REFLECTOR: Fixed pitch prop info
Geoff Gerhardt
geoff.gerhardt at gmail.com
Sat Mar 8 19:07:15 CST 2014
Folks,
I have two props from Catto for my 173RG. One, I had Craig build and
another is one I got from a Cozy owner who had it laying around. I have an
LIO-360, and he had a left-turning prop from an auto conversion that he was
no longer using, so I grabbed it.
The newer Catto prop is a 66" dia x 74" pitch. This was Craig's
recommendation for a 173RG. The other is a 64" dia x 76" pitch. So, the
newer one is a couple inches larger diameter, but less pitch. I have been
flying with both of them on and off, but other than some seat-of-the-pants
numbers, I never really did a good comparison of them to see which actually
performs better. Today, though, I put each on and took it out for a spin
following very similar flight profiles and collected the data.
I used an app on my iPhone called CloudAhoy to collect the flight data.
Pretty neat app - I've provided links to the two flights that you can look
over.
The newer Catto prop (66x74) has a static of 2150RPM, the older one (64x76)
has a static of 2300. Bottom line is, the smaller diameter, longer pitch
prop has a shorter takeoff roll (~1200' vs ~1600'), but they both have
about the same cruise speed (~175ktas, LOP, 2750RPM).
Have a look at the two flight profiles (links below). If you're wondering
about the funky pattern at the end of each flight, I did an overhead
approach.
Older prop (Catto: 66" dia x 74" pitch - static 2300RPM)
http://www.cloudahoy.com/api/S.cgi?tZdSdTJtntdj2U
Newer prop (Catto: 64" dia x 76" pitch - static 2150RPM):
http://www.cloudahoy.com/api/S.cgi?6vLxFSMb9IQOt4HdC9A8
I would actually like to send the newer prop back to Craig and have him
trim it to something like a 64x77. I can live with the longer takeoff roll
if it would give me a bit more on the top end.
Hope this info helps those trying to figure out a fixed-pitch prop to use.
Geoff
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20140308/88372c79/attachment.html>
More information about the Reflector
mailing list