I just wanted to post an update on our latest HRT propeller blade style, as well as answer some questions.
This year (2017) WhirlWind has released a new RV constant-speed propeller option, called the HRT74-200 Series. This is a constant-speed, 2-blade, 74-in diameter propeller. The HRT propeller was a direct result of our involvement over the last several years in working on a special propeller development program for the Reno Sport Class Racing. We developed new aero-design / structures, manufacturing and testing methods to meet the challenges of taking propeller design to a new level.
The new HRT propeller has shown performance increases across the entire flight spectrum compared to the already great performing 200RV propeller. The most significant improvements have been in take-off acceleration and initial rate-of-climb, there is also a modest top-speed increase.
The HRT hub system is the same as 200RV (based on the McCauley threadless design).
The HRT blade construction however, is all new. The HRT blade uses prepreg carbon-fiber with high-density foam-core that is compression molded in a 50-ton heat press using our proven patented design and manufacturing process. With this new structure design, the HRT blade can be manufactured with a very thin cross-section, and in most cases will be much thinner than a metal blade. Thin blade cross-section is one of several important criteria for an efficient propeller design, which gives the HRT blade an advantage.
Regarding grease leaks on older propellers, we have found that even with our proven hydraulic control hub system (McCauley based), grease leaks are more of a challenge for lighter composite blades than heavier metal blades. There were only a few occurrences of leaks, but testing of a new seal system seems to have solved the most challenging of these issues.
Below are pictures of the HRT blade design undergoing (strain-gauge) vibration survey testing, as well as cross-section of the HRT blade. *Notice the VERY thin HRT cross-section.
After several year of development, this entire HRT project was intense, and at times challenging, but definitely rewarding. The story of the this HRT project and engineering would make a good book someday.
The HRT constant-speed propeller is sold through our constant-speed propeller division, Whirl Wind Aviation http://www.whirlwindaviation.com