Hi,
I'm actually being paid to lift an rc plane as high as I can using a balloon and then release the plane to fly home on it's own.
I have my Permission for Aerial Work and an exemption from the UK CAA for this adventure, plus insurance, so the legal side is sorted.
I am a professional aerial cameraman with a few years multicopter experience for my day job and FPV racing. I used to fly fixed wing rc for fun without autopilot but now do large land surveying using fixed wings.
I have built the prototype plane using a Skywalker X5 and Pixhawk. The delta shape was chosen because it has very few sticky-out bits for the balloon lines to get caught on. The X5 was chosen because I can replace the frame relativity cheaply after "teaching" it it auto-land. It also has a big payload area.
Obviously I've not done this before so I'm hoping that people here will be able to help out. Here's a few questions to start with:
Recovery from stall: Once the plane has been released from the balloon lines, it will fall for a few seconds before trying to recover horizontal flight. I'm not going to try for a long range rc control so the pixhawk will have to fly it home. What is the best flight mode to have it recover? I'm more interested in what mode to use in testing since I will fly up to 100m or so and then force a stall before allowing the pixhawk to recover for me.
The full size plane will probably be either an X8 or a Buffalo, anyone have a better airframe which is easily available in the UK?
I've already sent up a balloon to test the pixhawk, cameras and batteries. I was going to use a Raspberry Pi and Pixhawk to run the mission and make decisions when to move the release mechanism servo, etc but the Pixhawk 2.1 with Edison module looks a neater solution with less things to go wrong. I'd prefer the more tried and tested original pixhawk but I'm happy to give it a good bashing and go back to the pi if the Edison is not up to scratch.
Any other helpful comments or ideas would be most welcome.
I'd like to get this right because it's going to be landing live on TV. :-/
Thanks, Tim
Replies
Hey, that's really nice David thanks!
DavidJames said:
Tim, I noticed this FPV flyback blog from a balloon drop that may have some useful information.
https://rcexplorer.se/projects/2013/03/fpv-to-space-and-back/
A small tube of Krytox is about £80 but I found some Rocol X33 silicone grease which is rated to -78C. I'll try with the silicone first but if that it's not performant, I'll get some Kyytox. Thanks.
DavidJames said:
Tim, The Krytox oils are pretty amazing. They are what makes the Krytox grease work. Krytox GPL103 might not be too viscous at low temperatures and has a low vapor pressure. I think you can get small bottles of it on Amazon. Krytox GPL103 is supposed to be useful down to -60degC.
You could clean the grease out of a low cost servo and try and use a few drops to lubricate the gears. For it to work well the old grease and oil has to be removed.
Tim Squires said:
I remember back in the early 90's a Canadian dropping a red and yellow glider that had made several attempts.They had a website showing the progress. They recovered one that I can remember and that was a big deal. Lost several to the Sea or water. I also believe the altitude goals where very high but lower than what we are doing today.
Lyn Rees said:
for that short time, and one time use, brushed servos are also ok, AND just remove the grease ;)
Thanks David. the BLS253 looks good. I'll buy one and put it on the trial balloon flight to see how it performs. What do you think about silicon grease instead of oil?
DavidJames said:
Tim, The BLS253 operates over a wider voltage range and costs a little less. Cleaning out the grease and oiling the gears and bearing lightly is a good idea too.
Actually I think most of the GPS modules made that we use today will work. It is pretty easy to verify which ones will and which ones wont. Back in the day the only real way to find out was try it!
Hans H. said:
Good luck and I hope you can achieve your dream .
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