Help with High Altitude FPV Glider
For the past 2 years I've been building and launching high altitude balloons (see this for more info on HAB) with increasingly complex payloads. I'm running out of interesting things to do with a traditional HAB - so with your help I'm hoping to try something new and much more challenging. Instead of a typical payload of various recording and tracking equipment and a parachute, I want to send up an FPV plane with long range capability and pilot it back to earth while recording the video of the flight.
HABs typically reach around 90,000 feet before the balloon bursts and the payload drifts back to earth on a parachute, so to be safe I'd probably cut the FPV loose around 85,000 feet (I have this part covered). I'll also be in a chase car trying to stay within 3 miles of the HAB/FPV (asssume a max distance of 20 miles), but because of the ultra high altitude you'd be really surprised what sort of range you can get from radio equipment.
Due to FAA regulations I have to keep total payload weight under 4lbs, so getting everything built within the weight limit is going to be major challenge, and I could really use your advice for what sort of kit I need. Here's what I think I need to make this work:
- A very light and strong airframe - The atmosphere is extremely thin at high altitudes, so airspeed is going to be very high and the aircraft will experience ~3gs pulling out of its dive.
- Sensors: GPS, Airspeed, Attitude, Pressure, and Airspeed - I've built these sensor packages for HAB flights, but I need advice about what plays nice with OSD.
- Video transmission with good OSD - In the past I've used a laptop to track HABs and sensor data, but I've never done live video, and I assume that to pilot it effectively having waypoints, altitude, and airspeed on the OSD is essential.
- I also need a great long range transmission/control system (I hear good things about dragonlink?)
I've done some research and have some ideas, but I'm very interested in hearing your advice and feedback before I firm up my list.
The other question I have is around training. I realize the best way to start with FPV is small - with simple more affordable kit and then work your way up. However, for my purposes I really want to use the FPV primarily for the HAB project and possibly keep flying afterwards. So here's my plan:
Train with the plane until I'm completely comfortable with it before the first balloon launch and then start launching from the balloon at lower altitudes (5-10 times) before I go for the full scale test. I live in Singapore and there's an airfield here I think I can fly at and I can do the test launches in Malaysia. Any thoughts on how I can improve the training/any specific challenges I should prepare for? I know I'm going to be facing some pretty tough flying trying to pull out of a high speed dive from 85 thousand feet with the strong possibility of uncontrolled spins and extremely high airspeed flying. Any way I can train for this type of flight specifically?
Thanks in advance everyone! If I can get a parts list together, I plan to start ordering and building immediately and I will keep you updated/post pics and videos along the way.
This sounds like a fantastic project and you clearly have a huge amount of relevant experience to pull it off. However, it might be worth you hooking up with a couple of well known FPV pilots who are also looking into this and who could undoubtedly provide you with all the plane and FPV relevant info you seek. For political reasons though they no longer frequent this forum, but you can find them over at http://fpvlab.com/forums/
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