Rocket with MT V-15-BCC/C198

[viperpilot]

Does anyone have any experience with the MT 2-blade propellers on a Harmon Rocket II?

Most interested in comparisons with the Hartzell 2-blade M2YR-1BF/F8475D-4 in the areas of speed, vibration, and weight.

I am trying to find a counterweighted prop that doesn't give up much speed versus the Hartzell 8475 or 8068 blade designs.

Thanks!

[RVjim]

MT Propeller has just agreed to make a 2 blade Rocket propeller, so there is no performance data available from flight test.

Their standard 2 blade propeller will weigh about 44 pounds with the spinner installed.

Their counterweighted 2 blade propeller will weigh about 50 pounds with the spinner installed.

BTW, from fight testing I performed on Ted Rutherford's HR2, the standard 3 blade Rocket propeller was 2 knots faster than the Hartzell "D" blade and just as fast as the Hartzell "J" blade at 2600 RPM, or below.

Jim Ayers

[viperpilot]

Thanks, Jim. The Hartzell props you referred to on the HR2 are 2-blade props or 3-blade props?

The scuttlebut on the web is that the 3-blade MT gives up about 10 knots at cruise versus the Hartzell 2-blade. Are you saying your testing showed otherwise?

I am trying to find a lighter prop (to move the CG back a little bit on the HR2), one that is counterweighted (to guard against oil system failure causing a run-away, and one that maintains the cruise speeds available with the Hartzell 2-blade.

Thanks

[RVjim]

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.

Jim Ayers