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Jim Miller
04-26-2011, 01:43 PM
This won't be possible with new sealed struts but for those making/using old ones
it may be of interest. My clipped wing project uses old strut material and when I saw
a friends Citabria I liked the way it connected the jury struts to the main strut. No
clamp, just a 1/4 inch ID bushing thru the strut and I-bolts. I added a couple of washers
under head of I bolt just in case I need some adjustment during rigging, but Citabria
doesn't seem to have any problem. The Jury strut blanks came from Back Country
cubs-good prices.

Jim Miller
04-28-2011, 07:30 AM
Does any engineer types see any problem with this mod? My struts are orignally PA-18 with about
three feet cut off fork end, inspected, reshaped and Alaska Airframes sealed barrels welded in for
5/8 forks. On the wing attach end the 5/16 open hole was drilled out to 7/16 and a 5/16 ID steel
bushing was welded in to seal. The jury strut attach bushings are 3/8OD, 1/4 ID thru the strut,
tig welded on both sides to seal. A few ounces of tube oil was placed in strut before final weld.
The struts are sealed as the oil has not leaked. I got the idea for the thru bushings from Citabria
but if a safety issue I would certainly reconsider.

Thanks
Jim Miller

Iflylower
04-29-2011, 11:11 PM
Jim, here's my 2 cent answer. You've asked on a couple threads, and not getting an answer.

I think it looks great, and will work as well or better than pipers. I was considering the same thing, cause I like the look and like how the citabria did it. I didn't do it cause I ordered lifetime struts from Univair and couldn't bring myself to drill em and weld em.

- citabria does it and they're aerobatic.
- cleaner look
- looks heavier duty than the little clamps.
- your already welding and building, throw a bushing in there and be happy - you're experimental
- you have a clipped wing and most short wings don't even have jury struts... You're miles ahead!

I vote GO. Ymmv.

mike mcs repair
04-30-2011, 01:41 AM
..
I think it looks great, and will work as well or better than pipers....

agree.....................

MainlandCub
04-30-2011, 04:19 AM
Jim,

Take a look at this video;
http://www.youtube.com/watch?v=H-YbK7rm-zQ
for a good close up shot of how it goes together on the carbon Cub thing.

Rans also have an eyebolt thru the strut like you have done.

From an engineering perspective, you have restored the tensile strength lost by putting a hold in the strut by welding in the bush. The only questionable aspect is the bent over lug on the jury strut as you've created an eccentric joint. I'm not sure it's an issue as these only stop the strut from collapsing when in compression.

Like Iflylower I have wondered why jury struts anyway if it's a short wing?

Cheers,
Andrew.

Jim Miller
04-30-2011, 06:57 AM
Thanks all for the reply. I thought the same thing about both of the points raised:
why use jury struts, and the bend in them. I went back and looked at the Citabria
after I realized I would have to bend the J Strut. Citabria's are bent also and much
smaller/thinner tubing is used. The jury strut material from backcountry cubs is very
hefty and on both the flattened ends, I slid in a piece of .040 4130 before welding.
The Pa18 struts are a lot lighter than the Colt or Tripacer especially the rear. The
PA22 also has internal support welded inside the struts.

Thanks
JM

N86250
04-30-2011, 08:49 AM
This won't be possible with new sealed struts but for those making/using old ones
it may be of interest. My clipped wing project uses old strut material and when I saw
a friends Citabria I liked the way it connected the jury struts to the main strut. No
clamp, just a 1/4 inch ID bushing thru the strut and I-bolts. I added a couple of washers
under head of I bolt just in case I need some adjustment during rigging, but Citabria
doesn't seem to have any problem. The Jury strut blanks came from Back Country
cubs-good prices.
The Citabria isn't the only model with jury strut fittings like that. Pretty much all the Bellanca Champs, the Champion Aircraft Champs, the Aeronca Champs, L3s, L16s, and Chiefs going back into the 1940s that have steel lift struts use the same welded bushings and eyebolts. They been doing it that way a long time. jrh

tempdoug
05-01-2011, 08:01 AM
Could anyone here post a picture of a cub that had a snow or wind load on the wing when it collapsed. Ive seen it but no pictures.

mike mcs repair
05-01-2011, 10:57 AM
Could anyone here post a picture of a cub that had a snow or wind load on the wing when it collapsed. Ive seen it but no pictures.


no pictures,
if you jury strut clamps on struts are loose they will slide on strut allowing it to bend under compression loads like these..

but wind from back load ussually bends rear strut right about a foot and half from top... sometimes at bottom??

wind from front shoves/collapses those jury strut attaches sticking out of wing as wing tries to bow down at struts...(you ever want to see scary, put wing & struts on plane without leading edge on, just ribs & internals, leave jury struts off, and go flex wing around some.. amazing)

snow load can bow ribs down like a bananna before it colapses strut.... the bent strut happens once snow starts melting underneath sending the watter weight that was up front to rear of wing.... or can happen from larger amount of snow while falling....