Controlled Flight of 4-Rotor Crafts: Beyond Military Use

[wolram]

How would one control a craft with 4 rotors in a square pattern, i imagine it would be best to have one power source and vary the rotor pitch, may be with a gyro controlling out of limit dynamics, apart from the military has anyone had one of these in controlled flight?

 

[RonL]

Using counter rotation, any blade will be rotating opposite to the one on either side of it.

 

[mgb_phys]

Control would probably be same as something like a 2 rotor Chinook
It's big advantage would be that you could hang any number of loads anywhere within the area of the for rotors.

 

[FredGarvin]

Having two rotors, even with the rather simple idea of having counter rotating and differential collective pitch, there is a HUGE amount of mixing and control system "behind the scenes" corrections. With 2 or 4 rotors, you'd have to have linkages to get all 4 moving at the same time, in the same direction as well as independent pivoting.

Honestly, I would think the "easiest" (if such a thing exists with control systems) would be to have actuators on each swashplate that are electrically controlled, i.e. no mechanical linkages, except to the swashplate.

 

[frogman]

quadrotor

with a quadrotor, having the four rotors- a pair turning clockwise and the others counter, the yaw is stabilized. you could adjust pitch or roll by speeding up one and decreasing the other rotor in a pair. you could actual have fixed rotors, no swashplates

 

[FredGarvin]

with a quadrotor, having the four rotors- a pair turning clockwise and the others counter, the yaw is stabilized. you could adjust pitch or roll by speeding up one and decreasing the other rotor in a pair. you could actual have fixed rotors, no swashplates

How would you handle forward flight? In your scenario, the only thing that would happen is the pitching action would happen. To obtain a forward airspeed without descending is to somehow vary pitch in the blades so you don't keep doing cartwheels.

 

[RonL]

How would you handle forward flight? In your scenario, the only thing that would happen is the pitching action would happen. To obtain a forward airspeed without descending is to somehow vary pitch in the blades so you don't keep doing cartwheels.

Going back to the Hiller flying platform, the motion in any direction was the results of luvers under the frame, in the propwash.
I like Wolram's idea of square, but see it as a slow speed lift system. I think current helicopter design for serious flying is about as good as it will get.

 

[wolram]

So if i wanted to make a model would it be best to have four motors with speed controllers
and may be a gryo linked in some how, this is an idea for a camera platform.

 

[RonL]

So if i wanted to make a model would it be best to have four motors with speed controllers
and may be a gryo linked in some how, this is an idea for a camera platform.

Sounds like a good project, and i feel electric is the way to go, and there are so many choices for electric power, and battery manufacturers. Everything depends on all-up weight, and duration of flight time. I'll give one link to start with in case you don't have a bunch already,

http://www.astroflight.com/e/env/index.html?sid=0001eK215LFVztESN8549Z6&link=/index.html

I bought Bob's book "Electric Motor Handbook", he has a section that gives small to large, model airplane propellers "dia/pitch, speed, and watts absorbed". Let me know if you don't find that info on his site, or some other one.

I did have a link in the past, of a fellow in Fl. that was using a RC helicopter to do camera work, for different companies, a lot of building contractors from out of state would hire him to do arial shots and send them to their websites, for dailey or weekly updates on progress.
Always a way to make money, doing something you like, if your creative.

 

[wolram]

Great site RonL, speed controllers are so small now, but would you know how to keep four rotors in in controlled flight?

 

[FredGarvin]

Going back to the Hiller flying platform, the motion in any direction was the results of luvers under the frame, in the propwash.
I like Wolram's idea of square, but see it as a slow speed lift system. I think current helicopter design for serious flying is about as good as it will get.

Either that or adding an axial prop for thrust purposes only. It could be quite a bit smaller than the others.

 

[frogman]

four rotors

How would you handle forward flight? In your scenario, the only thing that would happen is the pitching action would happen. To obtain a forward airspeed without descending is to somehow vary pitch in the blades so you don't keep doing cartwheels.

Hi Fred,

They actually make a RC four rotor aircraft called a dragonfly. It flies by controling the rotor speeds, I know it uses three gyros and some magic circuit board. you can check it out at http://www.rctoys.com/

Wolram
They make one with a camera/video

 

[wolram]

Hi Fred,

They actually make a RC four rotor aircraft called a dragonfly. It flies by controling the rotor speeds, I know it uses three gyros and some magic circuit board. you can check it out at http://www.rctoys.com/

Wolram
They make one with a camera/video

Wow , this exactly what i need

http://www.rctoys.com/rc-products/DF-VTI.html

Many thanks.