VTOL idea...

[Tram]

Hey guys-

I was on the way home from the movies tonight and started thinking..

Has anyone tried a 4 motor VTOL with a servo on each motor to change the pitch or transition from vertical to level flight?

I need to draw it out and scan it - to really show what I am thinking about..


Imagine a machine with 4 motors.. A motor on each "corner." A fore and aft set of motors, both controlled by a single servo for lateral movement and a servo on each motor for pitch control..


In the following drawing.. Red squares are servo's..

Each motor is driven pitch wise by a servo..
The fore and the aft sets of motors are driven laterally by a single servo, to provide lateral stability during vertical hover...

Traditional flight could be controlled via a/e/r on the fuse somehow..

ANyone think something like this would work?

[RCSuperPowers]

Yeah, I built a couple like that...

It will "work" as long as you get this ratio right:

Reaction force VS reaction speed.

If you have small fans that are pushing out less than about 5% of your total weight, you are going to need a tremendous amount of reaction speed to keep it from falling over (super fast servos, gyros, rpm changes, etc). Much like the real F-35.

http://www.youtube.com/watch?v=Xm7_PPE-8nk&mode=related&search=

It has this big old plane with these wee puffer jets stabilizing it. The puffers are so weak compared to that heavy plane, that they can not allow the jet to tilt very far before it passes the point of no return and tips over. A human could never be fast enough, it must be computer hovered.

So, the F-35 has a large amount of reaction speed and a small amount of reaction force.

A helicopter is just the opposite. It has a large amount of reaction force (the big movable blades) and a small amount of reaction speed (the dumb pilot).

Sooo, if you look at the RC VTOLs that do work, like the 4 bladed UFO jobs, they have good combo of decent reaction speed (their gyros and rpm changes) and good reaction force with those large blades.

So, the bigger the blades (and more helicopter like), the less you will need gyros and such. The smaller edfs are, the faster you are going to need your gyros and servos to be.

Dave

[v22chap]

Evidently Bell Textron helicopters thinks it will work ,,as they are working on a Quad tilt rotor :)
Can't find the pix right now ...but should be doable.
Good luck and keep us posted
Larry

[rctiltwing]

Check out the X-planes X-19 and X-22. For a model I would probably go with four variable pitch props. About the QTR: I assume they will drop the cyclic and use only collective? Or maybe the simplicity/weight gains are to small, and more flexibility in lateral movement is a big plus?

[v22chap]

RC
I doubt that they drop the cyclic on the QTR .. on larger craft you need to move laterally without dipping the rotors ...especially if you have troops / equipment slung under you or if you are trying to center yourself on tight landing spot of a aircraft carrier that is boobing up and down in the rough sea.

[Tram]

that is boobing up and down in the rough sea.

I love it when that happens.. ;)

[rctiltwing]

v22chap, you are probably right. Cyclic does allow for more flexibility and more precise maneuvering. And when you have an existing hub setup from the V-22 it would be pretty unnecessary to re-invent the wheel so to speak. I just figured that with 4 rotors there isn´t really an absolute need for it as there is with only 2, and in the interest of weight savings you could forgo it. But considering the size of the QTR, and the operational requirements and such I guess not. For a smaller craft built from scratch I think only collective could the best course though. This assuming that there actually is a substantial weight/complexity/cost difference between cyclic and collective control, but perhaps this is not the case, with full scale aircraft?