B330

OTHER: ~ Flight Dynamics - General

Overview:

General information on dynamics that may not relate directly to the specific projects at this web site.

Topics:

 

Topic:

Location:

 

OTHER: Flight Dynamics - General - Cross-coupling:

0842

 

OTHER: Flight Dynamics - General - Ground Resonance:

1246

 

OTHER: Flight Dynamics - General - Lateral Cyclic Force in Forward Flight and Friction in Feathering Hinge:

this page

 

OTHER: Flight Dynamics - General - Moments & Forces: ?

this page

 

OTHER: Flight Dynamics - General - Phase Lag

0998

 

OTHER: Flight Dynamics - General - Pitch-Flap Coupling (delta3)

0941

 

OTHER: Flight Dynamics - General - Power Loading

0939

 

OTHER: Flight Dynamics - General - Pitch-Lag Coupling

0682

 

OTHER: Flight Dynamics - General - Flap-Lead Coupling, for Intermeshing Rotors & Pitch-Lag Coupling

0433

 

OTHER: Flight Dynamics - General - Precession - Gyroscopic and Aerodynamic

0940

 

OTHER: Flight Dynamics - General - Information Related to Coaxial only:

this page

 

OTHER: Flight Dynamics - General - Rotor Coefficients

1099

 

OTHER: Flight Dynamics - General - Rotor Inertia

1013

 

OTHER: Flight Dynamics - General - Lead/Lag:

1239

Moments & Forces:

Aerodynamic:

My posting;

A leftward force on the cyclic stick is caused by a swashplate that wants to tilt to the left. This desire of the swashplate to tilt to the left is caused by the pitch link on the advancing side imparting an upward force while the pitch link on the retreating side is imparting a downward force. Assuming that the pitch links are only subjected to rotational forces about the feathering axis then there must be an aerodynamic force (drag or lift) that is wanting to increase the pitch of the blade when it is over the tail and decrease the pitch when it is over the nose.

I suspect that that the coning angle is causing this since the blade over the tail is experiencing more airflow from above it then the blade over the nose. For example; if a blade had angle of attack of 90 degrees, the force on the rear 75% would be greater than the force on the front 25%, and it would want to rotate the blade toward 0 degrees not 180.

If this argument is valid then the smaller the coning angle the smaller the force that is required to hold right cyclic in forward flight.

Portion of reply by C.A. Beaty:

Coning angle does introduce a sideways flapping component but it isn't much with shallow coning angles. The old Sikorskys with fabric blades had a considerable sideways rotor tilt because they flew at a 10 or so coning angle.

Centrifugal:

Ground Resonance:

See; OTHER: Flight Dynamics - General - Ground Resonance

Lateral Cyclic Force in Forward Flight and Friction in Feathering Hinge:

The swashplate is tilted forward during forward flight. In a conventional single rotor helicopter, this means that when the pitch links are on the starboard side they must move down and when they are on the port side they must move up. Any resistance to this motion, specifically friction in the feathering hinge, will resist this oscillation of the pitch links and attempt to pull the cyclic stick to the left.

In the SynchroLite it may want to isolate the cyclic stick in a lateral direction at 2P.

Information Related to Coaxial only:

For additional information see on Web:- NASA Technical Paper 3675, March 1997, A survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research. (I have a hard copy.)

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Last Revised: February 19, 2009