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Old Feb 04, 2013, 08:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,112 Posts
As you asked me to in a PM, I've looked at the videos and think that all the comments above have the problems or potential problems covered.

I think I also see a need for a little more stiffness in the wing. It looks like a single layer of foam with a spar top and bottom. If you added KFm2 top strip from the leading edge to the spar and glued that where it rests on the spar and also at the leading edge, it will add a lot of stiffness to the wing. You could even do that top and bottom like the KFm4 wings and get more stiffness. If that stiffening was in line with the rod the wing pivots on and another short two or three layer section KFm2 or KFm4 section added across where the two wing panels are joined at the leading edge, it should improve the wing strength.

I don't think a stronger wing is going to fix all the issues here though and make that easier to fly. It was just something I noticed...

You've chosen a tough task, it will need some effort to work it all out. Good luck with it!

Jack
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Old Feb 04, 2013, 09:29 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
i am using poly carbon sheet for doing this project, later i want to shift to foam. because due to fear that foam may break when crashed.

what do u suggest to use for stability FCB or Gyro




Quote:
Originally Posted by jackerbes View Post
As you asked me to in a PM, I've looked at the videos and think that all the comments above have the problems or potential problems covered.

I think I also see a need for a little more stiffness in the wing. It looks like a single layer of foam with a spar top and bottom. If you added KFm2 top strip from the leading edge to the spar and glued that where it rests on the spar and also at the leading edge, it will add a lot of stiffness to the wing. You could even do that top and bottom like the KFm4 wings and get more stiffness. If that stiffening was in line with the rod the wing pivots on and another short two or three layer section KFm2 or KFm4 section added across where the two wing panels are joined at the leading edge, it should improve the wing strength.

I don't think a stronger wing is going to fix all the issues here though and make that easier to fly. It was just something I noticed...

You've chosen a tough task, it will need some effort to work it all out. Good luck with it!

Jack
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Old Feb 04, 2013, 09:33 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
to be frank i was moved to tilt wing after looking at that video. as you suggested ealirer that tilt rotor is the toughest of all VTOL category.

now tell me which option is better for me

to use flybar with some modifications or FCB or Gyro




Quote:
Originally Posted by leadfeather View Post
Jyo,

Here is a video showing F&T's flybar stabilzed VTOL. I think this idea has some potential if the right stabilized rotors can be found. In his case, it look like F&T used rotors from a Blade CX helicopter which he modified quite a bit to get to work.

The flight of this plane does not look as stable as his later gyro stabilized craft, but with enough R&D it might be possible to get a good rotor designed and built for VTOL applications. AirHog did this on their toy VTOL.
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Old Feb 04, 2013, 09:34 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
what is differential flap can you tell me in detail



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Originally Posted by bz1mcr View Post
Rudder can control yaw in normal flight, but in hover it is not effective at all. There is just no air flow over the rudder in hover. Yaw in hover must be controled by differential flap which is like aleiron.
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Old Feb 04, 2013, 09:42 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,112 Posts
Quote:
Originally Posted by jyothibasu1k View Post
i am using poly carbon sheet for doing this project, later i want to shift to foam. because due to fear that foam may break when crashed.

what do u suggest to use for stability FCB or Gyro
I have no experience with either a FCB or a Gyro, the guys that suggested it should be able to answer that I think.

Jack
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Old Feb 04, 2013, 09:44 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
okey..
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Old Feb 04, 2013, 10:07 AM
Winging it >
leadfeather's Avatar
Joined May 2006
9,719 Posts
Jyo,

I think you can reach your own conclusion for fcb or gyro if you think the whole control scheme through from hover to transition to forward flight and back. Once you really think it through and understand what has to happen the best answer will become evident.

Here is another suggestion that may be much easier for you to attain success with the limited time you have for this project. Would you consider making your craft short take off and landing (STOL)? The wing would go from about 45 tilt to forward. This way you should be able to proceed quickly without adding gyros or a fcb and no need for the yaw and roll control switch over.
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Old Feb 04, 2013, 10:22 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
yes, i wanna maintain

VTOL, CTOL and STOL in my project if all comes together in my way

the title of our project is "Tilt Wing RC Aircraft "
any thing that is satisfying this project i am ready to do.


Quote:
Originally Posted by leadfeather View Post
Jyo,

I think you can reach your own conclusion for fcb or gyro if you think the whole control scheme through from hover to transition to forward flight and back. Once you really think it through and understand what has to happen the best answer will become evident.

Here is another suggestion that may be much easier for you to attain success with the limited time you have for this project. Would you consider making your craft short take off and landing (STOL)? The wing would go from about 45 tilt to forward. This way you should be able to proceed quickly without adding gyros or a fcb and no need for the yaw and roll control switch over.
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Old Feb 04, 2013, 11:02 PM
Registered User
Ran D. St. Clair's Avatar
United States, CA, Sunnyvale
Joined Dec 2006
993 Posts
Jyothbasu1k,

I received your PM. Leadfeather is giving you some very good advice. Success with VTOL requires either years of trying, failing and learning, or if you want to be smart about it, start from an existing successful platform and evolve from there. You have started down a more difficult path with your existing platform. If you want to see more immediate success then start with a proven quad-copter or tri-copter configuration.

Your tilt wing 2 rotor platform is one that can certainly be made to work, but you have a lot to learn and a fair amount of money yet to spend if you insist on going down that path. Most people can't take all the failure between you and success if you go that way. Better to choose an easier path at first. .

I suggest you buy a KK2 board.

http://www.hobbyking.com/hobbyking/s...rol_Board.html

The price is reasonable and it has the flexibility to do most anything you could want. There are many other fine flight controller boards out there, but this one is more "plug and play" than most.

If you insist on this platform then I suggest you go back to basics Build your prototype with the wing fixed vertical first. Get the CG correct so the wing hangs perfectly vertical from the props. At that point the fuselage is just a place to put the radio gear and has nothing to do with flying. Elevons on the two control surfaces behind the propellers and differential thrust on the two motors is all you need for a fully controlled hover.

You will be able to fly such a craft forward slowly but if you ever get it into anything approaching forward flight you will have serious CG problems, as well as control problems. Come back when you get that far and we will help you from there.
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Old Feb 05, 2013, 01:27 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
i have already tested CTOL with the similar wing on another fuselage

Test 3 (1 min 40 sec)


ya, i have to test fixed wing vertical take off



Quote:
Originally Posted by Ran D. St. Clair View Post
Jyothbasu1k,

I received your PM. Leadfeather is giving you some very good advice. Success with VTOL requires either years of trying, failing and learning, or if you want to be smart about it, start from an existing successful platform and evolve from there. You have started down a more difficult path with your existing platform. If you want to see more immediate success then start with a proven quad-copter or tri-copter configuration.

Your tilt wing 2 rotor platform is one that can certainly be made to work, but you have a lot to learn and a fair amount of money yet to spend if you insist on going down that path. Most people can't take all the failure between you and success if you go that way. Better to choose an easier path at first. .

I suggest you buy a KK2 board.

http://www.hobbyking.com/hobbyking/s...rol_Board.html

The price is reasonable and it has the flexibility to do most anything you could want. There are many other fine flight controller boards out there, but this one is more "plug and play" than most.

If you insist on this platform then I suggest you go back to basics Build your prototype with the wing fixed vertical first. Get the CG correct so the wing hangs perfectly vertical from the props. At that point the fuselage is just a place to put the radio gear and has nothing to do with flying. Elevons on the two control surfaces behind the propellers and differential thrust on the two motors is all you need for a fully controlled hover.

You will be able to fly such a craft forward slowly but if you ever get it into anything approaching forward flight you will have serious CG problems, as well as control problems. Come back when you get that far and we will help you from there.
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Old Feb 05, 2013, 03:44 AM
1400 watt RW Zephyr
matwelli's Avatar
Taranaki New Zealand
Joined Sep 2003
1,336 Posts
one issue to look at, apart from everything above (including getting a KK2 board, because you really need it, and it will handle the mixing) is when in hover, how far is your vertical CG location from the pivot point of your pitch control ?
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Old Feb 05, 2013, 03:49 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
under the pivot center.. i mean both at same line.





Quote:
Originally Posted by matwelli View Post
one issue to look at, apart from everything above (including getting a KK2 board, because you really need it, and it will handle the mixing) is when in hover, how far is your vertical CG location from the pivot point of your pitch control ?
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Old Feb 05, 2013, 03:54 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
@lead feather, Ran, jacks

we are trying to work with flybar. the FCB/Gyro's are our last hope. i will be updating my trail results here..
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Old Feb 05, 2013, 04:16 AM
1400 watt RW Zephyr
matwelli's Avatar
Taranaki New Zealand
Joined Sep 2003
1,336 Posts
No . The vertical distance between the pivot point and your cog . You need distance in order to have control
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Old Feb 05, 2013, 06:36 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
i am unable to catch your point. how can i keep distance between pivot and cg.

if distance is kept then how can the fuselage hing to pivot and balance cg


Quote:
Originally Posted by matwelli View Post
No . The vertical distance between the pivot point and your cog . You need distance in order to have control
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