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Aviation History
1986
1986 - 0683.PDF
Left The Pusher's canopy will eventually feature a one-piece windshield. Right Prescott, on the right, uses a CAD/CAM computer for design and tooling accuracy found it impossible to raise the nosewheel during the take-off roll. The elevator would suddenly take effect as flying speed was reached and caution was required to prevent over-rotation on lift off. Elevator sensitivity has been reduced by changing the single piano hinge for a Frise-type system which covers the hinge gap. By increasing elevator hinge arm "and incor porating a bob weight into the elevator system, more stick movement is now required for each degree of elevator displacement, says Prescott. Stick force per g. has also since been increased, he says. The 700ft/min rate of climb experi enced on my flight has been increased to 900ft/min, and will be even better when the new propeller is fitted, Prescott claims. The designer is sensitive to criti cism that his Pusher might be short coupled, and went to some lengths to demonstrate that the directional stability was good. Certainly rudder-induced yaw damped out quickly, though I was concerned that with 30° of bank it was impossible to level the wings by rudder alone. Application of full top rudder caused marked nose-down pitch with no reduction in bank angle. In Prescott's opinion this characteristic falls outside normal flight-test criteria, and does not pose a signifi cant problem. The large fin and relatively small rudder may well be the reason for this characteristic. Longitudinal stabil ity seemed satisfac tory, with a pilot- induced pitch disturb ance damping out in just two cycles. Stability in roll appeared neutral, with aileron control light and responsive. Once established in a turn, the Pusher will hold a given bank, hands off, with no tendency to spiral. Levelling at 5,000ft, FLIGHT INTERNATIONAL, 29 March 1986 we established a speed of 158kt with 25in of manifold pressure and 2,500 r.p.m. Normal cruise power is 22in and 2,300 r.p.m. The canopy offers excellent visibility to the side and rear. The first prototype has substantial blind spots, caused by struc tural members around the front of the canopy. This will be improved on the second prototype, which will be fitted with a one-piece wrap-around windshield. Noise level in the prototype was higher than I had expected, but will probably be improved later. The aircraft has been through prelimi nary stall tests which, Prescott says, have not shown any potential problems. I was asked not to over-cook the stall and recov ery was made at the "g break" without wing drop. Prescott hopes to fit the aircraft with a fuselage-mounted spin- recovery rocket system for spin trials. Tests using a radio-controlled 20 per cent scale model have so far indicated that the Pusher is unwilling to enter an erect spin. With the Sun setting over the drab brown of the winter Kansas prairie, we slid alongside the Bonanza camera ship for a photo session with Paul Bowen before returning to Wichita's Jabara Airport for some circuit work. Both landing gear and flaps are oper ated by a l,5001b/in2 hydraulic power pack mounted in the nose. (The prototype did not have gear doors. They would be added later.) The composite main gear oleos pivot and extend in only 4sec and are shown to be locked down with three green lights. An amber light indicates when the gear is in transit or unlocked. Full flap produces a firm nose-down pitch moment, and at the time of my flight, the trim system was unable to cope with the resultant trim change. Con siderable back pressure was required on the stick during the approach. The lack of elevator trim-tab authority has been a worry to Prescott, who expected the new elevator-hinge system to cure the problem. The company has already sent out the trim tab kit, which falls early in the kit assembly series. The problem is now said to be cured on the prototype by modifying the trim tab. Prescott sees the addition of a flat T- section plate along the trailing edge of the trim tab as the most desirable solution. "We are still working on the problem." The best approach speed for landing is 95 m.p.h. and with the pilot sitting close to the ground the landing flare is easily judged. On each touchdown the Pusher's nosewheel landed heavily on the runway, despite full up elevator, but the new modifications might well have offset this tendency. The Prescott Pusher has potential as an attractive kit- built touring aircraft with good comfort, visibility, and speed. It is, however, at an early stage of develop ment, and a number of areas require atten tion. This often applies to prototype aircraft, and the second example, due to fly at Oshkosh in June, will provide an inter esting comparison. • 23
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