Originally Posted by xviper
It may help to rotate the plane, but downward thrust does not equate to forward thrust and hence, acceleration would suffer as soon as the thrust diverges from the longitudinal axis of the plane. I think the only way to test this is the try it both ways. Remember early in this thread, someone had a very hard time getting the thing to lift off the ground. It took up a lot of runway before it flew. I don't recall seeing what he did to resolve this but he did manage to get it to lift off "normally" eventually. I do remember reading somewhere that vectored thrust jets should take off with the VT defeated till it's in the air. This is not counting jets like the VT Sebart Mig-29, which can be held at a near vertical position and lift off on its own power. Someone who has flown this plane should try it both ways and report back.
I have that very same jet and I'll tell you right now that TV will get the nose to rotate earlier and get you off the ground in a shorter distance than with out it. I've run a mix that puts in a little tail down TV with elevator application on my jet for take off.. The 'real' jet actually does a similar thing except the rudders are used instead to give a tail down moment on take off....