"Barnyard BOb --" wrote in message
...
On Sat, 20 Sep 2003 19:21:22 -0400, "Larry Smith"
wrote:

I have a wood prop on my Taylorcraft and the GPS says it's slow, at
around
65 kts. How about a discussion on the relative merits of wood and
aluminum
props. I understand that wood is easier on your engine but the aluminum
prop is more efficient. Another thing I notice too, especially on the
O-320 and O-360-powered RV's is that the wood prop is so light it has
little
flywheel effect and if you don't have your timing retarded, it will kick
back in a heartbeat. I figure the wood prop on a Van's aircraft is for
CG.

To retard the timing because of a wooden prop is nuts.
I've never met anyone dumb enough to even consider this.
YMMV.

No flywheel effect with the lightweight prop. Add to that one of those
hot-spark electronic ignitions and you have the engine's flywheel and the
starter trying to tear each other up. Kickback. Never had it happen to
me but have seen it, so you are supposed to retard the timing, but just at
starting time, by starting on the mag, NOT on the Electroair. After she
begins running then you turn on the Electroair and everything is running at
advanced timing. And btw I recall reading that Klaus Savier (Lightspeed)
would advance his timing from the cockpit to as much as 45 degrees before
top dead center. During a race. At altitude. But not when starting.
ymmav.


FWIW....
My 0-320 with wooden prop would attempt to shake
the airframe and itself apart below 900 rpm.
So, you accept the 900 rpm idle.
That's it.
Period.

With metal prop --
Idle is acceptably smoooth, even at 650 rpm.
Added bonuses - brake life is increased.
No longer does the RV3 with 79 pitch attempt to taxi at 20+ mph.
Running in rain is a joy. No varnish to be damaged - unlike with wood.

I think what I'll do is buy an aluminum prop and try it for a while. I
couldn't keep up with a DCO-75 last week and it was a little
embarrassing,
since his engine was sick. But he had an aluminum prop.

Sorry, there's more here than meets the casual eye.

Yeah, and a sick engine will still run like a scalded dog. We had a
210-horse Continental once with compressions in the 30's and that thing was
a running piece of plunder.


A friend has two 65 hp T-Crafts

Selfish. He should share.

with McCauley 45 pitch props.
Both run 90 mph at 2150 rpm.
Both will exceed 100 mph at WOT at 2000 ASL.

I want that. Must try to achieve it. It may be necessary to do a little
rigging and clean things up a little. Your friend probably has his faired
in a little better than mine, wheel pants, that sort of thing, to make it
slicker, and you can take some of the twist out of the wings too. Makes
them squirrelly but faster. One benefit, though, is that if you take out
all the wash-out it doesn't turn to wash-in when you're flying inverted.


P.S.
Unless you look real close...
A metal prop pitched the same as a wood one
will cruise about the same. Not worth the money
difference in speed, if that is all you're looking for.

If you have to go significantly faster...
remove the wings

Like those turkey buzzards and redtails hereabouts which fold theirs up and
drop like bottle rockets when the Pud and I chase them?

or at least clip them
and bolt on a C-85.

That's an idea. Maybe another T-Craft like your friend. I already have
the C-85. It needs a top but the bottom is sound. I called Sensenich
about an aloonium* prop and they want 2600 bucks for one. So I'll look for
a used one.

Our clipwing expert in this neck of the woods, down in Mebane, builds his
wings with lightweight ply ribs and uses a hopped up O-200. I think he
calls it a Swick.


Barnyard BOb --














*Aside: This one should really get him hopping.