RC India

RC Models => Multirotors => Topic started by: krishnateja on April 23, 2013, 08:59:40 AM



Title: VTOL help required
Post by: krishnateja on April 23, 2013, 08:59:40 AM
I am planning to build a VTOL aircraft like v-22 osprey.What is the mechanism of tilting the propellers at the wing tip? How to use the rudder to change the direction of aircraft when it is flying like a helicopter?

CAN anyone pls help me out?

THANK YOU. :)


Title: Re: VTOL help required
Post by: rohitgupta322 on April 23, 2013, 06:58:10 PM
If this the first time that you are building a multicopter, it is better that you start with a quad or a tri and learn first.

A tiltrotor is a very complex design. Stability is the biggest problem in such a design. Even though V22's are in operation, there are a number of precautions and restrictions in various flight regimes that the pilot must follow and take into account , a lot of research is on in this area but things have not been completely mastered/understood as far as the V22 is concerned.

Some of the problems are as follows:

While hovering, a bicopter has an inherent tendency to be unstable in the pitch axis, the fuselage starts oscillating about the axis joining the motors. Damping such oscillations require complex stabilization system(both mechanical and electronic). The real V22 has CCPM, variable pitch rotors, with gyroscopic stabilisation and pendulum damping.

The transition stage is the next major problem. Large forces arise due to gyroscopic precession of the rotors and the heavy engine and therefore have to be taken care of, the aircraft is most tentative during transition. Even the V22 has problems during transition and therefore, Bell Helicopters is working on a new design in which the engine doesn't tilt forward only the rotors do. It is called the BELL V280 Valor http://bellv280.com/ .

Therefore a lot of research is required in this front. Moreover, you might have to write your own code, because as far as I know none of the quad control boards available have a firmware for a tiltrotor. Multiwii codes for a tricopter tiltrotor and a quad tiltrotor are availabe though.

IMHO one needs to do a solid couple or more months of research before one attempts to build this.


Title: Re: VTOL help required
Post by: parichya.gautam on April 24, 2013, 07:09:01 AM
And thats the reason why ill be using 4 motors to make one XD


Title: Re: VTOL help required
Post by: vinayb1984 on April 24, 2013, 11:00:37 AM
parichya.gautam have you seen x19 humming bird it is a quad vtol plane it may help you
i am also working on it waiting for electronics from hk . soon ill start to build some thing like that .
below is the video hop it may help
https://www.youtube.com/watch?v=BWQiaYLgIaI&playnext=1&list=PLpjBzEYlFBlAI9f3EP-tITSEI7_DaCATR&feature=results_main


Title: Re: VTOL help required
Post by: parichya.gautam on April 24, 2013, 11:06:56 AM
i know about it :) i only have the frame left to be made all the other stuff is ready with me :)


http://www.rcindia.org/rc-maneuvers-and-skills/new-project-ideas-on-maneuverability/

My Thread where i had my share of queries ( designs too ) :)


Title: Re: VTOL help required
Post by: rohitgupta322 on April 24, 2013, 11:43:46 AM
That foam and tape's quad tilt rotor is the only "working" hobbyist quad tilt model that I have come across. It uses the multiwii code for quad tiltrotors. A similar code as I have mentioned before is also available for a tri tiltrotor. So you can basically use a crius multiwii board(or an arduino+nunchuck) with this code. However, the settings during transition in the code was specifically written for Foam and Tape's plane. You might have to modify it for yours.


Title: Re: VTOL help required
Post by: parichya.gautam on April 24, 2013, 11:46:56 AM
what about on KK2 board ??


Title: Re: VTOL help required
Post by: rohitgupta322 on April 24, 2013, 11:54:45 AM
The KK board AFAIK doesn't have any setting for a tiltrotor. How are you going to prevent the gyros and the accelerometers from sending feedback after the transition is over and then bring it back on once you go back into hovering mode. Also, you will need a servo delay to gradually transition from hovering to forward flight, and you will have to program it in such a way that to a certain point during the transition, the gyros are 'on' and then after that they 'shut off'. That time might be different for different planes and in F&T's plane, it was set up after doing multiple transitions and finding out which works best.


Title: Re: VTOL help required
Post by: parichya.gautam on April 24, 2013, 11:57:44 AM
Custom coding on the KK2 wont help ?