Gallery, Projects and General > The Design Shop
Rotary Engine Con Rod Crank Pin Assy
sbwhart:
Thanks for the input Guys
Russ:- I completely missed the fact the Elmer hub was fixed to the spool making it a master rod, thanks for pointing this out.
I can remember reading an article in model engineer about radial engines regarding, connecting the rods to the master and the effect on the engine timing, the article ran over a couple of issues, apparently with a full size engines the slave rods wern't spaced equally around the master rod to compensate for the geometry effects on the timing, it concluded that for scale models however the small differences involved were not significant to good running of the engine, it was these series of articles that got me interested in radials.
Thanks again
Stew
John Hill:
I think the master rod (aka 'king rod') is the technique used in real life aero engines.
bogstandard:
This is what I was on about, have a look at the conrod sweep on the lower left cylinder.
I don't know whether it is a drawing error or design error.
This Gif image came from the F.A.M.E site
John
John Hill:
--- Quote from: bogstandard on December 05, 2009, 03:24:01 AM ---This is what I was on about, have a look at the conrod sweep on the lower left cylinder.
I don't know whether it is a drawing error or design error.
This Gif image came from the F.A.M.E site
John
--- End quote ---
There has to be some variation as the pins on the king rod do not trace a true circle and this is worse for those furtherest from the king rod.
bogstandard:
John,
What I am trying to get over, on the original plans, it calls for something similar to a knife and fork arrangement on the big end, but in this case, two conrods are offset to each side of the main rod, using full length rods with a common crank pin, whereas when you go for this arrangement, with shorter rods and pivot point distances using a king rod and plate arrangement, the angles of operation of the rods change, and has to be proved before going any further as it might require modification to other components to prevents mechanical locks.
One thing I do know, having built it, the rods on this engine are very close to the cylinder bases as they are, and as I suspect, by changing the arrangement, problems will be found.
It is OK to modify things, but only if it benefits the original design, and even then, all related components have to be made compatible with the changes made.
John
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