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Aymar-Demuth prop info

M5fly

Well Known Member
Can anyone tell me what numbers Aymar-Demuth used to identify their prop types? I've got one with the composite overlay on my RV that is the 68x72. The serial number, diameter and pitch are written on the data sheet, but that's it. Based on the static RPM on takeoff (2350) and RPM at WOT in cruise (2600) it seems that this might be a climb prop but looking for validation and other info y'all may have.
 
Climb

Based on my experience... 2350 is a high static rpm for fixed pitch. I heard your prop was hard to beat, lots of positive comments on the prop.
 
Middle of the road prop

My prop did the same as yours and I was told it was a middle of the road prop. Not climb and not cruise, a little bit of both.
 
My prop did the same as yours and I was told it was a middle of the road prop. Not climb and not cruise, a little bit of both.

Have you since switched props? If you did, were there any noticeable differences? Went flying with another local 6A owner yesterday who has the 160hp with a Senenich 70x74 and he blew the doors off me. I was WOT and he was running away from me at 2100. He had to throttle back to around 1900 for me to catch up and even that took awhile. His first thought was the prop might be causing this large speed variation. I need to look and see if my engine has the same size studs as his, if it does we might throw his prop on mine and see what kind of a difference it makes. He also noted he's lucky to see 2450 with his setup.
 
I used a 68x71 Prince on a 150hp Smith Mini and got almost 2900rpm WO @ 2500'. Static was about the same.
WO throttle MPH was 155-160 with a draggy biplane.
 
Cato Prop

My prop did the same as yours and I was told it was a middle of the road prop. Not climb and not cruise, a little bit of both.
I went with a Cato cruise prop with my o-360-A1A. I picked up 10 mph at WOT. Had to go with a new prop due to finding a crack.

I true out over 200 mph above 7000 feet WOT.
 
I went with a Cato cruise prop with my o-360-A1A. I picked up 10 mph at WOT. Had to go with a new prop due to finding a crack.

I true out over 200 mph above 7000 feet WOT.

Catto has definitely been my number one choice for a prop change. I'm likely going to do some engine work this fall so I won't want to get a new prop before that, but having an idea of what I want and the differences will help quite a bit. 10mph is a significant improvement.
 
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