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Old 03-15-2012, 03:57 PM
RV8R999 RV8R999 is offline
Join Date: Dec 2008
Location: na
Posts: 1,457
Default Catto 3-Blade vs Sensenich Wood

When I built my -8 a year and half ago I installed a wood sensenich 2-blade prope 71" dia pitched to 83. I really liked the look of the wood prop and was very happy with the performance but happy is a relative term and often elusive so....

Today I installed a new Catto 3-blade 68" dia, pitched 75. I entered myself back into a 5 hour phase 1 test period and am not notifying the FSDO.

Here is a pic:

Several flights were conducted with both props at a Weight/Delta of 1800lbs. The OAT and fuel burn were noted for each data point and the altitude adjusted to account for decrease in weight as the flight progressed - altitude increases with decreasing weight to remain at the same Weight/delta of 1800lbs.

Once the Catto was installed I flew several flights at two differenct Gross Weights with (400lb delta) to highlight the advantage of this test technique. The plots below show an average of 3 runs with the Sensenich, and averages of 3 runs each for the Catto at 1700lbs and 1300lbs. - note the data for the two averaged Catto runs line up nicely. I'll refly this profile at 3 different Weight/Delta Values (2000, 2200, 1500). This will provide a family of 4 level flight curves. Linear regression will allow building actual performance charts at any gross weight and DA from those...

I'll let you guys chew on the data above for awhile...

Other info:

1 - Catto Prop climb rate was 200 FPM greater than the Sensenich through a 1000ft altitude band, WOT at Vy (110mph), 4000-5000ft AP at 62 deg F at a Gross weight of 1546lbs and was 1306FPM
2 - Sound dramatically decreased (almost eerie)
3 - Vibrations through entire speed sweep were noticeably lower
4 - T/O distance was improved by 200 ft
5 - CHT in climb were significantly cooler (I'm still crunching data on this so no numbers yet)
6 - Cost: Sensenich $1600 + Spinner Kit, Catto - $3000 w/ Spinner Kit
7 - Delivery time: Sensenich: 6wks, Catto almost 12 weeks
8 - The Prop Disk is invisible in flight at RPM above 1400. The sensenich was always visible and distracting.
9 - Installation/Removal of Cowl is much more difficult but doable. I have slightly less than 1/8" gap between cowl and spinner so this is part of it.
9 - My GF says "The plane looks much sexier now!" this is the most important data point of all!!

Last edited by RV8R999 : 03-17-2012 at 10:51 AM. Reason: new data
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