REFLECTOR: Do Plans include Carbon Fiber "Y"?

nmflyer1 at aol.com nmflyer1 at aol.com
Thu Oct 8 12:02:48 CDT 2009


Dennis is right. My fuselage changed a bit too when I hung the engine & wings on, so there was more adjustment to be done in order to make the doors fit.. again. I did put in some strengthening lay ups, but not carbon. Did it help?? I am not sure since I didn't test things before and after. 



If you are putting your doors in, it may be a good idea not to spend too much time getting the fit perfect until after you have your wings & engine on. 



I kind of wonder if the factory has addressed this flexing in their fast build fuselages. Unless they tell the buyer, it would be a bit of a surprise to find that the doors don't fit good anymore after you hand the weight back there. It makes sense that things flex, but is an eye opener to see how much. 



Kurt 


-----Original Message-----
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. 





-- 
All the best,
Dennis



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