Posted by mo fakahany on November 19, 2009 at 12:40pm
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.htmAs 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 desert7.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&Product_Name=DG-1000_Fibreglass_Glider_2.63M__(102in)_ARFhttp://royal-model.sweb.cz/b4.htmhttp://www.rebelflyingclub.com/photos/RFC/gliders/2003-08-00/jasons_applause.jpg•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 repliesRegardsFakahany,
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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.
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.
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:
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:
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
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.
Hi @ Gati, Tom
That was interesting to read and I see some merits to it with my very limited knowledge of such project. There are however few things that poped up in my mind, no disrespect but both your example( roc ket/ mis sile and Tom's( bom) were never expected to be recovered undamaged/ reusable with payload inside once the mission
(self dest ruct/inflict dam age to the target etc ) is complete :) keeping in mind the terminal velocity, well there is always drag suite and parachute recovery system etc but it will be whole different point of view and issues.
1. What happens when the wind speed is say 75 km/hr for last 2 or more hours of assent assuming it was total of 4+ hours travel? What happens if and when balloon hits the jet stream in upper atmosphere.? Be what ever glide ratio and speeds , will the recovery vehicle make it back to launch site ?
2. when did the project objective change from being safe and successful recovery of payload to high speed impact at launch/target site , coming to that where ever did I hear or read about one of the objective of such high altitude experiment is the get/ land the recovery vehicle on the launch site?!!! , The recovery teams usually track & chase the recovery vehicle with some sort APRS or some form position reporting system or becon with RDF technique is what I have read most of the time.
AP and other form of stabilization in this platform will probably be considered as secondary payload & will be useful for return/recovery journey only. keeping that in mind I do see and agree to the point that battery capacity for such payload recovery vehicle will of concern and a faster return home will be better idea but since it is not expected to land back at launch site does away with any propulsion power requirement( glide and gravity being key) and so to whole of available power capacity is used to run AP stabilization to some decency , logging, photography , position reporting system etc.
Or did I miss the big picture? Thanks any way for making me understand the usfulness of delta wing recovery vehicle over a glider.
Hi, I think that this similar project you referenced provides quite a lot of valuable information. I would assume that main concern is cold (below -40 degrees/celsius) and very high winds up there, so you may want to look into airframe design that flies very fast and may even be more similar to jet than to glider. If you go with glider design, then it may be good to seriously clip its wings at least. If you land with parachute, then high landing speed is not an issue.
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.
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).
Replies
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
here is a parafoil that would probably meet your needs and is cheap: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...
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.
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:
https://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.
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. :)
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...
That was interesting to read and I see some merits to it with my very limited knowledge of such project. There are however few things that poped up in my mind, no disrespect but both your example( roc ket/ mis sile and Tom's( bom) were never expected to be recovered undamaged/ reusable with payload inside once the mission
(self dest ruct/inflict dam age to the target etc ) is complete :) keeping in mind the terminal velocity, well there is always drag suite and parachute recovery system etc but it will be whole different point of view and issues.
1. What happens when the wind speed is say 75 km/hr for last 2 or more hours of assent assuming it was total of 4+ hours travel? What happens if and when balloon hits the jet stream in upper atmosphere.? Be what ever glide ratio and speeds , will the recovery vehicle make it back to launch site ?
2. when did the project objective change from being safe and successful recovery of payload to high speed impact at launch/target site , coming to that where ever did I hear or read about one of the objective of such high altitude experiment is the get/ land the recovery vehicle on the launch site?!!! , The recovery teams usually track & chase the recovery vehicle with some sort APRS or some form position reporting system or becon with RDF technique is what I have read most of the time.
AP and other form of stabilization in this platform will probably be considered as secondary payload & will be useful for return/recovery journey only. keeping that in mind I do see and agree to the point that battery capacity for such payload recovery vehicle will of concern and a faster return home will be better idea but since it is not expected to land back at launch site does away with any propulsion power requirement( glide and gravity being key) and so to whole of available power capacity is used to run AP stabilization to some decency , logging, photography , position reporting system etc.
Or did I miss the big picture? Thanks any way for making me understand the usfulness of delta wing recovery vehicle over a glider.
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.
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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