Blackbird

My contribution to the flat bottom subject, check out the latest update on the Morpheus thread.

ApexAddict

Man you did some solid work, so by cutting a spot for the exhaust rather than bending it to compensate for the bulge is smarter/more aero-dynamic?

Blackbird

Thanks!
If you follow the thread a few posts further, you'll note that I'm changing the outlet for a blown diffuser.

ApexAddict

I'm going to be building a flat underbody for my miata within the next few weeks, but I have a few questions before I dive into this whole process.

1) My biggest issue is where and how you guys are mounting the panels? I was thinking of mounting the panel over the outside of the frame rails and then on some of the bracing but some more insight on this particular topic would be much appreciated.
2) I see some people having the entire underside covered while others have a channel for the exhaust. What are the pros/cons to each one? If I decide to cover the entire underside, would I have to bend the panel in order to fit over the exhaust or what?
3) What material are you guys using? I've read that 2mm 5052 aluminum is perfect. Is this the correct thickness/grade aluminum?

I'm sure I'll have some more questions once I dive into the process, but this is all I can think of at them moment.

AlwaysBroken

edit: disregard, I just realized there's much better advice in this thread:

https://www.miataturbo.net/race-prep...ro-pics-63769/

cwatson

I've found this document and this website especially useful for under wing design considerations. Consider rake if limited to a flat bottom and CoP is too far rearward.




I recently made an underbody and diffuser for our race car from 0.050 (2mm) 5052. 5052 is preferred to 6061 for form ability and is only marginally weaker. I'd use 0.040'' next time to save some weight. Aluminum was selected over composites and plastics for cost ($160 for two 4x8 sheets), work-ability, hot performance, and flammability. Thinner panels required bending up on the edges or riveting reinforcements (L shaped). Rivet nuts and rivets were useful. Expendable HDPE or wood strips are used to protect the aluminum from the ground (it won't last long if it contacts). This stuff is great for those sharp edges you can't roll.



I know, it's a little crooked. Doesn't matter but won't happen on the next car (this one was totaled leading the race at WGI labor day weekend; underbody bent but reusable).