VariEze does it

Then up popped the now legendary Burt Rutan with this amazing design that could be comparatively quickly carved from hot wire cut foam sheets and blocks covered with a thin layer of fibreglass and resin. He claimed it would be “VariEze to make”.

Rutan’s unconventional pusher canard was claimed to be simpler and cheaper to construct than other homebuilts, and it flew almost twice as fast as anything else did on what was then the lowest power aero engine available. No wonder rows of VariEzes dominated the homebuilders’ fly-ins of the 1980s. But where are they all today? Steve Brown’s and Mike Roper’s Biggin Hill (south of London) based example is possibly Britain’s best. Being their second VariEze, they incorporated all the important lessons learned from their first, including all known improvements, while particularly concentrating on lightness and clean aerodynamics. The result is superb, lightweight (304kg) for such a well equipped example, and with a perfect shape, minimal filler, minute control gaps and a glossy finish. Steve has also gained maximum thrust from his nominally 100hp (76kW) Continental (TCM) O-200 motor by increasing its compression ratio from 7. 1:1 to 8. 2:1. A beautifully carved Hertzler Silver Bullet carbon sheathed wooden propeller and pressure recovering spinner complete the ensemble.

The long canopy swings up and over to the right for boarding, to be held securely in position by a gas strut. When empty, the VariEze’s centre of gravity is exactly over its main wheels so, to prevent inadvertent upsets, its nosewheel is retracted for parking. Rear seat entry is simplest with the nose down, but still not super easy, involving stepping up on to a tiny plate on the fuselage side and lifting your leg over the fuel tank-containing leading edge root extension to reach back and step down into the narrow cockpit.

The rear seat passenger has a removable sidestick but no throttle, rudder pedals or instruments, although direct reading wing tank fuel gauge tubes are at the backseater’s elbows. I got my first familiarisation flight from this position, and found it fairly comfortable once in place despite its narrowness, and with surprisingly good all round visibility into which the foreplane obtrudes less than it does for the front seater.

There is no luggage compartment, since the engine occupies the space behind the rear seater’s head, so any bags have to go beside and under your passenger’s feet, reducing the already limited room. It is alsoimportant this stuff does not obstruct the exposed air brake linkage running down the rear left of the front seat back. A few small items can also be stowed in the pyramidal front seat headrest, which doubles as rollover protection, and some builders have made external, underwing baggage pods.

With a weight limit of 476kg and generous tanks, the VariEze is somewhat restricted in its lifting ability and other, heavier examples must be severely curtailed.

Steve and full fuel weigh 156kg, leaving just 16 more kilos for a small bag if he wants maximum range. However, he and I were able to load nearly 40 litres of fuel – enough for two hours flying with a small reserve.

Entry to the pilot’s snug cockpit is easier, and can be effected with the nosewheel extended if the passenger is already in place, or if you’re careful to keep your weight on the airframe as you board.

Some examples have an electric nose leg motor so both occupants can get in and then raise the fuselage to level, but like most owners, Steve omitted this system because of its weight. Both occupants have a noticeably reclined seating position, with their legs well forward and their heads only just above the close set cockpit sills; inevitable consequences of the smallest possible cross section having been chosen for maximum performance.

Starting an O-200 is never difficult, and although pusher installations are notoriously prone to overheating, there should not be a vapour lock problem in this application because the fuel system is entirely gravity fed from both the 125 litre wing root tanks and a 12 litre fuselage reserve/header tank.

The fuel cock is a rotating lever under your right arm, and twists through 180 degrees for the main tanks, or just 90 degrees for the header, where it sticks up under your wrist, reminding you not to take off in this configuration. The only oddity is remembering to look over your shoulder for inquisitive bystanders before shouting “Clear prop”. After pressing the starter, the engine kicks into life with the typical bark and throb of a high compression motor.

Taxiing can be another matter. The VariEze has no steering, merely a fully castoring nosewheel, so directional control is all by differential braking – the wingtip rudders are no help, since they are well displaced from the propwash. The best technique seems to be to ensure the aeroplane is pointing in the right direction and the nosewheel is centred before you board, and then to get it moving under power before steering with gentle dabs of brake in the required direction. The brakes operate directly from each rudder pedal after a small amount of travel. Care must be exercised not to ride them, particularly when taxiing downwind when there is no cooling airflow, because the wheels are closely spatted and, as well as the usual consequences of brake overheating, if the S-glass composite legs become too hot, they can sag. This is easier said than done, because pedal pressures are light and both rudders can easily be fully deflected together, so this taildragger pilot’s feet tended to press too firmly, too often. One big advantage of this system is the ability to turn very tightly in confined spaces – around one wheel if necessary, provided you use a good blast of power at the same time.

I thought the suspension seemed a little bouncy, while the small wheels and high pressure tyres transmitted rumbles through the airframe. Five inch main wheels with special, undersize tyres and a four inch nosewheel are obligatory, since anything more conventionally sized causes landing gear resonance. With such small wheels, this is definitely not a rough field aeroplane, although Steve says that, thanks to the nosewheel’s guard, there is no problem with stones being flicked up into the pusher propeller.

Pre-takeoff checks are conventional with the exception of setting the spring bias pitch trim so that the trailing edge of the narrow chord elevator immediately ahead of you is deflected one centimetre down. Since the canopy can be held slightly open by its secondary latch for occupant cooling, it is important to ensure it is securely latched before takeoff, but there is a simple spring steel safety catch to supplement the dual over centre latches which clamp it down on to the fuselage sides. There are also a warning light and buzzer for the forgetful.

Rutan 33 VariEze
Technical specifications
Powerplant
One normally aspirated, fourcylinder,
horizontally opposed,
high compression Continental
(TCM) O-200A producing 100+hp
(76+kW) at 2750rpm. TBO 1800
hrs. Propeller: 160cm diameter,
175cm pitch, two bladed, allwood,
Hertzler Silver Bullet fixedpitch
propeller.
Performance
(Manufacturer’s quoted)
Sea level Vne 190kt
Max speed (11,000ft) 153kt
75% cruise 151kt
Economy cruise 138kt
Stall 55kt
SL climb rate 1200ft/min
Max range (45 min reserve)
1280nm
Max endurance (45 min reserve)
9h 15m
Weights
Equipped empty 304kg
Max takeoff 476kg
Max baggage nil
Standard fuel 137lit
Load factors +2.5/-1.5g
Dimensions
Wing span 6.8m
Wing area 6.12m2
Length 5.13m
Height 1.5m

Once the canopy is shut, I find my headset keeps touching it, and although this gives me the best possible forward view, I do intermittently receive a few odd buzzing noises in my cranium. The owner’s manual insists the pilot’s head must be within one inch of the canopy before takeoff, so that requirement is certainly fulfilled.

Steve emphasised the one flying limitation, which is that the canard must never be raised above the horizon when near the ground, both for fear of getting into a high drag, low performance regime, and because of the prop tips’ and wingtips’ proximity to the ground in a nose high attitude.

Entering the runway, we roll forward a few metres to centre the nosewheel.

Opening the throttle produces an uncharacteristic snarl from the little Continental (soon left behind as we accelerate) and an immediate smoothing in its rotation as the rpm increase. We surge forward unexpectedly enthusiastically, andI intermittently tap first one brake then the other to keep us somewhere near the centreline until the rudders start working aerodynamically at around 40kt. At 50kt I raise the nose a touch, being startled at first by the elevator’s sensitivity, and to my shame inducing a brief PIO (pilot induced oscillation) as I try to skim the nosewheel just above the runway surface while we continue accelerating. We subsequently lift off at around 70kt after a run of a little over 600m in calm, 20°C conditions.

As we climb away, I have to concentrate hard on not over controlling in pitch when I remove the locking bungee with my left hand and wind 10 easy turns on the nose leg crank until it is retracted. I discern no pitch force change during this operation.

Resecuring the handle with its bungee loop allows me to concentrate better on the aeroplane’s handling and performance. I am immediately stuck by the poor control harmony, with an extremely sensitive elevator but heavy and sluggish ailerons and intermediate weight rudders (yes remember, there are two of them). However, once our speed builds up to 110kt, the roll control greatly improves and I see a climb rate of around 1000ft/min on the VSI – remarkable for such a low powered two-seater at maximum weight, and more than double an identically powered Cessna 150’s. Only a slight right rudder pedal pressure is needed through takeoff and climb, just as in any American engined aeroplane, but less so.

Once above 1000ft I reduce power a little and keep the speed up at 110kt for good cooling, which has always been a problem area for pusher aircraft. Steve’s cowlings are to a later design, optimised for minimum drag with maximum cooling airflow delivered by a wide NACA duct under the belly, so our temperatures and pressures remain within limits. However, the aircraft subsequently sat on the ground for half an hour before the photo sortie, allowing the powerplant to become heat soaked, and requiring several minutes of low level, low powered cooling flight before the VariEze could climb up through the turbulence to 3500ft for smooth air and photography.

At 4500ft, a maximum cruise setting of 2500rpm results in a cracking 151kt TAS at just 16 litres per hour consumption with the mixture leaned out. This improved economy over standard is another result of Steve’s high compression conversion, and gives him an incredible 7. 8 hours flying with 45 minutes reserve, for a most impressive still air range of 1180nm! Reducing rpm to 2380 at 1500ft decreases consumption to 14. 5 litres/h while knocking back the airspeed by only 6kt to 145kt (TAS), meaning you can now fly 1250nm in 8. 6 hours. Economy cruise of 2250rpm, as well as being quieter and smoother, extends endurance to nine and a quarter hours and range to very nearly 1280nm at 138kt. This is no less than, in the old money, 53mpg at a whopping 160mph. What efficiency! All these figures are solo of course, because of the weight limitation.

Handling in the cruise is better, although the ailerons are still much heavier than the elevators, making it difficult to prevent small pitch excursions when making significant roll inputs. Rolling to the right is particularly difficult because you have to operate the sidestick backhanded. Our formation pilot found station keeping tricky at the 70kt imposed by our camera ship, frequently having to resort to bringing over his left hand to help the right when turning away from our old Cessna 120. This poor lateral control is probably due to the small ailerons, fitted well inboard on the wings, presumably because they would cause too much flexing if bigger or set further out, but it can be improved by appropriate use of the rudders.

I also found the dual finlet mounted rudders a bit difficult to get used to. I guess I habitually clamp my feet fairly firmly against rudder pedals to increase the effective fixed fin area for less fish tailing in conventional aeroplanes, but doing this in the VariEze merely results in excess drag from having both rudders somewhat deflected against their return springs. The best solution almost seemed to be to keep my feet off the pedals altogether, and they are hardly needed for coordinating turns up to quite a high roll rate, since its swept wing confers strong roll/yaw coupling.

Nevertheless, stability is good in all three axes, although I felt the aeroplane was slightly less stable in pitch than I would have preferred, and flying through light turbulence led to an odd little elevator feedback through the stick so that it bobbled back and forth against my gently clasping palmas the airframe nodded its way through the bumps. It is rumoured that some VariEzes can perform aerobatics in the USA, but many countries prohibit them.

The VariEze’s all-round visibility is superb, particularly in turning flight, with the small exception of directly ahead and down, where the foreplane gets in the way a bit.

The passenger also has good visibility, and better than in its Long Ez successor with its bigger wing root leading edge extensions.

Airflow sound levels in the cruise are low, thanks to excellent canopy sealing and the aircraft’s super clean lines, while what little engine noise there is blows away behind you. The generous canopy provides both occupants with plenty of warmth, even in winter (there is no heater) while a well positioned air vent above the front panel can be adjusted to blow a stream of cooling air right into your face.

One well known drawback of canards is their tendency to abnormal behaviour in pitch if the foreplane becomes wet or gets seriously covered in squashed insects. Steve told me there were several reasons for this, foremost among which was poor profiling of the canard’s aerofoil by some less than meticulous builders. The later Long Ez has an optional, improved Roncz section on its foreplane, and some American VariEze builders have adopted this for their VariEzes.

However, Rutan does not approve it, so Steve would not use it, assuring me he has flown in rain, and suffered no more disconcerting effects than a slight change in pitch trim.

After reducing power it takes us some time to slow down, further testament to this airframe’s exceptionally low drag. Once flying slower than 120kt the nose wheel can be lowered, while the underbelly airbrake can be extended below 90kt. Above 95kt its spring loaded, over centre mechanism succumbs to dynamic air pressure and it snaps back shut, so this is really a device for increasing the descent angle, rather than for reducing airspeed.

Eventually, our speed drops below 100kt and the ailerons are back in low-effectiveness mode. Canard types are deliberately designed so that the foreplane (a lifting surface) stalls before the main wing under all circumstances, so that there is always a pitch down. This renders their minimum flying speeds rather higher than the same wing could produce with a conventional tail, but it does prevent a true main wing stall.

In the VariEze’s case, the minimum speed I can achieve is 52kt, although holding the sidestick fully back against the stops to get this takes a massive, wrist aching effort. As I hold it there, the aeroplane nods up and down while the airspeed needle swings back and forth between 50 and 60kt. This is called the ‘pitch buck’ and is more gentle than on the only other canard type I’ve so far sampled – the Velocity.

There is no sign of a wing drop, presumably thanks to the vortilons and trailing edge flow straighteners on the outer wings, and although roll response is now positively ponderous, the ailerons do still work. Steve explains that those vortilons and flow straighteners not only improve roll control, but do actually reduce the VariEze’s minimum flying speed. Nevertheless, a glance at the VSI shows the hidden danger of a high descent rate which is right off the clock. Sideslipping should only be attempted with extreme caution, since it is possible to stall a winglet in a steep slip, inducing a sharp departure from controlled flight into a tight spiral for several seconds. Recovery merely involves centralising all controls, but can incur as much as 1500ft of height loss! On the other hand, being so clean, the VariEze glides quite well, a ten to one glide angle being quoted with a windmilling propeller at 80kt.

Returning to Biggin Hill, I disgrace myself but amuse everybody else on frequency by reading our registration off the panel as G-VEZE but announcing it as ‘Golf Victor Easy Zulu Easy’ – a form of the phonetic alphabet that was discontinued long before I was born! Slowing below 100kt on downwind, I crank down the nosewheel to get that out of the way and secure its bungee, then further reducing to below 90kt on base leg, extend the airbrake. This is a bit awkward, since the lever comes up and backwards under your left armpit, but it is not hard to move and there is no perceptible trim change with it out, only a slight airflow burble. Turning towards the airfield, I throttle back a little to 1300rpm, to give us a gentle 400ft/min descent at 85kt.

Flying down a straight final approach, you can clearly see the threshold plus some of the undershoot over the foreplane, although downward visibility is not as good as in many more conventional types.

It is relatively simple to maintain the required 85kt airspeed and a steady glidepath, only the tiniest wrist movements being needed for minor adjustments. Accurate speed control is very important in such a slippery airframe if you don’t want to gobble up the runway in a long float, but I found it no chore.

As with other canards, Steve tells me to check the descent and then hold the attitude, allowing the aeroplane to settle, and once again ensuring the foreplane does not rise above the horizon. This is very like jet technique, to which I am no stranger, so I find the flare, brief hold off and landing simple. Luckily, by the time we get back to base the crosswind has decayed, so there is little need for manoeuvring in roll or yaw, which I might find more challenging, particularly since, with the nose raised, the tips of those swept wings come very close to the surface, making accurate wing levelling vital.

The bit I do find awkward is consciously minimising rudder pedal pressures, so that I don’t land with the brakes on, while retaining adequate control in yaw should I need it. The resultant leg bending has my knees hard up against the sharp lower edge of the instrument panel, but the accompanying discomfort gives me a continuous tactile reminder to stay off those pedals.

As it happens, the actual touchdown turns out to be a non event. I let the speed dribble back to 70kt as we cross the airfield boundary, raise our nose the required three degrees (obviously the necessary amount if you’re flying a standard three degree approach), ease the throttle closed, hold my breath, and wait until our main wheels scuff the surface with a musical double chirp. Steve is kind enough to say it’s a good landing.

Squiggling along the centreline slightly as I try to equalise my differential braking while holding the nosewheel off the tarmac to below 50kt, we gently roll to a halt with light braking in perhaps 1500m. This could have been at least halved with more practice, better technique and harder braking, and Steve assures me he regularly stops in 400m with anything of a headwind. Nevertheless, this is not really a short strip or a rough field aeroplane.

Taxiing back, Steve routinely leaves the airbrake extended to afford some protection for his propeller, something he does not do when taxiing out, for fear of inadvertently attempting takeoff with the brake extended.

So, why don’t we see so many canards around these days? Well, they are definitely not best suited to short grass airstrips and small sized airfields, nor are they well able to cope with gusty crosswinds. On the other hand, they may all be away, roaring around the continent, because high speed, long distance cruising is definitely their métier.

Probably modern homebuilders prefer today’s quickly built kits to this once revolutionary, but nowadays comparatively laborious construction method. However, I suspect the true reason VariEzes have become less common is simply that Burt Rutan stopped selling plans for both them and the later Long Ez way back in 1984, although he did continue to provide support for builders who had already started construction.

Whatever the reason, Steve is clearly a canard convert, and very proud of his superb example – and rightly so. It is beautifully built, and performs astoundingly well on such low and economical power.

I’ll let him have the last word, comparing it with his previous version: “There’s a massive difference in performance – it’s miles better”.