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Firewall Weldments F302A&B F303A&B ?

M

mmcdonald

Active Member
Working on the firewall and noticed from pictures posted from Louise that
F302A&B and F303A&B were welded together. Is this how these parts came from Vans or did you guys add the welds?

No luck with manual or plans! Any help always appreciated.

Louise and Paul thank you sooooo much for posting the pictures via google
they are a great reference source when I have a question.

Mark
 
I don't have the plans handy in front of me Mark, so I'm not sure I know which parts you are referring to, but we haven't' done any welding, so the parts came as you see them. If these are the corner weldments that join the longerons to the firewall, I am pretty sure that there was a change to these from early to later kits - I know that we have the latest design - the "firewall face" is welded, but the "legs" of the weldments are left separate (from each other) so that they can be lined up with the longerons to which they have to bolt.

Paul
 
Corner Weldments

Paul,

Yes, working on firewall corner weldments where the longerons attach, I have a friend who can weld these parts for me, thanks for the prompt response.

Mark
 
Mark, the aft ears of these corner bkts aren't welded together on the the outside edge.
FWIW,t he parts I received appeared to be RV-4 parts and the angles don't match the longerons. Randy L encountered this also. You can put a jog bend on the last few inches of the longeron, force and rivet as some have done, or remake them as I did.
You will have a hard time getting edge distance for the rivets as is.
Mike
 
The firewall weldments are supplied by Vans as of late 1980's. They should consist of the triangular faceplate, and two legs welded separately to the faceplate. The engine mount bolt should go through all three layers. An important dimension is the 90deg angle between the two legs. This is so the longeron can fit snugly in that 90deg angle space. Plans show the longerons positioned on the *outside* of the weldments. However, if the gap between the two legs is too wide, you won't have enough edge margin when drilling for the rivets and bolts that ultimately attach skins to this assembly. Even if the legs are properly positioned on the faceplate, you still have quite a job of grinding and fitting. A simple alternative is to locate the longeron to the *inside* of the weldment legs. You end up with a small hump in the surface skin, but the longerons fit perfectly, and you will have more than enough edge margin when drilling for the bolts and rivets. I discussed this alternative with Van himself (back in the '80s when I was building, and he was the only guy answering the phone) and got the OK. This isn't a recommendation to do that, just letting you know an alternative (650hrs and still flying!)

- Steven
 
Longerons Inside Corner Weldments

Steven

Like this idea regarding longerons inside firewall weldment corners to eliminate edge distance problems. Thanks for suggesting this alternative, would not have thought of this without your help.

Mark
 
Mark - Glad to help. By now with your RV3 build you must be aware that it requires 3x more planning than the pre-drilled kits! For what it's worth, here were my rules for building: 1) Build parts to fit other parts, 2) Don't do anything until you have to, i.e., until the construction sequence forces it, 3) test unfamiliar cutting/drilling/riveting procedures on scrap and mockups, and 4) when you're tired, walk away from it.

Press on!

- Steven
 
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