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80" Prop on a RV8??

What did you find out?

I've been puzzled by Vans suggestion of a 72" prop for the -8, but 74" for the 8A.

Seems to me that the taildragger should accomodate at least as much prop as the nose wheel.
 
... I've been puzzled by Vans suggestion of a 72" prop for the -8, but 74" for the 8A.

Seems to me that the taildragger should accomodate at least as much prop as the nose wheel.
With the RV-8, on takeoff, you push the stick forward to get the tail up. If you overdo it, I guess you could cause a prop strike.
 
The short answer, no. Do not use an 80” prop on an RV-8.

Keep in mind the standard RV-8 gear gives way on hard landings, taking the prop closer to the pavement - so the recommendation to use the 72” prop. The nose gear on the 8A mitigates this problem.

That said, I have the very nice 74” prop on my RV-8. I note that the Grove gear gains me 1” to 2” of height over the stock gear comparing against another RV-8 spinnner to ground measurement.

Carl
 
Prop For -8

What did you find out?

I've been puzzled by Vans suggestion of a 72" prop for the -8, but 74" for the 8A.

Seems to me that the taildragger should accomodate at least as much prop as the nose wheel.

I think the wording on Van's website has changed since I bought the prop for my -8 14 years ago: The current wording is:

The 74" blade diameter propellers are applicable to the "A" or tricycle gear aircraft except for the RV-8, while the 72" blade diameters are recommended for the tail wheel aircraft to ensure adequate ground clearance.

Back when I purchased the prop for my -8 the way I recall the wording on their website back then was that on the -8 74" was OK but they only recommended the 72" for the -8A. Nevertheless I've been flying with a -74 on the -8 for 10years/1000 hours without issue. I think some folks have gone up to 76" and I'm pretty sure the few "super -8's" out there have 80" props. I don't think I would want a prop that big on a standard -8 but at least the 74" is fine...


Skylor
 
And from the Van's Hartzell Prop Order Form:

"Propeller size note:

  • The 74" blade diameter propellers are applicable to all "A" model RVs plus the RV-8.
  • The 72" blade diameter propellers are recommended for all tailwheel aircraft (except the RV-8 as noted above) to ensure adaquate ground clearance for those models."

So both diameters are applicable for the RV-8 per Van's.

OK, that's exactly what I remembered! Thanks for finding it.

Skylor
 
The short answer, no. Do not use an 80” prop on an RV-8.

Keep in mind the standard RV-8 gear gives way on hard landings, taking the prop closer to the pavement - so the recommendation to use the 72” prop. The nose gear on the 8A mitigates this problem.

That said, I have the very nice 74” prop on my RV-8. I note that the Grove gear gains me 1” to 2” of height over the stock gear comparing against another RV-8 spinnner to ground measurement.

Carl

What does the 74 inch prop do better than the 72? Does it pull better in climb but sacrifice speed? Or is it better on the top speed too?
 
What does the 74 inch prop do better than the 72? Does it pull better in climb but sacrifice speed? Or is it better on the top speed too?

All that is debatable - I’ll leave the conclusion to you. For me, I am very happy with the 74” Hartzell BA prop. But - I would probably recommend the 72” for those building the RV-8 with the standard gear.

One advantage (as I understand it) is if you have prop damage, the 74” prop can be dressed down to 72” or something between 72” and 74”. I hear this is not an option with the 72” prop.

Carl
 
What does the 74 inch prop do better than the 72? Does it pull better in climb but sacrifice speed? Or is it better on the top speed too?

Way back when I bought my prop for the RV-8 (15+ years ago) from Van’s, we had the same question - the conclusion was that the 74” prop could be shortened to 72” if you ever had to have the tip dressed for some reason....:rolleyes:
 
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