Monday, October 14, 2013

Sixth Time in the Air

Fully assembled once more, it's testing time!

With only the control circuit between the autopilot program on the phone and the plane for autonomous flights missing, the weight of the plane is now just below 1.9 Kg. Not bad for all the equipment.

But is it better? Yes!

First, the vibrations are almost gone:

Left picture, previous flight, fully loaded with the stock motor at full throttle.
Right picture, this flight, fully loaded with the new motor at full throttle.

The difference is enormous:

And that's not al. With the new engine, the plane now climbs effortlessly:

In this test, with no one around on the ground or in the air, altitude difference of around 300 m was achieved.

And with no problems with telemetry this time, we learned that the cruising speed at which the altitude can be maintained is around 45 Km/h, which takes about half throttle.

Unfortunately, but not unexpectedly due to all the extra equipment, the gliding profile is somewhat disappointing. With the engine off, the plane glides, but the vertical speed necessary to maintain the cruising speed is around -35 Km/h, peeking at -50 Km/h. In short, it flies but it eats up altitude like crazy as can be seen on the video above at 3:00 mark (yes, the propeller keeps spinning due to resistance).

But, smoother and more powerful motor means better images and video from the cameras, and that's what we want!

Warning, awesome stereo video of the flight:

Sunday, October 13, 2013


For better results, use better stuff!

The plane flies, fully loaded even. But! It couldn't climb very high and all the camera recordings were suffering from vibrations coming from the motor.

So, the solution is simple, replace the motor. Implementation, not so much but not on the account of having to turn screws.

Unfortunately the desired one, O.S. 3820-1200 didn't come trough in time, so we got the second best thing, KONTRONIK KORA 15-10.

Cue the montage sequence:

Just add a few more holes since the spacing on this motor a slightly bigger and drill the hole in the center of the prop from 5mm to 10mm because someone goofed up and got the wrong prop mount. But it all balanced out perfectly in the end.

New motor and better regulator. Some day maybe a bigger battery and then a larger plane with newer motor, and so on, but for now this is it.

Few quick tests with a piece of string and a scale, determined the motor with 11x5.5 prop gives out 1.6 Kg of thrust at full throttle. With more aggressive timing setting on the regulator it gave out 1.7 Kg of thrust, but the output was not linear with the throttle.

For comparison, the old motor gave 0.98 Kg of thrust at full throttle.

And another test on the battery capacity gave us: 3 minutes at full throttle and 9 minutes at at half throttle on the new motor. Compared to the 6 minutes at full throttle and 11 minutes at half throttle on the old one. 

Time to test in in the air to see if the trouble was worth it.