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Aviation History
1969
1969 - 0395.PDF
FLIGHT International. 6 March 1969 nebulous parameter which can be guaranteed even less than weight or payload or speed. All aeroplanes have this com modity, some have it in large quantities and in a few (the Phantom is one) it appears almost as a manufacturing process. The photographs on these pages represent the F-14A mock-up photographed recently at Grumman's Bethpage, Long Island, plant. It is curious that the illustrations should vary quite substantially with artists' impressions—also very recent—of the same aeroplane. The firm has spent $88 million on the F-14 project over the past four years; its aim was to design the best fighter in the shortest time with the minimum risk. The first flight will take place in early 1971 and initial operational capability with the Navy is scheduled for 1973. The aeroplane is a tandem two-seater with two engines mounted side-by-side in the rear fuselage, fed by sharply tapered inlets, and having a v.g. wing with a large glove. Extensive use will be made of advanced construction tech niques and titanium will be employed to a very great extent. Grumman say that the aircraft will be 8 tons lighter than the F-I11B at take-off in a comparable role, giving a "ball park" weight of 50,0001b, about the same as that of the Phantom. The airframe weight will be about 25,0001b giving a "zero-fuel" weight of about 35,0001b. The F-14 is factored for great manoeuvrability in combat and for Mach 2-plus cruise. The wing sweep will be automatically controlled under all flight conditions, but manual override will be provided (the F-1I1 system is manually selected). Supersonic air flow always needs to be cosseted if its goodwill is to be retained; with v.g. multi-role aeroplanes this consideration is even more impor tant and two features taken together mark the F-14 as unique: the presence of foreplanes which (at least on the mock-up, if not on published artists' impressions) grow out of the wing leading edge, and the use of two slightly canted vertical tail surfaces, resembling those of Foxbat. The purpose of the foreplanes, or "glove vanes" as contemporary jargon has it, is to control the centre-of-pressure shift and to provide an effectively lower wing loading, an important factor for pulling high g in both air combat and close support. Leading-edge flaps (not visible in the illustrations) are fitted. Standard armament will include Phoenix (developed specially for the F-lllB), Sparrow and Sidewinder missiles, together with a single nose-mounted M-61 six-barrelled cannon for air combat and interception, using the Hughes AN/AWG-9 fire- control system. Air/ground missile and bomb systems will also be included. The fuel system will have a capacity large enough to enable the F-14 to escort long-range attack aircraft (such as the Intruder) without recourse to tankers. The main undercarriage is developed from the same com pany's A-6 Intruder long-range subsonic attack bomber. It folds forward and up, rotating through 90°. The crew of two (pilot and missile-control officer) are housed under a one- piece clear-view canopy. The adoption of under-wing intakes seems rather remarkable in view of inlet-flow distortion at high g experienced with the F-lll. These intakes are of the two-dimensional (rectangular) all-external compression type (all shocks occur externally) with straight-line airflow to allow 371 the engines to accommodate the widest possible range of heights and speeds. They have multiple-shock ramp systems for good pressure-recovery at high Mach numbers, and details are evident in the illustrations. The slab tailplane is very large to counter the destabilising influences of high Mach, high g, variable sweep and non- constant fuel state, while the use of twin fins and rudders points to possible directional stability problems at high speed (always a difficult design case) or during combat manoeuvres. Under fuselage strakes are also fitted. The development programme envisages three different variants: F-14A. F-14B and F-14C. The differences will reside principally in the powerplant and equipment fits. The F-14A (VFX-I) has P&W TF30-P-12 turbofans, which can hardly be considered to be multi-role engines. A limited quantity (probably under 100) of this version will be bought. The F-14B (VFX-2) will employ the same airframe and avionics but will have a lighter and more powerful engine (believed to be the TF30-P-401). The F-14C (VFX-3) with lighter avionics and an advanced-technology engine appears to be the definitive version and production is to be brought forward. Engine commonality between the F-14 and F-15 is likely to pose one of the most difficult design problems. The Defence Department have specified a common core section so that the fan bypass ratio will be the critical variable. The Navy is understood to favour a bypass ratio of between 0.8:1 and 1:1 while the USAF, with a lower thrust requirement (23,000lb against about 25,0001b) will want about 0.6:1 or 0.7:1. Both P&W and GE are submitting designs based on concepts derived for both AMSA and the now-cancelled AVS (advanced vertical strike) aircraft studied by America and West Germany. The mock-up contains advanced engine configuration by P&W and GE in the left and right engine tunnels respectively. The F-14B and C models will have a combined thrust of between 52,0001b and 54,0001b giving a thrust/weight ratio in excess of unity under almost all conditions. Compared with the Phantom, the F-14 will be twice as manoeuvrable, especially at high speeds and altitudes. The approach speed will be about 120kt (20kt slower than the Phantom) and the spotting factor 1.5 (compared with the Phantom's 1.7). This quality is a measure of the deck space occupied for parking and manoeuvre. The initial contracts for the F-14 provides $40 million for research and development of pre-production aircraft. Incre mental financing under the development contracts will total $388 million over a four-year period, and this contract also provides for USN options to buy 463 production aircraft following the development stage. It is estimated that some 1,200 F-14s will be built and the entire programme (which includes such items as the cost of certain carrier modifications) may be worth as much as $5 thousand million. The F-14 is a significant project which is going to occupy a prominent place in America's military plans in the 1970s. It will be incredible if Europe is not affected in some way or other and Grumman's new brain-child is going to merit the closest attention. M.W Left, close-up of the Concorde-like inlet, and "glove vane." Right, wing fully forward. Full-span surfaces are prdminent Howard Levy photographs
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