Turbine taste of what MOSAIC may enable

Aviation et Pilote founder Jacques Callies and I have tested several VL3 models dating back to 2012. We were impressed by the performance of this aircraft, which is similar to the Lancair 235, a kit aircraft designed by Lance Neibauer in the early 1990s. The VL3 was the machine that, together with the Aerospool WT9 Dynamic, created a new type of microlight in Europe, much faster than any previously designed, except for Wolfgang Dallach’s Fascination, which did not enjoy the same commercial success. The VL3 was so fast that it couldn’t be classified as a light sport aircraft in the United States and had to jump to the experimental category.

Over the years, Belgian brothers Jean-Marie and Jean-Baptiste Guisset have offered improved versions of the VL3 and constantly improved their production and marketing techniques. With more than 570 units delivered to their owners, the VL3 is one of the leaders of the fast ultralight market in Europe.

When JMB Aircraft announced the upcoming installation of a Turbotech turbine in the airframe of a VL3, we were the first to fly the new turbine VL3.

Impatient customers

“Our pilots are generally frequent travelers,” said Jean-Marie Guisset, JMB CEO. “They are not content with just flying around their home base; they want to visit their vacation homes in Spain or Portugal, return to France, Belgium, or Germany, and then explore other countries. To achieve this, they seek fast, comfortable, and well-equipped aircraft. The Rotax versions of the VL3 meet these specifications well. However, some desire even more performance and greater independence from [avgas]. Few of our customers refuel at automotive gas stations using jerry cans! They want to use a universally available fuel.”

Doesn’t the extra cost associated with a turbine scare customers? Extended time between overhaul helps ease the long-term cost differential:

“It is compensated by the fact that the Turbotech has a much higher TBO than conventional engines (initially 3,000 hours), increased reliability, and offers a completely new flight experience to the pilot due to the total lack of vibrations,” Guisset said. He added that automatic turbine management ensures the pilot won’t make a mistake during start-up, nor cause any damage to the engine. “Turbotech has combined the engine and the electronics beyond anything we could have dreamed of, even when compared to turbine manufacturers such as Pratt & Whitney or Rolls-Royce. Combine these facts, and you’ll understand why the turbine version interests many pilot owners. We have over 70 customers impatiently waiting for a delivery date while we haven’t started actively selling this model.”

Briefing and start-up

Callies and I spend a little more time on the ground than usual. We need to meet the Turbotech turbine for the first time, and the VL3 we are about to fly is registered as a prototype, so we must fly solo to meet the regulations.

On the dashboard sits a conventional Dynon SkyView. To its right a 7-inch vertical screen made by Turbotech displays the turbine parameters, informing the pilot about the percentage of power delivered, temperatures, rotation speed, and pressures. This screen will eventually be removed, and all the data it displays will be moved to the Dynon PFD. What takes the most time, a good quarter of an hour, is the review of the various alarms that could come up on the turbine display and the action to be taken in these cases.

The start-up procedure couldn’t be more straightforward: Turn on the battery switches; check that they are delivering at least 25 volts, that both fuel pumps are working, and that the single lever is in the “idle” position; and press and hold the Start button. The screen then displays the start-up process, from the initial start to the complete ignition, including the phases of starting the igniters and opening the fuel system. If an anomaly is detected, the engine control system takes over the shutdown and instructs the pilot, if necessary, to press the button controlling the turbine ventilation.

Gone are the days when you needed three hands to start your turbine safely.

Ready? Set, fly!

The start cycle is normal, and the temperatures stabilize in the green. The warmup times, compared to a Rotax, are minimal. Despite the frigid outside air temperature, we are “in the green” almost instantaneously.

My four-point harness is buckled. The position is very comfortable, and my headset headband is far from touching the canopy. I can easily reach all the controls and don’t have to adjust the rudder pedals. The seat cushions are remarkably comfortable and will remain so even on long-distance flights.

Currently, the Turbotech is derated to 130 horsepower, a power comparable to that of the Rotax 915 and 916 iS engines. The latter are equipped with a turbocharger, so we should get relatively comparable flight performance figures. According to Guisset, the propeller, a beautiful and mean-looking four-blade by DUC Hélices Propellers is remarkably efficient.

I taxi to line up on the grass of this private French microlight runway. The timid winter sun has managed to break through, making the runway somewhat mushy. Once aligned, I opt for a soft-field takeoff. The rudder pedals easily control the aircraft, and I hardly notice any gyroscopic effect. This may be due to the reduced length of the propeller blades compared to those of a two- or three-blade propeller. The acceleration is comparable to that of a VL3 916 iS, but the ride seems longer than expected. After a takeoff run of around 590 feet, I am airborne, still fast enough to give a Piper Cherokee or a Cessna Skyhawk a crying fit. Once in the air, the machine accelerates sharply, and I have to retract the landing gear and flaps quickly to not surpass the speed limits.

That’s where things start to happen fast. The speed builds quickly, and to maintain the best climb speed, I have to pull on the stick, again and again, up to 12 degrees of nose-up attitude. With 85 knots indicated, the vertical speed indicator displays well over 2,000 fpm. As I plan to fly between 3,500 and 4,000 ft, the climb will not take long.

Guisset warned me that the performances observed will not match those of the final version. This prototype was reinforced more than necessary before the turbine was installed. The production aircraft will be much lighter, and it should obtain a climb on the order of 2,500 fpm and exceed 200 knots true airspeed in cruise.

After less than two minutes of climbing, I stabilize and set up for cruise. At full throttle, or 98 percent torque, the Dynon shows 181 KTAS. At 90 percent, I get 176 KTAS, and at 80 percent, 169 KTAS. Fuel flow is then 9 gallons per hour. Here in Europe, Jet A-1 is generally 30 to 35 percent cheaper than avgas or UL91, so a turbine can be fueled at a substantial savings.

Another world

As for the flying sensations, I feel I am in another world. I had never realized how much piston engines vibrate until now. Even the Rotax engines, renowned for their smoothness, don’t offer such a vibration-free ride. I feel like I’m flying in a perfectly compensated glider; I only feel the aerodynamic effects.

When it comes to noise, the VL3’s Turbotech is surprisingly as discreet as a Rotax engine, and the propeller, with its four blades, is also quieter than the ones used on the piston-engine versions of the VL3.

When I test the controls and various attitudes, there’s a second surprise: The feel of the controls has changed compared to what I’m used to on the standard VL3. Controls on all axes are more homogeneous and a bit heavier. I don’t feel I’m flying a very light aircraft, a sort of flying Formula 1. I feel a heavier aircraft, very stable, capable of making long flights without the pilot constantly trimming the aircraft and correcting trajectories. The flight controls remain nevertheless very demonstrative, and the aircraft is agile. Kind of a mix between a Mooney and a Lancair.

Guisset told us later that his design office worked hard to achieve this result. The aircraft’s center of gravity was brought a bit forward by lengthening the engine cowling. The wing loading has been slightly increased, improving the passage through turbulence.

After some 360-degree turns at various bank angles, during which it was easy to maintain a constant altitude, I moved on to stalls. It takes a little while to see the airplane slow down after reducing power. Before stalling, the airplane gives a pronounced buffet before a well-aligned nose drop. I just have to relieve stick back-pressure and add some power back to resume instantly controlled flight. I’ve lost less than 200 feet. The same effects are observed for clean stalls, not an ounce of vice during these maneuvers. The changes to the wing profile and other aerodynamic tricks have had the desired effect. The aircraft is predictable, safe, and does not tend to spin when stalling.

As the best things must end, it’s time to go back. I set up to enter the downwind leg at 1,000 feet agl. The VL3 is fast, and once the nose is lowered, the yellow arc appears quickly. It is, therefore, necessary to play with the engine power to avoid creeping toward V_NE. It’s the first time that I regret not having speed brakes on an airplane designed to be compliant with the forthcoming FAA Modernization of Special Airworthiness Certification. The difficulty is accentuated by the fact that I stayed close to the runway and that I need to lose 3,000 feet while being nearly overhead.

I reduce the torque, always keeping the temperatures in the green, and get a 1,500 fpm descent. I stay at the limit of the yellow arc; life is good. I integrate the downwind and prepare the aircraft. The landing gear extends and locks quickly, and I add two notches of flaps. I hold 80 KIAS in the downwind, then 75 KIAS on final. The wind has picked up; I estimate I have 10 to 12 knots of wind coming from the left. I have no trouble keeping the airplane lined up. I must lower the nose more than usual, but it’s an optical illusion caused by the unusual length of the engine cowling. Once the full flaps are extended (it requires more effort to move the flap lever to full down than for the two first settings), the flare is natural, and the cowling does not hinder forward visibility. I let the aircraft roll because the runway is even softer than it was during takeoff as the winter day has slowly warmed. I keep a trickle of gas and hold the nosewheel in the air for as long as possible. What I thought would be a long landing turned out to be a short landing. I’ve used less than 600 feet of runway without touching the brakes to come to a complete stop.

Once at the parking spot, I look at the turbine temperatures and press the Stop button. The turbine winds down, and all that is left to do is to cut off the avionics power and then switch the battery off. Silence falls on the airfield.

In conclusion

What more can I tell you? I loved it. The small Turbotech turbine’s performance is breathtaking, and the absence of vibrations will delight pilots and passengers. No sacrifice has been made in terms of interior design. We are facing a very high-end two-seater. Equipped with a modern engine and state-of-the-art avionics, the VL3 Turbine represents the best that can be hoped for in the category of high-performance light aircraft.

With 3,000 hours TBO, the Turbotech turbine has many advantages over piston engines: pleasure, reliability, use of the world’s most common aviation fuel, the possibility of using automotive diesel if necessary, or future biofuels; the list goes on. For those ready to put their hand in their wallet to benefit from a retractable machine, fast, with operating costs comparable to those of a Rotax 916 iS, no doubt, this is the ultimate two-seat racer.