The wonderfully crazy folks who strapped a miniature gas turbine to a skateboard for me were, at the time, working on an order for a matched set of eight such engines for a scale B-52 project (scroll down for pics). The result flew earlier this year, and was utterly magnificent. At over 7m, the span is greater than some light aircraft.
Sadly, it crashed, in what from the video (Windows Media Player) looks like a textbook copy of a real B-52 crash from years back. There’s much discussion in the R/C model forums about the cause, but the bottom line seems to be that roll spoilers do not provide adequate control authority when low and slow: B-52s apparently cannot recover from bank angles over about sixty degrees, which I think is how I’ve come to grief in them in X-Plane as well. Also, flying downwind in 25 knots and gusting is tricky. Still, builder/pilot Gordon Nichols was seriously experienced with flying large models, and the poor chap must be devestated.
There’s also ongoing debate about whether such huge models are safe to fly at all – the B-52 weighed more than piloted ultralights. I think it’d be a tragedy to rein these guys in, but by the same token, I wouldn’t want to have been close to the crash site. However, the Large Model Association is already involved in inspecting and certifying these things with the CAA. Hopefully the situation can be managed rather than bluntly legislated against.