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AlexEvans

Building an OSPREY

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Hi Guys

This will no doubt sound crazy... I am building an OSPREY (VTOL) look-alike, based around a couple of electric motors, one at each wing tip (AXI 4130/16) with JETI 77 ESC.

I am going to use ONE throttle channel on my Hitec Eclipse 7 tx, with a Y splitter to go between the 2 ESC’s, but what can I use (Gyro 1 or 2 maybe) to help me keep the machine leveled during take off time, if a Gyro is a good idea, which one? Should I have one ESC connected directly to the rx and only have one Gyro on the other motor to make it plus / minus … or should I have one Gyro per ESC

Any ideas will be appreciated

Cheers

Alex

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Good luck ;)

Well, a gyro on one of the motors could maybe help. But this would stabilise bank angle only. Then you should have a second one that would stabilise the tilt angle also, maybe by rotating the motors.

What could be a problem is that when a motor changes speed to keep the plane level, its torque will increase and make the plane turn around, like on a heli. You should ensure that the corrections are very smooth and not overcompensated. And don't forget that the 2 motors have to turn the opposite way :rolleyes:

What I would do is 2 mixes at the beginning: one between ailerons and motor differential speed (very little rate!) so that when you are flying at zero speed, you can still control the plane's bank angle manually like if you were in normal flight.

The second one would be elevator -> motor angle (very little rate also, around the top position) so you can control the forward/reverse movement.

But doesn't the full-size one have a heli-like pitch control for the blades? I have difficulties in seeing how you could keep the plane flat if you have to change the motors' angle to move forwards/backwards without a cyclic pitch control... :unsure:

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I remember seeing one someware and it did indeed use heli type heads and hand made blades with lots of twistand camber to them. Its a very big project !

Terry

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Hello again,

Well, to start with - I am only concerned about level of wings at take-off time, don't care about any othe axis (although I may find out other problems...)

Anyway - I do have two props, one trcator and one pusher, so thais is taken care of, and if a GYRO is a good idea, could some one please tell me

1) Which type to use

2)How to wire it

My props are props, NOT rotor blades and NO helicopter stuff, all the known attempts to do it the helicopter way that I am aware of failed, this can't be like a heli - because when it tries to swing the motors horixontally with a heli like rotor, the ting can't fly fast enough to create enough lift, so just forget about this idea and think of simple - fixed type props...

Hope someone can tell me some answers about my two questions.

Now also vey interesting - I am using a Hitec Eclipse 7, and I don't know how can I mix Ailrons with te throtle or anything like that, although it sounds like a good alternative – instad introducing a Gyro, but how will I disconnect this “mix” once I want to switch to level flight?

Thanks again

Alex

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Well, if you use a standard gyro it will only give monentary corrections that certainly won't be enough to hold it in place. And if you use a HH one, it will try to hold its angle, even if it's not the good one. Difficult to say which one would be better.

Also if you use it to control one motor only, the plane won't keep its height when corrections are applied. One motor should run faster and the other one slower. But from my point of view it will be very difficult to have something sensitive and fast enough with standard R/C electronics.

That's also why a heli rotor is better, as you can change pitch instead of speed to modify the lift amount. It's much faster than having to accelerate a motor and propeller. Also have in mind that some brushless controllers only accelerate smoothly, that is also slowly.

Concerning the mixes I don't know Hitec radios, but I've used different Futaba and Multiplex ones, they all had user-programmable mixes that can be activated / deactivated with a switch on the TX.

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Yeah, BTW the blades of the full-scale one are really unusual...

And rcgroups is still down :huh:

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Helo again

It seems this has managed to really make a storm in the water.. didn't expect that much feedback, thanks guys.

Now back to my story

1) I don't have the $$$ to go into the R&D that took the real thing with the special rotors / prop etc - so I will just have FIXED PITCH props 16 x 10 3 blades (BIG indeed) one tractor and one Pusher to help offset the torque.

2) All the attempts (that I know of) making this with a heli / rotor style deal have failed – the tilting of the motors does not go further than 60 degrees before the nose starts going up, and the machine goes into an almost vertical climb.

3) If a GYRO is a good idea, can someone please tell me which type / brand and how to wire it, and more important – how to disable it once I am into straight flight (I have no idea about Gyros at all)

4) If at all possible with my Hitec Eclipse- 7 radio, can I instead of Gyro – do some mixing of Ailerons / Throttle to be able to control each ESC through a separate channel and balance the take off by myself?

Hope someone can help, thanks in advance

Alex Evans

Melbourne Australia

alex.evans-AT-iinet.net.au

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OK, a bit of gyro basics, as we are not sure if a rate gyro or a heading hold gyro would be best, you should get a hh gyro as it can be switched between both. Try geting an onboard mixer as used for V tails and feed your motor control from your reciever into one input and the aileron into the gyro then out to the other input on the mixer. Connect the speed controllers for the motors to the outputs from the mixer. A good gyro will also have an other lead that can be connected to the receiver so the gyro can be switched off / gain asjusted or switched between hh and normal. Try a CSM 540 or simular. Hope this helps.

Terry

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Ive just been walking the dog ( I do all my best thinking when I walk the dog ), how are you going to control the aircraft in pitch when you go VTOL ? If you ar going to use a small motor/prop at the back you could use a CCPM type mixer and 2 gyros for full gyro stablisation.

Terry

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Well, to start with - I am only concerned about level of wings at take-off time, don't care about any othe axis (although I may find out other problems...)

said he.

From my point of view it wil be almost as difficult or even more so stabilise pitch (having read the thread mentioned above, which is very interseting by the way).

I agree with Terry. (taking into account that i'm still quite doubtful...)

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