Self-retrieving High Altitude Experimental Glider
Good day to all, Im new here in this great forum, been reading the previous posts, blogs and articles for a while now, and they are extremely useful for a UAV Newbie like me.
Im currently doing a project at college, and I need your help.
First things first; the aim of the project is to collect weather data from high altitude and retrieve the instruments/data back to launching point safely. This will be done via an UAV attached to a weather balloon that will descend up to a certain altitude and cut itself free and glide back to Launching position. Data collected will be via temperature sensors and camera taking picture of the horizon (hopefully)
After surfing the internet I found only one similar project (done from 7 years ago):
http://www.members.shaw.ca/sonde/index.htm
As design and aerodynamics is not exactly my field, I need your help in designing the high altitude glider/plane.
More details:
1.Equipment Loaded:
•Receiver, servos, battery, all Ardupilot stuff and Xbee.(didn’t buy them yet so you tell me how much they weigh??)
•Servos(super sub-micro 6g each)
2.Payload(on plane):
•Parachute (~170 g)
•Digital Camera(~500g)
•Sensors(~100 g)
3.Balloon Payload: the total weight of the whole setup shouldn’t be more than 3kg, preferably <2.7kg.
4.Range and altitude:
•Range: most probably it will travel +/-10km horizontally.
•How high: targeting 10-15km above sea level.
5.Speed: Doesn’t matter for me as long as it is stable.
6.Launching area/terrain: a Soccer Field or desert
7.Launching technique/method:
•Using a silicon rubber bungee cord or Hand launching (for the testing phase).
•Attach it to a Helium Balloon and let go of balloon at certain altitude.
8.Control system: RC (on takeoff and landing) and Ardupilot, but I will discus that on the Ardupilot forum as I have some questions about it.
9.Engine: I don’t want to use an engine (more weight; engine and battery) but will I need it any ways? Maybe while testing!
10.Rescue system: Parachute opens at a certain altitude; for smooth landing (max landing speed: 5m/s)
11.Material available for construction:
•Balsa wood
•Foam(dense and normal)
•High strength unidirectional Carbon Fiber (density=1.78g/cm^3, thickness=0.12mm).
12.What I think might be a good design:
•(I think) I want to build something made up from balsa wood/foam and carbon fiber, to be light and endure the high vibration and flexing of the wings at high altitudes.
•Is something like this is good? (Enough space for everything, but way too heavy).
http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8344...(102in)_ARF
http://royal-model.sweb.cz/b4.htm
http://www.rebelflyingclub.com/photos/RFC/gliders/2003-08-00/jasons...
•Should I go with a T shaped or a V shaped tail?
•Should I go with a Rudder, flaps and Ailerons
•Looking for previous designs, plans and advice.
Waiting for you replies
Regards
Fakahany,
Im currently doing a project at college, and I need your help.
First things first; the aim of the project is to collect weather data from high altitude and retrieve the instruments/data back to launching point safely. This will be done via an UAV attached to a weather balloon that will descend up to a certain altitude and cut itself free and glide back to Launching position. Data collected will be via temperature sensors and camera taking picture of the horizon (hopefully)
After surfing the internet I found only one similar project (done from 7 years ago):
http://www.members.shaw.ca/sonde/index.htm
As design and aerodynamics is not exactly my field, I need your help in designing the high altitude glider/plane.
More details:
1.Equipment Loaded:
•Receiver, servos, battery, all Ardupilot stuff and Xbee.(didn’t buy them yet so you tell me how much they weigh??)
•Servos(super sub-micro 6g each)
2.Payload(on plane):
•Parachute (~170 g)
•Digital Camera(~500g)
•Sensors(~100 g)
3.Balloon Payload: the total weight of the whole setup shouldn’t be more than 3kg, preferably <2.7kg.
4.Range and altitude:
•Range: most probably it will travel +/-10km horizontally.
•How high: targeting 10-15km above sea level.
5.Speed: Doesn’t matter for me as long as it is stable.
6.Launching area/terrain: a Soccer Field or desert
7.Launching technique/method:
•Using a silicon rubber bungee cord or Hand launching (for the testing phase).
•Attach it to a Helium Balloon and let go of balloon at certain altitude.
8.Control system: RC (on takeoff and landing) and Ardupilot, but I will discus that on the Ardupilot forum as I have some questions about it.
9.Engine: I don’t want to use an engine (more weight; engine and battery) but will I need it any ways? Maybe while testing!
10.Rescue system: Parachute opens at a certain altitude; for smooth landing (max landing speed: 5m/s)
11.Material available for construction:
•Balsa wood
•Foam(dense and normal)
•High strength unidirectional Carbon Fiber (density=1.78g/cm^3, thickness=0.12mm).
12.What I think might be a good design:
•(I think) I want to build something made up from balsa wood/foam and carbon fiber, to be light and endure the high vibration and flexing of the wings at high altitudes.
•Is something like this is good? (Enough space for everything, but way too heavy).
http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8344...(102in)_ARF
http://royal-model.sweb.cz/b4.htm
http://www.rebelflyingclub.com/photos/RFC/gliders/2003-08-00/jasons...
•Should I go with a T shaped or a V shaped tail?
•Should I go with a Rudder, flaps and Ailerons
•Looking for previous designs, plans and advice.
Waiting for you replies
Regards
Fakahany,
Replies to This Discussion
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Permalink Reply by Morli on -
Hi Fakahany,
I think with current setup, the flaps may not of great help at least in AP mode however if you are planning to go for manual landing once you have sighted the glider( paint it bright orange or some similar color for high visibility) , then it will. D1000 is great looking glider but not much of space inside the fuselage from what I can see( i have been looking at Ventus but don't know much about that either :) )
There is atleast one flying wing design in this forum which has/is being tested for AP found here & looks promising for ur requirement ,. BTW T tail with proper rudder and elevator seems better choice but wait until u hear from others. I am late bird. good luck
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Permalink Reply by mo fakahany on -
Hi Morli,
I will definitely check out that flying wing. you didn’t mention ailerons as I think it is important to keep the glider from rolling.
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Permalink Reply by Doug Weibel on -
The release altitudes you are talking about make this a non-trivial project. I an not an aerodynamics expert, but there are airframe issues to be addressed at 15000 meters. Suffice it to say that the air is very thin up there and there are aerodynamic issues when indicated airspeed (airspeed adjusted for reduced density) and true airspeed diverge.
Also it is very cold up there, and your instrument package and autopilot and control system will need to be capable of functioning at very low temperatures.
Finally, the two gliders you provide links for have good gliding performance. You may want to rethink that. If the glider has a low sink rate (ie. is a good glider) it will take a very long time to come down from 15000 meters (assuming it didn't break up due to aerodynamic issues).
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Permalink Reply by Morli on
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I agree with Doug on this , the main issue is cold temp more than any thing else, there are more chances of your instrument package failing then the airframe.The paracute release machanism is weak link which I know will fail if not taking in account 15K altitude . I still think the glider has( with the budget ) has better chance unless ur sponsered by NASA , Since you are going to be gliding down you won't need powered popultion unless you mess up. The strong delta wing might help only if you are in hurry to land which I doubt and does not have my vote. Hey you can wait for hours for baloon to assent , you can wait for few more to have safe landing. After all this was hobby project, where is the fun if u were to spend 100K on tested technology :)))). What is the worst that can happen? loosing 150$ glider??? + few 100$ on other stuff?:)! I wish I get to try these things without other legal issues :( , if your planning for telemetry, a simple down facing patch antenna ( copper foil is all you need) , need any help with that , let me know. good luck
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Permalink Reply by mo fakahany on
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Definitely I need your help on that... But that comes after the design milestone is finished.... thank you for the offer ...I will send you a msg when we come to that point
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Permalink Reply by mo fakahany on
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This is very true, up there at that height, g forces after dropping is really high, around 7-9g’s . So the wing should be designed to withstand those forces. That’s why I think that carbon fiber or fiberglass will do the trick!
the cold weather up there: In helium balloons people tend to insulate everything and rap the servos, circuit and camera in foam. But cold weather is not the real problem ...the problem is the moisture up there. that’s why the casing should be insulated.
The gliding time doeant matter for me! .. important if it didnt glid properly it will end up landing before the launching area .. it is better to make it pass over the launch area and descend in loops or so.
Through reading I know that there's two types of gliders: 1. one that glides the furthest 2. that stays on air the most... I guess the first option suits me the best..
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Permalink Reply by Krzysztof Bosak on -
'g forces after dropping is really high, around 7-9g’s'
F=GMm/r^2, a=GM/r^2, R0 at equator =6370km, at 15km r=R0+15=6385, so g(at 15km) is (6370/6385)^2=99.5% of G at the equator.
so it is actually easier.
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Permalink Reply by mo fakahany on
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what you are saying makes sense to me but check the second paragraph and graph here:
http://www.members.shaw.ca/sonde/digest_2.htm
any clue why the readings are high?
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Permalink Reply by Andrus Kangro on -
Their plane probably attempted to change pitch too fast, thats why there were G's.
Please also note, their glider "Cruise airspeed was 230 kph (125 kts) or more." (fly4)
and
"The glider's true air speed was only a little above the wind speed," (fly3)
If you fly that fast while being heavy, then you need to be very gentle with your moves.
"5) After the wings were leveled, the great amount of speed built up (200 kts or so at 24,000 feet ASL)..." - Yikes, this is fast and although air is thin, centrifugal forces still apply.
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Permalink Reply by Krzysztof Bosak on
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There are also peaks from parachute deployment.
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Permalink Reply by bGatti on -
A friend and I discussed this project in the early 90's - I went as far as building a crude prototype.
Since you indicate a parachute, the idea clearly is to fire the parachute when you are low and near the target landing site.
I would recommend you support multiple potential landing sites, with some decision tree as to which one to target.
You don't need an engine, and you don't need much of an airframe - or fancy airfoils. Mine was modeled after the space shuttle (simple delta wing).
I think you should avoid carbon fiber - you're only hope of using this thing is to convince the relevant FAA that it will not cause indigestion in captain Scully's next misadventure.
You only need a rudder - the airframe should be self-stabilizing - and I think a long way from a glider - which is designed to stay -up- as long as possible. What you want is the loser of airframes - like the space shuttle, which is a flying brick - or more precisely an airframe meant for controlled descent.
My airframe was a cardboard packing tube with a foam triangle wing. Keep the weight forward and low, provide fixed up-elevator, and it should fly down and stable with no problems. I used spray foam to create a soft, safe nose cone, and I had a disposable airframe. The up-elevators will limit terminal velocity. I suggest a long foil streamer for visibility.
You may not need a parachute, if our terminal velocity is survivable. As you are not so concerned about time aloft and aerodynamic constraints, you may find that a large foam nosecone is easier to manage then a parachute mechanism.
Essentially you will be backtracking through the wind until you get over launch position, then spiral down at terminal velocity. As the plane speeds up, the pressure on the elevators will lift the nose, slowing the vertical drop rate, and slowing the forward airspeed; as the airspeed drops, the elevator pressure will relax and the forward position of the weight will pull the nose down, increasing the forward and down speed. The angle and size of the elevators will establish the stable speed.
In high winds, it would be better to have a down-wind landing site pre-programmed.
Oh - and this is an imaginary product, because the FAA (along with the FDA, and the FCC) are doing everything in their power to see the US fail in any new technical economy. - so here's hoping you live outside the jurisdiction of the United F's of America.
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Permalink Reply by mo fakahany on
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In my opinion ailerons is a must, we must have a method of stabilizing the glider/plane if it rolls.
That’s exactly what happened in there first launch (the site I included earlier)
Quoted from (http://members.shaw.ca/sonde/launch_1.htm)
“By the time of this launch, it was obvious that the best direction for a design that would be able to reliably meet the original (very high) altitude goal would be to aileron/roll control using a rate-command and roll-gyro system.”
so I think the ailerons, elevators(pitch control; you don’t want the glider to dive down or stall and a rudder(I think we can go with no rudder, but the more control you have the better) should be included in the glider.
A glider or something else?
I think gliders with 12:1 gliding ration will best suit the needs. As I don’t want to be diving down with high speed (time doesn’t matter) and landing before the target. It is better to have something that will have a smooth glide and if it passes the launching point it will turn and make few loops before opening the shoot or manually RC controlled landing. Did you get my point? what do you think all?
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