The Rutan Defiant
Contributed by David Orr.
THE RUTAN DEFIANT
Burt Rutan 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. The cost of certification,
especially on such an unconventional design, apparently scared
off all the prospective investors, and the prototype became little
more than Burts 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.
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 Rutans 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-40s
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,
Rutans Defiant mounts a pair of 160-hp O-320 Lycoming engines
inline to eliminate any possibility of asymmetric thrust, ala
Cessnas now out-of-production 337 Skymaster. Pilots who
have flown the Skymaster will tell you that it was, like the Defiant,
a docile 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.
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 Rutans 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.
Its an amazingly forgiving airplane in single-engine mode.
It wouldnt be a particularly bright idea to initiate a single-engine
takeoff, however, especially at Mojaves 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
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 Id guess the Defiant could
easily achieve such a number.
Better still, the Defiant is capable of some tall
altitudes. Burts 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 shouldnt stall. To that end, canard
response is restricted so that you cant 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 theyre 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 youre realizing more than 10 nmpg,
even at high cruise, which is excellent efficiency for a twin-engine
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 Defiants
talents. Typical of all Rutan designs, the primary goal of the
Defiant is safety, and theres 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
The Defiants reaction was a 400-foot balloon
in altitude, along with a bleed-off of airspeed to around 55 knots.
Because theres basically no stall in the Defiant, you can
hold full aft stick with relative impunity. When Id 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 youre 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 arent 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 youve been flying a
Long-EZ or VariEze, youll be prepared for the Defiants
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 youre used to the airplanes power-off response,
youll 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 didnt. The Defiant defiantly glided as if both mills
were still turning. Because the Defiants glide is so flat,
theres an automatic tendency to assume that youre
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 youll float into the next county. The Defiant sets down
nicely on the mains, after which you can lower the nose gently
Like all of Rutans designs, the Defiant is
a cut above the average. Its an unusual machine thats
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
21st century performance and safety.
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
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