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Aviation History
1966
1966 - 0376.PDF
ucHT International, (0 February 1966 233 Alost amateur-built W-8s have detail modifications devised by their con- structors; this example has a very refined engine cooling and cowling arrangement, together with a swept fin craft is fitted with a Continental C.90; but never can a C.90 have run so smoothly, nor given such stallion-like horses. Questioned about it, Bud says with a knowing wink, "I earn my living on engines." Steve Wittman is known for his wide grin and it was never wider than when he observed the stopwatch poised at the runway holding-point after a smooth gallop over the surround- ing rough scrub to demonstrate the undercarriage. With full power, 374 broke away in 5|sec flat and climbed out with the VSI showing well over l,500ft/min and at a shatteringly steep angle of climb—all on 80 sq ft of wing and loaded to about 1,4001b, top weight being 1,4501b. A short cross-country enabled Steve to demonstrate the fact that apart from the ground passing very quickly under the 20ft-span wings the Tailwind has some excellent flying quali- ties. One of his tricks is to set the DG, displace controls at varying speeds, and then release in various combinations and orders. In all appropriate cases the aircraft falls back into the groove and continues on the same heading. The stall is ridiculous—merely a gentle nibbling and rumble, a positive but gentle nod and that is all; and it is the same in 30° banked turns right or left Wittman W-8 (Standard) Basic Data ":....:: Span, 20ft 11 in (as flown), latest version, 22ft 6in; length, 19ft 3in; wing area, 83.5 sq ft; empty weight, 7001b; gross weight, 1,3001b; baggage capacity, 601b; fuel, 21 Imp gal; Vne, I8S m.p.h.; US certification: Experimental, homebuilt category, recreational only. Longitudinal stability was found to be positive. Laterally, aided no doubt by the tip design on the no-dihedral wing, disturbances resulted only in the wing coming up again. Control damping was good, and altogether the whole deal was a speedy surprise packet of gentle behaviour. From this the reader should not consider that the Tailwind is a soft aeroplane; it is not. The elevator is light and the speed can build up quickly, but the positive and active feel is something refreshing after many of the woolly types around. After a Coke at the pleasant little Fond du Lac Airport Steve allowed me to drive 374 back to Oshkosh to check the handling and note some figures. Steep turns without rudder were easy, and it was possible to reverse from one turn to the other feet-off without the ball bank indicator going berserk. Mick force per g is not high, but there is a very proper neavying of the elevator as one increases displacement of the centre-mounted T-type control column. Rate of roll was not measured, but it was certainly brisk. With the aircraft trimmed for fast flight the ASI was gettingne ar to 200 m.p.h., and a fast cruise at 75 per cent power indicated 180 m.p.h. A power-on straight stall, flaps down, indicated below 50 m.p.h.; at 55 m.p.h. power-on it was Possible to rock the wings and make gentle turns while havingot h feet off the pedals. Power-off, the so-gentle bite came at a shade under 60 m.p.h. On this basis, approach speed used was 85 m.p.h. and this resulted in precise approach and land- ing characteristics. Because of the conventional position of the mainwheels and the much lower powered engine, Bud Harwood's standard Tailwind seemed to be almost another type; but it was soon apparent that blood is thicker than water. Take-off in an outside temperature of 25 °C and little wind took lOsec, and with a climb speed of 90 m.p.h. the first thousand feet were indicated on the altimeter 58sec from unstick. With 2,600 r.p.m. and 22in of mercury manifold pressure the IAS in level flight at 2,000ft was 158 m.p.h. Full out, the IAS crept to 170 m.p.h. with a position error assumed at some 10 m.p.h. on the optimistic side. Power-off, Nil UN stalled at 42 m.p.h. IAS and dropped its port wing about 10° if recovery action was delayed. Releasing the column at the stall resulted in a gentle pitch and recovery. Thus the stall characteristics of the Tailwind showed up really well, proving once again that stalling behaviour and not necessarily low speed is the important feature in this flight regime. The Harwood Tailwind would hold level flight at 45 m.p.h. IAS, feeling very solid and suggesting good poor-visibility creeping performance. Again lateral stability was positive; crossing controls, then releasing, made the aircraft swing back with slight nose-down pitch into the original flight path. Again the elevator was light; and, although Tailwinds on test have pulled over 4g without trouble, there is no room in this cabin for the reckless. Mississippi State College Aerophysics Department had shown the real economy of this basic version by measuring the performance in level flight as 34 statute miles per Imperial gallon at a calibrated airspeed of 140 m.p.h. and using in this condition 60 b.h.p.—a very fair cruise situation by any standard. From the same source a pitot static position-error curve with cabin static showed 40 m.p.h. IAS to be 55 CIAS and 60 m.p.h. IAS to be 66 CIAS. Another test computing the ratio of thrust horsepower in the glide to b.h.p. at various airspeeds showed that an overall propulsive efficiency of 85 per cent was obtained at 100 m.p.h., this peak figure falling off to 70 per cent at just over 140 m.p.h. All in all, the Tailwind well deserves its popularity; it is unknown to find a Tailwind owner who is not delighted with his aircraft. Here is a real cross-country performer—in fact, Chuck Wilford, a Tailwind builder, is hoping to demonstrate the capabilities of the type by a Los Angeles to New York non-stop flight. Certainly Steve Wittman has produced one of the most contradictory and fascinating light aircraft ever designed: contradictory because at first sight it is so strikingly unusual; and fascinating because of its performance and ability to transport two people side by side in a cabin of amply wide dimensions and with sufficient room for luggage. Plans to construct the standard W-8 Tailwind are available from Steve Wittman for $125 and include the latest 21ft 6in span wing and rib section of modified 4309 profile.
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