I'm not sure why, but your pm ended up in a different section under 'profile visitor'? But got it now. Yes, the differential drive takes a bit of head scratching, it's a bit like explaining a helicopter swash plate! For the weight you're looking at, belt reduction is probably best. I say reduction because I'm sure you're going to have to use a smaller pair of engines than VW's to stay in the 95:10 weight area, thus they will be by definition higher revving than what we want for our prop(s) I think the 95:10 'two engine' problem is a combination of 'grandfather' clause (Lazair) and the fact I'm fairly sure that no restrictions are actually written in the rules, I guess no one expected it? Extra cooling fans and Oil baths?!! This is one of those projects you have to approach sideways or it can get heavy real fast. Try as I might, I can't think of a better route than two small water cooled two strokes (best power to weight) or maybe a couple of small rotaries?!?! Scary picture at; Turbo-Rotary Aero Light! As for bearings, if there is any length involved with the shafts, you may need to look at some form of flexible coupling, then you need to fit a thrust bearing as well as the usual radial bearings to hold the prop shaft at the front. As for the SR-71, it's a bit of PhotoShop!!, although I still feel the idea is valid. I guess you looked here? Arthur.
