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Old May 06, 2004, 11:51 PM
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LPS Powered V-22 Ospry


This is something I have ben pondering for a long time, and finally got around to try it. Its an LPS powered 2S 700 mAh Lipoly. Ready to fly weight is 165g. The specs say I should have 260g thrust.

I am still working all the necessary mixing, but I think I am getting close. Tonight I powered it up for the first time. Engine vectoring seems to be about right. I need to work the differential thrust next.

My progress is slow due to limited time to work on my hobbies, but I'm hoping to be hover testing next week. I'll keep you posted on the progress.

Todd
Last edited by ToddL; May 08, 2004 at 01:56 PM.
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Old May 07, 2004, 12:01 AM
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Holy crap that's cool! Is there a gyro you can put in it somehow?? Watch out for ground-effect and junk. Does it not having pitch-adjustable rotors help at all? It'll make stable flight hard, I believe. Very cool!! What's it's guts? What kind of mechanism do you have to adjust the incidence of the props?
Old May 07, 2004, 12:02 AM
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Thats amazing. You need to make a video for us on the hover test.
Old May 07, 2004, 12:34 AM
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Pete,
Its fixed pitch for simplicity. I use 2 speed controllers for differential thrust.

I can use a gyro for hovering, but it will screw up forward flight. The controls for yaw in hover become roll in forward flight, and roll in hover becomes yaw in forward flight. I am going to change flight conditions as the engines transition forward to compensate. It will bring in an entire new set of mixing rules at some point (maybe 45 degrees) as the engines transition forward.

I am hoping that the need for a gyro will be minimized because I have counter rotating props. I fly a Piccolo heli quite a bit, and it needs a gyro to compensate for the main rotor torque. This wont have that problem.

Todd
Old May 07, 2004, 06:31 AM
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Wickedly cool Todd. LiPoly's have made so much possible now...
I hear you about the time issue, I was trying for a GWS 400C size tiltwing before life put it on hold. A note about thrust vectoring for roll - It takes a miniscule amount of "throw" into your aileron channel to get some strong results using the speed controllers and radios we use. Using a servo driver on the aileron input to the (onboard) mixer, I could get a usable roll rate with about 7% of "throw" max, but using my radio, my test rig would just kick up whichever wing and fall into the other. Computer radio may take care of that for you though. Best of luck man. I bet this thread is going to get long...
Old May 07, 2004, 10:36 AM
Nige is offline
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Hi everyone

Lots more stuff
here
and
here

I've been playing with something similar for a long time - without much success...

The stuff on the Gress site makes interesting reading.

nige
Old May 07, 2004, 11:03 AM
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totally cool
I've been dreaming of that for a long time - way out of my realm of skill and experience though.
I will follow your exploration!
Old May 07, 2004, 11:13 AM
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You would probably use the gyro to prevent too fast a roll responce in hover which probably wouldn't hurt the foward flight too much, could do with a switchable gain.

I suspect your main problem may be stability given inflexible rotors but I am just guessing as I don't have a V-22 on my table

Looks great, hope it works.

Graham
Old May 07, 2004, 12:34 PM
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Graham,
I had the same thoughts on the rotor. I have a second set of props that I plan to use to make a simple lead-lag type flexible rotor head if stability is a problem. I wanted to start out simple first, and add complexity only where necessary.

As you can see, I didn't put a lot of effort into the airframe, as I suspect it will meet the wall and floor a few times. This first airfram is just to explore the feasibility of the controls, etc. I have a more scale design in the works if this one flies OK.

What is not shown right now is the flaps for the wing that will add another 30% wing chord for forward flight. These will move down 90 degrees with the motor in hover mode. I'll leave them off while I do the hover testing.
Old May 07, 2004, 12:49 PM
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Where did you find reverse pitch props?

Kirby
Old May 07, 2004, 08:21 PM
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Kirby,
The props are available here:

Todds Models

They are 10-4.5, similar to GWS.
Old May 07, 2004, 08:56 PM
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ok that is the coolet thing i have seen i have been thinking of ways to make one for a long time what is it packin' what are the contolls hw did you mout the servos? and what are the flight times
Old May 07, 2004, 09:48 PM
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Now that is neat.

Little short on wing area, though, perhaps?

~Luke
Old May 08, 2004, 12:38 PM
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Todd
That is one cool micro V-22 .. Do you mind if I put your project pictures and progress up on my webpage "Welcome to R/C VTOL's" ??? I will title it Worlds smallest V-22 Osprey!!!
If so could you send me some more pictures and title them so that people can get a good idea what you are doing.
Your idea of engine vectoring is one that I explored for my large bird ,,, and it almost worked except for the pitch axis,, as I was trying to do scale and that long tail and small props made it hard to control without a swash plate.

A gyro on the roll axis ( even just one side) will help in hover ,,, and if you mount it to the nacelle pivot point it will rotate around with the motor unit and then augment the yaw axis which needs it in airplane mode because of the props being out that far on the wing tips.

It looks like you only get about 60 degrees or so for forward tilt ,,but that will be enough to get you wingborne as the full scale flies best at 68 degrees forward.

Keep me posted on your progress and a video would really be great.
email me at: v22chap@hotmail.com

Great job ,,keep up the good work
Larry
Last edited by v22chap; May 08, 2004 at 12:46 PM. Reason: SP
Old May 08, 2004, 01:54 PM
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V22chap,
Help yourself to the pictures. Give me your e-mail and I will send you more as I take some more.

The rotors actually do go full 90 degrees for forward flight. The pictures just show as far as they go before they become the landing gear

I actually did my first hover tests today. Apparently, I have the same pitch issue you did. If i BARELY give some back stick, it went almost 90 degrees nose up. I have the pitch travel at 20% with 60% expo!! It did get airborn, but then the pitch sensitivity killed it. I was thinking the pendulum effect from the battery slung low would help this, but apparently not.

Roll and yaw seem controllable (for the few seconds it was in the air). But I need to figure out this pitch issue.

I think I will try some teathered hovers next (after a few repairs) to give myself some more time to tune this in.

Reminds me of flying my Piccolo heli for the first time.


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