Hi All:
Here is what I would like to do. I want to make a large (6-ft span) autonomous plane that is powered by solar cells when available and has a 2 hour flight time under the backup battery power. My goal is to be able to have a platform that I can fly ANYWHERE in North America while take high quality photos and videos.

My plan is to have a solar powered platform with a large battery. When the battery becomes depleted the plane would land in a small pond (it would have to be a water plane) in some remote location. It would then re-charge it's batteries or wait until the sun re-appears (it would be capable of maintaining level flight using solar cells alone, the batteries would just be backup).

At any rate, I would need some way of controlling this thing, and that's where my question comes in. I simply can't restrict myself to LOS control if I want to fly really long distances, so I was thinking about using a smartphone to handle all the control logic and GPS way-point navigation details. I don't know much about USB driver programming, or whether this is the way to go, but I would need some way of controlling servos from the android platform.

What would be the best way to do this? It seems like USB control would be really complicated. Perhaps a better alternative is to write some application that uses the blue-tooth capability of the phone to communicate with custom-made servos remotely (I'm assuming both are 2.4 GHz here?). What do you guys think?

I know that this is a quite audacious project, but it won't be the first time I've been in way over my head.

Please let me know what you guys think and whether or not you think such a control platform is realizable.

Thanks,
John

Relatively speaking in software/hardware it's easy to make something do what you want it to do......the hard part is stopping it doing what you don't want it to do.

So, your idea can be done, but, and it's a BIG but...............

Ian.

... and with the FAA watching us very closely right now, keep to LOS!!! We don't need to be our own worst enemies.

How do you plan to see and avoid other air traffic when you're BVR? Remember - most air traffic has PEOPLE in it. A large model could easily bring down a small GA plane, perhaps larger ones as well depending on where it hits. AMA won't cover you, and you'll have a awful lot of angry modelers around.

Andy

I dont think it is possible until you solve this tiny part of the problem;

"it would be capable of maintaining level flight using solar cells alone, the batteries would just be backup"

Which for what you are suggesting has not, as far as I am aware, been achived using current solar cell technology.

Originally Posted by FLY...Please

My plan is to have a solar powered platform with a large battery. When the battery becomes depleted the plane would land in a small pond (it would have to be a water plane) in some remote location.

Ummmm

How is this going to work;

Autonomous plane somehow selects a small pond in some remote location, lands automatically, stays in one place in the small pond (so it does not get caught in weeds and trees etc) waits several hours or days till the battery is charged, works out what to do about the wind, and takes off again.

Originally Posted by AndyKunz

... and with the FAA watching us very closely right now, keep to LOS!!! We don't need to be our own worst enemies.

How do you plan to see and avoid other air traffic when you're BVR? Remember - most air traffic has PEOPLE in it. A large model could easily bring down a small GA plane, perhaps larger ones as well depending on where it hits. AMA won't cover you, and you'll have a awful lot of angry modelers around.

Andy

I wasn't going to say anything.

As far as solar is concerned, I think the only practical way to do it is with the newer flexible photovoltaic materials that are stupid expensive and impossible to obtain. They are lighter and have a decent output so you could skin the wing in them. It would also need to be a very large glider to carry the weight and work on very little thrust. The good thing is that the larger the aircraft, the more area for energy generation. The bad thing is that you would require more motor and prop with bigger aircraft and I'm not sure where the break even point will be.

... and with the FAA watching us very closely right now, keep to LOS!!! We don't need to be our own worst enemies.

How do you plan to see and avoid other air traffic when you're BVR? Remember - most air traffic has PEOPLE in it. A large model could easily bring down a small GA plane, perhaps larger ones as well depending on where it hits. AMA won't cover you, and you'll have a awful lot of angry modelers around.

Andy

This is a very good point. I definitely thought about this, but the best thing I can think of is to wait it out. I didn't know all this FAA stuff was going on until yesterday, after I posted this. This project would be a substantial undertaking, and would take several years. So hopefully by then the FAA will have some (not too stringent) protocol for small UAVs.

Ummmm

How is this going to work;

Autonomous plane somehow selects a small pond in some remote location, lands automatically, stays in one place in the small pond (so it does not get caught in weeds and trees etc) waits several hours or days till the battery is charged, works out what to do about the wind, and takes off again.

I dont think it is possible until you solve this tiny part of the problem;

"it would be capable of maintaining level flight using solar cells alone, the batteries would just be backup"

Which for what you are suggesting has not, as far as I am aware, been achived using current solar cell technology.

I didn't say it was going to be easy, but I diffidently think it's doable. Not cheap, but if designed correctly, diffidently possible. Like village_idiot said, very thin photovoltaic cells would need to be used, and would cover all the lifting surfaces (which would be on the order of 5-10 feet^2).

For example, some cells from Farnell are 6x20mm, 70mg in weight, and provide 40mA @ .6V. If we have a wing/horizontal tail area of 5 ft^2, this works out to 92 watts of power at a weight of 270 grams.

Originally Posted by FLY...Please

For example, some cells from Farnell are 6x20mm, 70mg in weight, and provide 40mA @ .6V. If we have a wing/horizontal tail area of 5 ft^2, this works out to 92 watts of power at a weight of 270 grams.

Well if you can sort out the auto pilot bit, selecting a landing site, get a job with NASA that the sort of thing they need for landing probes.

Got a link for the photocells at Farnell ?

With GPS the job is a lot easier, remember that things on other planets do not have that nice navigation system to tell you how high you are or how fast you are falling. Even with GPS and well programmed maps it is certainly an extremely difficult task, if it was easy we would have all sort of military autonomous machines cruising around and they would be cheap to manufacture.

Yes I think an android phone would be a good choice for the "brain" for this project. It would give you GPS and communication back to you. I assume you are preselecting the landing site(s) and programming it in, rather than trying to have it find one.

For the connectivity between the android device and your servos - maybe look at writing software that generates the PPM signal, and send that from the audio port directly into your receiver? Bypassing the part of the receiver that actually decodes the RF signal. From my understanding, the receiver decodes the RF signal, then it uses the PPM signal, which is basically or very similar to an audio signal. You want to inject your own PPM into the receiver, so it then breaks out the channels and sends them to the servos.

If that is too difficult you could just drive a spektrum TX module with your PPM signal, which would then transmit it to a spektrum receiver sitting right next to it. Kind of inefficient but it would work.

Here is a similar project for iPhone/ipod: http://www.lib.aero/iphly/

I thing Alishanmao's videos may help you with the auto pilot "problem". That's the link:

http://www.youtube.com/results?q=ali..._all&uploaded=

I think you need to spend some time in the UAV forum. This is not an electronics question..
..a