Real World Prop Performance Numbers

[sjhurlbut]

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

[yakdriver]

12 hrs labor to mount a Hartzell? I just put mine on yesterday in a little over an hour including safety wire. One other thing about a Hartzell is you put it on and run it 2000 hrs. The MT will probably require a trip to the prop shop three or four times in that time. Don

[sjhurlbut]

I meant making the spinner mounting plate, riveting nutplates, ensuring spinner is on perfectly, etc. Of course bolting the darn thing on is the same.

The point of the email is to share information.

You have never run a MT prop if you think it needs servicing 3-4 times in 2000 hours.

Steve
RV7A

[gmcjetpilot]

Originally Posted by sjhurlbut

2. Because of its greater mass, engine is harder to start with Hartzell

Really, do you mean it cranks over slower, but does it really take much longer or is harder to start. Just curious, what starter and battery do you have. What you say makes total sense, the heavier prop with more rotational inertia will crank slower. However do you notice you can idle slower and smoother with the bigger fly-wheel up there?

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.

What governor do you have. I have been flying the Hartzell with the Woodward Govs, and only if I get aggressive moving the throttle or prop control have I got any overshoot or delay. It makes sense the MT might react faster with lower weight blades. I just wounder if the Woodward Gov is better suited for the Hartzell and the Jihostroj Gov better suited for the MT? May be the Hartzell needs to loosen up?

I don't know about 10 kts either, but most talk about an average 5-7 mph faster for the Hartzell, may be 9 mph top end. You got 3.1 kts (or 3.6 mph) which is on the low end, but sounds reasonable. To get 3.6 mph by HP alone (no prop change) would be worth about 7.5 hp! That is not too shabby. Good stuff. Thanks for the data.

Service wise to grease the prop once a year takes 15 minutes tops, may be 20 minutes first time. Don't forget to take the opposite grease fittings out before pumping grease in.

[the_other_dougreeves]

Originally Posted by sjhurlbut

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.

I can believe this. With the composite prop on the Rotax, it typically stops within 1 rev. Starting is darn easy. Of course, our prop weighs about 13 lb...

TODR

[sjhurlbut]

I have PC680 battery and Skytec starter. I never had a problem starting with the MT. The Hartzell definitely cranks slower. I fly about twice a week and pre-heat so battery is charged and warm.

I have the MT governor P-860-4.

I haven't noticed the slower and smoother idle but I'll watch it next time.

Steve
RV7A