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Aviation History
1948
1948 - 0891.PDF
JUNE 17TH, 1948 FLIGHT 653 A production Prentice seen from one of its more attractive angles. the Prentice has good characteristics, being suffi- ciently sensitive on con- trols, requiring plenty of rudder to check skid and slip on going into or out of a turn, but holding well on ailerons and elevators alone when in the turn. The first few stalls and spins of one's flying career are usually rather alarm- ing, and for a trainer, recovery should be rapid, positive and according to the rules. The Prentice now meets these require- ments satisfactorily. The stall warning, in addition to sloppy controls, is in the form of a shudder together with elevator vibration. A 111 lie aileron control remains until the wing drops, which might be useful for some landings. I tried picking up a stalled wing with rudder and found that it can be done, but usually at the expense of stalling the opposite wing in a more pronounced manner. If held in the stall the Prentice almost always drops the left wing in an incipient spin. Solo, and without flap, the stalling speed was around 50 m.p.h. I.A.S. at 3,000 ft. With, flaps lowered characteristics were much the same, though perhaps gentler, and the speed was about 8 m.p.h. lower. An intentional stall on a simulated powered approach with half flap, was heralded by plenty of vibration, and came at about 55 m.p.h.. The aircraft could be held laterally level and recovered immediately action was taken. • '.'-.•• Spinning I tried spinning to left and right, both straight and off turns, and found two sorts of spin or, more correctly, two phases of the same spin. From the start, which is usually a bit lumpy, the nose is well down. If held for two or three turns the spin remains steep and the rate of turn becomes fast and even. Recovery takes about three-quarters of a turn, using full opposite rudder followed by stick fairly well forward. The comfortable pull-out speed is around 120 m.p.h. with no fear of a second stall arid spin. On one spin of exactly two turns I lost 1,200 feet from level to level. On spins to the right there seemed more tendency to buffeting and rattling of the canopy when going in. Aerobatics gave^less trouble than I had been led to believe. A loop at 150 m.p.h. I.A.S. is sweet and simple, and occasions no hauling on the stick or excessive g. Stalled turns are quite straightforward from level flight at cruising speed, and barrelly rolls are easy to do. True slow rolls, at 140 m.p.h. I.A.S. require full aileron all the time, and a nose-high start as on the Tiger. With a little practice they can then be made .Straight and smooth. The Prentice appears to fly nose-down when it is, in fact, level, and this should be remembered at the end of a roll, as an attempt to hold the nose on the horizon when coming out will probably cause it to drop and skid at the last moment. Much the same comments apply to rolls off the top which require about 165 m.p.h. and which I found needed practice to come out at 180 deg. Two things were noteworthy about aerobatics : first that a steep power-on dive with stick pushed forward is needed to build speed up to the 150-170 m.p.h; needed ; and second, a very close watch needs to be kept on the engine r.p.m. Not only was there lag, over and under shoot on the part of c.s. unit, but to allow the engine pick-up to fall behind the throttle opening to any extent due to coughing, etc.. invited serious momentary overspeedin<r when it did pick up. I foresee more than one Gipsy Queen unit putting up a protest- ing 3,000 r.p.m. howl when Prentices reach the E.F.T.S.s, although there is little chance of even the most determined pupil reaching or exceeding the maximum permitted diving speed of 250 m.p.h. Several approaches, landings, bounces and overshoots were tried in a strong wind and I discovered that glide or powered approaches with full flap at around 75 m.p.h. are pleasant to make, the angle being quite steep and the view of the landing path excellent. The maximum speed for flaps down is 100 m.p.h. and lowering causes slight nose up trim change. Slow approaches would not be too good for a pupil's first hours as the float period is negligible, even in ordinary circum- stances. No sooner is the Prentice levelled off than it " plops " sedately down and rolls to a standstill without swing or bounce. If the throttle is banged fully open after a mislanding the Prentice gathers itself more quickly than I had anticipated, and climbs away readily with flap half up. Flap can be brought from full-out to half-way at once. All the same, it is no Tiger Moth when it comes to a 30-ft hold-off, and the rudder tends to resemble a bag of feathers. Not unexpectedly, perhaps, the Prentice sideslips well, and a high rate of descent can be obtained. MAKERS' DATA FOR THE PERCIVAL PRENTICE 250 h.p. D.H. Gipsy Queen 32 Engine. Span 46ft Length 31ft lin Height (tail down) 8ft lin Wing area 305 sq ft Gross weight 3,850 1b Wing loading 12.6 Ib/sq ft Max speed at S.L 150 m.p.h. (130 kt) Economical cruising speed at 3,500ft ... ... ... 140 m.p.h. (122 kt) Stalling speed (Flaps down) ... ... ... ... 55 m.p.h. (47 kt) Rate of climb at S.L. 700 ft/min Take-off run (max load, still air) 200 yd Max. economical cruising range 4S0 miles Finally, I would add that for cross-countries, navigational exercise, instrument-flying practice, procedures and night circuits the. Prentice will be very favourably received by instructors. It is no more difficult to execute the various aerobatic manoeuvres than on pre-war elementary trainers, and the rather poor rate of climb to safe heights for such exercises may yet be looked after by the fitting of more powerful Queens. Supercharged engines are, however, less economical and are likely to be less reliable, so they might prove to be a mixed blessing. It seems to me that from the flying, if not from the operational viewpoint, the Prentice has a lot to recom- mend it for R.A.F.V.K. pilots, qualified, but refreshing their memories on training exercises as economically as possible, practising I.F. and navigation, and, at i present, learning up-to-date procedures.
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