Comment by UFO-MAN on August 11, 2009 at 12:40pm

You could connect more than one balloon together to increase lift. I would use a servo operated release mechanism other than counting on all three balloons bursting at the same time (which is unlikely to happen).

You could use baloons designed for radiosondes and helium. That can be readily purchased on the net.

The electronics and power sources need to be thermally insulated. Any battery taken to flight level 200 will have to be severely derated in terms of available capacity.

However, before you attempt to launch something like this, I would strongly advice you to get approval from the air traffic control center that is responsible for your area. In addition a NOTAM (notice to airmen) needs to be issued in advance. You also need to file an expected flight trajectory.

Good luck. Post any progress!

UFO_MAN

Comment by ernani reis on August 11, 2009 at 2:12pm

I think they have a CAA weight limit. Is it for the Vulture thing? I suggest that you wait as much as possible to open the parachute, paragliders are very slow, and you can drift out of control with a light wind, let alone a 20.000ft wind. I have had a good experience with the uflyrc.com sail, is very maneuverable, but very slow (they all are slow, the uflyrc.com is particularly maneuverable). should handle your 1,5kg (I would redo the strings, though). My gondola with ardupilot, receiver, battery, motor, power supplies and logger weight about 600g. I am still working on a passable control law, mine is barely under control right now - nothing I would send 7.000m high and out of sight.

Comment by Ed on August 12, 2009 at 1:05am

I don't think you will have any luck with trying to fly a parafoil at 100,000ft, because of a phenomenon called 'Added Mass' - when calculating the CoG and thus stability of a parafoil, which is usually somewhere in the rigging between the foil and the payload, you also include the mass of the air that is being accelerated by the parafoil at that time. At 100,000ft, there is barely any air mass to be accelerated, so the CoG shifts right back down towards the payload, greatly reducing the Moments of Inertia in the axes you care about, and leading to instability and collapsing parafoils. As others have said, if you want a parafoil, open it low.

You have a big project here, with a lot of material to cover. Parafoils are harder to control that fixed-wing aeroplanes because the flight control surfaces are not rigidly coupled to the payload, where you inertial/attitude sensors are - so your feedback does not represent the true state of the system. You have a bunch of annoying n'th order relationships between the two, and nothing linearises particularly well. The are some simple-ish tricks though to help you, like making turning stability control a function of bank angle rather than turn rate.

1.5kg is certainly possible. I would start by getting an off the shelf kit, as ernani reis has done, and get that under control. Then maybe try a dumb weather balloon experiment - a payload in a box with a pre-deployed parachute (check my homepage) will teach you a lot.

Best of luck with this, and keep us posted.

Ed
http://www.cuspaceflight.co.uk

Comment by JvdB on August 12, 2009 at 4:02am

This is what I use for a staged recovery: RDAS - http://www.aedelectronics.nl/rdas/tiny.htm For example it detects apogee to deploy a small drogue or release it from the baloon. Especially help full if you use several baloons for a heavier payload as they want pop at the same time. Then at a set altitude it deploys / releases the main parachute.

I have set myself the same challange using a ram parachute but not using a baloon but a rocket to get up to great heights. I'm only taking small steps at a time. First of all I want to get an easystar up and running (almost there) as this is a proven concept. After that I will try to adjust it to a paraglider.

www.verticallimits.nl - under the projects page, work in progress

Comment by UFO-MAN on August 12, 2009 at 6:11am

Since you speak about parachutes: where do I purchase parachutes? I need one for my UAV project, and find it hard to find serious suppliers. Need: Approx 3m diameter or maybe even larger. I plan to recover by parachute instead of by landing the small UAV normally.

UFO_MAN

Comment by Connor on August 12, 2009 at 6:58am

I'm plaining on making my own parachute. Been looking at some designs and i think its just easyer to make one rather then try to find the right one online. Hoping to test my first chute by next weekend i'll let you know how it goes.

Comment by ernani reis on August 12, 2009 at 12:28pm

If that is so, make sure to look at the Leonardo design, I haven´t tried, but it certainly looks good. The ufly seems to be a lot more maneuverable. Getting the string lengths right is obscenely tedious, to say the least, I tried and gave up.
http://www.youtube.com/watch?v=HFFpjSWMqPs

Comment by Ed on August 12, 2009 at 12:45pm

UFO-MAN: Try Aerocon Systems in the US. They've a nice range or surplus stuff.

Maybe elaborate a bit on your requirements for the parachute too, as that affects the design - drag vs stability, deployment speed and peak opening force, and so on. As a rule of thumb, Cross-form parachutes are almost as stable as 'stable' parachutes like ring-slots, but also an order of magnitude easier to manufacture. Constructing, by hand, a ~3m diameter ring-slot parachute is a bit of a tedious, thankless job.

There are some good books on the subject of parachute design - Knacke being generally the bible (Available from Aerocon), although the state of play has changed a little since it was written, and there are some incorrect parts. It should still be on your shelf though :)

Comment by Connor on August 14, 2009 at 3:31am

Thats a really good site. The chutes are fairly cheep to.

Comment by Andy Geppert on October 21, 2009 at 12:19am

Do any of you guys have links to anyone else who is actively pursuing or recently pursued the goal of a high altitude balloon launched glider? I have in mind a similar goal. I think one of the biggest attractions to this project for me is that it is a combination of all the technical stuff I like, and it is a gigantic "systems" sort of nut to crack.

Comment

• ‹ Previous
• 1
• 2
• Next ›
• Page