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Section 240 - Fuselage

05.11.2006 As the Mazda 13B needs more space above the engine for the intake runners, water pump, alternator and the crank angle sensor, we will need to redo the firewall with a little more height. Below you can see the standard firewall in red, with a semi transparent grey overlay of the shape I am aiming for. I'll model the changes to see what flow on effects this change will have. "Change one thing, change everything". If the chnages get out of hand, I will stick closer to the red countour.


I have never been a fan of the steep sloping down cowl on the MII anyway (although it must be good for ground visibilty). The cowl shape I am aiming for is similar to the James Aircraft cowl (below) made for the Power sport powered RV-8's.

James Aircraft cowl


Whoever assembled the fire wall we currently have would appear to have used a factory 240.301 (stainless fire wall) , but done a pretty crappy job of riveting the aluminium stiffners on. There are smilies everywhere.

The 240.303 reinforcement plates where the engine mount attaches appear to be per plans, but the way the corners aren't radiused, and the 0.050" reinforcement is samwiched between the firewall and stiffener (below) without a joggle or spacer could well cause cracking.

240.303 240.303