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ModeratorPermalink Reply by Morli on November 22, 2009 at 6:58pm

Thanks Gatti for the explanation, i take your word for it , yes I agree it must be more of a regulatory challenge after reading this story, I got carried away by the topic head line :).
I am almost sure that any decent high altitude( did you mean 15Km high or 15k baud rate for data transmission) experiment would have data telemetry package involved , 1 W packet/data modem I think can effectively send back data using packet protocols or any proprietary digital protocols . or how else could you safe guard the experiment data in case of payload loss and of course tracking assist. Just out of curiosity , is there other backup method to recover/ receive data that is gained in V.high altitude experiments ? I can only guess. Thank once again.

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Permalink Reply by bGatti on November 23, 2009 at 2:19pm

Assuming this is a modification of an existing weather balloon payload, the data systems are already in place. Image data would be more of a challenge, as the current baud rate is quite probably insufficient.

One way to extend range would be to chase the first balloon with a second repeater.
If you time it right, the second balloon would be neatly half way between the ground station and the first at the apex.

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Permalink Reply by bGatti on November 22, 2009 at 4:24pm

I might start with a standard rocket kit.
You would get a fuselage, a nosecone, and a parachute.
Add a pair of short dihedral wings, and control surfaces.

If your payload weight is always the same, You can probably fix your airspeed by using fixed elevators, if the weight changes, you might be better of with an airspeed indicator and elevators (elevons) to control airspeed.

If you chose to use a glider, then your risk of catastrophic wing failure is much higher than necessary. Any high rate of descent will have the ability to reach a high airspeed and easily fold a wing (been there done that). A Flatspin option would be difficult to attain using an autopilot, as I don't know of any device which has ever controlled a flat spin (could be wrong here) - plus, you lose the ability to recover your launch position during the spin.

The standard approach is a fairly large circle over the landing site - once you reach it.

Good luck - let us know how you get on...

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ModeratorPermalink Reply by Morli on November 23, 2009 at 5:14pm

Hi Mo ,
looking around for more info on the subject , found this project site with projects in 2008 site which i thought might be useful for you. click here and look @ menu on the left for more details. Solution for cold temp failure is here
Mission summariers are here

@ Gatti , good idea for airborne repeater. :)

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ModeratorPermalink Reply by Morli on November 23, 2009 at 6:08pm

One of Yahoo discussion forum on high altitude ballooning is here

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Permalink Reply by Martin Geldart on December 4, 2009 at 4:00pm

I found some interesting articles relating to this subject. I too am in design stages of high altitude flyer, which is dropped from a weather balloon. My interests are at a higher altitude, from when the helium weather balloon explodes, maybe 90,000 feet. Then I hope for my high-altitude designed craft, to glide home safely, using autonomous navigational instruments.

I read and learnt a lot from MIT's $150 sub-orbital photographs project, using a weather balloon, a parachute, a foam beer cooler, a camera, a mobile phone, fisherman's hand warmers and a mobile tracker system. The camera was programmed to shoot at 1/8000 sec shutter, every second and the fun thing was, they retrieved it.

I cannot find the exact link, but these guys replicated MIT's project for $250 and completed their mission too, check the link:

http://www.youtube.com/watch?v=v2XJUnkkXSU

For high altitude flights, temperature is a great concern, especially when you have a flying machine, rather than a falling beer cooler with a parachute. You need your equipment not only to stay alive but too work at optimum conditions, for speed, accuracy and without much latency, plus other factors. MIT in their project, wrapped their equipment in fisherman's hand warmers, which survived at 93,000 feet, so I'm sure you can think of a good idea that won't cause you problems at your lower desired altitude. You could insulate your payload area and recycle any warm air created by batteries or motors to your payload area too. Find someone with a large chest food freezer, drop your fuselage in their for 6 hours and see if your payload lives through it.

Another interesting article/product was the GPS Boomerang. This a commercial product, available today, which is exactly the same as the project you are trying to accomplish. It's a small high-altitude craft, with aerodynamics and materials to suit and is filled with weather instruments. Check it out:

http://www.gpsboomerang.com/

You may want to look at Boeing's Halo, high-altitude cruiser which uses hydrogen fuel cells to power it. Interesting. Check it out here:

http://envirofuel.com.au/2007/10/27/boeing-tests-a-ford-hydrogen-en...

Hope I haven't repeated any information on this post. Enjoy.

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Permalink Reply by Martin Geldart on December 4, 2009 at 10:50pm

Going back a post or two, mentioned was the drifting or jet streams issues.

Is it not possible to have written in to your program, a function that releases the balloon catch at?

a) Your desired height using your altitude sensor.

b) A calculated, safe RTF distance (altitude against RTH distance and GPS location).

Maybe set an altitude of 30,000 feet and a large diameter waypoint circle boundary. If the plane and balloon exceed this given altitude or drift past the boundary coordinates, then release the plane....

Also, could inputted wind direction, payload weight and wind speed possibly be calculated in the code to get a safe drop time/location? To get the approximate drift.

If these conditions fail then the aircraft is released from the balloon as a fail-safe.

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Permalink Reply by marshall scholz on September 26, 2010 at 7:30pm

instead of a plane / glider you could probably go with a paraglider which solves alot of problems with this type of setup.
here is a parafoil that would probably meet your needs and is cheap: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...

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Permalink Reply by Roberto Hawkowski on December 4, 2010 at 9:51am

Does any body made an autonomous motorized paraglider using "HobbyKing Paraglider Parafoil 2.15m" ?

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Permalink Reply by tuckerobie on December 4, 2011 at 10:07am

I am currently working on a project just like this and had considered a paraglider. The problem that I came up with was the sway of your vehicle under the airfoil and averaging it to get usable sensor data... with your sensors swinging it could be tough.

Tucker

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