Hi Guys, I too have been entranced by alternative engines - especially the rotary. The theoretical advantages are alluring (especially for us techies). But a hard lesson has been that iterative practical experience development cycles beats all.
I think there has finally been enough exploration of failure modes to finally result in an almost reliable VW based aero engine (though these good lessons fly out the window when we are too cheap to implement them). The rotary could get there, but there has been a LOT less exploration of failure modes with it. Not to discourage experimentation - that's part of our mandate as the Eaa. Just have to accept that its an experiment and almost certainly will fail. The rotary has a fairly low effective compression ratio, making it less fuel efficient (not necessarily the greatest concern for aviation) Counter-intuitively perhaps, lower compression ratios result in hotter, higher energy exhaust. The rotary is very well suited to turbo charging (something that _is_ very good for aviation). Turbocharging the rotary takes advantage of some of that wasted exhaust energy, reduces noise, and is well tolerated by the engine because of the rotary?s inherently low stress design (a good thing for reliability - and aviation). Cooling the rotary is a huge issue - perhaps partly because the engine is so compact (and it physically hurts to hang a big stinking cooling system on it!). Seal problems have mostly been fixed. Prop speed reduction systems are always a source of failures. etc. After years of messing with them - and even working with Paul Moller here in Davis, I am sadly aware that my time on earth is limited and I installed a Lycoming in my Osprey. Owen > On Aug 27, 2016, at 9:00 AM, krnet-request at list.krnet.org wrote: > > Message: 7 > Date: Fri, 26 Aug 2016 19:24:05 -0500 > From: Larry <laheze at yahoo.com <mailto:laheze at yahoo.com>> > To: KRnet <krnet at list.krnet.org <mailto:krnet at list.krnet.org>> > Subject: Re: KR> Wankel Rotary > Message-ID: <AF2E8959-2BCE-4AE4-85FF-F633088C76CB at yahoo.com > <mailto:AF2E8959-2BCE-4AE4-85FF-F633088C76CB at yahoo.com>> > Content-Type: text/plain; charset=us-ascii > > > >> On Aug 26, 2016, at 10:01 AM, Harold Wagenknecht wrote: >> >> Doran, >> >> ... Stay away from wankels.... Very hot exhaust.... Loud.... Sealing issues. >> >> Sent from my iPhone > > Harold, you may be right about your above statement. > Years ago one of my neighbors built an original Rotorway Helicopter and used > a Mazda Rotary engine on it. I stood nearby as he ran the engine rpm fast > enough to attempt an almost hover. That engine was screaming, the exhaust > pipe turned red, I thought the exhaust was going to melt and fall off of the > engine. It (the exhaust) was out in the open luckily. If it had been inside > of a fiberglass cowling who knows what may have happened. > I was very surprised to see that because I had known people who had Mazda > rotary automobiles and I had never heard anything about this. The engine on > the helicopter had a lite weight thinner wall tubing exhaust compared to an > automobile exhaust manifold I'm sure. Anyway, it was scary looking and > SCREAMING LOUD! >
