Lose 5-10 knots with a 3 blade prop on a 10?

[rocketman1988]

"...Posts like Paul’s above mean nothing; there’s too much variation from plane to plane..."

Then you also have to conclude the same about posts like David's...

[Jpm757]

The MT is virtually a maintenance free prop. Maintenance manual lists no required service other than visual inspection. Sealed maintenance free bearings do not require greasing. These props are not prone to slinging grease. First 10 hrs. on my -7 I was amazed how smooth the MT was and figured it wouldn't need dynamic balance. But I figured what the heck, turned out to be .38 out of balance. Got it balanced to .02 and it is now almost turbine like smooth. There is a lot to be said for engine/prop vibration and its long term effects on the entire airframe and components. To each his own, and say what you will about the MT, but IMHO it's one sweet prop!

[Bavafa]

Harsh or not, Bob has a very valid point.

[paul330]

Originally Posted by vic syracuse

To each their own.

Saying the other airplane was faster because one had a 2 blade and one had a 3 blade means nothing.

The only way to verify for sure is to take the same airplane, at the same weight and power settings, and fly it under the exact same atmoshpheric conditions (pressure/temp/altitude, etc). Period.

BTW, we did that with my RV-10 (swapped props) and noticed no measurable difference in speed. We even took my RV-10 back to the mothership and let Van fly my airplane right next to the factory RV-10, with both Van and I in mine (Van doing the flying) and Ken Krueger flying the company RV-10. At 8500' and full throttle, we were neck and neck. The GPS's on each airplane were within 1 knot of each other. Everyone was surprised. Without swapping the props it still didn't mean anything except it put to rest all of the hullabaloo that the MT is 10 knots slower.

There are advantages and disadvantages to each prop. one might be smoother, have more ground clearance, and better climb performance. The other might be more durable on unimproved runways, easier to get cowling off, cost less, etc..

Racing is a totally different arena.

Build the airplane for you.

Vic

...... and there we have it. Won't stop the myths though. Perhaps there should be a new section in "The Never Ending Debate" section

[Kahuna]

Some actual data. Vic is of course correct.
http://mstewart.net/super8/performan...omparisons.htm

[F1Boss]

Originally Posted by Kahuna

Some actual data. Vic is of course correct.
http://mstewart.net/super8/performan...omparisons.htm

I also removed an MT 3 blade and installed the 80" Rocket version of the Hartzell BA 2 blade. Substantial increase in speed as a result - 'almost stock' TCM 550. Mike - you need one of those on your nose!

Could be the design points for the Rocket P/N MT are optimized wrong - I spec'd economy cruise 2100RPM at FT/10000MSL, and it works great at that setup. So, it might be overpitched, or have a bit too much area? Dunno, but I still have that smooth operator upstairs - gonna try it on a higher HP version - with supercharger and RG. That testing will be interesting to say the least.

MT wants the data at several altitudes before they produce different blades, but they did agree to work with me. I think a Hartzell BA can still out-perform the MT (might take new - and more - blades to get there), but that sure is a lotta bux to let lay around...

[mciaglia]

Does MT or Hartzel prime their props?

Was trying to take another never ending debate and if we combine them...maybe they will both be solved

[BobTurner]

Paul (and others),
I apologize for sounding harsh - that was not my intent. But please re-read your own post. ?The winner was 5 knots faster for unknown reasons?. If the winner had chosen to run a brand X prop, lost 5 knots and run even with everyone else, would the correct conclusion be that brand X was just as good? You need to vary the prop, and only the prop (same airframe, wx, etc) to reach a supportable conclusion.

[rocketman1988]

Very true and valid points...

[rvbuilder2002]

Since Van's sells MT and Hartzell I have no reason to favor one over the other, but another point of consideration that might be of interest to some....
Investigate what the service and overhaul intervals and costs are of prop you are considering.
Years ago when there was a 3 blade MT on the prototype RV-9A (which all the pilots loved, BTW) it came time for an overhaul. Because of the costs involved in shipping it to/from an approved repair facility, and the quoted cost of the work, it was found to be close to the wholesale cost of a new Hartzell, so the MT went into storage (still there to this day) and a new Harzell was installed in its place.

That may not be the case any longer (was 10 years ago), but something that discriminating shoppers might what to investigate.