---------------------------------------------------------- Ultralight-List Digest Archive --- Total Messages Posted Mon 05/02/11: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:29 AM - Re: Re: What ultralight? (John Bolding) 2. 04:52 AM - Re: Re: What ultralight? (Wayne Bressler) 3. 08:13 AM - Re: What ultralight? (davecove) ________________________________ Message 1 _____________________________________ Time: 04:29:32 AM PST US From: "John Bolding" Subject: Re: Ultralight-List: Re: What ultralight? Why would you want to do that? if you have more hp get more pitch or a longer prop. JB ----- Original Message ----- From: "davecove" Sent: Monday, May 02, 2011 1:08 AM Subject: Ultralight-List: Re: What ultralight? > > So, could you realistically swing a 54x20 prop at around 4100 if you had > enough hp? (Do I calc correctly that a 54" prop at 4060rpm is 85% mach > and is thus OK?) > > Dave > > -------- > Dave > 701-wannabe-soon > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=338616#338616 > > > ________________________________ Message 2 _____________________________________ Time: 04:52:58 AM PST US Subject: Re: Ultralight-List: Re: What ultralight? From: Wayne Bressler The longer the prop, the better. Slower RPM's are more desirable for prop performance, yes? Wayne Bressler Taildraggers, Inc. www.taildraggersinc.com On May 2, 2011, at 7:24 AM, "John Bolding" wrote: > > Why would you want to do that? if you have more hp get more pitch or a longer prop. > > JB > > ----- Original Message ----- From: "davecove" > To: > Sent: Monday, May 02, 2011 1:08 AM > Subject: Ultralight-List: Re: What ultralight? > > >> >> So, could you realistically swing a 54x20 prop at around 4100 if you had enough hp? (Do I calc correctly that a 54" prop at 4060rpm is 85% mach and is thus OK?) >> >> Dave >> >> -------- >> Dave >> 701-wannabe-soon >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=338616#338616 >> >> >> >> >> >> >> >> >> >> > > > > > > > ________________________________ Message 3 _____________________________________ Time: 08:13:46 AM PST US Subject: Ultralight-List: Re: What ultralight? From: "davecove" Why? Only because a certain engine (not the vw) develops its best hp at that rpm. So what I seem to be learning is this... if the ground clearance only allows for a 54" prop, you could use 4100rpm (best hp for a certain engine) because the tips don't go over .85 mach, but it isn't very efficient prop-wise. So while you get more hp out of the engine, less of it makes it to the air. It might be better to turn the engine and prop at 3500 and while you get lower hp, more makes it into the air. Better might be to let the engine run 4100 and use a PSRU to get the prop down to 2500... unless the weight of the PSRU eats all the gains made by moving the prop from 4100 down to 2500. I think I am beginning to see what all the discussion is about... finding that balance. Dave -------- Dave 701-wannabe-soon Read this topic online here: http://forums.matronics.com/viewtopic.php?p=338639#338639 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message ultralight-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Ultralight-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/ultralight-list Browse Digests http://www.matronics.com/digest/ultralight-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.