IF YOU'RE OVER 50 YEARS OLD, YOU'RE BOUND TO HAVE A FEW
WRINKLES...
From: Bob Runge (ejectr@javanet.com)
Subject: Dimples
Hi Jim:
Attached is a photo of my Swift. Notice the dimples in the skin at this angle
of light. Can't say I can feel them, just see them. What do you think caused
this and what might I be able to do about it? Thanks Jim and have a good
day.
Bob,
I presume you mean the waves in the skin visible from the cockpit aft. Your
a/c is s/n 31. Some early Swifts had light skin on the fuselage. I would
guess yours is .020. My first Swift was s/n 42 and had the same thing, except
the factory had installed a vertical stiffener angle in each bay. It was
still kind of wavy. Later, I owned s/n 26 which had heavier guage aluminum,
.025 for the side sheets. It didn't have any waves in it. Evidently Globe
was aware of the fact that their little Swift was a little heavy for 85 hp.
Skin thickness varies on various s/n Swifts. I have seen late s/n's with
.032 for most of the fuselage. It doesn't do much good to save a few ounces
on skin guage, then put a 15 lb block of lead in the tail! Cessna uses .016
and .020 a lot in their airplanes. The Boeing 747 elevator end rib has .016
skin! I don't think there is much you can do about the situation, short of
reskinning your fuselage with heavier guage aluminum. I sold s/n 42 and bought
a later Swift! Mark Holliday is restoring s/n 76, the skin didn't polish
up to his standards, so he drilled it off and changed it! -- Jim
GETTING RID OF THOSE WRINKLES...(6499)
Has anyone actually tried the procedure on p.27 of the blue Swift Maint.
and Ops info book to remove wrinkles in the fuselage skin? It seems a bit
far fetched to me. Thanks. Keith Bracht <kab_bjb@skat.net>
Keith:
I've tried it, with varying degrees of success. If the airplane is more-or-less
hanging from the lifting eye on the engine (most of the weight between the
engine and the tailwheel) and the rivets in the row below the windshield
are removed, some skin wrinkles may come out. Then replace those rivets,
being sure to use 1/8". (some airplanes had 3/32" rivets from the factory)
Sometimes you can slip in an extra STEEL washer at the spacers in the belly.
The forward fuselage skins are usually .025, I like to replace them with
.032 (the side skins behind the firewall) If the spar web has wrinkles I
had a factory letter on installing stiffeners. (requires fuel tank removal)
Good luck! -- Jim Montague
FUSELAGE WRINKLES...(010202)
Subj: NC3232K
From: Allan Erickson <swiftalbon@earthlink.net>
Hi Monty
We are preparing to attach the engine to the firewall. Was looking at the
wrinkles on the side of the fuselage. Tried to eliminate them years age as the
blue book described, but did not have much luck. Do you have any other
suggestions? -- Allan Erickson
Allan
If those are the original skins, the forward section is only .025. The best
solution is to reskin that piece with .032. I didn't say easiest! I just
finished one of those this weekend and it is not too bad, except a couple of
rivets at the fwd top corner. Having said that, if your skins are otherwise OK
and have no venturi holes or other bad stuff they can be straightened. If your
engine is off this is the ideal time to do this. Or hoist the engine and see if
the wrinkles come out. If they do, bend up a couple of .025 or .032 angles to
bridge the area between the formers. Locate them so they push the wrinkles out.
Drill out one rivet in each former to hold the angle in place. A shim can be
slid in behind the angles to help. Release the hoist and make sure the wrinkle
stays out. Shoot the one rivet back in, capturing the new angle. No additional
rivets need to be installed, so it won't look bad. Structural adhesive can be
used to further hold the angle and any shims. Sometimes, with the engine lifted,
a rivet row can be drilled out and reshot to eliminate stress wrinkles. The aft
row in the forward skin should be 1/8" rivets. A few airplanes left Globe
with 3/32" rivets in this seam. I think all of these have been replaced by
now, but you never know! If I can clarify or elaborate, let me know. -- Jim
IF YOU WERE ALMOST 60 YEARS OLD YOU’D HAVE WRINKLES TOO! (FEB 04)
From: Jim Salmonsen <Topgunn62@aol.com>
Subject: Re: Question on a Swift.............
I was talking to a fellow who is interesed in my 172 for sale,says he knew a
little about Swifts,and advised the Earlier Swift Models had "thinner
skins" that were known to" wrinkle",any truth to this? Do you
have a/any favorite year(s)? ( You must be starting to look for my questions
each night, aren`t you?) As always,THANKS.........Jim Salmonsen
Jim,
The first 100 GC-1As varied a bit as Globe tried to get it "right".Some
early GC-1As only used .020 skin for the main sheets of the aft fuselage. Other
early airplanes used .025 skin for the same areas. Real late s/n's used .032 for
the aft fuselage. I would say the .025 was about right. I think .032 was
overkill. I suppose their thinking was "why save a few ounces on skin
weight, then bolt a 9 lb block of lead in the tail" for CG?" The early
airplanes used 15 pounds of lead ballast with a 125 installed. My s/n 42 had the
light skin and it had wrinkles in it. But so what? They didn't really hurt
anything. Later on, I owned s/n 26 and it had heavier skin The GC-1As had .050
stabilizer spars, where the later airplanes used .063. This has not been a
problem. The early wing/fuselage joint is superior than the later setup.
Overall, not much to worry about. See "Aluminum Wrinkles" in the
"Answer Man Archive." -- Jim