Barneybc12d
Well Known Member
My "first time builder" rudder has some oil canning. How did yours turn out? I am going to push on my 76 Cessna skin this afternoon to compare.
Van's Air Force
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Oil canning rudder
- Thread starter Barneybc12d
- Start date
HeliCooper
Well Known Member
My rudder and right elevator turned out great. My left elevator had some pretty significant oil canning. Advice from Van's was that its luck of the draw and there is really no way to know exactly what caused it or a way to build it to try and minimize it. They also said if you push on it and it pops back out on its own they wouldn't worry about it. If you push on it and it stays in that position then I would call Van's for further guidance.
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cln1owner
Well Known Member
An attempt to explain:
Flexing of the skin, with some spring to it, between ribs, similar to the skin of a drum. My rudder has some, other parts of the plane as well, especially when its warm out and in the sun.
rzbill
Well Known Member
The others are correct as it applies to the skins. However, to give a little more etymology to the term, you have to imagine (if you're not old enough to remember) the spiral paperboard oil cans before the blowmolded ones of today (Thanks Graham Engineering).
Anyway, you poked a penetrating funnel into the metal end cap of the can and inverted the whole thing into the filler hole of the engine. The other metal end of the can would pulse in and out as the oil "glugged" unto the engine. IE "oilcanning". As you can again imagine, there are many container types that will exhibit the same phenomenon when being quickly emptied. The term has evolved to cover nearly any thin membrane that has a bi-stable or nearly bi-stable configuration.
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Does anybody know why further guidance is suggested if it doesn't pop back out? I was quite sure that my rudder was perfect until I pushed on it just now and found a section that will not spring back when pushed in. It will just stay there until the section underneath is pushed in. Anybody heard guidance from Vans on this?
Chris
N804RV
Well Known Member
I don't know for a fact. But, I'm guessing Van's would say as long as it springs back, Pushing on either side, and doesn't deform or "crease" you're OK. Just keep and eye on it for any permanent deformation. When the structure deforms, there's a likely an eventual loss of structural rigidity.
Actually, the term is even older than that:
On the "old" oil cans, you squirted maching oil on a squeaky part to lubricate it, by pushing on the bottom of the inverted can. It had just enough give to do the job, and would spring back as you released.
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rzbill
Well Known Member
Actually, the term is even older than that:
On the "old" oil cans, you squirted maching oil on a squeaky part to lubricate it, by pushing on the bottom of the inverted can. It had just enough give to do the job, and would spring back as you released.
True dat. Was pretty sure the whipper snappers never saw one of those.
rudder oil canning
My first-time rudder has oil-canning on one panel. It springs back ok, but I still don't like to just leave it. At this point, before I bend the leading edges, it would be easy to insert a small stiffener through the spar lightening holes and glue it in place with 3M double-sided tape. Has anyone tried this?
My first-time rudder has oil-canning on one panel. It springs back ok, but I still don't like to just leave it. At this point, before I bend the leading edges, it would be easy to insert a small stiffener through the spar lightening holes and glue it in place with 3M double-sided tape. Has anyone tried this?
Oil Canning
My rudder is in the clecoed together stage and does have some oil canning on one side in the lower half. It may get better (or worse) as I rivet the parts together , but would like to take any preventive measures I can to end up with a non-oil canning version. I was planning on using the double-sided tape when riveting the trailing edge as called out in the plans, but know past builders used proseal. I wonder if the proseal may provide more support. I've also seen the threads on prosealing the stiffeners, but understand that was used for earlier models and shouldn't be required on the later models. Still on the table though.
I understand it's probably not a structural issue, but just checking to see if anyone has any new ideas.
Thanks.
Shawn
My rudder is in the clecoed together stage and does have some oil canning on one side in the lower half. It may get better (or worse) as I rivet the parts together , but would like to take any preventive measures I can to end up with a non-oil canning version. I was planning on using the double-sided tape when riveting the trailing edge as called out in the plans, but know past builders used proseal. I wonder if the proseal may provide more support. I've also seen the threads on prosealing the stiffeners, but understand that was used for earlier models and shouldn't be required on the later models. Still on the table though.
I understand it's probably not a structural issue, but just checking to see if anyone has any new ideas.
Thanks.
Shawn
A better statement would probably be "make sure all rib flanges are at the proper angle"
On a tapered rudder, the angle wont necessarily be 90 deg (I can't remember if that is the case for the RV-14 rudder).
