The spar is made up of the web with four angle caps top and bottom, the web is actually in three parts. There is the doubler in the middle to allow for extra strength and the fork for joining. The outer end has a thinner 0.020" piece added on the end. I think this is to optimize weight and also that the aluminium sheet size was only 2 meters long. Not sure what the engine talk is all about, the snowmobile engines are far to big for a CriCri making it so far off topic its not funny. Shannon.