Firewall & Fuselage Width Update


I had ordered my Carbon Fiber cowlings from Feather Lite, but with a twist: Mike & Larry were going to put a joggle down the center of top and bottom of the cowling so that I could adjust the cowling widths to my new wider fuselage.  Unfortunately, as they played around with the original plugs and molds— [these were the exact same molds that Mike Melvill designed for his armpit scoop cooling design that he installed before his round-the-world trip with Dick Rutan] —they realized that it was just too problematic and difficult to put the joggles down the center of the cowling halves.  Plus, it would add significantly more weight, minimizing the benefits and increasing the cost, thus nearly negating the reasons for using CF on the cowlings to begin with.

Thus, I would have to go with the original cowling size, meaning I had to trim my firewall down to it’s original plan-sized dimension.  Of course, the firewall being back to its original size does nothing for me if I can’t mount it to my top & bottom longerons… which was the case since my rear seat was widened by 1.2 inches.  So I recalculated everything, and not wanting to have go after my front seat (read: cut)  I compromised (the art of engineering, eh?) and narrowed my existing modified rear seat back by 0.4″ to only 0.8″ over stock. Which still is a decent amount of extra room in this narrow of a fuselage.

The one effect it did have was that it accentuated the curve of my cockpit to make it even more football shaped (fatter at the center, and narrower at the ends).  I’m not an aerodynamicist, but I have had some folks say that my shape is less desirable and less efficient than the original design.  Regardless, I think it will still fly even with a potential small increased drag penalty.