Two Helicoptor Questions
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Joined: Nov 2003
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From: truely asia
Two Helicoptor Questions
Never have worked on helicoptors, mostly do fixed wing aeroplanes.Heli aerodynamics seems more complex compared to aerplanes. have been struggling with these two questions especially the frist one.
Appreciate any comments not neccassarily answers, as the possibly first question may be incomplete.
Second question my impression is as CG (weight and drag) points are below the lift and thrust vector point of operation with increase in speed as the parasitic drag increases and dominates the other drag forces, helicoptor will have pitch down tendency due to parasitic drag
If stability lock switch is turned off
A. Returns all trim commands to normal
B. Returns cyclic stick to centre and keeps a/c at same attitude and speed
C. Returns cyclic stick to centre and keeps a/c at same attitude
1. What affect does parasitic drag have on the attitude of a helicopter in flight.
a. Helicopter pitches nose up
b. Helicopter pitches nose down
c. No effect
Thanks
Nomadd
Appreciate any comments not neccassarily answers, as the possibly first question may be incomplete.
Second question my impression is as CG (weight and drag) points are below the lift and thrust vector point of operation with increase in speed as the parasitic drag increases and dominates the other drag forces, helicoptor will have pitch down tendency due to parasitic drag
If stability lock switch is turned off
A. Returns all trim commands to normal
B. Returns cyclic stick to centre and keeps a/c at same attitude and speed
C. Returns cyclic stick to centre and keeps a/c at same attitude
1. What affect does parasitic drag have on the attitude of a helicopter in flight.
a. Helicopter pitches nose up
b. Helicopter pitches nose down
c. No effect
Thanks
Nomadd
"Just a pilot"
Joined: May 2001
Posts: 633
Likes: 8
From: Jefferson GA USA
>If stability lock switch is turned off
If the question concerns autopilot type equipment, the controls will remain at last command input position whether set by hand or servo command. All controls function normally, stability gear engaged or otherwise (largely- there are exceptions to this very broad statement).
>A. Returns all trim commands to normal
>B. Returns cyclic stick to centre and keeps a/c at same attitude >and speed
Helicopters are always in the process of diverging from trim. All attitude and speed settings are temporary. You set the controls for configuration desired and then correct for changes as they occur.
>C. Returns cyclic stick to centre and keeps a/c at same attitude
See above- there is no useful "center" for controls except once landed. The trim switch, in most helicopters, doesn't change control rod length, it reduces felt control load. In a helo with boosted controls, that force is artificial and trimming changes the centering position of the springs creating control feel.
>1. What affect does parasitic drag have on the attitude of a >helicopter in flight.
Yes. That's the correct answer because "in flight" could be in any or no direction, except up...
The fuselage vector is below the thrust line, so aircraft response to forward cyclic is nose down and follows the disk. That's the way pilots think of it anyhow- the fuselage follows disk inclination. There are times and aircraft where this rule of thumb has exceptions, however. For instance, some aircraft pitch down in rearward flight configurations instead of nose up, as you'd expect. The tendency is startling the first time you encounter it, but one continues to direct the aircraft as desired as long as attitude doesn't continue to diverge.
If the question concerns autopilot type equipment, the controls will remain at last command input position whether set by hand or servo command. All controls function normally, stability gear engaged or otherwise (largely- there are exceptions to this very broad statement).
>A. Returns all trim commands to normal
>B. Returns cyclic stick to centre and keeps a/c at same attitude >and speed
Helicopters are always in the process of diverging from trim. All attitude and speed settings are temporary. You set the controls for configuration desired and then correct for changes as they occur.
>C. Returns cyclic stick to centre and keeps a/c at same attitude
See above- there is no useful "center" for controls except once landed. The trim switch, in most helicopters, doesn't change control rod length, it reduces felt control load. In a helo with boosted controls, that force is artificial and trimming changes the centering position of the springs creating control feel.
>1. What affect does parasitic drag have on the attitude of a >helicopter in flight.
Yes. That's the correct answer because "in flight" could be in any or no direction, except up...
The fuselage vector is below the thrust line, so aircraft response to forward cyclic is nose down and follows the disk. That's the way pilots think of it anyhow- the fuselage follows disk inclination. There are times and aircraft where this rule of thumb has exceptions, however. For instance, some aircraft pitch down in rearward flight configurations instead of nose up, as you'd expect. The tendency is startling the first time you encounter it, but one continues to direct the aircraft as desired as long as attitude doesn't continue to diverge.
