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1. 08:02 AM - Re-Pitch to 17-degrees on a 601 with a Stratus (Grant Corriveau)
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| Subject: | Re-Pitch to 17-degrees on a 601 with a Stratus |
--> Stratus-List message posted by: Grant Corriveau <grantc@ca.inter.net>
(Note: I don't have the Stratus, but the CAM100 (Honda). However, due to
the small numbers of CAMs flying in the 601, I tend to monitor this list
because of the similarities with the Subaru engine).
So -- for what it's worth on this discussion, I also found that my engine
does better than I'd expected as I increase the prop pitch. (Warp Drive; 3
blades; tapered ends; CAM100 rated at 100 hp at 6,000eng/2,500prop RPM.
I have had the prop up to 18 degrees and found, as Larry reports, excellent
cruise performance with little noticeable loss of takeoff and climb
performance. I attribute this to the torque gained at the prop through a
PSRU (ratio 2.4/1), and also perhaps the Warp Drive prop's apparent
characteristic of twisting aerodynamically under various loads.
My max rpm at takeoff (i.e. static) with the prop currently set at 15
degrees is 5,000 rpm. When I had 18 degrees max (static) rpm dropped only
by about 100 rpm or so -- barely noticeable. I eventually backed off from
18 because I 'imagined'? that the engine was lugging a little -- but I'm not
certain of that. It may just have been an aerodynamic vibration that was
occuring at cruise speeds...?
With respect to fuel consumption, vs. power with automotive carburettors.
My engine has a stock Honda carb which means a second barrel that opens
towards full throttle. I have installed a K&N mixture monitor, and I've
found that in cruise at 2,500 feet, 5,000 rpm gives a 'normal' mixture
setting (one green led lit), but if I throttle back just a tad to 4900 the
mixture leans out 'one notch' to show all the amber led's illuminated but no
green led's illuminated. At this setting the fuel consumption works out to
about 3.5 USG/hour and the aircraft maintains 105+ mph. Not bad, especially
at current fuel prices! So for each engine, finding that spot where the
automotive carb leans out just a touch, is probably a good place to fly for
maximum range.
Hope some of this is helpful to Stratus pilots. As Red Green would say:
"... I'm pulling fer ya. We're all in this together."
--
Grant Corriveau
C-GHTF / HDS / CAM100
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