Very interesting day today. Had a chance to fly in a newly completed RV6A equipped with the 72FM propeller and thought some of you would be interested in some numbers.
RV6A Serial # 23678 built by Holmer Rogers of Revelstoke B.C. Empty weight 1053 pounds, equipped with a fuel injected 0360 Lycoming A4M. Engine has 245 hrs since factory reman. with differential readings of 77-78 over 80 on all four cylinders. Engine is equipped with electronic ignition. This is a very clean aircraft with a lot of attention payed to detail and is well rigged. With Roger doing the flying and me pushing the pencil this is what we came up with.
Surface temp. was 45 F with no wind and a elevation of 1720 ft. Static run showed 2220 RPM and 27.7 in. manifold press. Aircraft was fueled to give us a 1600 lb. gross wieght. Some of the following figures may be off a small fraction but are reasonably close.
Take-off starting with full power from brake release we were airborne in 12 seconds.
First climb to 8000 ft. was done at full throttle and 120 mph indicated.
3000 - 26.3 mp and 2350 RPM . Initial rate of climb was 1600 fpm
4000 - 25.4 mp and 2350 RPM
5000 - 24.4 mp and 2350 RPM
6000 - 23.7 mp and 2340 RPM
7000 - 22.7 mp and 2330 RPM
8000 - 22.0 mp and 2320 RPM rate of climb here was still 1200 fpm
Leveling off at 8200 ft and flying into 8000 ft RPM quickly built to the red line of 2700 RPM. With everything stabilized power had to be reduced to 21 mp to keep from running over 2700. The indicated airspeed at this point was 190 mph.
Second climb was done at 25 in.mp and 120 to 6000 with 2280 RPM showing going through 4000 ft. at 1200 fpm. Leveling at 6000 and maintaining 2500 rpm which required 20.5 in mp we had at true airspeed of 182 mph. This was verified with a hand held gps flying all four headings. At a power setting of 2400 rpm and around 19 in. mp the fuel burn was 7.2 US gallons per hour taken from the fuel flow meter. All cruise power settings were done with the mixture leaned to peak minus 50 degrees.
My RV6 is constant speed equipped and is 55 lbs heavier. With the exception of the slower initial acceleration on take-off and slightly longer run and slightly lower initial rate of climb I would be hard pressed to keep up with Roger's aircraft. Jim and I are just starting our fuselage for the 6A and after today's experience will probably go with the fixed pitch prop on our 180 hp engine rather than a constant speed as planned. If one has special requirements such as short field work, high airstrips or floats I would stay with a constant speed.
All in all my first impression is that Sensenich have really done their homework on this one and have given us a chance to have almost constant speed performance at a saving of almost 4000.00 US.
Hope this is of some interest.
Eustace Bowhay C-GHAY 20383
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