26/02/2013 'First Hop' of Project Skyflash
On the early morning of February 26th we arrived at the airport and build up the base station right at the end of the runway. After checking the airplane I was warmed up by our physiologist. Right after this I was connected to airplane for the first time this day. The checklists were completed, the engines fired up and after a five minute warm-up I carefully began to taxi down the runway. Noticeable is the extreme resistance that 15 - 20cm long grass creates at the tires especially at low speeds. The chase car assistant indicated me after about 200m of runway that I´d reached 25kph. I kept this speed, made a 180° full turn and rolled the 1300m back to start-point. It was like driving on grassland with a suspensed bike – except the aspect that you don´t need to power it.
After this run I was inspected in my original flying position. Wheels, Suspension, Plane and Engines had no problems with the vibrations and forces. After this I was separated from the plane and the plane was checked in detail - Again without finding problems. The plane was now refueled while I was having breakfast.
With the refueled plane ready for beginning the tests I was again strapped to the plane. After running up the engines we were making several runs accelerating to reach our hovering speed of 54kph. The faster the plane got the easier it was to control and the less did the bumpy ground stress me. In fact at 52kph I felt that my motion was more like jumping from bump to bump. During a heavier crosswind-gust from my right the planes heading was going to the right, but I could correct it by body motion - During video analyzation we found out that when going over 46kph without pulling the elevator a bit upwards, the planes rear-wheels lift-off before the front. When a crosswind catches the plane it of course turns on the front-wheel axis, if this is not aloft as well. Without knowing this, at that point, I dealt with the effect by pulling the elevator a bit while concentrating my steering impulses on the front-wheels.
After some successful runs at hovering speed I decided to do two more runs after lunch. Lying in the plane is quite comfortable in fact since the lots of stabilizers, protectors and the plane itself is keeping my body in a stable position. We looked at our results until that point and I felt that I could give the plane a go and take the front wheels up next time. The team decided to do one full-speed run before my try. We´d like to see if the gear is capable of landing at higher speed in case I accelerate too much when aloft. With one additional neck protector I accelerated down the runway while giving just enough elevator to keep all wheels down. Shortly before the ‘Half Runway’ mark I let the rear-wheels go and took my chest up a bit to let the plane come into a state of hover. The gear vibration reduced and I was touching the higher grass-bumps while beeing aloft between them.
After 800m I stopped the ride and was towed back to base by the chase-car. From the spotter in the chase car I got the information that my wings were bending upwards as planned. They couldn´t see anything potentially dangerous, I was speeding down the runway perfectly.
Because of these results we decided to go for the 'First Hop'. I was taking up speed not holding the rear-wheels down so they came up indicating me my speed. I was waiting a short moment more before I took my chest up and bended my legs into the jet - The heat was absolutely no problem at this point due to the aluminum-protectors and the surrounding 1°C airstream -. Although I had no elevator mounted I could feel how the plane reacted. An upcoming breeze from the side was easy to compensate at this point. The vibration of the tires was totally gone and the plane was hovering – What an incredible moment!
With the wind from the side and the plane accelerating while shifting slightly left with the wind, I decided not to correct the steering but set it down again. Later we found that the traces in the ground were totally gone for a distance of about 15 meters. I touched down with all four wheels at a time. Brakes weren´t needed due to the rolling resistance in the grass.
The next tests will be done with V-tail attached and at warmer temperatures. Since flying this aircraft is all about my body and feeling I need to have a warmer environment for more mobility and control.
Pilot - Team Skyflash
16/01/2013 Experiences of the first high-speed taxi runs