REFLECTOR: Fixed pitch prop info

[Geoff Gerhardt]

Herb,

Sorry for not including that important bit of info - their both three
bladed props.  I think that's all that Catto makes.

Geoff


On Mon, Mar 10, 2014 at 5:21 PM, Herb Sanders <herbsanders at earthlink.net>wrote:

>   Could you tell me if that is a two or three blade prop?  Herb Sanders
>
>  *From:* Geoff Gerhardt <geoff.gerhardt at gmail.com>
> *Sent:* Saturday, March 08, 2014 7:07 PM
> *To:* Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> *Subject:* REFLECTOR: Fixed pitch prop info
>
>  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
>
>
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