Daniel

On thread.

The problem can be broken down into two sub problems.

1. The 'club' is a flywheel and used to absorb the firing impulses
like a standard flight prop. Size can be back engineered as to weight
to give the proper flywheel. Home made one should be out of proper
wood, have proper hole pattern and front and back flanges to prevent
crushing wood and of course balanced. Should be re torqued and
inspected after each run. Should be run short runs until it has been
qualified for long runs.

2. Engine is air cooled (unless it is Corky's water cooled auto
conversion) and needs some cooling air which can be from the club or
an external fan. Since a 'club' is normally short you can put a high
pitch on it to blow air for cooling (you are not looking for flight
efficiency). You do have to balance the pitch load against the power
output at max throttle (and rpm).

If a water cooled engine, you can use a radiator and cool via the
'club' air or other means. Even make a water heat exchanger (put
radiator in a tub of water that you can let fresh water run in from
your facet to keep a cool bath. to bleed off the heat).

Hope these ramblings give Corky some ideas on what he can do (cheap
and in house).

One other thing he might do is check shops that rebuild engines and
see what they use and where they get any device (club) and if he could
rent or borrow for his tests.

Also contact EAA to see what they have. Also go on Internet to other
engine conversion groups and ask what they do to qualify their
engine(s). Don't invent the wheel if you don't have to.

Took a break and called around Houston with no success. One said to
look in Trade-a-Plane which might be a good idea.

Looked further on Internet and found data that says the club should
be calibrated to let engine put out max horse power at WOT. They said
that both Lyc and Con had bulletins about testing (they wouldn't apply
directly to Corky's engine but might give him some ideas of what
should be done and how?

Also if a auto speed shop with a dynamiter (sp) is available, use it
to document rpm, torque, etc. before reliability runs on test stand in
his shop.

Have at it Corky and keep us informed how things turn out.


Big John


On 14 Nov 2003 05:28:53 -0800, (Daniel)
wrote:

(Corky Scott) wrote in message ...
I'm looking for a club prop I can use to break in/test an engine. I
could use a regular prop I suppose, but the engine will be on a test
stand and I'd rather have something with a reduced diameter for
safety.

The engine will be producing around 180 to 190 hp and I'd like to be
able to run it up to full power/rpm for extended periods. Maximum
prop rpm will be 2400. The prop hub has a standard bolt pattern.

Any ideas? Suggestions?

Thanks, Corky Scott

Lots of OT responses, which is OK, but I'd like to hear an on topic
answer to how one sizes an appropriate club for any given engine.
Anybody have an answer?

Daniel