Pazmany PL4

Peter,

It really doesn't matter WHERE in the lineup the longest belt is. You can
have two, or "very many", and absolutely none of them will be the exact same
length. One WILL be longer than all the others, and (by very keen
observation it will be also found) one of them will be shorter than all the
others. Always, one will carry more torque, horsepower, heat, friction, wear
(or your malady of choice) than others and share the rest of the
difficulties among its companions, and will lead to premature failure of one
belt or another.

Those difficulties, along with uneven stretch pattern among the individual
belts - thus making it hard to maintain proper tension on each and every
belt in the setup, is what gave rise to the new style of belts and pulleys.

Even pulleys that are quite carefully manufactured will still have the
grooves nearly exactly same angle and depth and diameter- but never exactly.
It is actually kind of like shooting fish in a barrel with a shotgun. You
have just got to wait and see what comes to view after all the smoke clears.

The plane and installation in question did not take advantage of the
"poly-V" single belt with multiple grooves - much like the serpentine
alternator belt on your 1980 F-150. And the "cog" type belt, as in timing
belts and synchronized drives was not an option then, either. Multiple
vee-belts were a compromise solution, and the difficulties associated with
that solution were what came along with the perceived benefits, like rpm,
power, weight, cost.

Flash




"Peter Dohm" wrote in message
. ..

"Beryl" wrote in message
...
wrote:
On Feb 25, 10:58 pm, flybynightkarmarepair wrote:


I've since heard from Veeduber (who knew Pazmany, and flew out of the
same airport as the prototype) that you could smell the first ship
before you could see it, as it burned, errr flew off the first 40
hours with the belts constantly slipping.
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Well... mebbe it wasn't quite that bad... :-) But with multiple vee
belts it's impossible to keep ALL of them at the same tension. The
loosest of them would slip and there was a definite pong of hot rubber
after every flight.

Eh? I can't visualize it. Either all, or none, slip.

I must admit that I am having a little trouble visualizing this one as
well--unless that loosest belt was either the farthest from the engine or
the farthest from the prop. In those cases, I have no trouble at all.

Peter

On Feb 26, 12:02 pm, "flash" wrote:
.......
What he said. Plus the fact #4 ovaled out quick like a bunny as the
asymmetric load was increased (ie, trying to offset the belt
slippage) ... which also wore out the lower pulley.

The craziest part was that Walt Mooney had similar problems with the
Crosley (sp?) powered Mite... and he was standing right there :-)

-R.S.Hoover