"Bob" wrote in message
...
Wow!

Now that's what I was hoping to see.

Okay, maybe a PSRU using belts. But not vee-belts. There is two
examples of v-belt drives we can use to draw data from, the one on
the Headwind, another on the PL-4. Both call for some wizard
machining and both need matched sets of belts, in that v-belts stretch
and you end up with slippage. This was covered... 'way back when
sometime (and I've probably got the details wrong).

I have a Gibson tractor that has 4 belts running the transmission. It is
not as much load as the 40 HP will put on the belts, but with enough belts,
the load would be close enough to work I think. I found that if 4 belts
were purchased from the same lot, it was well enough matched. The tight
belts would soon stretch to shed their load to the looser belts.

The folks at Valley Engineering (sp?) have shown us how to do it with
a cog-tooth belt... which may also apply to some sort of serpentine
arrangement.

The toothed belt has been done at high HP levels (over 200HP) and have been
shown to last well over 200 hours. My concern with a setup like this is the
expense and availability of the pulleys and belts, and the machining needed
to put the whole thing together. Not do-able, IMHO.

Would a timing belt work? I usta have a Pontiac that had a belt-
driven cam...

I think the belts on a timing belt are square profile, and the ones being
used in commercially available PSRU units are a rounded profile. I seem to
remember that the square profile belts wore badly, and got too hot to be
reliable.

I'm thinking more of the machining here rather than the belt, on the
assumption that a cog-tooth belt WILL work... the main question being
how LONG it will do so. Which brings to mind the mention of a rear
axel something. Turns out, the bearing used for a rear axle is NOT
suitable for any kind of prop-drive. Slow prop turns more than 1200
rpm whereas a fast rear wheel is something less than that. Kinda like
the belt problem... you have to keep changing the thing BEFORE it can
fail, which it will in fairly short order. Cost is probably another
factor that needs to be considered here, in that a bearing that WILL
hold up at prop-speeds is probably priced a lot higher than your basic
rear wheel bearing.

How about the wheel bearings used on those itty bitty trailer tires? They
turn a lot more RPM's. With a good oil supply (from the engine) they ought
to last for a couple hundred hours, then they are cheap enough to just
replace them.

Then there's the problem of starting the thing. Direct-drive we can
tweak the timing so it will start at a flip of the prop. But put a
PSRU in there we've got to 'wind it up' to get it to the proper firing
point.

Yep. Gotta have a starter.

I wish I had a shop full of TATA engines to play with. There may be a
combination of cam & rod-length that can give a reliable 40hp at an
rpm most suitable for a prop.

TATA?

Speaking of props, has anyone ever heard of one made from bamboo?

I can't imagine. Props need to be solid with no voids, and voids bamboo
gots plenty of! g

I've got to go. Zometa. IV. About a quart. Takes a while (drip-
drip-drip...) Then I gotta look at a faucet that is doing the same
thing (drip-drip-drip...)

You make it sound so tempting. I almost want to go out and get some for me!
;-)
--
Jim in NC