My Mustang II would glide like the spare tire out of your car with the prop stopped. Bobby
> During my 40 hour test flying on the Mustang I got bored to tears and > decided to test the windmilling or not theory. I was surprised to find > that > on that plane I had a better glide ratio with the prop windmilling than > with > it stopped. With my particular prop and engine combination the prop would > windmill until I slowed to about 90. It would not start spinning again > until I speed up to about 140 so I had a pretty good range where I could > choose a windmilling or stopped prop. I actually did something like 5-10% > better glide with it still windmilling. > > Keep in mind that this was one particular airplane, prop, and engine > combination and I don't doubt that many, if not most, other combinations > will glide further with the prop stopped. With a lower pitch prop and a > higher compression engine you also might not be able to keep it > windmilling > at anywhere near your best glide speed. It all boils down to if you want > to > know try it yourself in your plane. Now that I have cut two inches off > the > prop and had it pitched 4" lower I will try again and see if I still get > the > same results. > > Oh, and don't try this experiment if you don't have a mixture control. > Shut > your engine with the mag switch and then turn it back on with the prop > windmilling and you are going to get the backfire from hell. > > Brian Kraut > Engineering Alternatives, Inc. > www.engalt.com > > -----Original Message----- > From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On > Behalf Of Mark Langford > Sent: Saturday, March 11, 2006 9:15 AM > To: KRnet > Subject: KR> windmiling props > > > Bobby wrote: > >>When the engine quit for real, it amazed me how fast it >> came down with a prop stopped. > > That's interesting, because conventional wisdom is that planes glide > better > with the prop stopped than with it idling or windmilling, so I've always > used my idling glide rates as "worst case". See > http://selair.selkirk.bc.ca/aerodynamics1/Multi/Page2.html#Windmilling for > more on drag produced by windmilling props, or idling props. The small > diameter props and high compression engines that we use on KRs won't > windmill anyway, so engine-off glide should be better than idling glide. > I > haven't proven that yet, but once it gets warmer and shock cooling isn't > as > bad, I plan to test that one too. > > Anybody want to give me a speech on shock cooling? > > Mark Langford, Harvest, AL > see homebuilt airplane at http://www.N56ML.com > email to N56ML "at" hiwaay.net > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
