Propeller speeds

Moderator: stan.hornbaker

Forum rules
Be nice!
Post Reply
jfhesse
Posts: 2
Joined: Fri Nov 03, 2006 9:09 am
First Name: joe
Last Name: hesse

Propeller speeds

Post by jfhesse »

I have just assembled a model MM-5 engine, coffee cup type, and I
want to know what some of the prop speeds other people have obtained
with the same or similar S. engines. In it's intial run, it seemed
the prop speed was abt 400 rpms, but two subsequent runs (all with
boiling hot water in a mug) seemed to get up to abt 300 rpms for a
few mins. After that, the prop slowed down slightly, abt 200 opr so,
and would run for another 15 mins until I removed it from the mug.
Is 300 rpm a decent speed? Can one go much faster with the MM5? The
initail temp on the indicator was 72F. It works pretty slick.
stan.hornbaker
Posts: 532
Joined: Thu Jun 20, 2002 6:01 pm
First Name: William S.
Last Name: Hornbaker

Propeller speeds

Post by stan.hornbaker »

Most usually refered to as engine rpm.
If you want to see it 'fly' try it outdoors on a real cool or cold day!
Rpm is dependent on the difference in temperature between the hot bottom plate and the top of the displacer. It is also affected by friction which should be minimized where ever possible. The engine was designed an assembled with in mind.

If you don't want to wait on a cold day put a few ice cubes in a plastic bag to contain the water of melting.

Thermal energy or heat enters the engine by way of the bottom plate, some is converted to mechanical energy to turn the crankshaft and propeller, and the balance exits the engine by way of the top plate.

Go to the "Site Map" where you will find links to a more detailed explanation of how Stirling engines work.
Post Reply