posted on Feb, 27 2006 @ 11:25 AM
The first clip takes too long for my dial-up, but the second clip was interesting.
Thanks for posting.
That said - and aside from the brave-enough-to-do-it factor - it may not be that difficult.
Once a plane is trimmed out and power settings remain unchanged it will remain at the trimmed altitude.
If you're trimmed for say 3000' with auto-pilot disengaged stick the nose down a touch via the stick or yoke the plane gains speed which equals
Release the stick/yoke and the plane will level out then start a gentle climb.
It will gain altitude until it passes through the originally trimmed 3000'.
Then (still hands-off the controls) it returns to level and due to lack of power for the new altitude - say 3100' - the nose goes down and you get a
gentle up and down ride until the plane settles out at 3000' once again.
Ground effect enters into very low flight.
Ground effect maximum altitude is roughly equal to the wingspan.
In fact, low wing private plane pilots have been heard to comment - just about every time - that making a wheels up landing, the last few feet seemed
to take forever since ground effect is strongest at the extreme low altitude prior to belly touching the runway.
Ground effect occurs - the way I understand it - due to the down-wash of air is unable to escape downward and compresses which adds lift.
At altitude this compression of air or increased lift is absent.
So it looks to me like the pilots of these low flying aircraft are setting the plane up for level flight and using the trim control to bring it down
into close proximity with ground or ocean.
It looks to be a fairly predictable process and there's a balance attained between very slight nose-down trim and the added lift from ground
And once trimmed, the plane stays pretty much where it is height-wise due to the self-correcting that goes on between trim and ground effect.
Sounds simple and it is, but it still requires a pair of brass ones to fly like that.
As a small aside, flying extremely low over an open dirt field as shown in the short second clip I would imagine the pilot is keeping a close eye out
Hitting one may not hurt, but there's probably some downward air flow on the outside of thermals.
Air going up has to come from somewhere.
It would be advantageous flying over the ocean waters, no thermals there due to the constant temperature of the water.
Same thing over ice fields.
Alaskan flying in the winter (on non-stormy days) is reputed to be about as smooth as it ever gets.