A couple fellas got together and decided to actually test different props on one particular plane. I'm trying to recall names - Jim Ayers had a RV3 with a LOM engine in it. That fella is no longer with us.
I am not sure who's ship they did the testing with. Ted Rutherford's? Also passed..
I recall they tried a range of RPM - the std Rocket prop (80"/D blades) was almost the fastest in the end, and the MT 3 blade was not able to keep up. I'd like to have this document for comparison with the current set of props.
The Blended airfoil @ 80" was not included in this test as far as I know, but I could be wrong. I recall one prop simply going faster than the rest as the RPMs came up past 2700..sounds like Reno testing on the BA prop if you ask me.
By golly I found it - left my memory mistakes in the 1st part. I still don't think they tested a BA prop.
"The flight test data I obtained in a HR2 was with 2 blade Hartzell's and the 3 blade MT propellers.
The HR2 had the "D" twist 2 blade Hartzell, and the owner already knew that at full throttle the aircraft slowed down by 3 mph when going from 2600 RPM to 2700 RPM.
We focused on full throttle performance at 5,000' for the Reno Air Races.
The 3 blade MT Rocket propeller (198-52 blade) was 2 mph faster, but had the same characteristics as the "D" twist 2 blade propeller.
The HR2 slowed down by 3 mph when we went from 2600 RPM to 2700 RPM.
The "J" twist 2 blade Hartzell gave the same performance as the 3 blade MT propeller.
Except, going from 2600 RPM to 2700 RPM, there was a 3 mph INCREASE in airspeed.
And going from 2700 RPM to 2800 RPM, there was another 6 mph increase in airspeed.
This was on a stock 260 hp Lyc. IO-540 engine.
From another source using a 330 hp Lyc. IO-540 engine, this Rocket pilot saw an airspeed decrease when going from 2600 RPM to 2700 RPM using a "J" twist Hartzell.
Sometimes there are no simple answers.
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