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Old 06-29-2022, 11:37 AM
jclark jclark is offline
 
Join Date: Jan 2005
Location: Columbia, SC
Posts: 967
Default There is hope ...

Quote:
Originally Posted by scsmith View Post
I recently changed from the Whirl Wind 200RV prop to the Whirl Wind 72HRT prop. I have a standard Vans cowl.

... <SNIP> ...

Of course, there is no way to put the prop into full coarse pitch statically to verify the clearance. I am kinda worried that the prop could hit.

Anybody else have an 72HRT prop on an RV-8 with a Vans cowl? How much clearance do you have between the blade trailing edge and the cowl?
I have been helping my friend Scott (who is traveling on vacation) with his new RV8. He too changed from the 200RV to newer (actually now "legacy") blades.
Standard Van's cowl, (already painted), IO390 EXP upfront.)

With two people, you CAN turn the blades to the mechanical stop.

The issue (as you are probably concerned about) is what happens at the stop in flight when the engine can MOVE. Thus some extra space is in order.

WW supplies some "spacers" that can be used to limit how coarse the blades go. We were concerned about overspeed if the blades were not coarse ENOUGH, especially given that he now has that IO390 up front.

Before the spacers, we were able to turn the prop past a set point of say 2500 RPM. (Never pushed it past 2600 in the tests).

I don't remember what size shim we used but there was a size that worked throughout the speed range and (so far) no hitting of the BEAUTIFULLY painted cowl.

I have done some of the flight testing and I know that it works up to Vne without overspeed.

There is hope ...
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James E. Clark
Columbia, SC
Former EAA Board Member
RV6, RV8 Flying
RV6A Hoping to get back to finishing soon
APRS
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