This is an interesting question and from my limited knowledge of this aspect of heli v ground. For my part there is NO ground effect because unless the landing profile is truely vertical for some reasonable period of time No ground effect will be produced. As most practice EOLs will start from a suitable hight and speed the resultant landing will be performed with some run-on forward speed utilising 'Translational Lift' and leaving the ground effect behind, but catching up. Unfortunately by the time the GE has caught up the RRPM is unable to support the helicopter.
What do you think about the Translational Lift idea. I know it exhists and I think it's there for me to use.
Any thoughts?
For RobboRider....
You can see the pressure that a rotating rotor produces.
Sit in your heli. Adjust the Altimeter to Zero. Start up and once at Flying RPM look at the altimeter. Note reading. Lift off into a very low hover (skids just clear of the ground) look at the altimeter again. In each case you will see that according to the altimeter you have descended (ie pressure increase)
And for others. And my three cents worth. Ignor the Grouind Effect theory and think 'Translational Lift' as the benefactor helping to cushion the landing
DeltaFree. I actually agree that when an aerofoil is in close proximitry to the surface a pressure increase will affect the AoA giving a benefit of less power required. There will be a Translational Lift element reducing as forward speed reduces and Ground Effect will be increasing as the heli slows. During this phase of an EOL the RRPM will be reducing fairly quickly and my logic forces me to consider that 'yes ' there will be a GE but in reality of no damm use 'cause what little there was to start with is dissipated in milliseconds and there isn't going to be any real benefit.
A wonderful subject which has increased global warming which that in it's self must reduce lift by the factor of 'n' due to the reduction in density.
Just one last point.
During my Military Helicopter Course and thereafter we were taught and practiced a Constant attitude EOL. Timing was all important and the application of too much collective lever at the point of landing would certainly produce an effect of blowing grass and an unconfortable feeling of running out of collective lever for the final touchdown. But we never did. Can I put it down to Ground Effect? In my mind I shall.
Last edited by Tail Bloater; 28th November 2002 at 13:34.