1995

Item 1995

DESIGN: Electrotor-SloMo - Rotorhead - Hub - A - Grip-S2

It looks like 1953.html can and should use the same mechanism for pitch stops. This mechanism is currently on 1970.html also.

Seriously consider an elastomeric bearing for the radial load-only-bearing, at least if the Rotorhead-Motor elastomeric bearing works out.

Drawing:

A greater then 1.5" spacing between the pitch bearings can Probably be achieved with the Grip-S2 if the inner bearing is put on the pitch link before the other bearing and the pitch-link is Inserted into the hub.

Concern:

The distance between the centerline of the blade and the centerline of the rear pitch bearing when the blade spar is directly above this bearing [ upper blade is at 246º azimuth and the lower blade is at 186º azimuth] is 3.243". The vertical distance from the pitch axis in the lower bladed to the top of hub directly above this bearing is 1.602". This leaves 1.64" for the upper blade thickness and clearances, at 19" radius. The upper blade will be about ???" thick at the grip and slightly less at this 19" radius. This should be JUST OK IF the dimensioning, etc. are correct. ~ Test on mockup.

Notes:

The chordline of the blade, at all locations along the span should probably be inline with the centerline of the pitch axis in the grip. This will mean that the lower thickness of the blade, at the point of the widest chord, will need to start increasing increase as a percentage of the overall thickness until it become 50% at the root end of the blade. Will this reduced clearance between now higher blade and the hub, and its bearings, below have clearance?

The attachment pin could be horizontal, if desirable.

Alternative: Consider reducing the size of both pitch bearing by 5mm. Will it be strong enough?

Consider using the pin slots in the hub as the end stops for pitch change; ~ autorotation to maximum pitch. Concern: This puts a load on the pitch arm etc. that can probably be better handled directly between the motor-rotor and aero-rotor. The locating of the pitch axis higher in the blade should result in the pitch link taking some of the load. Concern: Will this high pitch axis add to the aerodynamic drag without contributing anything to lift?

Probably have Blade Retention Pin ~ as 8mm metric. For calculations see 1957.html

The Ring and the End Block might be made as one item.

May want a small diameter passageway down the center of the root pin. This will allow the insertion of weights etc within the blade's spar for balancing.

It may be advantageous if the retention pin has a very slight taper. The taper will have no effect on changing the exact radius of the centrifugal forces of the blades. The shaft cannot be tapered because this could change the radius.

Use tapered pin to attach blade to hub. Metric Taper Pin Hand Reamers

To assure exact pitch angle alignment between airfoil and Pitch Arm.

Place completed airfoil into female curing jig.
Attach Pitch Arm positioning jig to female curing jig.
Insert blade Pitch Arm over the Blade Root.
Drill (and hone?) through Pitch Arm and Blade Root.

Last Revised: ~ January 27, 2011