Prop Comparisons

I installed yesterday 3/28/07 a new MTV-9-B/198-52 SN 070325 on my RV-8 io-540 C4B5. It replaced HC-C2YR-1B blades are F-8465-7R chopped 2 to 76.

I'm working on the performance numbers for the new prop. I've taken one flight and right now I'm very concerned but wont release data till I've done actual tests. You can read the Hartzell performance numbers here. Excluding performance numbers, here are my initial impressions:

  1. Very smooth. Like a new plane really. What is the most noticeable is the full rpm range from 2700 to 2000 is smooth at every point in between. I did not get this with the Hartzell. There was a noticeable vibration from 2400 to 2000 rpm with the hartzell that was noticeable worse as you approached the lower RPMs. Dynamic balance done on the Hartzell 3 times by 3 different people.
  2. Sounds fantastic from the ground. High speed passes make your hair stand up on the back of your neck.
  3. Looks great on the plane. Gives the plane a whole new sexy look that is very impressive.

Ill be painting the spinner soon to mach the dark green trim. But for now it stays white till I get around to it.

Update September 2007

Prop Performance

I had the opportunity to fly an F-1 Rocket that had a 260hp lyco with an MT 3-blade. I was stunned at the smoothness. I was also able to do some head to head comparisons of my 2 blade hartzell  260hp RV-8 against this Rocket. Climbs and climb speeds were identical from takeoff 1k' to 6k'. We were both solo 20 gallons and we were stunned that these 2 airplanes were exactly the same in the climb, both steep and not so steep. We did not do shallow climbs cause, well, what fun is that with planes like these?

In level flight @6k' 2700rpm WOT fast as they would go, my RV-8  was slightly faster, couple knots at most. This was particularly interesting since my rv-8 wing is a couple feet longer than the F-1 Rocket wing. Boy did I have a smile on my face as I pulled away from the rocket. SAH WEET!!!

After flying the Rocket MT 3 blade though, I immediately went out and bought one. I was willing to loose a couple knots to get that 3 blade smoothness. But my results were not good going to the 3 blade on performance. You can see from this chart that at any given fuel flow, the Hartz is ~7kts faster at 2350 rpm ROP 8k'

Next is an even larger gap at 10k' 2450 rpm ROP seen here. The gaps here in speed are even greater at ~13kts again in favor of the Hartzell.

 

After all this testing it was clear that the MT was much slower than the Hartz. Enough so that I pulled it off and returned it back to MT for a full refund. One thing was clear, the MT was smooth and I needed to figure out why the Hartzell had vibration harmonics that the MT did not. Read On on how I solved the dreaded vibration of the 2 paddle blade Hartzell. Its worth your time reading how I got the 2 blade silky smooth.

Actual spreadsheet data on all this stuff is here. I only put 2 charts on this site. But the spreadsheet has ROP and LOP , various altitudes and RPM's, data on both props for comparison. Lots of good data in there.

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