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Rutan 40 Defiant / 74 Defiant

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The Model 40 is the first of Rutan's designs intended for the commercial market. It is an overgrown push-pull version of the VariEze, seating four plus baggage (or plus two children), using two Lycoming engines of 160 hp with fixed-pitch propellers. As on the VariEze, the Model 40's main landing gear is fixed, but the nosewheel retracts. An all-flying rudder protruding from the bottom of the nose is connected in a very simple manner to the turn-and-bank gyro and provides wing-levelling.

The prototype of this research aircraft, Rutan Model 40 Defiant s/n 001 N78RA, flew first on 30 June 1978. The Defiant was intended as a proof-of-concept of a very safe light twin design, requiring little trim change and no pilot action in case of engine failure, and with good single engine performance. In 1979, the Rutan Aircraft Factory announced they would proceed with certification of a Model 40 Defiant based light twin. Adequate financing was not secured for this project, and the design was modified for homebuilt construction as the Model 74.

In a significant gesture, Rutan presented his twin to the public not at Oshkosh, where his other designs made their de-buts, but at the National Business Aircraft Association meeting. Rutan has had to insist that the Defiant now flying is a "proof of concept," composite construction prototype rather than a preproduction prototype. Some features that would be necessary in a marketable airplane, such as doors and entry steps, have been omitted in favor of a structurally simple hinged canopy. This free-blown canopy, furthermore, is semi-circular in section and hat, imposed that shape upon the top half of the fuselage, which in a production airplane would have a more squared-off section for better headroom. The cabin, which in fact is as wide and long as any light twin's, though shallower, is very hard to get into and out of; and, because of the incorrect roof shape and a not very astute placement of armrests and consoles, it is less than comfortable to sit in. If its present empty weight of about 1,500 pounds rose to 1,700 in a production airplane, the Defiant would continue to perform superbly.

The Defiant has fixed landing gear, fixed pitch props and no flaps; when an engine fails, the pilot merely goes on flying as before. The whole problem of fast reaction of identifying the bad engine, feathering, retracting gear and flaps and of precisely holding a certain airspeed disappears. The wings are swept in order to move their center of lift aft with respect to the rear engine, and to put the vertical surfaces as far aft as possible for considerations of general arrangement, in short, not aerodynamic refinement.

To this add cruising speeds of over 170 knots at economy settings, astonishing rates of climb and excellent hands-off stability, as well as a useful load that can handle both full cabin and full fuel, and you have an airplane that promises to do everything well. You also have a potentially powerful competitor in the light-twin market, and one that demonstrates convincingly an alternative to conventional airplane design. The Defiant could por-tend a revolution comparable in importance to the abandonment of the biplane in favor of the monoplane.

What makes the Defiant a performer is its light weight and small size. Its span loading (the quotient of weight and wing-span, and a powerful determinant of climb rate) is about the same as that of the Cougar, Duchess and Seminole; but, with the same engines and a gross weight 1,000 pounds lower, the Defiant climbs better than they do on two engines (it takes it 11 minutes to go from sea level to 12,000 feet at gross weight) and at least as well on one. With centerline thrust, like the Cessna Skymaster's, the Defiant escapes the asymmetry problems of conventional twins. Its power loading is good even on one engine: at moderate weights, in fact, it is that of a 172. Fixed-pitch props mean that you get the best performance at high altitudes.

The Defiant is economical not only in flight performance, but also in design and construction. The choice of fixed-pitch wooden propellers, fixed gear and extremely simple systems is part of Rutan's ruling philosophy of design: less is more.

There are two separate electrical systems - two batteries, two alternators and two busses - for true redundancy. The fuel system is simple, and the last 45 minutes of fuel are measured and reported with extra accuracy. The control system is as simple as they come: the actuating rods for the elevators (on the front wing, or canard) and the ailerons (on the main wing) are contained mostly within the fuselage.

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Model 74 Defiant


Work began on production Defiant Model 74 in 1982. Plans were offered in mid-1984.

By 1990 the Rutan design stable of VariEze, LongEze, Defiant and Solitaire were no longer offered for sale.

Engines: 2 x Lycoming O-320, 160 hp
TBO: 2,000 hr
Props: wood, fixed-pitch, 69-inch diameter
Length: 23 ft
Height: 1.9 ft
Wingspan: 29 ft
Wing area (total lifting surface): 127 sq. ft
Wing loading (total lifting surface): 23 lbs. per sq. ft
Power loading: 9 lbs. per hp
Seats: 4
Empty weight: 1,525 lb
Useful load: 1,375 lb
Payload with full fuel: 835 lb
Gross weight: 2,900 lb
Usable fuel capacity: 90 USG/540 lb
Maximum landing weight: 2,900 lb
Maximum rate of climb: 1,650 fpm
Single-engine rate of climb: 330 fpm
Single-engine climb gradient at 85 knots (Vyse): 233 ft. per nm
Single-engine service ceiling: 7, 100 ft
Maximum speed: 196 kt
Max cruise, 70% power (2,800 rpm) at 9,500 ft: 188 kt
Econ cruise, 55% power at 12,000 ft: 170 kt
Duration at max cruise: 5 hr
Duration at econ cruise: 6.5 hr
Stalling speed, clean: 64 kt

 

 


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