View Full Version : Extra rib and a great new friend!!!!
boardmant
03-31-2008, 08:24 PM
Hey there..I just read there is a requirement for an extra rib in the engine upgrades on certain model short wings. Does this apply to the Colt or just Pacers? It wasn't clear regarding the Colt...any help appreciated. Thanks Tom
BTW...I have my wing apart... had to reset the aileron hinge afterall..the aileron was too low and my hinges didn't line up..I am now learning the techniques of wing modification and riveting....rib repair, trammeling, rib alignment. My teacher, master mechanic and inventor, Al, is showing me more than I ever could have imagined. He is truly a higher life-form. He makes all his own tools and machines and has been designing machinery for over 60 years. "Al, should I buy a rivet setter for the project? No Tom, I made a better one, here you go." He's also made his own internal combustion engine with "a third the moving parts and four times the horsepower!" of anything in production. Ah, the people you meet in the misty hills of western Massachusetts! "I should have been a professor!" says Al.
He said Piper didn't use jigs or if they did, they were spent and shot because rarely did they line things up CONSISTENTLY! Apparently my wing is typical by being out of square, out of alignment, out of whack, out of plumb, out of tomato, out of everything with nothing lining up correctly. Best first student project I guess. And what crappola these ribs are turning out to be! One of my ribs had 12 repair jobs in it. (yes, replaced it) Although I hope I look that good when I'm 50 years old!
Cheers!
Tom
Gilbert Pierce
03-31-2008, 08:47 PM
The extra rib was installed when the VNE and gross weight was raised. It is not necessary for horsepower upgrades because even with the extra power, your V speeds and gross weight all remain the same.
There are pictures around taken in the Piper factory of all of the jigs they used. You would be hard pressed to build a steel tube fuselage without a jig of some sort. I doubt your wing came from factory out of shape and out of plumb with 12 repairs in one rib. Sounds like poor repair at some time in it's long ago past.
You can very easily build a wing with no jig. You just need a level table and the appropriate block under the rear spar when you install the leading edge skins. All of the dimensions are on the Drawing CD.
The following was posted by Jay Heil in May:
PIPER LETTER ON THE DIFFERENCES BETWEEN 135HP AND 150HP WINGS
From: glenn bauer
Date: Wed, 05 Jan 2000 07:22:11 -0800
Subject: SWPC: more about your wings
Well as luck would have it today, I was rummaging through the library's
holdings (talk about a cool Christmas present) looking for some STC's for a
member when I stumbled on a couple of letters from none other than Clyde R.
Smith Jr. On Piper letterhead and address to someone named Jim. Youkins
maybe???? Two letters dealing with just this issue about the number of ribs.
Here's some quotes....
"engineer to contact who worked with him on the change over from the 135
PA-22 to the 150 version"
"due to stress requirements resulting from the higher speed and also the
increase in gross weight required the installation of another rib"
"The problem is not with the spar or the fabric, but with the device that
transfers this load to the spar, namely the rib"
"To prevent collapsing the existing ribs and to distribute this increased
load more evenly along the spar, an extra rib addition and re-spacing the
existing ribs evenly..."
"... STCs on converting 125 and 135 PA-22 to 150s but if you look closely a
gross wt increase or red line (Vne) speed change is not included"
The 2nd letter reads....
"Vne of the PA-22-135 model is 158 mph (137 kts). The Vno or maximum
structural cruising speed is 126 mph (110 kts). The Vp or maneuvering speed
is 106 mph (92 kts)."
"I gave you information on what changes were done to the wings for higher
horsepower.......few others things....... such as reinforcement channels and
a couple different rib numbers"
"our aerodynamists people.....do not suggest and can not give permission to
convert a 135 wing"
"would be too many holes left open and many new ones to drill. The open
holes could be a place where a crack could start"
"would have to completely disassemble each wing, build a wing jig and start
from scratch. That's right, with just 2 single spars."
"that the addition of one measley rib requires complete re-spacing of all
the others except the gas tank ribs. And all that just to change your Vne to
170 mph and Vno to 135 mph"
He finishes up by saying the V speeds he gave are at gross wt, if you fly at
less than that, then the speeds can be increased and he gives some examples
of people doing that. Finally he says to sell the 135 wings and by some 150
wings. Now if only he said something about colt wings.... Better put these
back where I found them before I lose them
Steve Pierce
03-31-2008, 09:50 PM
Colt wings have the extra rib already though not needed for the STC I know of. The Colt wing is the same as the 150/160 hp Tri-Pacer wing except no flaps.
Bultaco Jim
03-31-2008, 10:03 PM
Steve, I was wondering where the Colt wing gets it's extra length-if anyone knows!
Steve Pierce
03-31-2008, 10:06 PM
I have a pair hanging in my hanger and they are exactly the same length as a Clipper, Pacer or Tri-Pacer wing.
Bultaco Jim
03-31-2008, 10:27 PM
That's confusing. Not only is my Colt's wingspan longer, (30') but Piper lists it as longer.(could the fuselage be wider?)
Steve Pierce
04-01-2008, 06:30 AM
What do you have that lists it as longer? A Cub or Super Cub wing is longer by a rib bay which is more than 30". One thing you will find about Piper, they didn't change much between the models. The metal spar J-3 wing uses the same parts and design as a Super Cub wing as does all of our short wings.
Bultaco Jim
04-01-2008, 10:32 PM
Steve, here are a couple of websites that list 30' 00"
http://www.airliners.net/info/stats.main?id and http://www.aerofiles.com/_piper.html=300
But there's just as many with the 29'4" numbers. The more I look, the more I think that they just feed off other peoples websites. I'll go with your number.
( I'll take a tape measure with me next time, just to see how short the Pacer wing is, cause it's WAY shorter than the Colt going through the hanger door.)
JohnW
04-02-2008, 08:16 AM
Well, according to the Piper drawings, from the PA-22 (4) drawing 14698 "Complete Airplane", the tip to tip measurement is shown as 29 feet 3 1/8 inches; the PA-22-108 drawing 15145 "Complete Airplane", the tip to tip dimension is 9...wait for it!...29 feet 3 1/2 inches (ARGHHH! A fat ugly typo! Should be 3 1/8 inches!!!). There is TWO possibilities whereby a Colt and and TriPacer might have noticeable clearance differences going out the same hangar door. One is that there have been non-stock wingtips installed on one or the other (or both) and the other is that Piper didn't have very good Quality Control. :o
If these numbers aren't correct for either of the ships -except taking into consideration the possibilties stated- then you have stumbled upon what JW has popularized in the Culture as "Another Infamous Piper Anomaly". A quick look at (all) the wing drawings for the 20s and 22s all show the same overall dimension (and they all bolt right onto my same wing rack), and all the fuselage assembly drawings call for the same dimensions between wing hinge fittings, and a whole bunch of us know that all the ShortWIngs except for the Vagabond fit into the same fuselage jig (the Vagabond is appx 8" shorter, from my memory). So "go figure". JW
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