Mechanical Functions [Manually Operated]

Pull Back Motors

Hey, so I am currently working with an idea to build a dual rotor transport helicopter. I am basing it off of this:


Anyways, I'm designing a system which will involve both rotors counter-rotating (rotating in opposite directions to eliminate torque) while only one rotor needs to be physically spun. Needless to say this involves some technic parts and gears, but I figure I pretty much have it under control.

I had another brainstorm today however, that if I could attach a pull back motor to the central shaft connecting the two rotors down the middle of the chopper that I could simply wind one rotor up and they would both spin for a limited amount of time on their own. Does anyone think this is feasable or have recomendations to me on what specific pull back motors to look at for this function? It would need a technic four poster pin to fit in as the central shaft is such.

For sure I'll draw a picture and post it.

EDIT:

1. Axel through wheels into pull motor
2. Right angle gear box at end of axels on both sides going up from bottom to top of fuselage using vertical axels
3. Right angle gear box at end of axels on both sides going out to wings using horizontal axels
4. Right angle gear box at end axels on both sides attached to short axels to drive propellers

That's some pretty good rendering Rook! I had a very similar idea in mind and I've already tested it without the motor. It is a bit simpler as it has only drive shaft that connects the two rotors which go up at a 90 degree angle from that shaft. I'm assuming that pull back box works well then? I think I may have one of those...I will try to find it and let you know how it works!

Yeah you could even gear up coming off each of the junction. And then with minimal pull back you’d get increased propeller speed.

Yes I did make big gears coming from the main driveshaft attached to the pull back box and little gears attached to the rotors, when it works it works well. Only problem is I don't have gear boxes so I have an system that is sort of working and based around the technic pins going through the hole blocks and all that, the gears don't perfectly mesh...It's gonna take some time but it does look promising.

I originally was going to have one propellor be turned to wind the motor but the torque is just not going to let that work. I will have to have a knob at the back of the chopper attached to the main drive shaft that can be turned. I did find that powerfull pull back motor though, similar to the one pictured! Nice power.