Dear all,
I have been working on a high altitude balloon system with a glider to return your equipment called GPSBoomerang a product I bought from New Zealand. After spending a lot of effort developing a payload section based around the Arduino Nano system to control an onboard camera and live telemetry feed we had what we believe was a structural failure. This resulted in the equipment been damaged beyond repair and I am having difficulty contacting the supplier.
My plan B is to look at Ardupliot as a solution as I already understand the Arduino system.
However I have some questions that it would appreciate your comments on
1.Can the Ardupilot operate 20KM away from you ie in this case upwards or are there built in failsafe’s? if so can they be removed?
2.I noticed that you recommend planes like the easystar glider, how much payload could that system carry? and could I remove the motor + battery to replace with my a payload to take scientific measurements?
If the answer is YES to 1 then Ardupilot could be a good replacement, remember the aim is to launch from a weather balloon to 20KM taking some photo's and measurements. Then drop to 12KM and start gliding once enough atmospheric pressure is available then glide to a given GPS landing site. In this way you increase your chances of getting your equipment back.
Please could I have your comments
Thank you
Replies
Defiantly a cool project.
Might be a little late to offer a suggestion on the airframe of your glider but here goes.
How about using a model of Spaceship One. Skip the rocket motor and you have a glider designed for dropping from space (like a badmitten birdie); transitioning to a glider when the altitude is appropriate.
Interesting thread read.
I'm no expert, but a few thoughts cross my mind that for me at least, raise some concerns. Natha wants to keep to an off the shelf model. If foam is to be the basic material, that raises the need to study how different foams react to high altitude. With low pressure a lot of foams will have, from subtle changes to very strong reactions. The structure made mostly of trapped air surrounded by a cell membrane and the affect even if subtle, could very well still change the shape of the airfoil and alignments of the various main structures. Warping twristing right up to disintegration with loss of structural strength could be some of the outcomes. Add cold to the altitude and brittleness may play a role to the loading properties. I'd suggest running some vacuum chamber tests on any model under consideration or sub-assemblies at least. Even at the best there might be a need to add some extra structural carbon fibre in key locations to maintain alignments and add strength.
With the low pressure and cold, the next thing that comes to mind is to ensure moving surfaces don't bind up. What works on the ground may not up high due to shape changes, but also some things like hinges may stiffen up. Control rods or horns maybe become brittle or stiffen.
The closer to space, the weirder things get for many materials. Some glues will just boil away, as could the moisture in the electrolyte that's used in some cheap vented electrolytic capacitors.
Servos exposed out on a wing may fail or become unreliable. Beyond protecting them, just as important perhaps, is to ask yourself. How many do you actually need, to do what you need to do? Fewer things to fail, means the less chance something will fail. Don't build for manoeuvres you really don't need to do. Often this also means not flying on days that makes operation outside the envelope of your simplified design not possible. Still this is often better than increasing your other risk factors through added complexity.
There are a many more problem areas I'm sure of that. I guess, what I'm trying to say to Natha and everyone. Test and test again, as much of it as you possibly can on the ground, simulating as many of the conditions you expect to see and your equipment, as you are physically able to. You don't need big million dollar environmental chambers or high end structure or electrical rigs to do it. There are relatively cheap ways on the net and in technical literature to do the testing you need. The biggest hurdle is to decide what you need to test and then be imaginative in finding a cheap, simple way to get you the answers you need. Of course a whole full size plane needs room, but breaking out smaller sub-assemblies doesn't and often scaling things down, like a wing, can usually tell you just as much. If care is taken setting up the test criteria and setup.
So how about I kick off some creative thinking here. One thing that crossed my mind that perhaps should be looked at from different angles.
Do you really need to fly the plane at high altitude? What is wrong with falling for a while?
Obviously there could be several solutions to answer this question. So I'll throw one out just to get the ball rolling. What if say a drogue shute or anything wlse to slow decent, until the aircraft reaches a desirable altitude.Then it is released and flying begins. This brings up next. What is the simplest set of solutions to make this as foolproof as possible. How to get from a very high altitude, to a lower altitude, where flying a simple aircraft is possible.
Anyway. this sounds like a cool project and the solutions from top down aren't trivial. But it doesn't mean those answers are complex, nor expensive.
Hi from New Zealand. While i dont no the GPSBoomerang developer, i do no he is from Christchurch. For the past year there has been huge destruction down there with massive earthquakes (In the thousands of quakes) so that could possibly be why you have not had any contact with him. There is still a large disarray with people having to use porta loos, not having running water, power, internet etc. I look forward to reading more of your project! you have viewers all around the world!
Really I don't understand why everyone thinks an aircraft should freefall to 12km or whatever number you choose. If you do the sums, you'll see that an airframe should be capable of flight at 100,000 feet or more with relatively normal operating speeds - certainly less than Mach 0.8, which is where it will probably become transonic.
I have been using this NASA atmospheric model to do some modelling of a very like-minded concept (see my blog entries if you want to see where I'm heading) and my calcs show it potentially airborne - although not necessarily in level flight - at 150,000 feet with the right wing loading!
The thing you almost certainly won't be able to do is power it by a propellor due to the enormous true airspeed (TAS) you'll be travelling at when at such altitudes.
Anyway, if you look at the NASA atmosphere model above, you'll see it gets bloody cold up there, but only up to the tropopause where it's at -56°C (~ -68°F). Thereafter it starts getting warmer. At 150,000 feet (45km) it's a balmy 10°C outside! ;)
The data is out there - take the time to crunch the numbers before opining at some length.
Keep an eye on this one, as we may be adding an APM to the next launch, (if we can get the hardware all setup in time.)
iHAB - Iowa High Altitude Balloon Project
http://www.ihabproject.com/
I think you all are forgetting about the temperatures at that altitude - a plane flying at 10KM experiences temperatures of -30F, and temperatures at an altitude even higher than that are going to get lower and lower. I think there's a good chance your battery will blow due to the temperatures or something else.
You guys would probably need a much tougher plane for this or a container to hold the plane on its freefall until it hits warmer temperatures and a less hazardous environment.
Please do continue with this idea - I am very interested in how it will work! Good luck!
APM can operate as far away as the battery can last. As far as failsafes I believe the only one that cannot be removed is the hardware failsafe channel (Ch8) which allows manual control whatever the circumstances (needs to be in range of transmitter though).
Recommended planes for APM are Easystars because they fly really well thanks to wing loading. An experienced pilot could stick it in almost anything. As for payload calculations you may wish to use my spreadsheet to help you (although the values will need to be changed for your purpose).
As I have often fantasized about doing this (even got a model for it) there are several major problems.
What model to use?
Gliders (low wing loading craft) are useless as the wing will be torn off within 20 seconds of release thanks to hitting 150+mph on the way down. Flying wings are the right idea but still have wing loadings to high for the rather fast descent so modifying them to be much like the space shuttle (a gliding brick) will help survive and maintain attitude but gliding capabilities will be much less. The Skyfun IMO is no where near brick-like enough.
Autopilot calibration
APM initialises the system on power up, this includes gyros, accelerometers, magnetometer, GPS, barometer and airspeed. Doing it this way usually means that the system is in a cradle, on a lap or being held so will be flat and level. You can do this at one of two points: before launch or after release. If you do it before launch you must have the battery capacity to cope with a couple of hours (at least) flight time. If you do it up there it won't be level even if you wait until the is enough air for you to glide properly. My idea (and design) was to accommodate thermopiles into the IMU setup as well as all the rest and have a staggered initialisation after release with the thermopiles taking control of the descent into better air then hitting level flight and calibrating the other sensors (I know it would be perfect for them) and then using a mix of sensors to continue guidance. Guidance would then be from release all the way down and battery power could be cut back.
Protection from the "elements"
In the launch (usually a lovely clear day) you get little rain if any and some gentle gusts but not once you get higher. Lack of atmosphere has cooked many attempts, high winds has battered and broken some, resultant quick cooling has broken cameras so no pictures are recovered. Foam is excellent insulator but when the heat rises make sure the is enough air space to have some circulation to help. Electronic sensors rarely need room so seal them as best as possible. I would attempt to solve your model choice and protection ideas into one by moulding the model from scratch with parts fitted ready and then adding a big block for the controller parts.
Sorry if I've waffled and just raised things you already knew but its always worth saying something just incase.
IMO the Skyfun is limited by the location of the payload bay and keeping the CoG in an efficient (and flyable) location. I would imagine 350g of payload + control system in the existing volume would make the Skyfun a bit of a handful. Hence my decision to start a clean-sheet airframe design project.
From my calcs, it should be possible to get an aircraft to fly at 20km altitude, although it will be moving at quite a rate of knots. I am limiting my design parameters to M0.8 and ensuring my stall speed is well within this range, so some form of flight control should be achieveable within 1000' of release.
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