Fork and blade con rods
Fork and blade con rods
(OP)
http://www.boddice.co.uk/bpic526.htm
These were pretty popular in V aero engines around WW2. Any idea why? C LF Taylor says it minimises the length of the engine, but I can only see a saving of about half a big-end's length, not much in return for the complexity and uglification involved.
My guess is that it drmatically reduces the loads on the mains due to the reduction in rocking couple from each pair of pistons, so you can have a smaller lighter crank.
These were pretty popular in V aero engines around WW2. Any idea why? C LF Taylor says it minimises the length of the engine, but I can only see a saving of about half a big-end's length, not much in return for the complexity and uglification involved.
My guess is that it drmatically reduces the loads on the mains due to the reduction in rocking couple from each pair of pistons, so you can have a smaller lighter crank.
Cheers
Greg Locock





RE: Fork and blade con rods
Mart
RE: Fork and blade con rods
I helped in the engines on my cousins Cessna T-50 and an R-1340 once when I was a lot younger. I'm with Mart, I am totally fascinated by the big radials (I worked on the Hughes flying boat for a year or so).
Come to think of it, the big V-16 turbocharged methane burning Orange County CoGen units were fork and blade. Absolutely no good reason I can see. These engines are, like, 25 feet long and 10 feet tall with an 8' dia flywheel operating at a max rpm of something like 800 rpm --- if memory serves. Five of the biggest pushrod engines I ever worked around. I have no idea as to the overall balance problems on an engine of this size!!!
Rod
RE: Fork and blade con rods
John Woodward
RE: Fork and blade con rods
I don't know why the aircraft guys did it, but I do know a guy with 30 years of aircraft engine design experience. I'll be sure to harrass him about it next time our paths cross.
RE: Fork and blade con rods
http://www.nelmes.fsnet.co.uk/paxman/paxeng34.htm
About 80% of the way down the page, the description of the Valenta engine notes it had fork-and-blade rods to minimise engine lenth. Keep on going, and the later engines had side-by-side rods to reduce cost!
PJGD