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Rutan Defiant
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The Rutan Model 40 Defiant is a four-seat, twin-engine homebuilt aircraft with the engines in a push-pull configuration. It was designed by aerospace engineer Burt Rutan for the Rutan Aircraft Factory.
Key Information
Development
[edit]The prototype Defiant, N78RA, was first flown on 30 June 1978. It had been 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. A comparison of the Defiant single engine climb rate with a Gulfstream Cougar had shown about 390 feet (120 m) vs 280 feet (85 m) per minute at low altitude with both aircraft in a clean, gear up and flaps up, configuration. The prototype is now owned by the Hiller Aviation Museum.
In 1979 the Rutan Aircraft Factory announced they would proceed with certification of a Defiant-based light twin. Adequate financing was not secured for this project, and the design was modified for homebuilt construction as the Model 74, with the second aircraft (built by Fred Keller) appearing at Oshkosh 1983.[1] Plans were offered in mid-1984. 176 sets of plans were purchased before RAF discontinued selling plans in 1985.[2] Nine examples were known to be flying as of mid-1987. Nineteen are registered with the FAA as of 2005.
Design
[edit]The Defiant is built using fiberglass layup over polymeric foam core shapes in the same manner as the Rutan VariEze. The main gear is fixed, and there are no flaps. The Propellers are fixed-pitch non-feathering,[3] which is unusual in a twin-engine design. Cockpit entry is through a side hinged canopy.[1] The winglets provide yaw stability.[3] Unusually, the Defiant has a ventral, port offset, forward mounted rudder, as can be seen in pictures of the plane taxiing.
Specifications (Defiant)
[edit]General characteristics
- Crew: one, pilot
- Capacity: 3 passengers
- Length: 22 ft 10 in (6.95 m)
- Wingspan: 30 ft 9 in (9.4 m)
- Height: 9.33 ft (2.84 m)
- Wing area: 139.4 sq ft (12.95 m2)
- Empty weight: 1,701 lb (771.5 kg)
- Gross weight: 2,997 lb (1,360 kg)
- Max takeoff weight: 2,997 lb (1,360 kg)
- Fuel capacity: 120 gal
- Powerplant: 2 × Lycoming O-320 , 160 hp (119 kW) each
Performance
- Maximum speed: 188 kn (216 mph, 342 km/h)
- Cruise speed: 167 kn (192 mph, 309 km/h)
- Range: 980 nmi (1,130 mi, 1,808 km)
- Service ceiling: 18,000 ft (5,485 m)
- Rate of climb: 1,600 ft/min (8.1 m/s)
References
[edit]
Wikimedia Commons has media related to Rutan Defiant.
- ^ a b Garrison, Peter (January 1984). "Doing the Defiant". Flying. New York, New York: Ziff-Davis. Retrieved October 17, 2014.
- ^ Dan Linehan (2011). Burt Rutan's Race to Space: The Magician of Mojave and His Flying Innovations. Zenith Press. ISBN 978-0-7603-3815-5.
- ^ a b Garrison, Peter (December 1978). "Rutan's Defiant". Flying. New York, New York: Ziff-Davis. Retrieved October 17, 2014.
- Barnett, Cliff (25 November 1978). "Defiant: the shape of twins to come". Flight International.
- Aerofiles information
Rutan Defiant
View on Grokipediafrom Grokipedia
Development
Design Origins and Goals
The Rutan Defiant originated from Burt Rutan's efforts in the mid-1970s to address longstanding safety and performance challenges in twin-engine general aviation aircraft, particularly the risks associated with asymmetric thrust during engine failure, high operating costs, and suboptimal single-engine climb capabilities compared to singles.[7][8] Traditional wing-mounted twins often suffered from violent yaw and reduced control in such scenarios, prompting Rutan to explore a centerline thrust configuration inspired by earlier push-pull designs like the Cessna Skymaster, but refined for better efficiency and handling.[5][9] Rutan's primary goals centered on creating an "idiot-proof" twin that prioritized safety through balanced propulsion, stall resistance, and practical utility for personal transport.[5] By aligning two engines in a tandem push-pull arrangement—one pulling at the nose and one pushing at the rear—the Defiant aimed to maintain neutral yaw and stable flight on one engine, allowing pilots to apply full power without exacerbating control issues.[9][1] The incorporation of a forward canard surface was intended to prevent wing stalls entirely, enabling safe low-speed operations and landings by ensuring the main wing remained unstalled even at full aft stick deflection.[8][5] Additionally, the design targeted efficient four-seat capacity in a composite structure to support cross-country missions, with an emphasis on reduced drag and weight to mitigate the cost drawbacks of conventional twins.[9] Conceptual development began in late 1977 at the Rutan Aircraft Factory (RAF), where Rutan sketched initial configurations blending canard control with inline twin propulsion to achieve these objectives.[10] The aircraft's unconventional "Star Wars-like" appearance stemmed from this bold integration of features, and its name was drawn from a popular wood-burning stove model, suggested by a family member during a casual discussion.[5][1]Prototype Construction and Testing
The prototype of the Rutan Model 40 Defiant was constructed at the Rutan Aircraft Factory in Mojave, California, using a moldless composite technique involving fiberglass layup over a foam core, with additional Kevlar reinforcements in components such as the vertical fins, ailerons, elevators, main landing gear, and rudder.[11] Construction began in early 1978 and was completed in time for the aircraft's maiden flight later that year.[10] The Defiant prototype, registered as N78RA, made its first flight on June 30, 1978, from Mojave Airport, piloted by designer Burt Rutan.[12] This initial test flight confirmed the aircraft's basic stability and handling characteristics, with Rutan noting its responsive controls and minimal trim changes during maneuvers.[11] Flight testing continued through 1979, encompassing evaluations of performance, stability, and single-engine operations to validate the push-pull twin-engine configuration's safety goals. Key results included a single-engine climb rate of 330 feet per minute with gear up and excellent overall handling, characterized by damped oscillations that settled within two cycles and no adverse yaw tendencies. Stall speeds were measured at 64 knots in both clean and gear/flaps-down configurations, demonstrating the canard's stall-resistant properties.[11] During testing, modifications were made to the rudder to improve yaw stability, including its relocation beneath the cabin and considerations for a twin-rudder setup in future iterations.[11] The prototype remained in Rutan's personal use for several years before being donated to the Hiller Aviation Museum in San Carlos, California, where it is currently displayed.[12][2]Plans Release and Production Shift
In 1979, the Rutan Aircraft Factory announced plans to pursue FAA certification for a Defiant-based light twin-engine aircraft, but the effort was abandoned due to difficulties in securing adequate funding and the significant regulatory challenges posed by certifying composite material designs in that era.[3][5] Following the successful flight testing of the original prototype, attention turned to enabling homebuilt production in the experimental amateur-built category. The second prototype, designated Defiant II and constructed by Fred Keller, made its public debut at EAA AirVenture Oshkosh in 1983, serving as a demonstration model for potential builders. In mid-1984, RAF released detailed plans for the Model 74 variant, which incorporated refinements from Keller's build to facilitate amateur construction using composite techniques.[3][5][10] By 1985, RAF had sold 176 sets of plans, reflecting initial interest among homebuilders despite the project's complexity; however, plan sales were discontinued in June 1985 as RAF shifted resources toward new composite development initiatives, including the formation of Scaled Composites. To support builders during this brief production window and beyond, RAF offered comprehensive construction manuals, ongoing guidance through the Canard Pusher newsletter, and educational seminars at events like Oshkosh, emphasizing safe composite fabrication and assembly practices.[3][10] Economic considerations played a key role in positioning the Defiant for amateur builders, with estimated completion costs ranging from $20,000 to $40,000 in mid-1980s dollars, driven by the need for specialized materials and extensive build time, though this appealed primarily to experienced enthusiasts capable of investing significant personal resources.[5]Design
Airframe Configuration
The Rutan Defiant employs a canard airframe configuration, featuring a forward-mounted canard foreplane for primary pitch control integrated with a high-mounted, swept-back main wing to generate lift.[2][13] The main wing, constructed as a cantilever structure, has a span of approximately 30 feet 9 inches and incorporates tip-mounted winglets that enhance directional stability by reducing induced drag and providing yaw control through integrated rudders.[14][4] Additionally, a unique ventral rudder, offset to port and positioned forward beneath the fuselage, contributes to overall directional stability without requiring traditional tail surfaces.[1][15] The fuselage is designed as a wide-body structure to accommodate four seats in a two-by-two arrangement, with a cabin width of 46 inches allowing side-by-side seating for pilot and copilot up front, and two passengers in the rear, followed by a dedicated baggage area of about 41 cubic feet.[4] Access to the cabin is provided via a side-hinged bubble canopy that opens outward, offering unobstructed entry for all occupants while maintaining a low-profile greenhouse for visibility.[13] The overall airframe measures roughly 22 feet 10 inches in length and 9 feet 3 inches in height, optimizing the integration of structural elements for compactness and efficiency.[14] Landing gear consists of a fixed tricycle arrangement, with non-retractable main gears faired for low drag and a manually retractable nose gear to balance simplicity and aerodynamics.[13][4] The airframe lacks flaps on the main wing or canard, relying instead on the inherent aerodynamic properties of the configuration for low-speed handling.[2] Construction utilizes a moldless composite sandwich technique, consisting of fiberglass/epoxy skins over rigid polyvinyl foam cores, which forms the fuselage, wings, canard, and control surfaces for lightweight strength and ease of homebuilding.[15][5] This method integrates the push-pull engine mounts directly along the fuselage centerline, ensuring balanced thrust lines without wing-mounted nacelles.[4]Propulsion System
The Rutan Defiant employs a push-pull twin-engine configuration, with a front-mounted tractor engine and a rear-mounted pusher engine aligned along the fuselage centerline.[11][13] This setup provides balanced thrust and simplifies engine-out operations by maintaining directional stability without asymmetric yaw.[1] The aircraft is powered by two Lycoming O-320 flat-four piston engines, each rated at 160 horsepower.[11][5] These air-cooled engines, originally 150-hp units modified for increased output in the prototype, drive fixed-pitch, non-feathering propellers constructed from Kevlar-reinforced wood.[11] The propellers are pitched differently front and rear to account for airflow variations, ensuring efficient performance across the operating envelope.[5] Fuel is stored in two wing-mounted tanks integrated into the strakes, providing a total capacity of 115 gallons of 100-octane aviation gasoline.[1][5] The system features separate selectors for each engine, with sumps and low-fuel warning lights for monitoring; in production plans, this setup supports extended range without requiring in-flight fuel management.[11] Both engines are mounted directly to the composite fuselage using steel-tube frames secured by four 3/8-inch bolts each, aligning thrust precisely on the aircraft centerline.[11] This fuselage integration avoids the vibration transmission, structural complexity, and induced drag associated with traditional wing-mounted twins, enhancing overall efficiency and handling.[13][5] For homebuilders, maintenance is facilitated by removable cowlings and access panels on both engine nacelles, allowing straightforward inspection of cylinders, ignition, and exhaust systems without specialized tools.[11] Cooling relies on an updraft design with ram air inlets, eliminating the need for oil coolers or cowl flaps; cylinder-head temperatures remain manageable even in single-engine climbs, as evidenced by a 20°F reduction during prototype testing.[11] The detailed plans include over 750 photographs to guide builders in engine installation and routine servicing.[5]Aerodynamic Features
The Rutan Defiant employs a canard foreplane for primary pitch control, which generates lift ahead of the center of gravity to maintain longitudinal stability. This configuration ensures that the canard stalls before the main wing at high angles of attack, preventing the main wing from unloading and reducing the risk of a deep stall.[4][9] Yaw stability in the Defiant is addressed through winglets incorporating rudders at the main wingtips, which counteract sideslip and spanwise flow while enhancing directional control. A ventral fin, combined with a forward-mounted belly rudder offset to port, further improves yaw damping, particularly at high angles of attack where traditional tail surfaces might lose effectiveness; this setup mitigates torque imbalances from the push-pull engine arrangement without relying on differential thrust.[11][7] The aircraft's centerline thrust from the tandem engines eliminates asymmetric yaw moments during single-engine operation, obviating the need for coordinated aileron-rudder inputs in turns or power asymmetries. Its clean aerodynamic profile, featuring semilaminar-flow airfoils and minimal protrusions like the absence of wing-mounted engines or flaps, contributes to low induced drag and a high glide ratio, enabling efficient unpowered flight.[2][11][4] Overall, these features define a flight envelope characterized by a low stall speed—around 64 knots in clean configuration—and strong spin resistance, as the canard-limited angle of attack prevents wing drop, and the stable push-pull layout aids recovery if autorotation occurs.[11][4]Operational History
Builds and Registrations
A total of 176 sets of plans for the Rutan Defiant were sold by the Rutan Aircraft Factory before it discontinued sales in 1985.[3] By 2005, approximately 19 examples were registered with the Federal Aviation Administration (FAA); as of 2024, approximately 19 remain registered.[3][16] International registrations include at least two in Australia, VH-OOU (built 1988, first registered as VH-OOI in 1988 and re-registered as VH-OOU in 2007 with O-360 engines) and VH-DFY (built 2006).[17][18] Build times for the Defiant vary significantly due to its complexity as a plans-built twin-engine design, with one builder reporting 14,000 hours for completion without kits.[19] Common modifications among completed aircraft involve avionics upgrades to modern standards, though specific data on prevalence is limited.[1] The Defiant maintains an active builder and owner community through dedicated online forums such as the Canard Zone, where discussions on construction, modifications, and performance continue.[20] Recent visibility includes participation at EAA AirVenture Oshkosh 2024, with N603TB on display at Wittman Regional Airport, and at EAA AirVenture Oshkosh 2025, with N57KS arriving for display.[21][22]Notable Examples and Legacy
The prototype Defiant, registered N78RA and designated Model 40, is preserved at the Hiller Aviation Museum in San Carlos, California, where it serves as a key exhibit highlighting Burt Rutan's early innovations in twin-engine design.[2] Originally retained by Rutan as his personal aircraft after its 1978 maiden flight, it accumulated significant flight hours under his piloting before donation to the museum.[12] Fred Keller constructed the first kit-built Defiant, completing it in approximately three years using Rutan Aircraft Factory drawings and debuting it publicly at EAA AirVenture Oshkosh in 1983, ahead of the official plans release in 1984.[3] This aircraft, known as the Model 74 variant for homebuilders, demonstrated the feasibility of amateur construction for the push-pull canard configuration and supported the transition to plans sales.[1] A Defiant built by Harry Manvel, involving over 4,800 hours of work spanning 15 years starting in the mid-1980s, represented a notable example of long-term dedication to the design and was highlighted in aviation enthusiast circles around EAA events.[23] Defiant aircraft, including examples like this, appeared at EAA AirVenture Oshkosh in 2024 as part of celebrations for Rutan's designs.[24] The Defiant has experienced rare incidents, such as minor gear-up landings, including a 2006 event involving N726RD where the pilot failed to extend the nose gear during approach, resulting in substantial damage but no injuries.[25] Another gear-up occurrence affected N147LF in 2013 during touch-and-go maneuvers at Leer-Papenburg Airport.[26] While the design aimed to enhance safety through centerline thrust to mitigate asymmetric failure risks, built examples have recorded at least one fatal accident, such as the 2018 loss of control involving N17DR.[27] As Rutan's 40th design and the first twin-engine project from the Rutan Aircraft Factory, the Defiant exemplified RAF's innovation in applying canard foreplanes and composite construction to push-pull configurations, influencing subsequent experimental twins.[4] It contributed to the evolution of safer light twins beyond traditional side-by-side engines, echoing and advancing concepts seen in aircraft like the Cessna Skymaster while promoting modern composite use in homebuilts.[7] The Defiant's unconventional appearance and performance garnered cultural attention in aviation media, often portrayed as a "futuristic" homebuilt that inspired trends in experimental aircraft toward innovative, efficient designs.[1] Its role in Rutan's portfolio underscored the potential of amateur builders to adopt advanced aerodynamics, fostering broader interest in canard and composite trends within the experimental aviation community.[9]Specifications
General Characteristics
The Rutan Model 74 Defiant accommodates a crew of one pilot and up to three passengers in a side-by-side seating arrangement for the front two occupants and individual seats for the rear pair.[5][28] The aircraft measures 22 ft 10 in (6.97 m) in length, has a wingspan of 30 ft 9 in (9.37 m), and stands 9 ft 4 in (2.84 m) in height.[28] Key structural dimensions include a wing area of 139.4 sq ft (12.95 m²).[5][28] The empty weight is 1,600 lb (730 kg) standard or 1,680 lb (760 kg) equipped, while the maximum takeoff weight is 2,950 lb (1,340 kg).[5][4] Fuel capacity totals 115 US gal (436 L), providing extended range capability for cross-country flights.[4][1] The Defiant is powered by two Lycoming O-320 flat-four piston engines, each producing 160 hp (120 kW).[11][5][4] Each engine drives a two-bladed fixed-pitch propeller, with the forward engine configured as a tractor and the aft engine as a pusher to maintain centerline thrust.[11][5]| Characteristic | Specification |
|---|---|
| Crew | 1 |
| Capacity | 3 passengers |
| Length | 22 ft 10 in (6.97 m) |
| Wingspan | 30 ft 9 in (9.37 m) |
| Height | 9 ft 4 in (2.84 m) |
| Wing area | 139.4 sq ft (12.95 m²) |
| Empty weight | 1,600 lb (730 kg) standard |
| Max takeoff weight | 2,950 lb (1,340 kg) |
| Fuel capacity | 115 US gal (436 L) |
| Powerplant | 2 × Lycoming O-320, 160 hp (120 kW) each |
| Propellers | 2-bladed fixed-pitch, tractor/pusher |