Sky dog, maybe you should consider getting a bigger crank in your engine to
be able to swing the props you have. Tip speeds with a 52 inch dia prop are
OK till you get over 3600-3700 RPM.
-----Original Message-----
From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Sunday, June 07, 1998 8:39 AM
Subject: DFLY: Dfly Props
>Hi all:
>
>My Dragonfly was built in CA and most of the hours were flown in CA.
>I need some input on props. The previous owner had 2 props, the one he flew
is
>a Great American 52X42. The other one is a Sturba 52X44.
>
>Max RPM with the 42 is 2900, and for the 44 is 2600 at 4500 MSL, at these
>RPM's I am below peak output for the VW.
>
>I have a HAPI 1835 with Mosler individual heads , total time less than 300
>hrs.
>
>I talked to Great Plains and they said that they like to run their VW's at
>3400 to 3600 RPM.
>
>I have calculated the tip speed at these RPM's and it is close to 900 fps.
>Is any one running a 52X40 prop and if so any problems with that pitch?
>
>I am based at 4470 MSL and have 11,000 ft MSL mountians all around me and
need
>to be able to climb well. The ballpark calcs show that top speed should
also
>improve a bit with a lower pitch prop.
>
>Any advice or experiances with selecting the right prop would be
appreciated.
>
>To date 5 hours and 25 landings
>
>One Sky Dog
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