Kyle Boatright wrote:
"cavelamb himself" wrote in message
link.net...

Kyle Boatright wrote:


Those of us who fly behind (or in front of) wooden props usually reduce
RPM significantly when entering rain. I reduce RPM to 1900 in rain, or
I see minor damage, despite the urethane leading edges. For me, 1900 rpm
results in a rotational tip speed of about 400 mph. This doesn't consider
the forward motion of the aircraft.

In WWII, more than a few combat aircraft used wooden propellers -
Spitfires, Hurricanes, and Me-109's being high profile examples.
However, I have never heard of any rain/prop issues with those aircraft.
And I'm sure there were plenty of occasions where those aircraft were
flown full-out in rain. FYI, with the Spit/merlin combination, the prop
is geared to roughly half the engine speed of 3,000 RPM. At 1500 prop
rpm, a 10.75' diameter prop has a tip speed of roughly 575 mph.

That's the kind of tip speed that will supposedly wreck a wooden prop in
the rain. So, what was different about those props? Were the blades
essentially disposable and nobody gave a second thought to trashing a
set? Did the blades incorporate some sort of technology that I've missed?
(Brass leading edges don't count - to the best of my knowledge, Spits
didn't have 'em.)

Thoughts?

KB






I believe most of those old wood props had a brass leading edge cover.
That ought to protect the wood from rain erosion.


I'm 99% sure that the props I'm talking about didn't have brass leading
edges. The next time you're at an airshow where a Spitfire is on display,
take a close look at the prop. On many (most?, all?) the prop is wood, and
you can't see a transition between a brass leading edge and the wood blade.
I've done this inspection several times at Osh and SnF...

KB


Sorry 'bout that, Kyle.

I was thinking Spads and Sopwiths...

Richard