I just finsihed real world testing on MTV-15B and Hartzell Blended airfoil on Oct 31. I have a Mattituck TMX-IO-360 on RV7A.
Thought I would share my findings:
At 6000 ft, 2400 RPM Hartzell is faster by 1.8 kts.
At 6000 ft, 2500 RPM Hartzell is faster by 2.5 kts.
Rate of climb from 4000 to 6000 (@110 kts IAS) Hartzell is faster by 157 fpm
At 9000 ft, 2400 RPM Hartzell is faster by 1.4 kts.
At 9000 ft, 2500 RPM Hartzell is faster by 3.1 kts
Rate of climb from 7000 to 9000 (@110 kts) Hartzell is faster by 209 fpm
Other observations (lessons learned) people may not consider:
1. Hartzell is 11 lbs heavier (55 vs 44 lbs). Recalculate C of G
2. Because of its greater mass, engine is harder to start with Hartzell
3. Because of its greater mass, engine takes longer to shut down. This really surprised me. My MT would stop very quickly (within 1 engine revolution), the Hartzell averages 3-4 revolutions before stopping. This sometime causes it to turn past the 10-4 o'clock position where the MT would stop every time.
4. The Hartzell takes longer to change pitch. This is evident when adding power fast. During several overshoots I pushed in the power quickly and RPM would exceed 2750 and cause the engine warning to flash. The prop caught up quickly (back to 2700) but this was never an issue with the MT. Same with initial take-off. Add power slowly with Hartzell.
5. MT is smoother. At 2400 RPM Hartzell is good but at 2300 RPM it has noticably more vibration. I'm going to dynamically balance the Hartzell.
6. MT is a bolt on and forget. Spinner made and no grease nipples to worry about. Hartzell you need to make the spinner, backing plates, etc. Putting on the MT prop takes 1/2 hour. Hartzell takes ~12 hours of labour.
So both props in my opinion are good. Very close in performance. People claiming 10 kts increase between the two may need to review the flight test technique, speed calculations, and consider other factors.
I'm going to sell my MT prop eventually if any early takers out there. Total flight time on it is 136.5 hours.
Steve
RV7A
Thought I would share my findings:
At 6000 ft, 2400 RPM Hartzell is faster by 1.8 kts.
At 6000 ft, 2500 RPM Hartzell is faster by 2.5 kts.
Rate of climb from 4000 to 6000 (@110 kts IAS) Hartzell is faster by 157 fpm
At 9000 ft, 2400 RPM Hartzell is faster by 1.4 kts.
At 9000 ft, 2500 RPM Hartzell is faster by 3.1 kts
Rate of climb from 7000 to 9000 (@110 kts) Hartzell is faster by 209 fpm
Other observations (lessons learned) people may not consider:
1. Hartzell is 11 lbs heavier (55 vs 44 lbs). Recalculate C of G
2. Because of its greater mass, engine is harder to start with Hartzell
3. Because of its greater mass, engine takes longer to shut down. This really surprised me. My MT would stop very quickly (within 1 engine revolution), the Hartzell averages 3-4 revolutions before stopping. This sometime causes it to turn past the 10-4 o'clock position where the MT would stop every time.
4. The Hartzell takes longer to change pitch. This is evident when adding power fast. During several overshoots I pushed in the power quickly and RPM would exceed 2750 and cause the engine warning to flash. The prop caught up quickly (back to 2700) but this was never an issue with the MT. Same with initial take-off. Add power slowly with Hartzell.
5. MT is smoother. At 2400 RPM Hartzell is good but at 2300 RPM it has noticably more vibration. I'm going to dynamically balance the Hartzell.
6. MT is a bolt on and forget. Spinner made and no grease nipples to worry about. Hartzell you need to make the spinner, backing plates, etc. Putting on the MT prop takes 1/2 hour. Hartzell takes ~12 hours of labour.
So both props in my opinion are good. Very close in performance. People claiming 10 kts increase between the two may need to review the flight test technique, speed calculations, and consider other factors.
I'm going to sell my MT prop eventually if any early takers out there. Total flight time on it is 136.5 hours.
Steve
RV7A