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Sealed Struts Question
Hi All,
Took my airplane (PA-20) in for some radio work today and got a question from an on-looker that I didn't know the answer to! I've owned this Pacer since April.
My airplane has the sealed struts installed (per the previous owner AND all logbooks/paperwork - it's all there), but my struts have these "raised bumps" along the surface of the strut. They look like rivets, but not - they blend in with the paint smoothly, etc. I have no clue what these are... anyone know? These are the Univair struts, according to all paperwork.
Still learning.
- Casey
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Re: Sealed Struts Question
They are welds, mine has them also. Not sure what they are there for though, never cut one open!
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Re: Sealed Struts Question
Thanks for the reply. I had read that they were welds of some sort and that they were supposed to be there, but couldn't find anything online to support that. Sounds like they are normal, though (based on what you've said and what I've found).
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Re: Sealed Struts Question
Casey - these are "rosette" welds that lock a reinforcing U channel down the centre of the strut. (With a rosette weld you drill a hole in the top cover and weld the bottom layer to the top as you fill in the hole - locks the two together. Used a lot in repairing and reinforcing tubing.)
P.S. These are out of the rubbish bin - I didn't just take them off the aeroplane IMGP3879.jpgIMGP3881.jpg
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Re: Sealed Struts Question
The sealed strut has a piece of channel slipped inside to add to the strength (compressive, most probably). What you see are the rosette welds used to fix the channel in position within the streamline tube.
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Re: Sealed Struts Question
How's that for simultaneous replies? Looks like we Aussies are awake with nothing better to do. My excuse is a strapped up wrist--what's your's Curley?
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Re: Sealed Struts Question
Supposed to be clearing the back yard jungle of lions, tigers and assorted other critters - any excuse to get out of yard work!
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Re: Sealed Struts Question
You learn something new every day. I've wondered about this myself, but now I know...
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Re: Sealed Struts Question
I had always assumed that the inner piece was a piece of tubing the OD if the minor id of the streamlined tube, but I guess I was wrong.
The piece is added to stiffen the strut to reduce the possibility of bending and failing in negative g. the rear strut does not have this added since it has less compression loads negative than the main strut.
You could say that this maked it stronger in compression (and it does) but mostly it helps control bending and misaliging the forces in compression and buckeling the strut..
JDB.
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Re: Sealed Struts Question
Thanks for all the replies! Learning something new every day.... now I can explain these when people ask. The guy asking me wondered why I had holes in my sealed struts. :P
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