Peroxide take-offs and transition to autogyro forward flight
Earlier we have made vertical take-offs with the gyro glider, tied with a tow rope and the towing car was standing still. -See report here.
On July 3 2004, we went to Feringe Airport for further testing. Hans Krugloff was the pilot and his brother Torbjörn drove the towing car. I was sitting in the trunk and took pictures and movies.
Pre-rotation by hand
First we made some attempts with conventional gliding without using peroxide powered pre-rotation. The rotor was pre-rotated by hand, but we never managed to take-off, because the rotor did not accelerate enough.
Hans thought this was because the rotor is too heavy. He also suspects that the angle of attack, 4 degrees, is too big for this take-off method.
Peroxide powered take-offs
We then made 5 or 6 different take-offs, using the rotor tip rockets.
At the first one the rotor was pre-rotated with the rockets to a fair speed of maybe 200 rpm and the glider was towed after the car until the glider lifted after about 100 meters or so, when the forward speed was around 50 km/h (31 miles/hour). It auto-rotates with about 315 rpm at flight.
Than we made several, more or less vertical, take-offs. The transition from powered lift to forward autorotation gyro-gliding was always smooth and not at all dramatic:
- If the glider was towed too slow after a vertical take-off it descended slowly back to the ground before it lifted once again, when the forward speed was high enough.
- If the car accelerated fast enough to 50 km/h (31 miles/hour) the glider stayed in the air after the vertical take-off.
I was shooting movies of all the take-offs, but the last couple of take-offs, which were the most spectacular and mostly true vertical, I was shooting with Hans camera, because the memory in my own camera was full at the time. Of course I messed it up! The most beautiful VTO:s were never recorded to the camera memory. (I feel sorry for Hans, because he made a skilled and brave pilot effort with no proof to the world!)
Anyway, the best take-off that was in fact recorded can be seen here below. It is not perfectly vertical, but at least it is a nearly zero runway take-off -which I believe is spectacular enough for those of you that knows about conventional autogyro flying!
The second movie, that can be seen here , is just showing a few seconds of normal forward towed auto-gyro gliding.
Hydrogen Peroxide Concentration
For these tests I had prepared two 5 litre bottles of HP. The concentration was 79.6% and 77.5 % only. Earlier we have used higher concentrated HP: 81 to 82%
The rockets were running clean and stable also with the lower concentrated HP, but they had less power than before. When using 77.5 % conc. HP, the power was just barely enough for VTO.
This lower thrust was something that came as a surprise to me, because when I make rocket calculations, I can see that the rocket exhaust gas becomes colder and the gas velocity lower when using low concentrated HP, but at the same time the density of the gas and the mass flow increases, which compensates and make the thrust almost exactly the same - but at a higher fuel consumption. My theory did not fit with reality this time. We would need to increase the nozzle diameter to compensate, but instead we will return to use 80%, plus, concentration HP.
Next report here.
This article was updated on October 11th, 2011