ORIGINAL: ffkiwi
Then there is the utterly counter-intuitive observation that some engines where there is no attempt whatsoever at any form of counter balancing-and with heavy pistons to boot-run quite smoothly-I give you the ED Bee, Elfin 149, DC Spitfire and Sabre and the Frog 100/149/150s as examples. Go figure...........!
ChrisM
'ffkiwi'
I am going to run with the idea that heavy pistons, heavy flywheels, solid blocks all tend to resist movement.
The piston acceleration from rapid onset diesel ignition is resisted better with a heavy piston, a heavy full circle flywheel stores energy better between cycles and a solid block absorbs the vibrations.
And the use of large prop, low revs and the old less powerful fuel mix of 33% of each helps too.
But surely all of these old designs don't make 'that' much power in order to create the thump in the first place?
So, if you'could' push any of the above engines to say 18 000 rpm and beyond, would they then start to vibrate badly?
Would they then be really better off with proper counter balancing?