valiant does is to give a magnificent combination of the three factors. The Comet air- liner, using the same engines, will carry a pay-load of 14,000 lb. over a distance of 2,500 miles at a speed of 450 m.p.h. All that can be said of the Valiant bomber at present is that it will do better than that, for bombers are free from many of the inhibi- tions which lie heavily on the designers of passenger aeroplanes.
If we were right in aiming direct at the supersonic fighter in our ten-year programme, we were assuredly slow in getting off the mark. We chose humanely to start our supersonic research not with manned aircraft but with pilotless models. We wasted two years in getting these robots and proving to ourselves that they were unsatisfactory. By that time the United States had built two aircraft for full-scale research into supersonic speeds, and, although there has been no hint of it, Russia, with German help, may have done the same. Again, we had a good excuse. The large amounts of power required for supersonic flying could then be obtained only from rocket motors, and the average dura- tion of a rocket-driven single-seater at that time was three minutes. Today the best is eight minutes. That would be of • little practical use to us. We were after a fighter, not a long- range shell. And we,had a line of gas turbines in development which should give us a supersonic fighter of much better duration.
We alone had those gas turbines. All the signs were that we could afford to wait until we could get our 7,000 lb. or 8,000 lb. of static thrust for supersonic flying from gas turbines instead of from rockets. We are still ahead with our jet engines, but we have still to overtake the United States in research into speeds beyond the speed of sound. We are plodding, as the British so often do, after something which is better than the best possible at the moment In the end we shall probably get something amazingly good, but by then we shall also have shared our basic advantages with our friends—as in fact we are doing with our gas turbines at present. With our eyes still set on the original objective, we have been forced by events to manufacture the intermediate types of aircraft which are officially described as trans-sonic. They appear to be remarkably good, and they will afford a lot of experience towards the next step. These are the aircraft with thin wirigs swept back. No one knows with certainty yet whether or not they lead straight on, for speed purposes, to the delta wing which sweeps the wing-tips still farther back and joins them with a straight trailing- edge. Theory says they do. It is a simple, logical theory which seeks to fit the shape of the aeroplane into the form of the shock-wave of compressed air which breaks around it from the bows as it crashes through to supersonic speeds. The theory says that this conical shock-wave narrows as the speed rises. It argues that an aeroplane shaped like a dart will fit into it like a finger in a glove. If the theory is right, the aeroplane with the triangular wing can be designed for a Particular speed, with the line of the leading edge swept back to the angle of the cone of the shock- wave appropriate to its top speed. This trimming of the wing to fit the cone stops only when the angle becomes too acute to allow the wing to develop the requisite lift, at low speeds, for landing.
In all these matters today the State determines the programme an pays for it. A Government department decided how we siguld tackle research into supersonic speeds. It is still the arbiter of pace and direction. Aircraft manufacturers cannot afford to take an independent line. They are serving brilliantly in designing aircraft to given specifications and in conducting specified research. Occasionally they can get proposals adopted, but there is no longer the surge of new ideas that once came out of the industry, or the readiness to lay out capital to show the customer what he wants. The battle is in Government offices, where the risk of expensive failures is always a drag on the wheel.
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