L

Larry DeCamp

Well Known Member
Friend
The plans call for 1/8" plastic plate with 1 3/4" hole at the carry through spar bulkhead. This is a very rough area with bulkhead overlap and rivets, thus making a poor surface to secure a flat plate. Is this plate to restrict potential 'buckling' of the pushrod tube, or to protect against 'abrasion' from the bulkhead/carrythrough spar ? Wouldn't it be more elegant to put plastic tube on the pushrod to protect it?

Your comments are appreciated..Larry
 
Hmmmm....I agree with you that putting a plastic guide there is just about impossible due to the uneven surface Larry. We just made sure that we had no rubbing at any point in travel. Plastic around the pushrod sure wouldn't hurt. I can inspect this area for wear through our (rear) battery access point.
 
I don't see any benefit to having a bushing where the pushrod
penetrates the rear spar bulkhead. If there is any contact at
this point, you either need to re-rig your pushrods or enlarge
the hole in the bulkhead (or both!).

Small changes in the elevator pushrod lengths or stick/mixer mounting
can alter the clearance at this point, but it is worth the effort to eliminate
any potential contact there. If you have put primer on the pushrod you
will be able to see marks on it if you are getting any contact there under
flight loads. On the ground, sound and feel will reveal contact.

Adding a bushing or sleeve would just require removal of
more metal at the bulkhead, possibly including more of the rear-spar
carry-through. My strategy of keeping the bulkhead hole as small as
possible lead to some challenges during final rigging, but like most
things in RV building, perseverance prevails!

- Dan Benua
RV-3B (and others...)
 
RV3 elevator push rod hole

I don't have any plastic in mine. I just made sure that the push rod would not touch the sides of the hole, I even ground out a little extra to make sure.
 
No plastic required

Thanks for the feed back gents. My conclusion was the high loads were in tension during UP elevator. Any buckling loads would be in down elevator, and I don't plan on outside loop activity ! So, the only question is why did the plans suggest plastic ?? I shall proceed with good clearance and move on...Larry
 
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