REFLECTOR: Do Plans include Carbon Fiber "Y"?

[Dennis Martin]

Don, I forgot that tiny detail about the NACAs. My Chevy engine required
adding two inches to the top, rear of my cabin. The NACA scoops did not cut
into my original cabin interior. There must be some guys out there who have
improvised a solution around the NACAs. Is there enough lateral space
between the rear windows and the NACAs? Or, perhaps the best idea is your
suggestion - tie the leg of the “Y” into the B pillars. Sorry for delay in
responding - traveling and having too much fun.

Dennis

On Thu, Oct 8, 2009 at 2:38 PM, Don Johnston <don at numa.aero> wrote:

>  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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-- 
All the best,
Dennis
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