arf uav platforms?

[apcopresta]

hi everybody-

i'm looking for a good ARF kit to use for a simple UAV. i probably only need about a pound or so of payload, but more would be nice. right now, i'm thinking of starting with this:
http://www.rchomebuilts.com/Challenger.htm

unfortunately, it looks like the challenger wont be available for a few months, and i would like to get something sooner. im thinking i probably need a 46 or larger engine. i would prefer a pusher prop(so the camera can be in the nose), but there dont seem to be many kits out there that meet these constraints.

any other ideas?

thanks
--tim

[killr0y]

Another thing to think about is range/endurance. A stable platform is great but for the purposes of UAV you should also think about something that is going to be able to make a 20 mile round trip. I've been looking at platforms and my guess is some kind of powered glider in the 60"-80" wingspan form factor with either an extra large fuel tank or some really high capacity li-poly battery pack. You'd still have to wind up riding thermals and do lots of gliding though.

[HELModels]

What kind of guidance will you use? What is your mission? Riding thermals to accomplish a mission beyond LOS invites trouble. Why not build to suit the mission?

[apcopresta]

mostly looking for some sort of test platform to cut my teeth on. planning on using an autopilot of some sort, probably a micropilot one. initially, range and endurance isn't my biggest concern. right now i mostly want to play with the autopilot and see what kind of imagery i can get. i may eventually want to pair the autopilot with some sort of on board computer(gumstix, or maybe something slightly more capable).

my thinking is that the airframe is probably one of the cheapest components, so i would rather get something now to test with, and change airframes later on if need be.

what kind of platforms are you guys using for camera uav work?

--tim

[typicalaimster]

I'm working on something of the sort. I currently have an electric version out of beta. However it will only carry up about 10-12oz worth of equipment. It uses a AXI motor and a 2100 lipo pack.

As far as a bigger sized plane..I just sent the first 'concept airframe' off for laser cutting. So far we're talking about a $150-$200 investment for the airframe itself. I won't have all the testing done till the end of September. The new plane takes a 50 sized nitro 4 stroke and is designed alot like the plane above. If everything goes good, I could get kits out by Dec / Jan.

-Scott

[sesat]

Stratos.

R

[clolson]

hi everybody-
i'm looking for a good ARF kit to use for a simple UAV. i probably only need about a pound or so of payload, but more would be nice....any other ideas?
--tim

It sounds like you are leaning towards gas, in which case I will gladly recommend the Sig Kadet Senior ARF as a platform for your consideration. It's built with extremely light wing loading, and I estimated at one point that you could probably load up 6-8 lbs in it before the wing loading started to get out of control (although it is such light weight construction that you wouldn't want to fly aerobatics or abuse it after you've put some weight on it.) My progress with turning my Kadet into a UAV is painfully slow, but I setup a web site with some pictures and my thoughts and comments here:

http://www.flightgear.org/~curt/Models/Current/EGN-1/

The Kadet is a bit on the pricey side as far as trainer arf's go, but in my opinion it's worth it in terms of quality, and it's big and gives you a lot of room (relatively speaking) to work with.

If you want to go even bigger, a lot of people have used a Sig Rascal 110 as a UAV platform ... even some local Lockheed Martin guys are flying one of these for some of their tests. It has the advantage of being really big and still having a pretty light wing loading meaning it has a lot of payload capacity. I estimated you could fly at least an additional 9-10 lbs with out getting too crazy on the wing loading. Plus it looks and flies awsome. I get to fly one of these for a university project I'm helping out with, and I'm in love with the big Rascal. If I had the funds and the space I'd sell all my rinky-dink 40 sized stuff and go *big* ... but somewhere along the lines, reality has to creep in so for now I have to be happy flying other people's big stuff. We've put probably 1-2 lbs in our Rascal 110 and you can't tell the difference between that and empty. We powered ours with an OS 1.60FX turning an 18x8 prop and performance is outstanding. Not quite unlimited vertical, but it flies really sweet, big, swooping, elegant, authoritative maneuvers that force me to keep reattaching my jaw, it just a wonderfully gorgeous plane both in looks and in it's flying characteristics. I suspect that after I've been out to the field with ours a couple times, we'll start seeing a few more of them showing up. Here's an informal web page on our Rascal:

http://www.flightgear.org/~curt/Models/Special/Rascal110_1/

The knock on all of these though is that the engine is up front where it get's everything behind it messy with oil. That's bad for photography. Also the cabin layout (especially on the Rascal) gives you most of the open area behind the CG, so with our Rascal we are always fighting to get the CG forward as we add new stuff. Oh, and once you put the wing on (which is a slightly time consuming process, especailly on the Rascal) you don't have easy access to the cabin any more for turning your equipment on and off. That may or may not be a problem if you can rig external switches (depending on what equipment you are using.)

There are a lot of reasons why people who really get into the UAV scene end up building themselves a twin boom pusher design ... messy bits are in back, convenience of access to your payload, ability to mount a camera in the nose, etc. But as far as I know, there are no good pusher ARF's out there.

I've been tempted to look at something like a Mariner or SeaMaster (seaplanes) that have the engine on a pylon above the wing. These have nose bays that would be wide open for equipment. But the Mariner doesn't have a landing gear option with out significant hacking so there's a downside with that too.

But to summarize, if you want an ARF option that is not too cheap, not too expensive, has decent payload capacity (size and weight), and has nice stable forgiving flight characteristics, it would be really hard to go wrong with a Sig Kadet Sr. ARF. I loved flying mind (manually) so much that I was thinking about chucking the UAV idea entirely. :-)

Oh, and I don't work for Sig, I just have assembled 2 of their ARF's and have been really impressed with their fit, quality, and flying ... especially compared to some of the cheaper ARF's I've put together.

Curt.

[alexcmag]

If it is only for testint porposes, how about the "Draganfly predator"? http://www.draganfly.com/predator.php

The kit is a little expensive, but is ARF and appears to be a good flyer.

If you like to make your own plane, the "BigBrother" is a good base for your project. Just replace the tail by a inverted V-tail and it is a "Aerosonde" style UAV.

The airfoil is not the best but will be enough for you, and using LiPoly and brushless instead of a speed 600 with NiCads you can save over 20oz for payload...

[typicalaimster]

If it is only for testint porposes, how about the "Draganfly predator"? http://www.draganfly.com/predator.php

The kit is a little expensive, but is ARF and appears to be a good flyer.


I think littlebirdz.com or something of the sort puts out a $100 version of the Predator. It takes a 300 sized motor and will take up a small digital camera.

--Scott

[apcopresta]

thanks for all the feedback!

Scott- looks like a pretty cool platform youre building! what kind of wingspan is it?

Curt- thanks for some great suggestions, looks like it might be the way to go.

i'm not dead set against electrics(in fact all the planes i have are smaller electrics), but it seemed as though gas is the easiest way to get a pound or two of payload into the air for long enough to do something useful. perhaps w/ lipos and brushless this is less of a problem.

--tim