Item 1207

DESIGN: Dragonfly ~ Control - Flight - Assembly - Phase Lag

Sources:

 

Due to delta-3:

Delta-3 is currently 0º. This is an option, which may be included in the future. It involves putting a slight twist in the slider spline. OTHER: Flight Dynamics - General - Pitch-Flap Coupling ~ Method C

Due to Flapping Hinge Offset:

See below.

Due to Gyroscopic Precession:

Due to Forward Velocity: ? Active

Total phase lag should be:

0º [delta3 contribution], + (90-65)º [flap hinge offset contribution], -?º [gyro contribution], = 25º.

Flapping Hinge Offset: To establish the amount of phase lag required to work with the rotor's offset.

Damping ratio = damping / critical damping = c/cc

Frequency ratio = RRPM / natural frequency of blade flapping (undampened) = Ω/ωN undamped

Ω = 68 rad/sec

c =

cc =

ωNundamped =

Assuming a constant mass distribution in the blade; ωn /Ω = root( 1 + (((3/2) * (e/R)) / (1 -(e/R)))) = root( 1 + ((1.5 * (13.5/96)) / (1 -(13.5/96)))) = root( 1 + (0.211/ 0.859 )) = 1.116

For Ω/ωNundamped I think that the value will be 1/1.116 = 0.8960

 

c/cc = ( γ / 16) * (1 - (e/R)4 * ((1 + ((1/3) * (e/R)))/(1 - (e/R))) * (1 / (ωn /Ω)) = ( 6.54 / 16) * (1 - (0.141)4 * ((1 + ((1/3) * (0.141)))/(1 - (0.141))) * (1 / 1.116) =0.409 * 0.544 * 1.219 * 0.896 = 0.243

The value used above for ' γ ' [blade Lock nbr.] is the SynchroLite's value of 6.54

From figure 7.3 [Source ~ RWP1 p.447] the phase angle will be 65º. This is certainly low ~ recalculate to check.

This should give good clearance between the swashplate and the pinion.

See drawing on; DESIGN: Dragonfly ~ Control - Flight - Mixer - Overview

Related Pages:

DESIGN: Dragonfly ~ Control - Flight - Cyclic - Overview

MAKE: Dragonfly ~ Control - Flight - Spider - Stick

OTHER: Flight Dynamics - General - Phase Lag

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Last Revised: December 4, 2003