Van's Air Force - Western Canada Wing
Van's Air Force
Western Canada Wing
Please make only one selection at a time.
Support this site with a donation...

Sensenich 72FM Propeller

Eustace Bowhay, Blind River, BC


Very interesting day today. Had a chance to fly in a newly completed RV-6A equipped with the 72FM propeller, and thought some of you would be interested in some numbers.

The aircraft is RV-6A serial number 23678, built by Homer Rogers of Revelstoke, BC. The empty weight is 1053 pounds, equipped with a fuel injected O-360 Lycoming A4M. The engine has 245 hrs since factory remanufacture, with differential readings of 77-78 over 80 on all four cylinders. The engine is equipped with electronic ignition. This is a very clean aircraft with a lot of attention paid to detail, and is well rigged. With Roger doing the flying and me pushing the pencil this is what we came up with.

Surface temperature was 45°F, with no wind and an elevation of 1720 ft. Static run showed 2220 RPM and 27.7 inches of manifold press. Aircraft was fueled to give us a 1600 lb gross weight. Some of the following figures may be off a small fraction but are reasonably close.

Take-off roll, starting with full power from brake release, was 12 seconds (to airborne).

First climb to 8000 ft was done at full throttle and 120 mph indicated. Initial rate of climb was 1600 fpm.

The rate of climb at 8,000 feet was still 1200 fpm.

Leveling of at 8200 ft and flying into 8000 ft, the RPM quickly built to the red line of 2700. With everything stabilized, power had to be reduced to 21 inches MP to keep from running over 2700. The indicated airspeed at this point was 190 mph.

The second climb was done at 25 inches MP and 120 mph to 6000, with 2280 RPM showing going through 4000 ft at 1200 fpm. Leveling at 6000 and maintaining 2500 RPM--which required 20.5 inches MP--we had a true airspeed of 182 mph. This was verified with a hand held GPS, by flying all four headings. At a power setting of 2400 RPM and around 19 inches 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.
 

 Altitude

Manifold Pressure

RPM

3,000 26.3 2,350
4,000 25.4 2,350
5,000 24.4 2,350
6,000 23.7 2,340
7,000 22.7 2,330
8,000 22.0 2,320

My RV-6 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 probaably 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 propeller.

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 US$ 4,000.

Another interesting thing happened during our testing. We got a bit too engrossed in the numbers and let a tank run dry. Gets pretty quiet in a hurry. But what I learned from this was that after we switched tanks and put the boost pump on there was a fair delay in getting a restart. It looks to me with this particular fuel system that a blown tank below 1000 ft could prove quite interesting.


This article originally appeared in the December, 1998 issue of the Western Canada RVator.

Please send comments to: editor@vansairforce.org.
 


A member of the
Web Standards Project

Support free speech.
Built on...
Linux Logo
...FreeBSD

Van's Air Force Western Canada Wing is not affiliated in any way with Van's Aircraft Incorporated. Western Canada RVator is not a publication of Van's Aircraft or any other corporation. All products reviewed or mentioned are not necessarily recommended for use by RV builders, but are described for information only. All builder's tips are presented only as a source of information and a forum for exchange and the sharing of ideas and construction methods. No responsibility is assumed, expressed, or implied as to the suitability, accuracy, safety, or approval thereof. Any party using the suggestions, ideas, or examples does so at his or her own risk and discretion and without recourse against anyone. The members of Van's Air Force Western Canada Wing, the editor of the Western Canada RVator, and all authors and contributors are not responsible for any product or builder's tips misuse, incorrect construction, or design failure, nor any other peril.

All material on this web site is copyright Van's Air Force Western Canada Wing, or copyright the attributed author, unless otherwise noted.



For comments or suggestions on this web site, please write to