The lower plate in my firewall reinforcing set is not there so much for
normal flight stiffening as it is for prop strike protection to prevent
airframe damage. Even a light idle prop strike, one blade into sand will
joggle the firewall at all 4 mounting spots a good 1/2". The lower plate
prevents this and stiffening the floor only will have no beneficial effect
for this...although it sure will for the rudder/brake pedal attachments. The
top plates are there for both prop strike protection and more so for
compression protection..... as a hard landing will try to pull the top two
mounting points together when the engine tries continue in it's downward
path when the airframe stops it's downward movement.
As for doubling the rivets up the door post, I hope you have Al or I can
show you pics of what happens to that area as well. The rivets don't "pull"
they get sheared clean and the "shop" ends stay tight inside the upright
tubes when they do. Since you haven't painted yet.....
Cheers,
Wayne
----- Original Message -----
From: "Alan Hepburn" <
ahepburn@renc.igs.net>
To: <
rebel-builders@dcsol.com>
Sent: Saturday, June 04, 2005 10:03 PM
Subject: Re: firewall plates
** Check your subject, does it still reflect the message? **
Mike:
If you double up on the forward floor (I had some pics in the archives -
should still be there) that also provides a lot more stiffness between the
lower motor mounts - achieves much the same as the plates, plus something
is
necessary to provide better mounting for the brake pedals and stop
oil-canning of the forward floor, especially with an O360. Also, use the
thicker corner wraps for the nose. MAM has them for the trkie version,
and
they again help to stop oil canning.
Be sure to use longer rivets to rivet the forward side skins to the door
posts. I don't believe the instuctions don't tell you to do this, and
that
may be why some folks have had trouble with pulled rivets in this area. I
know there's a recommendation to double up on the rivets, but if you
happened to use RV1410s, that would sure be a problem waiting to happen.
There's far too much metal to go through in this area for 1410s.
Regards, Al
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