Spaz,
Many thanks - very useful. The items you've posted are really useful, in that they illustrate the complexity of getting a powered lift vehicle to work properly through all points of the transition from hover to forward flight (and back again).
dat581 - The VTO is a great illustration of the fact that 'just because it looks like a non-event, it's really not'. Coming down to the ground from hover height will cause the airflows of hot and cold gas under and around the aircraft to set themselves up in a certain way, especially the cold air 'screen' between the hot exhaust and the air intakes. Staring with the aircraft on the ground will generate a different pattern of gas flows, some of which you might not want. These flows will also be affected by relative wind.
As ever with powered lift aircraft, you start with clever and thorough design, and then go into careful and thorough testing.
Hope this helps,
Engines