Item 0918

DESIGN: UniCopter ~ Trim, Stability & Control - Trim - Vectored Efflux

Symbol Definitions - Flight Dynamics

Vectored Efflux (exhaust & cooling):

No effect during autorotation, unless directed down to assist with nose down pitch change on loss of power. If vectored downward at end of tail boom it will offset rotor torque changes.

What is the volume of the exhaust at 100% RRPM

What is the volume of the cooling air at 100% RRPM

see Thrust

If it can be vectored to each side then it could assist with yaw. See: DESIGN: UniCopter ~ Trim, Stability & Control - Control # Pitch Change & Autorotation

Forces on End of Boom:

k is a constant that is the thrust of the exhaust and cooling for 1 RRPM [Ω]

 

XE =

Ω *  k * cos(δ)

 

YE =

Ω *  k * sin(δ)

 

ZE =

0

 Notes:

Exhaust drag D ex = m ( V - Vex * cos(χ) ) | Where m is engine mass in slugs per second and χ is the exhaust cant angle.

Exhaust drag will be thrust if Vex > V but this thrust could cause problems in hover. [Source ~ RWP1 p.304]

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Last Revised: May 8, 2002