Autonomous airplane project

Hello everyone, I'm a researcher at Taylor University and was hoping for some advice from RC airplane experts about the best choice for a
plane to convert into an autonomous plane. We believe we want something in a glow engine trainer, something stable and easy to fly, with as few moving control surfaces as possible. We've looked into electric planes like this http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEWL3&P=0 which are simple and stable, but they don't seem to have the space or power to accommodate additional electronics to control the plane. Essentially we want that plane, but heavier duty and gas powered for the range and space and horse power. It's a funded project so cost is not a big concern. If anyone knows of someone who manufacturers such a plane or has run accross a similar project I'd be very interested in hearing about it. Thanks in advance! Nathaniel Colson
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Correct.
Here's the top of the heap:
http://www.aerosonde.com /
They flew one of their planes across the Atlantic with a 1.2 ci motor. I'm not sure whether it was gasoline or alcohol-based fuel.
A ready-to-fly aerosonde is probably in the $25,000 range or thereabouts. (I'm in the category of those who are too poor to ask the price.)
At the other end of the spectrum, you've got Maynard Hill's team, who sent a 5 kg (WET!) aircraft across the Atlantic:
http://tam.plannet21.com /
He used a highly reworked OS .61 four-stroke on naptha-based fuel.
A huge amount of work has been done on aerial robotics in any number of competitions:
http://avdil.gtri.gatech.edu/AUVS/IARCLaunchPoint.html
If I was on a decent budget, I'd go with Bruce Tharpe's Super Flying King:
<http://www.btemodels.com/sfk.html
But you have to be willing to build the plane. I'd think that $1500 would give you a very nice platform with plenty of payload capacity.
There are lots of excellent .60 ci (10 cc) planes that are cheap and serviceable. My buddy loves the Hobbico Hobbistar:
<http://www.hobbico.com/airplanes/hcaa2125.html
You can buy this in an Almost Ready to Fly condition. I'm sure it could carry a decent payload moderately safely (3-4 lb), but the fuselage is narrow. You might have to provide a larger bay under the wing for your onboard equipment.
You need a good RC pilot to help you trim your plane and make sure that it can fly before you commit it to the care of your avionics. You can find AMA clubs in your neighborhood, and they should be able to help you find someone who would help you learn to fly and/or act as your safety pilot.
You should expect to be vetted by the FAA and Homeland Security as well. If I were you, I'd take proactive steps to make sure that you don't violate any of their rules. Some of them probably saw the Man from Uncle show in which an RC plane was used as a weapon.
Commercial UAV Autopilot GPS system:
http://microboticsinc.com/rc_uav_autopilot.php
A bunch of hobbyist UAV links:
http://www.rcgroups.com/forums/archive/index.php/t-358497.html
A few years ago, I came across a wonderful page on a UAV team flying in Canada. I've lost the link, but it sure seemed like they were having fun.
Good luck with your project.
                Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See http://www.big-8.org for details.
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On 24 Oct 2006 16:57:48 -0700, "NathanielC"

While it's by no means "that plane", have you considered a Telemaster. Comes in both a 6' and 8' wingspan version, as well as a "mini" version. The two larger are really designed for glow power, but can be electrified.
The telemaster looks like an old-fashioned high-wing aircraft. It is very stable, will fly quite slowly, and the fuselage has LOTS of room for any additional equipment you may want. It will also carry quite a bit of extra weight. It can be built with or without flaps, and normally is built with ailerons, elevator, and rudder. Looks old-fashioned, but is stable and large enough to carry anything you would need for an autonomous plane.
Bob
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On 24 Oct 2006 16:57:48 -0700, "NathanielC"

Nat-
Two good replys already from Marty and Bob - you're on a roll! I think an essential spec to narrow down the field of airframe candidates is the estimated weight of your avionics/payload package. The 'toy' you looked at is marginal with just the battery aboard to power it, but that certainly doesn't rule out electric power. What Bob and Marty suggested can both be powered with electric motors too, readily available but much more capable in terms of power density and efficiency. Give us a guesstimate at weight and volume of what you want to loft and for how long, and I'm sure the denizens of this group can give you some useful pointers.
Abel
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Taylor? That's in Indiana, so why not go to Muncie and talk with the AMA museum folks?

They had Maynard Hill's "Spirit of Butts Farm" displayed there for some time, and will likely be able to dig up some good information for you.
Regarding Marty's superb comments, I'll add that Bruce Tharpe is aquainted with the chief engineer on the Aerosonde project, and I'm guessing that he knows a thing or three about making the Flying King autonomous! By all means contact him.
Good luck!
Geoff

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The Senior Telemater is a fine plane for reasonable cost and can carry a substantial load. It can (according to the originial German instructions) be flown with Rudder only (elevator and motor, of course) by fixing the ailerons in place and increasing the dihedral from 2 1/2 inches to 5 inches...and a word to the wise...be sure the dihedral braces are beefed up... This plane can be flown wth any .40 to .61 cu. in. glow engine...anything more is beyond the riginal specifications.. Frank Schwartz
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I have flown the Telemaster at weights exceeding 20 pounds.
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Exerpt from this article http://www.prisonplanet.com/articles/january2005/150105droneplane.htm
"Chang Industry is also working on a larger and more sophisticated version of the plane. These eight-foot wide planes would have a rigid wing, and a camera with the ability to pan, tilt and zoom and to provide night vision capabilities.
More important, these advanced planes would have autonomous flight capability, meaning they would not have to be guided constantly by someone with a remote control. Using a Global Positioning System receiver and programmed maps, Dr. Chang said, the plane could be programmed to fly to a target and circle it before returning. This larger plane would cost approximately three times the Kite Plane, about $15,000.
Chang Industry will have to compete with autonomous U.A.V.'s already on the market. L-3 BAI Aerosystems, based in Easton, Md., makes a 44-inch-wide plane called the Evolution, which sells for $25,000 and flies on its own with live video feeds that can be transmitted up to 12.5 kilometers. The Evolution, which can be transported in pieces in a backpack, is designed to collapse into its component pieces upon impact, leaving open the chance for reassembly.
Jay Willmott, the company's executive vice president, said that the United States Marshals Service uses the Evolution plane, and that the Maryland Port Authority is also interested in acquiring a small fleet.
One obstacle to more widespread use of U.A.V.'s is the lack of Federal Aviation Administration regulations for their use.
Paul Takemoto, a spokesman for the F.A.A., said that U.A.V.'s must be evaluated on a case-by-case basis, and that using them in an urban area required F.A.A. approval through a one-year "certificate of authorization" for a particular plane in a specific area. A rural or remote area, such as a testing zone, would not have the same restrictions, Mr. Takemoto said.
However, the F.A.A. is currently drafting sweeping regulations on the use of U.A.V.'s. The agency hopes to have the regulations completed by September."

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Thanks for the replies and links guys! Sorry if I was vague on a few points. Here are some specific requirements for what we're looking for, in order of importance:
- 2 or fewer moving control surfaces (so a rudder and perhaps elevators, but no ailerons or flaps) - Enough power and lift to handle a couple extra pounds of electronics, about the size and weight of two or three decks of playing cards (and shaped however we want). - Durable enough to withstand rough landings (microcomputers aren't notorious for their landing finesse, so balsa wood is less than optimal) - Inexpensive enough that we could crash one and not be too sad (preferably < $500) - 30 - 60 minutes of flight time
We're emphasizing minimal moving control surfaces to make the plane as easy to control as possible, because it would take a huge amount of effort to make our microcomputer smart enough to control a 7-channel plane, especially when all we're interested in doing is flying straight lines between waypoints. We're pretty set on a bent wingtip design with no flaps or ailerons, and possibly no elevator or rudder either like the v-tail design. We have a fairly good idea what we want in a plane, we're just not sure where to look to find one with the cargo and range requirements.
Electric vs. gas-powered is still up in the air. I think if electric can supply the range and lift it would be preferable simply because it's cleaner and quieter, and because I get the idea that fewer things can go wrong with a motor as compared to an engine. Perhaps you guys could shed some light on that decision too?
Thanks again! Nathaniel
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NathanielC wrote:

That's an electric senior telemaster to a T. Crank up the dihedral and scarp the ailerons. It will be a bit faster and have less duration with a couple of pounds of payload, but it will lift them.

Definitely possible.

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It all depends on how good your GPS is. Turning off the engine at the right time and floating into a large field for a landing is not wholly inconceivable.
The more crash-proof you make an airframe, the heavier it gets. Then you need more power to get it off the ground and keep it in the air, which means more fuel, which means more weight, which means more momentum to cause damage in a takeoff crash, which means you need a stronger airframe, etc.

$500 of damage is probably doable, depending on how bad the crash is. Many parts survive that can be re-used in the next plane.
$500 for all-up expenses is a very tight budget.

Not impossible with a large gas tank and a fuel-efficient engine, but you need to calculate the weight of the fuel and the change in CG caused by it burning off during the flight. The change in distribution of the fuel in the tank is also tricky, because unpumped engines have difficulty drawing fuel very far.
You might look at powered gliders or other designs with high-aspect wing ratios if speed over the terrain is not an issue.
Which reminds me--there is a Canadian company producing commercial GPS systems to do photo-reconnaissance of farms. I don't have time to search for the link now. I saw the link in rec.aviation.piloting in a thread about the dangers of piloted planes sharing airspace with unpiloted planes.

Study Maynard's design. I think he used minimal controls in order to reduce induced drag (something like aileron and one elevator just on half of the horizontal stab).
I have flown lots of combat models with just aileron and elevator. The Gremlin, a flying wing, uses ailevators (two servos mixed to produce aileron and elevator functions).

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.
                Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See http://www.big-8.org for details.
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Martin X. Moleski, SJ wrote:

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, and a $500 target is IMHO achieveable.

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| 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.
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Doug McLaren wrote:

And pretty wrong.
I find that a slowish plane needs about 20W/lb to keep it flying. Actually at about 20mph you only need theoretically about 3W/lb for a clean airframe. However there are motor, and prop inefficiencies..
Thats a 15lb plane you have there..not sure a Telemaster is anything like that.
and each emoli cell

Yeah, but a bushed 40 is turning a matchstick 10x6 at 10K RPM. AND ist maxiumum outpoyt is usually quoted at an RPM that is way above what we us in flight - maybe 16-18K RPM. If you gear or use an outrunner, you get more like a thin blade 13x10 at 6K RPM. that takes about half the power for a start to give the same thrust and pitch speed.
And half throttle I have found to be about 1/4 the power of WOT.
The nearest thing I have is a 60" span black magic that flies at 3lb AUW. On 200W. On an 11x7 prop doing at most 6500 RPM. On a pretty inefficient can motor (60-70% over the throttle range). Flight times and what goes back into the pack suggest I average about 50W on that during a gentle flying around sort of thing. Thats precsiley *16W/lb* *average*.
Motocalc tells me it will stay up on a 2000mAh pack for half an hour. This is borne out in practice.
Power to stay up, as opposed to climb, is simply the models weight, times its speed, divided by its lift to drag ratio at that speed.
You can see that a low wing loading model - large and light, and therefore slow - with fairly clean aerodynamics , therefore high L/D..takes almost nothing to stay up really.
I originally built that plane to carry a camera, but its too nice to hack it about..
Now a senior telemaster I am fairly sure can be built at 6lb or so.
It probably needs 300W or more to get it to climb decently, but I doubt it needs more than 90W to stay there.

In general for floaty type vintage models, I find that 60W/lb gives a brisk climb of around 600 fpm, and if I target for a 6 minute flight time based on full throttle, on the ground, I get at least 30 minutes in the air.
So targetting 12 minutes WOT statuic will net over an hour.
On a 6lb model thats 360W. Lets say its running a 3s LIPO pack, thats 35amps..so I want a 3s 4000mAh pack roughly.
Here's a suitable pack http://www.maxamps.com/index.html?lmd9014.919236 at $75.
AS for the motor..well an AX 2826/8 is ticking over and nicely efficient on a 12x8 on 3s LIPO. Thats $96 for the motor from a web site I googled.
http://www.modelmotors.cz/index.php?pagea&product (26&serie=8&line=GOLD
Needs a 55A ESC or thereabouts..
Heres the Jeti 70A with built in BEC - so no need for receiver batteries - for $130
http://www.hobby-lobby.com/jetiblue.htm#70
So to date we have $301 for a power train to replace a 40 2-stroke..and fly a 6lb plane for over an hour.
Total weight of everything is 150g for the motor, thats about 5oz, and 224g for the pack. am 1.5 oz for the ESC. I make that a shade under a lb.
Remember that replaces the motor, tank, fuel, engine mount, throttle servo and receiver battery. So its actually pretty close to similar weights on a sport model.

Then we are just about on. However I assumed the $500 for for the bits that would break in a crash.

I made it $230 for quality gear.
At

350W brushed motors are almost as expensive unless you pick up Ebay bargains.
There are a lot of 350W Chinese brushless at very keen prices tho. And cheapo ESC's are about as well. BUT whilst suitable for those who know what they are doing, I quoted branded gear that I know is reliable and will do the job.

Er. Three cells. Yor power calculations were way out.

No, they aren't. You just don't know how to calculate power requirements and where to buy LIPOS.

As I said, $500 for the smashable parts of the plane.
Anyway, the bit of the post I replied to originally was referring to the cost of the batteries alone. I simply said you could easily get batteries for under $500. In fact I found a suitable pack for about $75...
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| I find that a slowish plane needs about 20W/lb to keep it flying. | Actually at about 20mph you only need theoretically about 3W/lb for a | clean airframe.
When I think of clean airframes, I think of gliders. Not the Senior Telemaster, which is what we're talking about here.
| However there are motor, and prop inefficiencies..
of course ...
| Thats a 15lb plane you have there..not sure a Telemaster is anything | like that.
Doing some math (http://www.hobby-lobby.com/srtele-arf.htm gives the weight of their plane at 10.5 lbs, and their battery pack should be 34.9 oz and the motor 14.4 oz, so the plane itself comes in at 7.4 lbs.) That's 7.4 lbs without any power plant at all.
(Though maybe you can make the Sr Telemaster kit lighter -- I've never built one.)
| And half throttle I have found to be about 1/4 the power of WOT.
Fair enough ...
| Power to stay up, as opposed to climb, is simply the models weight, | times its speed, divided by its lift to drag ratio at that speed.
Simple ... once you know all these figures. Weight is easy, but the rest will require some calculations or in-flight measurements.
| You can see that a low wing loading model - large and light, and | therefore slow - with fairly clean aerodynamics , therefore high | L/D..takes almost nothing to stay up really.
Perhaps 300 watts was too high, but it's more than `almost nothing'.
| I originally built that plane to carry a camera, but its too nice to | hack it about.. | | Now a senior telemaster I am fairly sure can be built at 6lb or so.
Is this an all-up weight or with the power plant?
| It probably needs 300W or more to get it to climb decently, but I doubt | it needs more than 90W to stay there.
Even assuming 90 watts to stay there, a 3s1p 3000 mAh pack can't provide that for an hour. To be more precise, assuming 100% efficiency and an average voltage of 3.9 volts/cell, a 3s1p 3000 mAh pack can provide 90 watts for only 23.4 minutes.
| On a 6lb model thats 360W. Lets say its running a 3s LIPO pack, thats | 35amps..so I want a 3s 4000mAh pack roughly.
Well, from what I can find, you can't get a Senior Telemaster going that lightly. Looks like 7.4 lbs without any power plant at all, at least for the ARF. Maybe you can shave an ounce or two off that by not having ailerons ...
I went ahead and ran all these figures through Motocalc myself -- sedate flight, 30 minute flights, 94" wingspan, 1330 sq. in. wing area, 7.4 lbs w/o power plant, flat bottom wing, 2nd thinnest airfoil, sea level, brushless only, direct drive or geared, any size prop, lipo only, up to 8 cells, and it came up with me needing a lot more than a 3s 4000 mAh pack. In fact, the smallest configuration that came close to an hour up (54 minutes) is 9x 3000 mAh cells (in a 3s3p) configuration -- an Astro brushless 020 3T with a 5:1 gearbox (not something I'd have really considered myself) and a 12x6 prop, and it could maintain level flight at 76% throttle drawing 98 watts into the motor, with an AUW of 148 oz.
(I don't know what assumptions Motocalc is making for the `dragginess' of the airframe or anything like that (and it didn't ask), so we have to treat this as a pretty serious approximation.)
So it sounds like I was off by a factor of about 2.7 too high, and you were off by a factor of about 2.25 too low. So I guess you were indeed closer -- but we were both pretty far off.
| Here's a suitable pack http://www.maxamps.com/index.html?lmd9014.919236 | at $75.
A 3s 4000 mAh pack for $75 is a good deal. I couldn't find it on that site -- can you be specific about which pack it is? (They use frames, so your link didn't seem to go directly to that pack.)
| Then we are just about on. However I assumed the $500 for for the bits | that would break in a crash.
Fair enough.
| 350W brushed motors are almost as expensive unless you pick up Ebay | bargains.
Yup. Really, the motor/ESC isn't a good place to save money when you start getting into the bigger planes.
| > 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. | | Er. Three cells. Yor power calculations were way out.
Well, I used the cells I could find the cheapest -- per amp-hour, the Emoli cells are even cheaper than what you found. (I wasn't getting into the exact configuration of the cells.)
Roughly $100 (on ebay, but new/unused packs) gets you 7x 3000 mAh emoli cells, vs. $75 getting you 3x 4000 mAh cells with your pack -- your cells are 30% more expensive. (Granted, the emoli cells don't perform as well as some, but they're not too bad.) But for only 30% more and not having to make your own pack, what you found may well be worth it.
| > And those Emoli cell are roughly half the price of anything else out | > there -- but you'll have to build your own packs. | | No, they aren't.
No, apparantly not. The pack you found (but I can't find it on their web site) is only 30% more per amp-hour.
| You just don't know how to calculate power requirements and where to | buy LIPOS.
Apparantly we both have problems there ...
| Anyway, the bit of the post I replied to originally was referring to the | cost of the batteries alone. I simply said you could easily get | batteries for under $500. In fact I found a suitable pack for about $75...
I don't think so. Your pack is not sutiable, at least not without two or so friends ... but yes, it appears that you can get just the batteries for your Senior Telemaster to fly for an hour for under $500.
Of course, Marty was being more practical, and you'll want at least two packs of batteries, so double that cost ...
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| | | It probably needs 300W or more to get it to climb decently, but I doubt | | it needs more than 90W to stay there. | | Even assuming 90 watts to stay there, a 3s1p 3000 mAh pack can't | provide that for an hour. To be more precise, assuming 100% | efficiency and an average voltage of 3.9 volts/cell, a 3s1p 3000 mAh | pack can provide 90 watts for only 23.4 minutes.
Sorry, I should have done this calculation with a 4000 mAh pack, not a 3000 mAh one -- so we're up to 31 minutes, and two packs could provide this 90 watts for an hour. (Still assuming 100% efficiency in the pack, however.)
(Motocalc said 98 watts, but we're pretty close to the ballpark here -- and that 98 watts was for a different battery pack, and who knows how it guessed at the dragginess of this plane.)
| | On a 6lb model thats 360W. Lets say its running a 3s LIPO pack, thats | | 35amps..so I want a 3s 4000mAh pack roughly.
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| On a 6lb model thats 360W. Lets say its running a 3s LIPO pack, thats | 35amps..so I want a 3s 4000mAh pack roughly. | | Here's a suitable pack http://www.maxamps.com/index.html?lmd9014.919236 | at $75.
A 3s 4000 mAh LiPo pack for $75 would be a good deal -- but I can't find any on that site for $75 -- the closest I see is $95 (which still isn't so bad, but I know nothing about that vendor.)
So who's got the best LiPo deals lately? I'm currently interested in 3s or 4s 4000 mAh packs or so, perhaps 15C continuous and 20C burst, though I'm not married to those exact specifications.
I've got some Emoli cells (from the Milwaukee power tools) that I've been using, and they're OK, and they're cheaper, but they don't perform quite as well as other packs out there. And I'd rather buy pre-built lipo packs anyways :)
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On 24 Oct 2006 22:19:32 -0700, "NathanielC"

To handle the extra weight requirement, you will need either a glow-powered model, or a larger electric, or electric-converted glow model.

$500 is going to be a very tight budget, especially since I assume you will need regular radio gear to control take-off and landing (although this CAN be controlled with some of the more elaborate and expensive GPS-based units)

You can do this with a glow-powered aircraft for considerably less than an electric. With a glow aircraft, you will need to watch both wet and dry CG closely. I use a Telemaster for semi-autonomous flight, mainly used for airborne video using an rf downlink. Some of its missions are well over an hour. To solve the shifting CG problem, I built a partially wet-wing with the fuel on the CG, which drains to a snall header tank (and also use a perry pump to stabilize the fuel pressure). To get that sort of flight time in an electric that is capable of carrying an extra pound or two will require batteries that will by themseslves be WAY over your $500 budget. My semi-autonomous set-up simply uses an "autopilot" (basically a device that keeps the plane level in 2 axes, as well as a gyro to control heading. It still requires a regular RC transmitter and receiver for take-off and landing, as well for any course changes. You can, however, allow it to flly outside of radio range, and then use the passenger vehicle of your choosing to get back into range to regain direct control. My video transmitter/receiver setup actually has more range than my RC gear (and the transmitter/camera is powered by an on-board generator (Genesys -- Sullivan).

Your microprocessor is still going to have to handle quite a bit of data, even if you minimize the number of control surfaces. Assuming a V-tail design, the processor will still have to handle rudder AND elevator inputs, and will also have to mix these inputs to get the desired outputs to the control surfaces. There will also be the question of some form of altitude control using signals from your GPS through the microprocessor (or barometric, etc.), and you will likely also need some form of engine channel, unless you plan on the entire flight operating at a single throttle setting (not real practical during take-off and landing).

Glow-fueled will be cheaper, but you can perform this function with electrics as well. Be aware that the electric motor needed to fly a model large enough to handle your electronic bay and "a couple" of extra pounds will likely cost as much or more than a comparable glow engine, and batteries that will allow for flights this long will be much more expensive -- conceivably as expensive as the entire model and engine along with some of your electronics. Just the batteries to handle an electric model of this size for that length of time may weigh as much as 30 oz.

There are a couple of companies making more-or-less turn-key solutions for what you are seeking to do in terms of the gps and control electronics. I don't have the links readily at hand, but will see if I can't find them tonight.
Bob
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wrote:

And don't forget the cost of insurance (AMA won't work) and legal fees, which you will surely have once someone catches wind of what you are doing.
Unlicensed/approved autonomous aircraft are not considered to be on the government friendly list these days. One could probably argue that they are not recreational models and therefore are not permitted to share our airspace without special exception (where the lawyer enters the picture BEFORE an incident).
Just because you can do a thing, is no reason to assume that you should do a thing.
Ed Cregger
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wrote:

Which begs the question, "What are you doing with the plane?" I don't wish to be cynical, but how do we know its a university project, or did I miss something?
Harlan
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