September 8, 2016 at 11:10 am #3101
I’m planning to send up a modded skypod with an acrylic dome attached to the side to accommodate a steady cam.
Something like this: http://ecx.images-amazon.com/images/I/51hIklCuIeL._SX425_.jpg
The steady cam will be a DJI OSMO with X3 camera and an external battery. This will obviously be much heavier than the usual GoPro setup, with an estimated total payload weight of around 1.5kg.
I was going to try two clear domes, one slightly smaller inside the other and sealed to provide an air gap for insulation. This should allow the steady cam to stay mostly level while the box jumps around and not get in the way of the view.
The external LiPo battery is from a drone and should power the camera for about 4 hours, hopefully long enough for the take-off and landing. Instead of taping it down, I was planning to cable tie it to the box.
If anyone has any insights, ideas or warnings, please let me know.
Thanks, TimHide replies
September 8, 2016 at 12:20 pm #3102
Hi Tim, Sounds ambitious! We love the idea of using a gimbal on a flight.
Our first thought is that 1.5kg payload is certainly doable, but you’d want at minimum a 2000g balloon, probably a 3000g if you want to achieve a really impressive height.
Second thought is that in order for the two domes to provide much insulation, they’ll have to be sealed together to trap the air, but at that point the changes in relative pressure and temperature as the payload rises could well result in condensation inside the domes obscuring your picture, which I’m sure you don’t want.
When we send up a payload, the lens of the camera is actually exposed, although we use a lot of insulating tape around the rest of the body to keep the circuitry from getting too cold. We expect a single dome would be sufficient as long as it’s securely mounted and all the edges are sealed. It’s probably better to get decent images for the majority of the flight and risk losing power before the payload has landed than to get a whole flight with obscured footage, right?
Third point to note is that the temperatures can drop to -60 degrees centigrade over the course of the flight and all batteries suffer dramatic drops in efficiency at low temperatures; if anything, insulating the battery is more important than insulating the camera circuitry. With that in mind, securing the battery outside the payload could actually make all your other insulation efforts moot.
It’s also worth looking into how the gimbal orients itself, since some accelerometers respond oddly to flight and most GPS devices are capped to stop reporting above a certain altitude.
Let me follow all this with a disclaimer: we haven’t used a gimbal on a flight before, I don’t know much off the top of my head about the insulating properties of acrylic domes and we use lithium-ion batteries, so a lot of this insight is educated guesswork. Whatever happens though, it sounds like you’ve thought this through extensively and we’d be really interested to see what results you get!
Alex (Sent Into Space Operations Assistant)
- This reply was modified 4 months, 1 week ago by Alex Keen.
September 8, 2016 at 12:44 pm #3104
Thanks Alex, I’ve ordered the Advanced Launch Kit from you so (when the black boxes are available) I’ll be able to play with the setup for real.
The gimbal is a spare from my drone, so is the external battery, and it’s pretty good at orientation unless the whole thing is turned more than 100 degrees so hopefully not too much turbulence on the way up. I’ve flown the gimbal and camera in -20c over a glacier and it still worked well. It also takes a good beating attached to mountain bikes going at speed down hill. This will probably be one of the most travelled cameras ever!
The external (to the camera, not the box) battery is necessary because the OSMO only works for 30 minutes on the internal battery. If there’s room/weight left, I may strap a carbon hand warmer to the battery to keep it warm. It will also be wrapped in a LiPo fire protection bag which is very good for insulation too.
Good point about the condensation, I think I’ll risk a single layer dome.
If it all goes well, I’ll have to do it again but with a bigger better gimballed camera. If it does not go well, I’ll still do it again but maybe change the design….
Thanks again, TimHide replies
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