72" vs 74" Hartzell prop

Hi guys:

About to order the c/s prop for my new RV-7 (Aerosport IO-375). As you know Van recommends the Hartzell 72" prop diameter for the -7 vs. the 74" diameter. I assume this is a result of adequate prop clearance. But out of curiosity, has anyone put a 74" prop on the -7 taildragger? Any performance comparisons?

Don't know about a 7, but

a friend of mine recently had a prop strike on his 6 during a very difficult landing (25G30 45deg. off the rwy) with a 74" prop. Just nicked the tips. A 72" would likely not have hit

prop

Len Kaufman has a 74" on his RV-8 and it's been fine. He chose this because the blades can be dressed down to a 72" diameter but the 72" (new) prop can't be shortened at all, he was told. One more thing to think about.

prop clearance on -8 vs. -7?

On the -8, there is loads of prop clearance, 74" would not be an issue at all.
I don't know if the -7 maybe does not stand quite as tall?

I have a Whirl Wind, so it wasn't an option. Love that prop though.

From Van's web store:

PROP C2YL-1BF/F7663-4 (I)O-320 diameter: 72"
Application: RV-3, RV-4, RV-6/6A, RV-7/7A, RV-8/8A, RV-9/9A

PROP C2YR-1BF/F74972 (I)O-360 (180/200hp) diameter: 72"
Application: RV-4, RV-6/6A, RV-7/7A, RV-8/8A

PROP C2YR-1BF/F7497 (I)O-360 (180/200hp) diameter: 74"
Application: RV-7A, RV-8/8A

Kinda looks like they don't want you to use a 74 incher on the 7 (only the 7A). I'm guessing it's because of ground clearance issues.

I was going thru the same thing when it was time to order the prop. When I asked Vans about it, their first question was tail dragger or nose dragger and there was my answer. They really don't recommend 74" on tail draggers.

Mehrdad
RV7A - IO360M1B

I went with a 72" on my 7A, wanted the extra ground clearance to help avoid picking up debris. I can't say that I've ever seen damge to the end of blade which would cause me concern about "shortening" blades at overhaul. So far nothing more than very minor nicks which are easily dressed out and I have taxied over quite a few "unimproved" taxiways.

Depends on how you fly your 7. In the 3 point attitude you will have a lot of ground clearance even with a 74" prop, way more than a 7A has. If you land the 7 in the 3 point attitude or a tail low wheel landing, the longer prop will not be an issue. The story changes when you make wheel landings in a level attitude. I live at the runway at Pecan Plantation and watch many RV6's and 7's land in this mode. It is scary to see how close even the 72" prop gets to the pavement. The combination of a botched touch down and the 6's/7's springy gear is all it takes to feed the prob a serving of asphalt.

Martin Sutter
building and flying RV's since 1988
EAA Tech Counselor

I have a 74" Hartzell on my -7 and it hasn't been a problem. I always do 3-point landings though.