Don
If your C-85 is a strong performer, you won't be disappointed with a 71/51 McCauley. Not every engine is the same, so results will differ. The best is to find a prop that you can test fly before you pitch your prop in a certain way. I learned that the props can only be re-pitched a few times... Hartmut To: [email protected] From: [email protected] Date: Sun, 24 Jan 2010 17:43:51 +0000 Subject: [ercoupe-tech] Re: PROP PITCH Where I get lost in all that, is the figures get skewered by available horsepower, drag, and such. In theory one could get some high number pitch, and cruise 150 mph in a coupe. I wonder if someone has ever made a chart, listing takeoff distance, climb rate, and top speeds, perhaps on a chart so one could make better choices. For instance I am told that I will be quite disappointed with my McCauley 71 by 51 on the C85 engine, but I hope it will cruise with the big boys. . --- In [email protected], "Ed Burkhead" <e...@...> wrote: > > > Larry, > > I presume you have an O-200 in your Coupe? The STC for putting the > O-200 in Coupes calls for the regular C-150 prop to be used. (Many > installations on LSA eligible 415-C and 415-CD planes used that STC as > "accepted data" even though they didn't actually use the STC to > authorize the installation.) > > On a Coupe, the pitch called for makes it a climb prop with a cruise of > only about 108 mph but with quite good climb. Sorry I can't remember > which pitch is called for in the STC. > > The first number is the length of the prop. The second number is how > many inches forward the plane would move (with no slippage) on each turn > of the prop. (Slippage usually runs around 5%. > http://edburkhead.com/Ercoupe/enginepropeller_efficiency.htm ) > > Thus, a pitch of 50" goes forward farther than would a 48." The flatter > 48" is better for the low speeds of a climb so it gives you greater > climb. > > Ed > _________________________________________________________________ Windows Live: Make it easier for your friends to see what you’re up to on Facebook. http://www.microsoft.com/middleeast/windows/windowslive/see-it-in-action/social-network-basics.aspx?ocid=PID23461::T:WLMTAGL:ON:WL:en-xm:SI_SB_2:092009
