DEFIANT:

Burt Rutan is one of those designers for whom the sky has never been the limit. He has a long history of reaching for seemingly unattainable goals and winding up with designs that truly lead the way for other builders.  Since his first canard machine, the stall proof Vari-Viggen of the mid-70s, Burt has dominated the homebuilt aircraft market with airplanes such as the VariEze and Long EZ, the Grizzly and, more recently, the innovative Beech Starship.

In 1975, however, Burt applied himself to the problems of building a canard-controlled, centerline thrust twin, and the result was a Star Wars design know as the Defiant.  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.

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.

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.

Plans are available from Rutan Aircraft Factory in Mojave, Calif., to build the Fred Keller version of the Defiant.  Currently, RAF is only offering plans ($490). The company may soon be producing some components to ease the homebuilding job.

Make no mistake about it; constructing a Defiant will probably be a major task, whether it’s your first airplane or your tenth.  Although the Defiant won’t necessarily be any more difficult to build, it will be a large machine by homebuilt standards.  A builder will be doing nearly twice the work he’d put into a Long EZ.  There are obviously two engines to be mounted, total wing/canard area is significantly greater and the fuselage is proportionately larger in order to accommodate four people. Construction hour estimates may not mean much at this stage, but one source at Rutan said he wouldn’t’ be surprised if total buildup time ran 3000 hours.

At least when finished, a builder will have an unusual and talented airplane.  Like the canard designs that preceded it, the Defiant reflects 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.

To better understand exactly what Rutan and Keller had achieved in the Defiant, I went to Mojave and flew the prototype with RAF pilot Mike Melvill. Once you walk up to the Defiant on the ramp, you know this is a different breed of airplane.  Like all recent Rutan designs, the Defiant (technically designated the RAF-40 – Rutan’s fortieth design) utilizes a canard on the nose for pitch control, winglets and a retractable nosegear with fixed, slickly faired mains.  Typically, the Defiant realizes economies of design not possible on normal twins.  The RAF-40’s airframe has a wetted area only 56 percent that of normal twins, and the winglets offer 30 percent less induced drag by increasing the effective span.

Unlike even his single-engine designs, however, Rutan’s Defiant mounts a pair of 160-hp O-320 Lycoming engines inline to eliminate any possibility of asymmetric thrust, ala Cessna’s now out-of-production 337 Skymaster.  Pilots who have flown the Skymaster will tell you that it was, like the Defiant, a docile twin, but that it suffered from other problems which virtually doomed it to failure from the outset.  Rutan’s ultimate concern for safety has effectively sidestepped most of these problems so that the defiant is a seemingly impossible ideal, an idiot-proof twin.

Climb aboard over the cabin walls and you find that the cabin configuration is comfortable for the pilot and all three passengers.  The panel is spacious and wide, easily large enough to accept almost any avionics you might install. (Radar would present a slight problem because the wing is too narrow to accommodate the dish antenna.) Rutan’s prototype is equipped with a full King package.

Engine start is conventional carburetted Lycoming.  Power controls are similar to those of twins with engines on the wings.  The left throttle controls the forward engine and has a small horn pointing forward mounted to its left side, while the right manages power on the rear, and accordingly has a horn pointing aft.  On Rutan’s airplane, you can, 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, is one of the great joys of the Defiant.  It’s an amazingly forgiving airplane in single-engine mode.  It wouldn’t be a particularly bright idea to initiate a single-engine takeoff, however, especially at Mojave’s 3000-foot pressure altitude. (Cessna 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 developed the procedure of advancing the rear throttle first on takeoff, then the front throttle.)

With both mills turning, normally, the Defiant responds quickly to power application on takeoff, but don’t plan to use short runways. The Defiant isn’t exactly a ground lover, but it’s not a STOL airplane either.

Off the ground and stabilized at 100 knots with the nose gear retracted, the Defiant climbs as if something big were chasing it. With just Melvill and me aboard, I saw initial VSI readings of nearly 2000 fpm.  The spec for full gross (of 2900 pounds) at sea level is 1600, and I’d guess the Defiant could easily achieve such a number.

Better still, the Defiant is capable of some tall altitudes.  Burt’s brother Dick has had the airplane above 25,000 feet.  Remember the Defiant is carbureted and normally aspirated, not injected and turbocharged.

For our purposes, we tried altitudes from 6500 to 10,500 feet.  At the higher altitude, I tried some “stalls” and found them to be typically nonexistent.  Rutan has always been adamant that airplanes shouldn’t stall.  To that end, canard response is restricted so that you can’t get the airplane into an attitude that will stall the wing.  Power-off, the Defiant will simply mush downhill under perfect control.  The right side stick is sensitive at high speeds but loads up rapidly as angle of attack increases.

At 6500, the density altitude was probably about 8000 feet, so we tried some cruise numbers with both throttles full forward, representative of a maximum 75 percent effort.

Specifically, I saw an easy 175 knots True.  Pulled back to 65 percent, the number was more like 168 knots.  These are impressive numbers, but they’re even more significant when you consider the low fuel consumption necessary to achieve them.  The O-320 Lycoming has always been an efficient engine, in addition to being one of the most reliable general aviation powerplants on the market.  Specific fuel consumption (sfc) is low .44 pounds per horsepower. High cruise costs only about 18 gph, while a 65 percent effort drains a mere 15 gph.  In more familiar terms, consider that you’re realizing more than 10 nmpg, even at high cruise, which is excellent efficiency for a twin-engine aircraft.

In terms of cross-country cruise capability, the Defiant should be a winner.  With 110 gallons aboard and burn rate of only 15 gph at 65 percent, a pilot and three passengers should be able to cover an easy 1000 nm between refueling stops.

But efficiency is only one of the Defiant’s talents.  Typical of all Rutan designs, the primary goal of the Defiant is safety, and there’s no question that Burt has produced an unusually docile twin.  Mike Melvill let me discern exactly what the airplane could do under the worst possible conditions: a single-engine go-around.  First, I set up for a 90-knot glide, gear down, with partial power on both engines.  Then, at 5500 feet altitude, Melvill abruptly shut down the front engine and instructed me to cob both throttles and lever the side stick straight back to the stop.

This could be insanity on any other twin, even one with inline engines.  It would violate blue-line speed and result in a short zoom, followed by a rapid descent, and out-of-control roll toward the dead engine and an abrupt landing in a vertical attitude.

The Defiant’s reaction was a 400-foot balloon in altitude, along with a bleed-off of airspeed to around 55 knots.

Because there’s basically no stall in the Defiant, you can hold full aft stick with relative impunity.  When I’d reached the top of the zoom, I began to milk the stick forward to see how much of the altitude I could hold as I tried to stabilize airspeed at the same 90 knots. To my amazement, the Defiant finished the exercise 300 feet higher than it had entered. 

The point is that 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.  Remember, too, that Melvill and I flew this exercise at 5500 feet, certainly not the best altitude for single-engine go-arounds. 

Like the Cessna Skymaster, the Rutan Defiant will perform a little better on the rear engine, alone, than on the front engine, solo.  If you’re doing everything right, the rear engine should provide about 300 to 350 fpm, whereas the front engine will deliver more like 250 to 300 fpm.  (The propellers are pitched differently in order to compensate for the difference, which is due to less fuselage drag with the front engine shut down and not blowing confused air back across the rear prop.) 

Admittedly, these numbers aren’t that much better than conventional twins, but the difference is it takes little technique to achieve them.  The pilot of the Defiant can do more things wrong when an engine fails and still come home with the airplane – and, more importantly, himself – in one piece. 

Back in the pattern, the Defiant exhibits some characteristics that are atypical of other twins.  If you’ve been flying a Long-EZ or VariEze, you’ll be prepared for the Defiant’s glide ratio. Otherwise, it may come as something of a shock. The airplane loves to fly, and even power off it gives up speed and altitude grudgingly.  Melvill suggested that I hold 90 knots in the pattern.  My lack of recent experience with extremely slick Rutan designs almost forced a go-around on the first attempt.  Until you’re used to the airplane’s power-off response, you’ll tend to consistently overshoot the touchdown spot. 

To further emphasize how clean the defiant is, Melvill had me shoot several more approaches with the front engine shut down.  I might have assumed that the additional drag from an unfeathered, fixed-pitch prop would have dramatically reduced gliding efficiency, but it didn’t.  The Defiant defiantly glided as if both mills were still turning.  Because the Defiant’s glide is so flat, there’s an automatic tendency to assume that you’re too low and thus add power, thereby only making things worse. 

The touchdown itself is ridiculously easy, provided you keep the speed down.  Come across the fence 10 knots too fast and you’ll float into the next county.  The Defiant sets down nicely on the mains, after which you can lower the nose gently to earth. 

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 a little different – make that a lot 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 21^st century performance and safety. 

Rutan Defiant:

Specifications:

Homebuilt price: $20,000 to $40,000

Engine(s) make/model: Lycoming O-320 (2)

Horsepower @ rpm @ altitude:

160 @ SL

Horsepower at takeoff: 160

TOB hours: 2000

Fuel type: 100 Octane

Landing gear type: Partial retractable

Max Ramp weight (lbs): 2950

Gross Weight (lbs) 2950

Max Landing weight (lbs): 2950

Empty weight (std) (lbs): 1600

Equipped weight (as tested) (lbs): 1680

Useful load (std)(lbs): 1350

Payload (full std fuel) (lbs): 580

Fuel capacity (std) (gals): 115

Wingspan: 31ft 5in

Wing area (sq.ft.): 22.2

Wing loading (lbs/sq.ft): 22.2

Power loading (lbs/hp): 9.2

Seating capacity: 4

Cabin doors: 0

Cabin width (in).: 46

Baggage capacity (cu/ft): 41

PERFORMANCE:

 Cruise speed (kts):

75% pwr: 8,000ft @ 184 best power

55% pwr: 9,000ft @ 168 best power

Max range (reserve/no reserve)(nm):

55% pwr: 1044

Fuel consumption (gph):

75% pwr: 17.8

55% pwr: 13.9

Estimated endurance (55% pwr) (hrs): 8

Stall speed (gear down) (kts): 64

Best rate of climb (fpm): 1900

Single-engine rate of climb (fpm): 310 (rear)

Service ceiling (ft): 28,000+

Single-engine service ceiling (ft):6500

Aircraft Comparison Chart: