Yet another twin.

Oldenginerod Fri Nov 21, 2014 4:17 am

These things keep coming up.
http://www.ebay.com/itm/TWIN-CYLINDER-COX-049-MODEL-AIRPLANE-ENGINE-/390977207091?pt=Radio_Control_Parts_Accessories&hash=item5b080ebb33
At least this one looks to have a legitimate attempt to make a crankcase, but it looks like the maker chickened out on trying to come up with a proper crankshaft.
Rod.

KariFS Fri Nov 21, 2014 5:15 am

Yeah, making a crankshaft for that one will be difficult. The pistons should move as "mirrored", in a true boxer engine fashion, and to create such a crankshaft with only one end supported by main bearings... hmmm. I see some strength issues Huh...

At least this seller points out that there is no crankshaft at all.

That kind of engine might be possible to make using a Medallion or a TeeDee as a donor. You could cut the cases and arrange the cylinders the same way, and substitute the back plate with an extra main bearing. Then with a new boxer crankshaft you would have the necessary pressure/vacuum cycle inside the crankcase and the engine would breathe through the crankshaft as a normal Medallion.

Of course anyone who has the skill and equipment to make a crankshaft for that application could easily whip up a crankcase too, with better results than butchering innocent little engines Sad