The Steamboating Forum

what rpm should i run my Richard Burleigh compound at? its 3+5x4.

Somewhere between 300 and 600 rpm is probably about right. It depends how well balanced your engine is, for one thing, lubrication used, and stiffness of engine bearers, etc British practice is towards higher speeds; modern US practice seems to be somewhat larger engines turning somewhat slower.

- Bart

One thing to keep in mind, the lower the RPM with the same torque output (HP) results in much higher loads on engine wear surfaces. I ran with a tolerable clicking wrist pin for two years on a 20 X 20 3 blade prop. Went up to a 21 X 23 4 blade and the click quickly became louder and it had to be repaired. I prefer the slower RPM.

-Ron

With each boat/engine combination there will be a 'sweet spot' where the vibration is less and one enjoys the experience. It's very hard to predict this. That's why most of us go through a couple, if not more, propellers as we sort out our boats.

It's tempting to try to get everything just right the first time. Good luck with that! (grin)

Mike

I have to say I'm in the 'run it slow' brigade, I like to hear the beats. That probably means best to have a bigger than needed engine, and under-run it. I had enough of high speed things when racing two-strokes (2/cycles).

Also consider that steam consumption may be different if the engine is loaded down too much. I am gradually tweaking Zeltic's propellor to find a sweet place where revs and engine load are comfortable and steam consumption isn't too great. With the initial prop setting, the revs were lovely to live with, but the engine was trying to pry itself out of the beds on every stroke, and even now the feed pump is struggling to keep on top of the demand. About to go back to the old prop for awhile to test how far out we are.
Best solution would be to find another engine the same working in a similar size boat, or any published material if any exists. While typing this I did a google search and came up with this http://www.steamboat.org.uk/register/html/phoe0456.htm
Daniel