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RV-7 MT Propeller

R

rv7flyer

Member
Hello:

Does anybody out there have real top speed numbers for an MT prop installed in a RV-7? please advise.
I am trying to decide between MT or Hartzell Blended Airfoil and understand there is a top speed difference.
Have heard all the other arguments i.e. money,weight,maintenance,etc.
Appreciate your unbiased, respectful comments.
 
Which one?

Which MT prop are you wanting to know about? I believe Jim Ayers has some info...but I don't know that there's ever been a "speed run" on the MT blended airfoil (aluminum blade) prop, only the 3-blade (composite) MT.
 
You need to be very careful to look at the prop model when reviewing performance reports. The older composite MT props (-59 blade, I think) were much less efficient than even the older Hartzells, so aircraft with these props were slow. The newer MT props, with the -59B blades are supposedly much better. There is some evidence to suggest that they might be getting close to the BA Hartzell.
 
MTV15B/183-402

This is the aluminum 2 blade prop comparable to the Blended Airfoil prop from Haertzel.

So far I have 175 hrs on this prop. The blades have been re-sealed twice due to excessive grease leakage. The first time it went in for a re-seal at 75 hrs. The MT authorized repair shop did not know because MT had not told them that there was an upgraded new seal they were supposed to use. Of course it leaked again like crazy. MT did pay for the work the first and second time. It was just done two weeks ago and they used the new seals so I have not flown it enough since to see if this fixes the problem.

This all said, I fly often side by side with my friend in his -8 and he has a 180hp Superior O360 with the Haertzel Blended Airfoil prop. Mine is a 7A with IO360. He is easily faster than me by about 10kts, some of this 8 vs 7 and A vs TD so not sure if the prop is really the reason. Mine is also unpainted and so a little rough on the exterior. However....I can out climb him any time.

When I was having all sorts of problems with the grease leakage I entertained switching to the Haertzel and spoke to one of the Haertzel reps. He said I would probably not see any performance difference between the two props....pretty honest from a guy that should be biased.

At 8000' I get 175kts TAS average for a top speed which is pretty much in line with Van's numbers for a 7A with 180hp.

This is a very smooth prop and after it was dynamically balanced it is even better. No speed restrictions also make it a great way to go. Just hope the new seals fix the problem.

Would love to hear others performances with this same prop.
 
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