Status: company demonstrator (Model 40), initially designed for Pug Piper
Type: four-seat "push-pull" experimental canard prototype (Model 40) / homebuilt (Model 74)
Powerplant: 2 x 160 hp (119 kW) Avco Lycoming
First flight: 30 June 1978
In 1975, Burt Rutan applied himself to the problems of building a canard-controlled, centerline thrust twin, and the result was a Star Wars-like design know as the Defiant. The Rutan Model 40 was an experimental canard prototype. This proof-of-concept four-seat "push-pull" engined light aircraft of unconventional design, was derived from the experience gained with the previous smaller VariEze. It retained the rear-mounted swept cantilever wings with winglets, canard fore-plane and retractable nosewheel/fixed main-wheel type landing gear. The prototype Model 40 (N78RA) made its maiden flight from Mojave, California, on June 30, 1978. The Defiant was then offerred as the Model 74 in kitplane form in mid-1984.
Rutan’s Defiant utilized a canard on the nose for pitch control, winglets and a retractable nosegear with fixed, slickly faired mains. Typically, the Defiant realized economies of design not possible on normal twins. The RAF-40’s airframe had a wetted area only 56 percent that of normal twins, and the winglets offer 30 percent less induced drag by increasing the effective span.
When the airplane was introduced in prototype form, it caused quite a stir in the general aviation market, especially considering that Rutan announced plans to try to certify the Defiant for production. Unlike even his single-engine designs, however, Rutan’s Defiant mounted a pair of 160-hp O-320 Lycoming engines inline to eliminate any possibility of asymmetric thrust, a la Cessna’s now out-of-production 337 Skymaster. Pilots who had flown the Skymaster considered that the Skymaster a docile twin, but suffered from other problems which virtually doomed it to failure from the outset. Rutan’s ultimate concern for safety effectively sidestepped most of these problems so that the Defiant was a seemingly impossible ideal, an idiot-proof twin. Like the canard designs that preceded it, the Defiant reflected an overriding concern for the health and safety of its passengers. Rutan pulled out all the stops when he built the Defiant, designing an airplane that would effectively avoid all the traps of twin-engine airplanes flown on one mill.
The Defiant might have been relegated to the file of those ideas whose time hadn’t quite come but for the efforts of Fred Keller of Anchorage, Alaska. Keller was a veteran VariEze builder who had won Oshkosh with his remarkably slick airplane. In mid-1981, Keller asked Rutan if he could build his own Defiant. Knowing Keller’s reputation for quality workmanship, Rutan agreed provided that Keller documented the building process so that Rutan could use the information in the event he decided to offer the Defiant as a homebuilt or kit airplane. Keller finished his Defiant in 18 months, an unusually short time for construction of an airplane, much less redesigning much of it (with Rutan’s help and encouragement) and writing a full set of plans in the process. Keller shot more than 750 photos of the buildup process and detailed every step along the way. When he was done, he had an airplane that was superior to the prototype in almost every respect, plus he had one of the most comprehensive sets of plans ever assembled for a homebuilt airplane. The Model 74 Defiant was born, and soon plans were made available from Rutan Aircraft Factory in Mojave, Calif., to build the Fred Keller version.
In terms of cross-country cruise capability, the Defiant was a winner. With 110 gallons aboard and burn rate of only 15 gph at 65 percent, a pilot and three passengers were able to cover an easy 1000 nm between refueling stops. Efficiency was only one of the Defiant’s talents. Typical of all Rutan designs, the primary goal of the Defiant was safety, and there was no question that Burt Rutan had produced an unusually docile twin. The Defiant exhibited some characteristics that were atypical of other twins. The airplane loved to fly, and even power off it gave up speed and altitude grudgingly. Because there was basically no stall in the Defiant, one could hold full aft stick with relative impunity. The pilot of the Defiant could do more things wrong when an engine failed and still come home with the airplane – and, more importantly, himself – in one piece. The cabin configuration was comfortable for the pilot and all three passengers. The panel was spacious and wide, easily large enough to accept almost any avionics one might install. (yet radar would have presented a slight problem because the wing was too narrow to accommodate the dish antenna.) Better still, the Defiant was capable of some tall altitudes. Burt’s brother Dick once had the airplane above 25,000 feet. All of this with an airplane that was carbureted and normally aspirated, not injected and turbocharged.
With both mills turning, normally, the Defiant responded quickly to power application on takeoff, but short runways were better off not to be considered. The Defiant wasn’t exactly a ground lover, but it was not an STOL airplane either. Off the ground and stabilized at 100 knots with the nose gear retracted, the Defiant climbed as if something big had been chasing it. One could, for all practical purposes, fly the airplane as if it were a single and move both throttles together, whether on or both engines are running. That, in fact, was one of the great joys of the Defiant. It was an amazingly forgiving airplane in single-engine mode, though it wouldn’t be a particularly bright idea to initiate a single-engine takeoff, especially at Mojave’s 3000-foot pressure altitude. (Cessna had found this to be a particularly vexing problem on the Skymaster, as some pilots would blindly attempt to depart on the front engine alone after the rear engine had idled out during taxi or runup. As a result, the company had developed the procedure of advancing the rear throttle first on takeoff, then the front throttle.)
All a pilot need do on a single-engine go-around is push the throttles full forward and pull back on the stick to keep the airplane flying. Like the Cessna Skymaster, the Rutan Defiant could perform a little better on the rear engine, alone, than on the front engine, solo. In normal flying conditions, the rear engine was able to provide about 300 to 350 fpm, whereas the front engine could deliver more like 250 to 300 fpm. (The propellers were pitched differently in order to compensate for the difference, which was due to less fuselage drag with the front engine shut down and not blowing confused air back across the rear prop.)
"Like all of Rutan’s designs, the Defiant is a cut above the average. It’s an unusual machine that’s sure to be attractive to the pilot who wants something different. Not everyone will be able to afford the time necessary to build a Defiant, however. The cost will be more than money. For those who can justify the effort and expense, the Defiant is a Tomorrowland design here today. It offers truly 21st century performance and safety." As promising as this may have sounded, however, things didn't quite turn out as bright as they might have seemed. The cost of certification, especially on such an unconventional design, apparently scared off all the prospective investors, and the prototype became little more than Burt’s personal transportation airplane. To call this a shame is an understatement, as the Defiant was a definite step ahead in safety, performance and efficiency. Unfortunately, it was perhaps a little too far ahead. A total of 200 plan sets were sold, with about 20 kits actually built. Nine examples were known to be flying as of mid 1987. Nineteen were FAA registered in 2005.
From the experience gained with the Defiant, Beechcraft developed the troubled Starship in the form of the Model 115 scaled-down proof-of-concept prototype, but despite its huge qualities, the business jet didn't fare much better than its kitplane ancestor.
Population: approximately 20 [N23TR, N9EK, N770JL, N726RD, N2HM, N57KS, 5B-HAC, LN-DDD, LN-RTI, G-OTWO (c/n 114), VH-001, etc.]
Specs (Model 40):
Span: 29 ft 2 in (8.89 m) (initially given as 28 ft 10 in)
at 55 per cent power: 181 kt (335 km/hr)
Specs (Model 74):
Length: 22 ft. 8 in.
Horsepower at takeoff/at sea level: 160 hp
Crew/passengers: 1 pilot, 3 passengers