iamscottym

Hey everyone,

I'm looking to build an R/C 'snake' for my uncle, who was a gunner back in 'Nam. Strictly speaking, I havent done any work with true R/C helicopters, though I have made helicopter-like things. I understand the basic mechanics of a heli, and I have worked with gyros. Oh, I should mention, I'm a mechanical /eletrical and computer engineering double major, so I know my way around the mechanics and robotics. I plan on using a microcontroller and a couple accelerometers to help in the flying, in addition to the gyro- basically it will allow me to have a level hover fail safe, as well as programming in maneuvers. This stuff is all really light, so weight shouldnt be an issue.

However, I havent found any material on big heli's- I'm looking for probably 5-6' main rotor, not sure what scale that would be. I am more than capable of making the the fuse and the gearing and such, though any tips would be appreciated, espcecially in regards to the mechanics of the rotors. I can turn/mill my own parts so thats a non-issue. I would also like to keep it electric, because this particular uncle isnt one who would do the maintanence necessary on a nitro, and frankly I prefer electric. Right now I'm probably going to make the motor- a brushless, because I will likely need something with much more power than is currently available. Lipos seem like the way to go, though if NiMhs have a good enough power to weight ratio they would substantially reduce the cost

I will also need several ounces of extra carrying capacity...because well, if it doesnt shoot my uncle wont like it. I have the recoiless rocket designs done, but I'll leave that part out- I think the DHS might take interest.

Thanks,

iamscottym

Helijack

You have a lot of research in front of you. Electric for heli's isn't that far yet, you are talking an 8-10 foot fuse. I think you need to downsize a bit and you will find readily available parts. Why not turbine power? The fuse is out there, why reinvent the wheel, power can be either a weed eater type motor or turbine. Regardless of power, they all take maintanence....frequently

Unless you want to make all that stuff for class projects or the fun of it, why reinvent the wheel? Improve on what is there. Make a small gas turbine for a .60 size heli, there is desire for one, none produced yet.

Essentially you are talking UAV with the electronics for predetermined flight. There are systems out there that can stabilize the rotor system already. Again improve on what is there, decrease the cost or size of it. Sounds like you have the talent, just need a slight course correction to a more attainable goal.
Jack

iamscottym

Could you give me a link to a fuse/ mechanics for a heli that large? -the size doesnt matter, so long as I have the carry capacity for maybe 1/2 lb of rockets. I figure the mechanics would be the biggest challenge, so I'd prefer to buy them. I cant seem to find anything that large, and also I would need to gear down the motor a bit for scale flight/heavier load. From what I've read, finding the higher ratio gearing can be difficult. As for making the motor- its really not that hard, and there wouldnt be as much maintanence. Just charge and go. I'm sure the gears and such would need to be oiled once in a while, but my uncle probably do that. I doubt he'll be flying this that often, so electric is just more practical to store- you dont need to worry about fuel and things going bad.

Yes and no on the UAV. The stuff I need isnt really available software-wise, but I'm more than capable in that area. Basically the software works like a gyro- a sensor says, 'i'm tilted so many degrees'..then you send a signal to the rudder or whatever to correct that. For the collective, its slightly more complex, but basically an acclerometer says 'I'm falling at such an accleration' ...and the signal goes to the collective. Really, doing all this yourself is much cheaper than buying it. I plan on buying the RC gyros, rather than buying a gyro and having to write software for it, but everything else will be done myself.


Can you point me in the right direction for a heli? Like I said, the size doesnt matter, except to the point of carrying the rockets and the extra electronics- the electronics can be kept to a couple ounces, and the weight of the rockets will always be proportional to the heli (well, to a point)..but i could cut the number of them to save weight if its an issue. I think the biggest thing here would be cost- how much are we talking?(unpainted fuse, my brother has a real knack for that sort of stuff) and no radio(I'm going to use a data radio, and a joystick, and possibly levers for collective and such, though that will probably all get programmed in for computer assisted flight).

heli143

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try contacting Joe Howard at East Coast Scale helicopters. Vario sells a large scale Cobra and Joe has an electric conversion for the Vario models. Darrel Sprayberry of Unique Aircraft in Dalton, Ga, has a 7 foot eletric cobra and is the designer of the electric motor conversion.

http://us.vario-helicopter.biz/shop/...ducts_id=35975

good luck