I've watched the Oshkosh aerobatics show a couple of times now, and many of those guys did a torque roll of some kind. The way they do it looks like the plane is hovering anywhere from maybe 5 seconds to possibly 10 seconds before it tail slides. With the distance involved, I couldn't for sure tell when the plane stopped climbing, and started to fall or how long in between. I did not see Wayne Handley fly the ill fated Turbo Raven. I've never seen a video of him showing a hover and vertical climb out. All I can say is that if there ever was a plane to do it, it was the Turbo Raven. A plane at 1900 pounds at 2800 pounds of thrust has the power to do it, and pilot orientation is not an issue. All they care about is having the bullseye level with the horizon. The only hinderance I'd see is the overheat problem someone else mentioned. Turbines like smooth airflow in and out. If all the sudden it was having to pull hard to breath, it might want to heat up, or just plain quit. I guess that doesn't say it can't, won't, or didn't do it...

I did see Kirby Chambils do his "Cobra". He is all but 90 degrees nose up. He isn't there long, and he also does not climb straight up, or anywhere near it. He pushes the nose right back down and flies the plane out. The poor Lycoming 580 is howling when he does that, and the prop is way supersonic.

I would say that there are many full scale pilots with planes that would harrier, but none will hold a hover for more than a handful of seconds. At the (model aircraft) field, I've heard guys say, "it's almost hovering", and all I see is a real slow tail slide. Does it count? Well, to them it did. I guess it's one of those "eye of the beholder" things. When does a hover become a hover? If one second counts, then most Gullows planes will hover.