Peter wrote:
I agree – unless the controls are locked (as they should be).
It was “take-off with no back-pressure on the yoke.” I don’t think controls should be locked for that. 
I also don’t understand why the aircraft can’t move in pitch? How else would you rotate to lift off? The aircraft is free to rotate in pitch both ways on the ground… either as a wheelbarrow, or nosewheel off. The trim will determine how early it lifts off.
I agree – unless the controls are locked (as they should be).
Peter wrote:
On the ground, the trim tab will have only the same effect which it has in flight with a totally jammed elevator i.e. it acts as a tiny adjustable elevator (and it works in the opposite direction to usual ).
What do you mean with ‘totally jammed elevator’? The original question was take-off with no back pressure on the yoke … not a frozen yoke.
I also don’t understand why the aircraft can’t move in pitch? How else would you rotate to lift off? The aircraft is free to rotate in pitch both ways on the ground… either as a wheelbarrow, or nosewheel off. The trim will determine how early it lifts off.
RobertL18C wrote:
…in a tailwheel you are ideally sitting at stalling AoA on the ground, so a lightly loaded Super Cub should start to levitate with around 40mph winds…
That reminds me of the video that was here recently from the Air Force Academy. 
…some of us have variable incidence tail plane trim, just like on a jet…now why didn’t Piper install a Mach trimmer on the Super Cub…
…in a tailwheel you are ideally sitting at stalling AoA on the ground, so a lightly loaded Super Cub should start to levitate with around 40mph winds…
Does the trim have any (significant) effect when on the ground?
The trim tab + elevator system works in flight, as a negative feedback control system for maintaining pitch (i.e., for a given load config and power, maintaining airspeed).
But it only works thus if the whole aircraft is free to move in pitch.
On the ground, the trim tab will have only the same effect which it has in flight with a totally jammed elevator i.e. it acts as a tiny adjustable elevator (and it works in the opposite direction to usual ).
Basoutos wrote:
Actually the AoA is probably similar to the one in cruise, so the wind would need to be a lot closer to your cruise speed in the configuration than the stall speed. I don’t believe that ground-effect would change that significantly.
True, but, it would be quite possible to raise the nose, by applying elevator input. With enough wind over the horizontal tail surface that should enable you to raise the nose at least a little. Fun question
Basoutos wrote:
Easy to test: take-off with no back-pressure on the yoke, see at what speed that is actually achieved at lift-off (assuming a flat runway)
A small boast about my record which was a very genuine 50 knots gusting 55 in a DA42. I recall the taxi turning cross wind was interesting. I also recall aborting the landing at the home base very early on (why did I even have a look), electing to divert where it was almost staight down the runway which fortunately I had considered before because there was almost no where with a suitable runway heading. The only other aircraft flying was a Warrior which was clearly having fun and I think almost managed stationery in the over head.
As so often the case with a northerly it was unpleasantly turbulent and the flight was also memorable because I recall so well just how hard I hit my head on the canopy – there is a lot to be said for proper four point harnesses. Even the CATS into Gatwick were working hard that day!
I could tell a story about my Husky flying skils on a somewhat less windy day but that was mildly embarassing, and as others have said your and their assessment when it comes to high wing is exactly right!
At Vs you would also need a high angle of attack to produce the lift necessary. Which wouldn’t be the case for a tricycle aircraft.
Actually the AoA is probably similar to the one in cruise, so the wind would need to be a lot closer to your cruise speed in the configuration than the stall speed. I don’t believe that ground-effect would change that significantly.
Easy to test: take-off with no back-pressure on the yoke, see at what speed that is actually achieved at lift-off (assuming a flat runway)
I would guess it doesn’t make a difference whether the ground moves at 0 kt, or whether the ground moves at -59 kt. I.e. ground speed has no effect on ground effect.
I agree. So one would need a head-on wind substantially below Vs2 (etc) to lift the plane off.
