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Message
Err... do I detect a missing motor mount tube
in the vicinity of the exhaust headers?.
It's not missing. I still have it in a pile of scrap
metal :-)
I was afraid someone would notice that. OK, I had
promised Fred that I wouldn't mention cutting off the tubes (yes, on
both sides), but since you asked, it's probably better to tell the
full story. Originally, Fred designed the mount to be strong
enough without those top tubes. This is a challenge on a small
firewall like the RV-3. I can't recall if you can see it in the picture,
but there's a 5th attachment point on the bottom of the firewall, which was
reinforced on the aircraft structure so it could take part of the
load. As the mount got close to being complete, I decided to
install the turbo, and the big heavy radiator (strapped to the
mount). Considering all the extra weight, and the potential for up to 6
G's, Fred thought it might be wise to add the upper tubes as
insurance. I agreed, particularly since it wouldn't be in the way of
the turbo manifold.
When I dumped the turbo, and giant radiator, I noticed
that the tube would be in the way of the exhaust. I called Fred, and
asked about hacking them off. For the record, he would prefer that I had
left them, but considering the reduction in weight, and my reduced interest in
high G aerobatics, he agreed that it should be fine, as long as I cut off both
tubes, so as not to introduce a twisting force in the
mount.
It is important to note that I am assuming all the
responsibility for cutting those tubes off. It is also important to
remember that you should never cut, drill, fold, spindle, or mutilate a tube on
your mount. This was a special case, where the tubes were added after
the stress analysis was done.
Cheers,
Rusty
(have hacksaw, will hack)
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