There are just so many variables when selecting a prop such as gross plane and pilot weight, engine horsepower, amount of drag hanging out in the airstream and density altitude that you just have to go with what you feel will work the best. At least now you have a starting point to work from. I would just caution on going with the longer prop that length seems to kill RPM. Have you looked on the KRNET.org performance spread sheet for VW's ?
Mike Sylvester kr2s builder Birmingham,AL. Cell no.205-966-3854 ________________________________ From: KRnet <[email protected]> on behalf of Dave Acklam via KRnet <[email protected]> Sent: Tuesday, February 25, 2020 3:08 PM To: KRnet <[email protected]> Cc: Dave Acklam <[email protected]> Subject: KR> Revmaster Props (carry-over from the FB page) I have a Tri Gear KR that I bought from John Bouyea, which I am considering re-propping. The plane currently has a small-valve Revmaster 2100D & 52x52 Sterba prop. Climb performance is not-so-great, and airspeed is ~115mph. Static RPM is high - although I haven't used a digital tach on it just-quite-yet to get a number for how-high. Although I've asked this on the KR FB page & not gotten much in the way of solid answers (lots of discussion & people reminding me that I am under-propped with the 52, little else), I am wondering why ~52in props are so common with VWs... A 60" prop turning 3200RPM = 75% Mach. 80% at 3400. There appears to be enough ground-clearance for a 60" prop on this aircraft. Am I using the wrong RPM numbers? Do people typically cruise higher than 3200 with this engine? Has anyone else used a 'big' prop, and if so what are your thoughts? _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/[email protected]/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to [email protected] _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/[email protected]/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to [email protected]
