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Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
I thought about this a bit, and recalled that on a helicopter the gyroscopic torque is 90 degrees out of phase with the rotors. Therefore, your tilt control is similar to a cyclic pitch only system with rpm emulating collective pitch.
Since your tilt axis is 45' relative to the body, the gyroscopic forces will tend to pitch and roll your craft at the same time. Indeed, if the roll torques are mostly cancelled by each prop, there is still the pitch component which is why your craft is unstable.
The more blade weight you added will not change this effect.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
As you are unable to use swash plates with fixed rotation speed for controlling lift, What about a sliding counterweight to move the C of G away from the C of E (C of L) as the speed of rotation (and hence torque reaction) increases? (ie keep the craft level by moving the C of G automatically while in flight)
(You could use the battery pack as movable ballast, for example, to maintain trim.)
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
im trying to figure out how gyroscopic precession works, but the wiki article is complicated, the flat spinning disk has two axis of rotation and im confused, is there a better explantation anyone can point to?
i thought the rotations (torque, and spin) were suposed to oppose each other (CW and CCW),the difference between the two then generating the straight vector out the prependicular "top" ? right? or am i crazy?
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
A suggestion that might help you to 'get your head around it'. I assume you have access to a 4-4 1/2" angle grinder. Fire it up, and hold it in one hand (a grinding disk rather than a cutting disk will have more gyroscopic effect), now try to move it around in a controlled manner (observe all safety precautions here), and you will 'feel' the various torque reactions, etc through your hand. You will also 'feel' forces as it builds up to speed, etc. This might help you to understand what is happening, and give you a better 'feel' for it. (be safe, wear suitable personal protective equipment).
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