1061

Item 1061

DESIGN: UniCopter ~ Rotor - Disk - Stall Recovery

Blade stall due to low RRPM is the second highest cause of fatal accidents.

A plane can recover from a stall by pitching the nose down, increasing the forward air speed and restoring lift on the airfoil (wings).

Assuming that a helicopter was manufactured which had;

Symmetry, due to twin (side-by-side or intermeshing) rotors.

Advancing Blade Concept.

Absolutely rigid rotors.

Adjustable horizontal tail (elevator).Why? The CG is ahead of the rotors (wing) so the nose will automatically want to drop.

If this helicopter was to experience totally stalled rotors, why could it not do the same as the plane? Pitch the nose down, increasing the forward air speed and restore the lift on the airfoils (blades)?

Concerns:

Rotor blades may not have sufficient area.

Possibility of advancing tip exceeding Mach

Possible Solutions:

The rotor is a compromise between optimum hover and optimum fast forward speed. Perhaps it might have to be compromised for stall recovery.

Small wings (that are normal for a compound helicopter) will assist in providing lift.

A small drogue chute from the end of the boom may assist with the initial recovery.

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Last Revised: April 27, 2005