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The Tandem, weighing about 684lb with full fuel tanks and me, accelerates fast and straight. It lifts off at 26kts IAS by itself. A small left rudder input is necessary to compensate for the propeller torque. After accelerating to 40kts, the best rate of climb speed, I reach 2,000ft above the airfield within 3.5 minutes, giving a climb rate of about 600ft/min. The elevator forces are very low, and I think there is probably no need to order the optional trim system, which, nevertheless, works perfectly well and precisely covers the whole speed range. If the trim is installed, it would be practical to place its switch by the stick or the throttle.

Of course, the Tandem's cruising speed cannot compete with modern microlights with the type of wooden propeller fitted when I flew the aircraft, the airspeed indicator did not rise above 56kts with the engine running at 6,000rpm. However, this propeller (which is driven via a 1:3.74 drive reduction gear) is probably not the optimum prop for the Airbike, and later models will use a different propeller. This is why the data sheet gives a slightly higher cruise speed of 62kts. And anyway, those who fly an Airbike do not aim to travel from A to B in the fastest time, their intention is to enjoy the flight. Most pilots will probably cruise at about 45kts, just a bit below the speed where the airflow starts to ignore the small windscreen and starts pulling at your helmet! If there is somebody sitting on the front seat, not only are they better shielded from the airstream by the small windscreen but they also protect the rear-seat occupant from the turbulence.

Visibility is good. The pilot's view is only obstructed upwards by the wing, and by the front seat's shoulder belts hanging down just in front of the pilot's face. By moving the head a bit to the left or right, it is possible to get a good view forwards along the nose structure. Thanks to the 152ft2 wing area and low wing loading, the Tandem Airbike can be flown extremely slowly. With the engine running at idle and the flaps in, buffeting starts at 26kts and mushing at 24kts IAS. It is possible to keep it mushing along for some time by using the rudder, before it finally wants to drop a wing. Easing the stick a bit forwards stops this movement immediately.

With full throttle, even slower speeds become possible, and with full flaps I got the airspeed back to only 20kts before the stall started. There is no position indicator for the flaps you just have to look at how far the flaperons go down while pressing the switch. The control forces are comfortably low and rise proportionally to the flying speed, although the ailerons do feel a bit soft. For serial production, it is planned to increase the stiffness of the control system a bit.

In my opinion, if you build this aircraft without the flap system, it will still fly slowly enough to fulfil all the certification requirements. Furthermore, the aircraft becomes even lighter and the control system without the 'flap mixer' will be stiffer. I measured the 45° roll-rate to be 3.1 seconds at 30kts, later aircraft built from the actual plans should roll even faster this prototype does not yet have the flaperons covering the whole length of the trailing edge. The wing from the single-seater version has been used but it has been strengthened and enlarged by 3ft. The control harmony is very good, but the rudder feels very 'direct'. However, directional stability is quite low due to the open tube frame fuselage. A slightly enlarged rudder fin or cloth covering of a rear fuselage section might result in better stability. Changing the power setting has barely any influence on the trim balance. If the flaps are set to landing position, the nose goes down and the speed increases by 6kts. With the low directional stability, sideslipping is possible at high angles with the rudder being sucked to its stop, but only with very low forces. However, the sideslip is not very effective because the open fuselage only provides a small amount of drag-producing surface. If you really want to get the Bike down, just pull the throttle back and dive to obtain a very steep glide angle without the speed increasing much.

Under calm wind conditions, the approach can be made using full flaps at a very slow speed, resulting in an extremely short ground run. Under turbulent conditions, such as during my test flights at Kropp, it is wise to leave the flaps at '0°' and approach the airfield with a basic approach speed of 40kts. Using this setting, the Tandem Airbike is still quite easy to land in weather conditions that might already being causing problems for other slow, lightweight microlights. Completely held off, the Tandem touches the ground at minimum speed in the three-point-attitude. It actually lands rather like the old Piper Cub if the stick is not fully back, it likes to balloon a bit on its well-sprung undercarriage. Even with the flaps in, the low minimum speed, combined with the effective wheelbrake, makes very short landings possible.

The 'Airbikes' are real fun-flyers for nice weather. Their pilots will not be interested in cruising performance, fuel consumption per mile flown or the comfort of a closed cockpit. While flying above the countryside, they just enjoy their bike sitting as if they were in a garden chair with an integrated sunshade and a particularly good view. They drop in and take off from small airfields, always having a happy grin on their faces (despite the dead flies stuck to their teeth). The Tandem version also seems suitable for use as a basic trainer, as it flies gently, offers nearly the same flying characteristics as a 'real taildragger' and will probably bring the pupils trained on it to a higher standard of airmanship than the nosewheel varieties of the first microlight generation.

Finally, and unusually for many aircraft in its class, its payload offers legal flying with two adults aboard. Its design is also very passenger-friendly, as I found during my visit to Kropp airfield as soon as Hans Schaller had pulled his 'Tandem' out of the hangar, he was surrounded by visitors asking for a ride on the back saddle. Sadly, he had to ask them to come back another day, as at the time of my flight, the Tandem was still awaiting the certification that would allow it to carry passengers.

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