MIT ACL - Variable Pitch Quadrotor

[Gaza07]

Ok who fancies one of these   

http://youtu.be/Vy5Ky50eGJs

[usnooz]

would flight time be really reduce due to being on full throttle constantly?

[usnooz]

I thought about this idea myself a while back but i was planing on using 4 heli booms and tail rotors with one central motor driving
ain the middle. not belt drive but using the direct drive method

[Gaza07]

Very good point but I would think the load would be quite low when the motors are spun up at zero pitch, Im tempted to have a go at one of these as there is a version of multi wii about for variable pitch multi rotors 

[Gaza07]

That would work well but I wouldnt have the knowledge to know what gearing to use, or if it was available to buy 

I thought about this idea myself a while back but i was planing on using 4 heli booms and tail rotors with one central motor driving
ain the middle. not belt drive but using the direct drive method

[usnooz]

I might give it a go as a project with my spare fc. i have all the bits already but the tails would be beltdrive.

parts i have for this

1x align xl motor
1x esc
1x gear large
4x 450 size belt drive heli assemblies + booms
1x fc
1x rx
4x servos

I'll just have to design a central mounting plate

[Gaza07]

Sounds good keep us posted if you do continue with it would, you use the multi wii firmware ? or is there other variable pitch firmwares available 

[usnooz]

planning to use my spare kk black board. i know people plug in servos to test it so it should work fine in theory unless im missing something? the Fc will not control the motor just the 4 servos. This sound about right to you guys?

[Gaza07]

I never thought about a KK board, I think it should work as it drives a servo for a tri, I have an old multi wii board that I will use if I do go ahead with it,
I suppose it would have to use the tx in heli mode single servo and setup throttle and pitch curves much the same as an heli, so once spooled up you would switch to idle up at mid stick zero pitch, sounds like it could be fun 

[usnooz]

the other thought is do you even need and fc?
Could you not have its 4 sevos controllered straight from the rx and have total manual control?

[secretman]

ya it's cool but... too mutch expensive... only a propeller strike cost a boom a axle a complete rear end. im stiking with my monster hexa next project :P

then no you cant control the stability like the fc ...

[usnooz]

yeah i've had a look a bit more at the mechanics and i'd want it to be a small quad.
My idea is to cut the booms down to 100mm in legnth each making the quad about 250mm rotor to rotor.
It will be small, light and less likely to incure any damage in a crash. it would be pretty cool as a small stunt quad. the one concern using the kk board is how its acts when the quad is inverted hence maybe the total manual route is better

[Gav]

interesting!   

I would personally not bother building one myself even if I could get a flight controller for CP.  What I love about quadcopters is the fact they have minimal mechanical parts / things that can go wrong. 
Collective pitch x 4  oh man you'd be fiddling for ages setting it up not to mention adjusting the tracking for each.

Need a massive net too like the one in the video for all the setup and maiden test flight.  no way can't be bothered with it.

Who has crashed a quad on their journey in this hobby?  everyone has.  with CP the repair bill goes up a helluva lot.

[usnooz]

well i've had a look and i only have 3 tail assmeblies so its probably not going to happen now.
I was only going to do it because i thought i had all the parts. I've got other things i want to spend my money on at the moment. 

[Gaza07]

That's a shame but I may still give it a go with 4 motors and 4 servos but it wont be for a while until funds will permit 

[usnooz]

yeah. On friday i'll be ordering 4x batteries, Nazza gps and immersion ezosd. That should be me done then.

[sausageroll]

The FC may be able to do this, the output from them is normal PWM, so it will move a servo no problem. Its just wether it moves it in the right way to control a CP multi.

I thought about doing this and having a turbine engine in the middle, make a big one, maybe 2-3ft rotor diameter...

[secretman]

no i think the kk will level upsine down... then manual forget about it

[sausageroll]

I think if you could take the PWM from the controller and trim the ends of the servos, as it will try and control the servo over either 180 or 90 degrees, which probably wont tally up with 0 pitch and full pitch on the blades. If you could set the end limits on an intermediate bit of electronics, then it would probably work.. as long as you controlled the throttle of the motors separately...