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Old Mar 02, 2013, 10:34 AM
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Originally Posted by Peter Seddon View Post
You presumably know of the work of Gary Gress? His website is but a shadow of its former self but I have the attached paper.

Peter
Really good stuff Peter. I had not seen this before. He confirms the gyroscopic control effect in his writing.
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Old Mar 02, 2013, 02:24 PM
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Quote:
Originally Posted by leadfeather View Post

http://m.youtube.com/watch?v=W3FS3D1rCos
(old video of man on personal heli thing)
That thing looks like a blast. Segway of the skies!

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4) Conservation of angular momentum. Discussed in the first few posts.
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I am ONLY Stating my opinion based upon my observations and personal experiences. With the Props that I've used on my builds, the gyroscopic effect is minimum and do not overcome the other flight dynamics. In a total or near vacuum, then gyroscopic effect is supreme. The mass and the speed of spinning object is very important but to add enough mass or RPMs is a very hard challenges. I have a number of videos to support my claims but I digress.
I agree with rimshotcopter, too. Just watch the video of the tilt rotor with the vinyl records on the motors again. Pitch and roll are not held. They wobble back and forth, but can't hold an angle because the string holding the craft + gravity creates a constant torque on pitched/rolled airframe, which the gyroscopic forces can't fully overcome.
Old Mar 02, 2013, 03:08 PM
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Originally Posted by ilektron View Post
That thing looks like a blast. Segway of the skies!





I agree with rimshotcopter, too. Just watch the video of the tilt rotor with the vinyl records on the motors again. Pitch and roll are not held. They wobble back and forth, but can't hold an angle because the string holding the craft + gravity creates a constant torque on pitched/rolled airframe, which the gyroscopic forces can't fully overcome.
Do you have a link to this video please?
Old Mar 02, 2013, 03:16 PM
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3-axis Control in Space with Propellers? (/LPs?) (2 min 28 sec)
Old Mar 02, 2013, 03:30 PM
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Thanks for the video.

I think we are saying the same thing. The conservation of angular momentum will be conserved and rotation continues unless the system is acted upon by an outside force...such as gravity/pendulum effect, flying surfaces etc.

In the vinyl record experiment, had the pivot point of the string been at the cg instead of above the cg (no outside force this way), I think the the copter would continue rotating when the flywheels are canted..
Old Mar 02, 2013, 03:36 PM
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I think we are saying the same thing.
Indeed
Old Mar 02, 2013, 06:51 PM
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Great stuff. Thanks for discussing my issue of today - today. Just hovered my first bicopter but pitch seem really odd..-sometimes :/.
Old Mar 02, 2013, 08:43 PM
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Great stuff. Thanks for discussing my issue of today - today. Just hovered my first bicopter but pitch seem really odd..-sometimes :/.
Any photos of your copter? What did you observe that seemed odd?


For a bicopter VTOL I was thinking a nice control set up might be fans angled like Rimshotcopter's Mini-Mollie so that you get tilt and cant at the saem time, but then as the tilt continues for forward flight, the fans end up straight ahead. I'd like to figure a simpel way to do this so that only two sevos are used, one on each side to tilt the fan.
Old Mar 03, 2013, 04:17 AM
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i'm not sure if it will help your pursuit, but i think you guys will like these videos:
Eric Laithwaite's lecture part 1 (14 min 45 sec)

Eric Laithwaite's lecture part 2 (14 min 41 sec)

Eric Laithwaite's lecture part 3 (14 min 38 sec)

Eric Laithwaites lecture part 4 (14 min 36 sec)

Eric Laithwaite's lecture part 5 (1 min 14 sec)


some really neat experiments
Old Mar 03, 2013, 12:41 PM
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Search for OAT or scorpid 500 or scorpid 450 on www.DIYDrones.com. Gary Gress sometimes posts there as well.

Peter
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Originally Posted by leadfeather View Post
Really good stuff Peter. I had not seen this before. He confirms the gyroscopic control effect in his writing.
Old Mar 03, 2013, 01:53 PM
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This thread may be of some interest: https://www.rcgroups.com/forums/show....php?t=1238357
Old Mar 03, 2013, 06:09 PM
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Hey
Like Rim said, a key factor in this would be the mass of the propellers.
IMHO this in a flying machine would limit this phenomenon to only help with very small control adjustments?
Hence make this path, a very narrow oneto foollow
Old Mar 04, 2013, 12:11 AM
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Any photos of your copter? What did you observe that seemed odd?

Yes i need to upload a little video to youtube today. My pitch was weird until i put fixed vertical vanes under the pivot points.. -Now its only difficult -im way behind you guys..
Old Mar 04, 2013, 08:47 AM
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Gyroscopic Precession (3 min 49 sec)
Old Mar 05, 2013, 02:04 AM
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Quote:
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What? No Mini-Mollie?
This thread should be closed for such a blasphemous omission

Here are some picts of Osprino-V2, call sign Foamy-Charlie. The "canting" of the motors in Osprino-V1 was done by accident due to not compensating for dihedral in the wing and the wing bending under the load of the aircraft. Foamy-Charlie has a stiff wood front spar that doesn't bend when the aircraft leaves the ground. It's just a tricopter T frame without a rear motor.

The motors point straight up and straight forward. Nothing fancy here. Foamy-Charlie should hover regardless of prop rotation direction. Should work with two of the same direction props also.

You just have to play with the PIDs and stable mode a little. That's all. Osprino V1 and V2 don't work if "Stable" mode isn't on. That is the key my friends.

With the CG back, it hovers nose up. Stable mode keeps knocking the nose down though.

FoamyCharlie-FirstHover (0 min 52 sec)
Last edited by RCvertt; Mar 05, 2013 at 02:19 AM.


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