Autonomous airplane project

I seriously doubt this plane is going to carry even 6 ounces, and even if it does, it's unlikely that the standard battery would give you anywhere near 10 minutes. With a bigger motor and stronger battery, it might carry 6 ounces, but I still doubt you would see very long flight times, since the stronger battery will also weigh more. Oh yeah, don't you also need batteries (weight) for your electronics? If the voltages are compatible, you can probably run them off the planes battery, but the current draw will shorten your run a bit, and who knows what kind of interference you may get when you start interconnecting the systems. I think you still need more plane, unless you can perhaps find a location with good slope lift, and can fulfill your mission whilst keeping the plane in or near the source of the slope lift.

Small RC models are pretty weight-critical, and 6 ounces is 25% of the weight of this plane with battery. The location of the weight will also be critical. Very far from the CG and it will either fly like a dog, or simplly crash. I don't know how large your pc boards are, but there isn't much spare room in this plane.

Bob

On 25 Oct 2006 14:04:08 -0700, "NathanielC" wrote in :

Here is the link I didn't have time to search for this morning:

Glider-like construction.

Specifications Length 4 feet Wing span 8 feet Weight 6 lbsx Engine displacement 0.15 cu in Fuel tank 6 oz Altitude Up to 2200 feet in Canada Flight time / 160 acres 20 minutes Camera Pentax Optio S5i

You probably need a larger payload--a roomier bay, at least--and a larger wing & engine to go with it.

You might get some of your students to check out all of the links people have given you and start sorting out the various options you have.

If you or some of your staff have time, you can cut some dollar costs by learning to build planes yourself.

If you're not going to buy off-the-shelf GPS/autopilot hardware, you'll have to do some proof-of-concept flights to make sure that your system works.

As someone said in another post, performing the takeoff and landing with a standard TX, then turning the system over to its autopilot for the mission will simplify a lot of your headaches. Stuff happens pretty quickly in both of those phases of flight, especially if you have a crosswind or turbulence. Humans learn to handle those situations moderately swiftly. Training machines to have the same skills seems to me like a fairly hard task and not central to what you hope to do.

The downside, such as it is, is that you will have to have a more-or-less permanent person or group of people you can count on to do your takeoffs and landings for your various projects.

If I lived closer to you, I'd volunteer in a heartbeat. It sounds like a lot of fun. You may find other RC pilots in your area through the AMA who would be willing to volunteer as well.

Marty

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On 25 Oct 2006 15:10:35 -0700, "NathanielC" wrote in :

Buy one, LEARN HOW TO FLY IT, then strap 6 oz. of lead on it, and see what it does. It may be all you need for your computer engineering project at present.

You can't trust that your first iteration of flight software is going to be reliable, so you need to have a dual-control system with someone on a transmitter who can take over from your autopilot if something goes wrong. You need to budget for both control systems onboard.

"One observation is worth ten thousand expert opinions."

Go out to a flying field and see what people are flying.

Ask about the electric gurus in your neighborhood. It's pretty amazing what people are doing with electrics nowadays.

That's OK for starters.

For carrying payloads to test them for use in satellites and balloons, you will probably need a bigger plane.

Here's a Senior Telemaster ARF designed for electric power:

Here's the Senior Telemaster kit for glow engines:

The electric ARF can be converted to glow power without too much difficulty.

Marty

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One more thing...do you know how to fly a radio controlled model airplane? If not, either learn how before you try your experiment, or find someone who is a good radio control flyer.... I guarantee you will crash your plane if you do not know how to fly it. Sort of trying to ride a bicycle the first time and you have never ridden one before. Guaranteed that you will fall off!! Frank

That was going to be my next point, then I sort of wandered off - forgot what I was - uh - doing and - what were we talking about?

Ed Cregger

The EasyStar is widely used by guys into aerial photography, and a few with real time downlinks from an onboard camera (complete with pan and tilt mechanism) for remote piloting using VR goggles. One has reported in another on-line forum that his EasyStar is flying at a gross weight of 96 oz. That's a far cry from the 24 oz. nominal weight of a ready-to-fly stock version.

BTW, he reports that it lands fast - no surprise there!

Abel

Boy, do I stand corrected. I wonder if he's flying that 96 ounce monster on the stock motor, or if he's upgraded the drivetrain/battery?

I've flown a friend's stock Easy Star a couple of times, and wasn't terribly impressed with the performance. I would never have imagined that it could carry that kind of weight, at least not in the stock configuration.

Bob

Sorry I can't offer more details or a link at this time, Bob. I heard of it just yesterday from a clubmate who, like me, has taken an interest in getting into VR flight. I very much doubt the stock can

400 motor could come close to being up to the task though. This is a very popular model at my club field, even amongst some of the most experienced modelers. A number of them fly with brushless motors, like the Himax 28 mm inrunner with turns for 2000 rpm/v, and a 3S LiPo. Odd to see this very docile trainer type going unlimited vertical, and accelerating rapidly at that. I will see if I can get a link to the description of that heavyweight I mentioned and post it here. I would have guessed it would struggle to fly at something less than half that weight even with ample power, and the foam wings must need some additional support beyond the stock CF tube spar, so I well understand where you are coming from.

Abel

Follow on to my last past. Here is link to some recorded video from a pioneering VR flyer in Quebec. It's what got me turned to the notion of flying VR, and views of the plane and equipment give you some idea of what the EasyStar can carry around effortlessly:

Abel

I can see flying the brick with a brushless motor and some LiPo cells. At times I have subscribed to the idea that ANYTHING will fly, so long as you put enough motor on it. However, stock, the EasyStar comes in at a docile 9.4 oz/ft, while the brick will be around 37.6 oz/ft. Besides a "brisk" landing speed, I rather suspect that kind of wing loading will make for some other interesting behaviours if one isn't VERY careful. I'd also bet that some carbon reinforcement would be required in key areas. When you mentioned the weight, I immediately started thinking about a brushless Hacker and LiPos. The last 20-25 years has been a very interesting time to watch RC electric development -- going from tiny toy motors and models weighed in grams to BIG electric models that are the size and weight of what only recently required a hot .60 to 1.20 2C to fly, with electrics now being able to do 3-D and anything else that the glow planes can. Advances in motor and battery technology has been nothing short of amazing in more recent years.

Bob

I put a 2S 1500mAh lipo pack in mine (new esc, stock brushed motor) and it seems to fly forever. I had to add weight to the battery pack because it weighed so much less than the stock pack. I don't doubt that you could keep it in the air 30 minutes using a larger battery (especially if you didn't do loops and rolls....). If you switched to a brushless motor and flew it bascially straight and level the whole time I think it'd be easy.

Steve

I get at least 30-40 minutes of powered flight running LIPO batteries at

6-8C peak..in essence say a 2000mAh pack runs at 16A peak, that's enough for a brisk 600fpm climb., Once up at altitude it takes only about 4A to keep the plane airborne. Less if gliding back in to land :-)

Since the pack weighs very little, its easy enough to add more capacity without unduly affecting the weight.

A vintage style plane with a large battery pack will easily do an hour, even with a decent payload. However these are slow flyers and not so good in wind, or if you need to get to a remote site and back fast. An electric sailplane is a better way to do that. Low drag and a belly landing.

You can also pick up some tips there as well 'crow braking ' where flaps go down and both ailerons go up - will land a glider in an almost level attitude with very little forward airspeed..its a great way to kill lift and bring a model down safely..the model sort of parachutes down.

What you need is large wing area and low weight..that tends not to be so common in ready to fly planes. Built up balsa/plastic covering is more desirable.

One possible candidate is an electric Sig Rascal..with about 200W of power and a 4000mAh battery that should loft a payload of around 6-8oz no problems for an hour or so. As long as you have sufficient smarts to keep it level, it should glide in to a reasonable landing on its own.

If you use the MicroPilot board, you have a multitude of choices since the darn thing only weighs 28 grams!

Most .40 or .60 size ARF trainers are fully capable of carrying 1-1.5, maybe

2 pounds of payload without breaking a sweat, as long as you keep the power at the upper end of the recommended range. Likely you will have good results with a proven trainer airframe and engine, it's certainly been done before with projects like yours (sorry). If budget, i.e. a few hundred here and there, is not a big concern, then my recommendation would be a decent quality .60 size trainer (which will happily fly at 30-60mph depending on trim and power input) with a good .61 2Cor .82-.91 4C engine. You can always transplant everything into a more advanced airframe later if need be.

MJD

Bob-

Make that half a brick. The fellow that told me about that one told me today that 96 oz was a typo since corrected by his correspondant. Actual weight is reported as 46 oz. About 20 oz payload seems more within reason to me, so we can stop wondering about the apparent violation of the laws of gravity. Sorry for passing the Amazing Tales info.

Abel

18.8 oz/ft should be do-able, IMO. He might still need upgraded motor/battery, and perhaps a bit of extra reinforcement at key points, but it should be flyable. I have a couple of balsa models that have been through the repair process so often that they are probablly running weight to area numbers around this, and they fly fairly well, although I have had to upgrade the glow engine to get very decent performance.

Bob

I have flown the Telemaster at weights exceeding 20 pounds.

| Martin X. Moleski, SJ wrote: | | > You're not going to get batteries that are crashworthy and can | > keep your payload in the air for 30-60 minutes for anywhere near | > $500. That kind of battery technology will cost you around $3000 | > just to get into the ball game (chargers & extra sets of batteries | > to allow more than one flight a day). If you crash the best | > batteries (lithium ion), they may blow up and set everything on | > fire. | | I beg to differ on that. | | The battery for taht duration will not be highly stressed or get at all | hot. | | Packing them in foam in a crash cell would be entirely feasible

That much I agree with.

| and a $500 target is IMHO achieveable.

I'm not so sure.

The cheapest LiPo batteries I'm aware of are the emoil cells that come with the Milwaukee power tools. You get 7 3000 mAh cells that can do

10C discharge rates for about $100. (NiCds are cheaper, but since we're looking for very long duration, LiPos are likely the way to go.)

Assuming that we'd need 300 watts average to keep the Sr. Telemaster in the air (this is just a ballpark figure) and each emoli cell provides about 12 watt-hours, to keep things up for a hour will require about 25 cells, which will cost about $350.

I didn't run it all through Motocalc, but that 300 watt figure is based on roughly half of a bushing 0.40 engine's maximum output. As long as the plane is lightly loaded, that might be enough to keep it up. (Of course, those 25 cells will weigh more than the 0.40 engine and fuel tank they're replacing, so my estimate may very well be low.)

However, that $500 figure is supposed to also include the plane itself. A Senior Telemaster ARF is $209 at Hobby Lobby. Let's assume that nothing else is needed to assemble this.

You're probably looking at about $200 in brushless motor and ESC. At this price you won't get a big one -- probably just big enough to fly the plane around, but you're not looking for high performance here. Going for a brushed motor probably won't save enough money to justify the generally lower efficiency.

A RX will cost you about $50. Two servos (we're going for bare minimums) $20 more. Any old TX will do, so let's say that's free.

With 25 cells to charge at once, you'll want a pretty serious charger, but since we're on a pretty serious budget, let's say $100 for a charger.

So with only one battery pack (remember, Marty is playing a different ball game -- he's being a bit more practical) we're looking at $350 + $209 + $200 + $50 + $20 = $829 -- signifigantly higher than that $500 budget. Even if we go for half the cells so we only get a 30 minute flight, that's only $655.

And those Emoli cell are roughly half the price of anything else out there -- but you'll have to build your own packs.

It could be done relatively cheaply, but I don't think $500 is reasonable unless you already have a lot of the needed gear.

Conversion sounds like a poor way to go, to me. You need to find a person that has scratch building experience and design and build your own models, to the specifications you need, and nothing more. Build light using carbon fiber where needed, endurance as you specify, speed as would be optional, payload arrangement like you have to have. You will not find all of the perfect characteristics in any ready made model.

A part time paying job, for a modeler? Getting paid to use someone else's money to design and build state-of-the-art model airplanes?

Priceless!

You will need a RC qualified pilot to help fly it and act as a safety pilot, as you test it, and set it up. The right person is out there. Put an classified ad in some model magazines, especially AMA magazine.

Any other solution would be a compromise, IMHO.

On Sun, 29 Oct 2006 19:38:41 -0500, "Morgans" wrote in :

I think you're right for their long-range plans.

I get the impression that he needs something quick-and-dirty as a proof-of-concept in the short term (sounds to me like the next few months) so that the later versions (testing some serious and expensive high-altitude equipment) get funded.

But even for the q-a-d demo, I think they need help from a qualified RC pilot. Flying looks easy until you try it yourself. Cf. the Mythbusters episode when the youngsters failed to teach themselves to fly a light electric heli.

(Note to all the self-taught naturals out there: I'm not denigrating your accomplishments. That there are exceptions to general rules is to be expected. A laboratory can't count on finding enough naturals in its population to bet big bucks on a project like this.)

Marty

Marty

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