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Aviation History
1979
1979 - 0800.PDF
770 FLIGHT International, 10 March 1979 Sequoia" high-performance homebuilt A 300 h.p. single with 1,000 miles range and 250 m.p.h. cruise; fully aerobatic capability; the potential to take on such military trainer competi tion as SF.260, Bravo, Bulldog and NDN-1 Firecracker; and designed to be built from a kit or set of plans. That's the Sequoia, now taking shape in several American workshops from a design by David Thurston, who created the Lake and Teal amphibians. Sequoia began life four years ago, intended primarily for the personal use of Alfred P. Scott of Richmond, Virginia. Then he began to sell plans and kits to selected builders, and now the project has become the Sequoia Aircraft Corporation. Some 12 aircraft are under construction in America, the first complete example is expected to be ready by this summer, and over 25 sets of plans have been sold. Like Desmond Norman's Firecracker (see Flight for July 23, 1977), which has some similar design parameters, the Sequoia could form the basis of an aircraft industry for developing countries. While Firecracker evolved as part of a "technology transfer" scheme under which the aircraft was part of a large package, the Sequoia is designed to be built from a kit by a maintenance organisation. Only hand tools like drills and rivet guns, plus bandsaw and drill press, are needed. Scott claims that two aircraft could be put together by a small group of mechanics and flown in about six months. Labour time per aircraft would be about 2,000hr, each kit cost ing about $15,000, plus engine, pro peller and avionics. Aircraft could be built either from a kit or from a set of very detailed plans. The drawings cost $400 a set, including the right to build one air craft, plus a royalty of $300 for each additional aircraft produced. Though it is described by Scott as a "build- it-yourself military trainer," the Sequoia will not depend for its success on the military or the developing countries. The US homebuilt market is already showing strong interest in plans and parts, and a licence agree ment has been signed with a South African company. The Sequoia was originally con ceived as a two-seater with side-by-side (Sequoia 300) or tandem (301) seat ing arrangements. Current design efforts are however being concenr trated on the side-by-side 300. Various engine options were in the 235-300 h.p. range, but at present a turbo- charged 300 h.p. Lycoming is stan dard. Alfred Scott has acquired two small children since the project began, with the result that there is now pro vision for two small aft-facing seats. Also in prospect is a genuine four- seat development called the Kodiak. In the Bonanza class, the Kodiak will share many common parts with the Sequoia, including wing, tail, landing gear and engine. A prototype should be complete by the end of this year. The Sequoia's structure combines old and new techniques. Wings and tail are all-aluminium with flush rivet- ting, while the fuselage combines a steel-tube frame with a glass-fibre covering. Because the steel tubing does not have to follow the fuselage skin surface, it is square in cross- section and easily fabricated. On initial aircraft the fuselage will be skinned with a glass-fibre/PVC foam/ glass-fibre sandwich made in a female mould. The PVC foam will be heated and vacuum-formed in place, although it would be possible for homebuilders to use a polyurethane foam technique, as on the Rutan VariEze. The Sequoia has a relatively small wing, and the resultant high wing loading should give a smooth ride in turbulence. Aerofoil section is NACA 642A215 at the root, changing to NACA 64A210 at the tip. The wing carries slotted flaps and contains fuel tanks holding 38-5 US gal each side. The fairly long tail arm should avoid over-sensitivity, especially at high speed. Because of its wing and power loading, the Sequoia is expected to handle like a medium twin, with a fairly high power-off sink rate, a tendency to increase speed rapidly in a dive, and the ability to get behind the power curve. The controls are linked by cables and pushrods, with ball-bearings used throughout, and are expected to be precise and responsive with little friction or play. The Sequoia is designed to meet the structural requirements of the new FAR Part 23 Amendment 16, although the design has not yet been certificated. Aerobatic-category ( + 6g/ — 3g) requirements will be met at a weight of 2,8001b. To allow for growth, a gross weight of 3,0001b has been used in all calculations, but load limits at that weight would be + 4-8g/ —2-4g in the utility category. Maximum design speed is 310 m.p.h., with a VSE of 280 m.p.h. and manoeuvring speed of 200 m.p.h. Normal flap limit speed is 150 m.p.h., although an emergency extension is designed for use as a dive brake at a higher airspeed. Both flaps and gear will be hydraulically operated. E The Kodiak is a four-seat development of the Sequoia with many common parts and a gross weight of 3,2001b, A prototype should be completed this year
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