Item 0442
DESIGN: SynchroLite ~
Rotor - Disk - Blade to Hub Clearance (CVJ+HS)Note ~ it looks like the stagger may now be 25" if power train 0008 is used.
Drawing:
Notes:
Pitch rods to go at trailing edge.???
Blade Pitch Angles (θ theta)
Swashplate
Cyclic –
Longitudinal
Lateral +/- 8º; total of 16º.
- Note that the outward tipping rotor tips twice the amount as the inward tipping rotor. I.e. when left lateral cyclic is applied the port disk will tip say 6 degrees to the left whereas the starboard disk will tip to the left only 3 degrees. This means that there is greater clearance between the blades and rotor hubs. This can be done by the azimuth of the mixer box tabs on the lateral cyclic tube.
Collective: +17º to -3º; total of 20º. (Note: -3 is large because of –1.4 zero lift angle?)
Rotor Hub
Up - +13 & +17 = +30º. Make +20º.
Down - -9 & -3 = -12º. Make -5º.
The normal pitch angle for level flight at 55 knots will be around 6 degrees. This is 11 degrees above the minimum and 14 degrees below the maximum rotor hub pitch range. Therefore put pitch arm at 90 degrees to mast when blade is at approximately 6 degrees. I.e. 6 degrees of blade chord line.
Does this take –1.4 into account?Position Blade angle off perpendicular to mast
Max. Up 20
Median 6 0
Max. Down - 5
From Drawing 0442; With -4º of inward lateral teeter, +3º coning angle and at maximum pitch of +20º the blades trailing edge will hit the other mast's rotor hub. This is probably not a problem since if the pitch is this high then this side of the disk would be tipping the other way.
Make the top of the hub and grips as low as possable. Also give them 20 'flatish' surfaces at an angle of 20 degrees off the horizontal; so that any blade strike will cause little or no damage. Might want to consider a small wear plate on the underside of the blade at this location. This way any minor contact will temporarilly decrease the pitch instead of causing damage. The blades could also have a small notch-out in this location; infact there could be a large radius notch from lead-lag pin out say 3' since very little lift is generated in this area and some of it is wasted on the fuselage. Don't forget need to cool engines.
Twist:
May 1, 2000 ~ It would appear that the drawing and above notes do not take twist into account and twist will reduce the clearance. Note: I think that Kaman's blades have no built-in twist and also no pitch change at ther root.
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~ Dragonfly ~ UniCopter
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Last Revised: January 27, 2005