Larry H. wrote: > I was wondering how the Corvair engine is going and if you are happy with > it. Are you still thinking about going back with the larger engine or are > you satisfied with this one.
I'm still going to build another larger 3100cc engine, but I'll put a shorter extension on it, since the longer one isn't necessary to work with my cowling. I'm very satisfiied with this engine/prop combination. It pulls just as good as the old one did, and is noticeably smoother, despite the fact that the first one was perfectly balanced, and this one was just "thrown together", paying attention only to cc'ing the chambers, rather than overall balance (well, I did buy matched rods and pistons, but didn't have the whole engine dynamically balanced like I did the last one). This engine has higher compression than the old one, which is partly responsible for the good power, but only about a third of it. I attribute the rest to a more efficient prop. I can turn this engine the same speed as the old one, and go about the same airspeed. > Did you ever find out why the crank broke in the first one. I was always > under the impression that the Corvair crank was it's best asset. John Kearney's engine vibration tester showed that prop forces were the largest contributor to overall engine vibration. This in itself isn't a smoking gun, but it tells me that the prop is a very important factor in what the crank sees. Given no other smoking guns on my crankshaft, I now believe that the handmade prop that was on my engine was the source of a vibration that was amplified by the longer prop hub and eventually broke the crank. The new 54 x 54 Sensenich was CNC'd to perfection, and is very smooth. I feel a lot more confident behind this one. I've started work on a Corvair College #9 page, which shows some engine parameters from the flight. See http://home.hiwaay.net/~langford/flights/cc9/ . I'll be adding to it later...this is just a start on it... Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net
