REFLECTOR: Do Plans include Carbon Fiber "Y"?

[Don Johnston]

A very timely post for me as I'm doing "The Big Flip" this weekend.
Something I noticed was that my doors (fastbuild fuselage) fit flush until
the strakes went on. I don't know if the engine will make it better or worse
(who am I kidding. It's going to be worse with the engine). :-(

 

The carbon "Y" makes sense that it will reduce the torsional distortion but
where is "3 inches down onto the wall"? I mean, the firewall is a big
honkin' oval, right? And this goes over the inside of the NACA's? 

 

The big downside for me is that my B-pillars are already in. So the best I
could do is to tie the leg of the "Y" into that.

 

-Don

 

 

From: Dennis Martin <dennis.doc at gmail.com>

To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>

Sent: Thu, Oct 8, 2009 9:07 am

Subject: REFLECTOR: Do Plans include Carbon Fiber "Y"?

 

 

 

Al Gietzen mentioned this geometry issue in a post yesterday, and Jim Agnew
advised me to install carbon reinforcement back in the late 90s. Here's the
thing. The entire fuselage will distort after you hang the engine on - and
doors may no longer fit properly. Physical forces from engine weight will
change all of the geometry.

 

Jim advised laying up a 2-bid carbon fiber "Y" on the top of the fuselage
(inside cabin). I don't know if it's in the plans by now, but I think it
should be a standard part of the build. I did this about 6 years ago before
installing the engine. I laid up a 12" wide carbon fiber "Y" on the ceiling
of the fuselage. The two branches of the Y go to the firewall, and attach
about 3 inches down onto the wall to add extra strength where firewall and
cabin intersect. The two branches of the Y meet about in the middle of the
cabin, then the trunk of the Y runs all the way to the front windscreen.

 

Added benefit is a stronger "egg" in case you ever end up in a ground loop.

 

My engine weighs 450 pounds, and my cabin is true to the original. Doors fit
same as when I first installed them. Door pins are tight, so there might be
minor distortion. But that should be easy to fix. 

 

 

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