Gallery, Projects and General > How do I??

Dimensions for slow runner

<< < (5/5)

bogstandard:
Nick,

If you had to run the engine at the higher speed, then yes, it would use more steam. But in model boat situations, you can in fact run the longer stroke engines a lot slower, so you really don't use as much steam if using a shorter stroke engine.

I have people coming back to me saying, in some cases, they have had 50% longer sailing times using the same amount of water and gas, and the boat is performing just as well as before.

John

CrewCab:

--- Quote from: NickG on July 23, 2009, 06:56:13 AM ---If anybody wants a copy of the spreadsheet, PM me, it might be easier to visualise what I have said.

--- End quote ---

Yes please Nick, whilst I'm quite enjoying this thread and think I'm understanding most of it, a visual aid would be useful .............. Cheers

Dave

foozer:

--- Quote from: NickG on July 23, 2009, 06:56:13 AM ---I agree a bore to stroke ration of 1:2 should be ok for a slow running engine and it might start to look a bit silly if you go to 1:3. I can't quite figure out in my head whether the ratio would effect the running speed or just the actual stroke? Would a 0.5" bore 2" stroke run at the same speed as a 1" bore 2" stroke with the same pressure applied?  :scratch: :scratch:


--- End quote ---

General long stroke engines produce more torque but are run slower. Slower, not so much as the increase stroke makes it so but to keep the piston speed down. It does have to travel farther per cycle as same engine with shorter stroke both running same RPM. Heat build up from that can kill a long stroke running at elevated revs. Connecting rod length also effects performance, longer rod reduces the piston side loads but increases the rotating mass.

I need an aspirin now ..

Robert

Navigation

[0] Message Index

[*] Previous page