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tcraft128
03-09-2011, 01:23 PM
Anyone have a full size print file for the US35b? I need to make a rib repair jig and it would be nice to start with the correct shape.

:lol:

J5Ron
03-09-2011, 06:20 PM
Would the Wag-Aero 2+2 wing work?

Bugs66
03-09-2011, 06:46 PM
Drawing 13814 on my web site should be it.

tcraft128
03-09-2011, 07:36 PM
I think the 2+2 will work. I am looking for something that I can print actual size and I am not savoy enough to do it from a pdf. Is there an option to print it scale?

Bugs66
03-09-2011, 07:40 PM
The drawing is 36x24 or so. Take the PDF on a flash drive to Kinkos or maybe you have a friend with a plotter.

Edit: was just looking at 13814, the scale is half (6in = 1ft) so yeah, you would need to enlarge.

D.A.
03-09-2011, 11:09 PM
...I think the 2+2 will work...
You probably already know this but the Wag Aero airfoil is different than the Piper airfoil. You are correct, the Wag airfoil is the US35b, while the Piper is "Modified".

Your project is awesome!:up

D.A.

mike mcs repair
03-10-2011, 12:05 AM
..... I need to make a rib repair jig and it would be nice to start with the correct shape.

:lol:

and WHICH version of piper rib sizes/shapes do you HAVE to repair?

bothering to make a print that's 3/8" different from your ribs you got might not be to useful for you.....

D.A.
03-10-2011, 12:28 AM
...I need to make a rib repair jig and it would be nice to start with the correct shape...

That's why I bought a Dakota rib. Nice crisp line to lay the jig airfoil out with. I had an original Piper rib for the trussing.

tcraft128
03-10-2011, 06:05 AM
I have a mix of Super Cub and Pawnee. I did not know there was a difference. :oops:

Thanks for keeping me straight!

Bugs drawing and Kinko's sounds like the best bet. The engineers here have a plotter, but they are kinda hard to talk to....:roll:

Bugs66
03-10-2011, 10:56 AM
I was able to scale the rib drawing full size using Photoshop. I attached here but will put a copy in my drawings site soon. The drawing size is now 36x72 so you will need a plotter for sure. Make sure you turn off any scaling when printing this PDF. If anyone prints this let me know if the dimensions are ok. As far as I know they are.

1583

D.A.
03-10-2011, 11:42 PM
The drawing is 36x24 or so. Take the PDF on a flash drive to
I did the exact thing Bugs. I attached the 12183 drawing from your website to an email and sent it to our local OfficeMax. I called them, asked them to print it on their 36" printer and it was done when I got there. Thanks for having the resource available!

MainlandCub
03-11-2011, 12:58 AM
You're really heading off in the wrong direction. Never scale off drawings. That is a hard and fast rule from those of us from the pre-CAD age.

Bugs' drawing has the co-ordinates on it. Plot that out on the piece of board or whatever you're using for your rib jig. If you can't do that, buy a rib from Dakota or Univair and build your jig around it. That's all I did with a good Piper rib.

Seriously if even if the Piper draughtsmen drew that profile out accurately and without error, the scanning will have distorted it for sure, no matter what machine was used.

I hope that helps.

Cheers,
Andrew.

Bugs66
03-11-2011, 02:14 AM
You can easily measure the printed drawing to verify if accurate. If a CAD wizard wants to contribue a fresh drawing that would be welcome! ;) I will host it on my site.

canopyflier
03-11-2011, 04:30 PM
Is there and advantage to having the "Modified" airfoil over the US35b?

Dave Calkins
03-11-2011, 05:02 PM
I like the straight '35B better, I think.

Would love to hear what the smart-guys have to say about the "advantages" of the "modified".

.....? DAVE

D.A.
03-11-2011, 11:21 PM
Is there and advantage to having the "Modified" airfoil over the US35b?
I'm not an expert by any means, but I don't think there is a standout advantage to either airfoil. Here's a link to the thread where I compared them one on top of the other:
http://www.supercub.org/forum/showthread.php?39427-Chris-amp-D.A.-s-SC-Build/page2&highlight=chris

If anything, with the higher camber, I'd say the Wag airfoil is probably a higher lift airfoil. The airfoils are very close, but they're "Just different enough" that you can't mix and match them. Chris and I went with the Piper version because of all the research and support and ready replacement parts that are available. Other than that, I wouldn't think there would be much difference. Just my 37 cents worth.......

SpainCub
01-20-2013, 03:22 PM
Hi,

Here is a files I picked up somewhere (I canīt recall where) but it was nicely drawn by Keri-Ann Price.

I will be emailing her soon to see if she could come up with the 613.5 Airfoil fully drawn as this file... :D

BTW Bugs file measures out if you print, but this file will give you better lines to work from.

http://www.j3-cub.com/forum/attachments/f88/37169-some-small-progress-my-j-3-wings-usa-35b-modified-piper-dwg-13814-airfoil.pdf

Ok, so I could not find the file on this computer, but I did find the link where I had gotten it.

http://www.j3-cub.com/forum/f88/some-small-progress-my-j-3-wings-21816/index12.html

We should try to get her to build a PA-18 or a Wag Areo 2+2, she could be very resourceful. :D

All the best,

fobjob
01-20-2013, 05:12 PM
I thought the upper ordinates were increased by 4 %, not .4%.... what would be the point of changing them only .4%???

...unless it was a mechanical fit issue...??

Darrel Starr
01-20-2013, 07:58 PM
Here are some great references to airfoils. Covers just about every plane built.
http://www.ae.illinois.edu/m-selig/ads/aircraft.html
http://www.ae.illinois.edu/m-selig/ads/coord_database.html#T
The web site has the USA35B but not the "Modified USA35B" as used in Pipers.
http://www.ae.illinois.edu/m-selig/ads/afplots/usa35b.gif
http://www.ae.illinois.edu/m-selig/ads/coord/usa35b.dat

fobjob
01-20-2013, 08:10 PM
Here's the wind tunnel data, anyway.. http://www.supercub.org/photopost/showphoto.php?photo=28113&title=usa-35b&cat=500

skywagon8a
01-21-2013, 07:13 AM
Here's the wind tunnel data, anyway.. http://www.supercub.org/photopost/showphoto.php?photo=28113&title=usa-35b&cat=500
This is very interesting. It shows that the stall angle is just below 20 degrees. I would not have suspected that it would have been that high. My guess was that it would have been nearer to 16 degrees. I think that I shall make a angle of attack indicator on a pole mounted on the wing. Perhaps I'll also fit a floating pitot tube to the same pole? The results should get us into some interesting conversation.

fobjob
01-21-2013, 09:28 AM
Probably more with the VG's on.....

JimC
03-16-2013, 05:49 PM
The AOA of the USA35b and USA35bMod were referenced to the bottom of the wing, not the chord line as is done now. That's the reason for the seemingly high stall angle.

The coordinates of the USA35b are screwed up at the leading edge radius. There are also discrepancies between different Piper rib drawings (false rib and full rib noses are shown different -- they aren't). There are quite a few mistakes in the Piper wing drawings.

qsmx440
03-16-2013, 09:13 PM
The AOA of the USA35b and USA35bMod were referenced to the bottom of the wing, not the chord line as is done now. That's the reason for the seemingly high stall angle.

The coordinates of the USA35b are screwed up at the leading edge radius. There are also discrepancies between different Piper rib drawings (false rib and full rib noses are shown different -- they aren't). There are quite a few mistakes in the Piper wing drawings.

Any chance of naming those errors or at least the ones you remember?

SpainCub
03-17-2013, 08:26 AM
The AOA of the USA35b and USA35bMod were referenced to the bottom of the wing, not the chord line as is done now. That's the reason for the seemingly high stall angle.
The coordinates of the USA35b are screwed up at the leading edge radius. There are also discrepancies between different Piper rib drawings (false rib and full rib noses are shown different -- they aren't). There are quite a few mistakes in the Piper wing drawings.


Please share which drawings you are referring to and what errors you have found? I am reviewing and redrawing some of the wing parts based on both Piper and Wag Areo drawings, so your feedback would be greatly appreciated.

I think that one of the many issues with the Piper drawings are the revisions, they are not all there... what I am trying to do is get the latest rev, then used that as a base for parametric relationship of the parts, ad you stated the false rib is something I was looking into.

BTW, can you clarify your comment of high AOA? I am not following you there... (I know it's me... so can you be so kind to please explain this further with a bit more detail? :roll:)


Any chance of naming those errors or at least the ones you remember?

+1 Caught me typing and walked away thinking I had posted, then saw your post!!!

Longwinglover
03-17-2013, 09:47 AM
OK 25 posts of people giving their best guess. Let's go to "the" source, Clyde Smith, Jr. - The Cub Doctor. Quoting from the Sept/Oct 2005 Cub Clues newsletter A Study of Piper Ribs Clyde says in part:

"All fabric Piper ribs employed one airfoil design, the USA 35B, but were modified by increasing the upper coordinates by 4%. Thus the terminology "USA 35B Modified" was the typical description of the Piper rib and the chord was 63 inches. All the ribs were similar from the J2 through the PA-25 Pawnee.
...
In my weekend siminars, I divide the wings into two classes, the "Cruiser Wing" and the "Cub Wing". The Cruiser wing was used on the J4, J5, PA-12 and PA-14. The Cub wing was used on the J3, PA-11, PA-18, PA-25 and all the short wingers. The differences here were that the Cruiser wing had the "S" or "Sloped" type of false spar and had a stamped nose plate rivited into the leading edge or nose section of each rib, rather than the individual truss type bracing.
...
The Cruiser wing panels did not have the short nose rib sections between each main rib either
...
The Cub type wing had the concave type false spar and the nose of each rib had the individual brace members. These wings also utilized the short nose rib sections, forward of the main spar, between tha main ribs."

John Scott

behindpropellers
03-17-2013, 09:51 AM
I would be interested in milling out some jigs for you guys.

I'm not sure what the demand is but if people wanted 10 or so Jigs built I would do it.

Thanks

Tim

JimC
03-17-2013, 10:05 AM
I'm installing tile in the washroom today. Will get back in more detail later. In the meantime, as just one example, on different Piper drawings, the leading edge radius varies between 1.00 and 1.39 inches, and the radius point moves around. Just aft of the radius point on the top surface there are mistakes in the listed coordinates that make the upper front surface too flat. This has adverse effects on the stall characteristics of airfoils built to the coordinates shown (Piper didn't always build to the drawings).
fro
Note the zero reference line in Post #20. In modern wind tunnel work, the aoa is referenced to the chord line (a straight line drawn through the trailing edge and the radius point of the leading edge radius). In older airfoils like the 35b and 35b Mod, it was referenced to a straight line drawn from the trailing edge tangent to the lower surface of the wing. That makes the stall aoa of these older airfoils seem to be several degrees higher than it would be in modern usage. just subtract the angular difference between the two reference lines to adjust the old wind tunnel data to modern usage.

qsmx440
03-17-2013, 11:49 AM
I'm installing tile in the washroom today. Will get back in more detail later. In the meantime, as just one example, on different Piper drawings, the leading edge radius varies between 1.00 and 1.39 inches, and the radius point moves around. Just aft of the radius point on the top surface there are mistakes in the listed coordinates that make the upper front surface too flat. This has adverse effects on the stall characteristics of airfoils built to the coordinates shown (Piper didn't always build to the drawings).
fro
Note the zero reference line in Post #20. In modern wind tunnel work, the aoa is referenced to the chord line (a straight line drawn through the trailing edge and the radius point of the leading edge radius). In older airfoils like the 35b and 35b Mod, it was referenced to a straight line drawn from the trailing edge tangent to the lower surface of the wing. That makes the stall aoa of these older airfoils seem to be several degrees higher than it would be in modern usage. just subtract the angular difference between the two reference lines to adjust the old wind tunnel data to modern usage.

Thank you Jim. Probably 20 people looked at your original post and twenty different worries came up. In my case I was worried that some hole location in the spar was off or a bracket was called out in the wrong place or missing. The thread is about rib design and I forgot that for a moment. There are so many types of builders from "order a kit" to Marty 2+2 (the only thing he didn't do was chop the trees down and brew the glue). We draw from various sources and are willing to spend different amounts on "plans" and parts. For some reason I'm determined to use strictly the free plans from Buggs site so those are the ones I worry about. I finally bought my ribs from Dakota after the pedigree of my "garage sale but new ribs" came into question.

SpainCub
03-17-2013, 02:57 PM
Jim, thank you, that does make alot of cense to me now!

Regards,

JM

SpainCub
03-17-2013, 03:52 PM
OK 25 posts of people giving their best guess. Let's go to "the" source, Clyde Smith, Jr. - The Cub Doctor. Quoting from the Sept/Oct 2005 Cub Clues newsletter A Study of Piper Ribs Clyde says in part:

"All fabric Piper ribs employed one airfoil design, the USA 35B, but were modified by increasing the upper coordinates by 4%. Thus the terminology "USA 35B Modified" was the typical description of the Piper rib and the chord was 63 inches. All the ribs were similar from the J2 through the PA-25 Pawnee.
...
In my weekend siminars, I divide the wings into two classes, the "Cruiser Wing" and the "Cub Wing". The Cruiser wing was used on the J4, J5, PA-12 and PA-14. The Cub wing was used on the J3, PA-11, PA-18, PA-25 and all the short wingers. The differences here were that the Cruiser wing had the "S" or "Sloped" type of false spar and had a stamped nose plate rivited into the leading edge or nose section of each rib, rather than the individual truss type bracing.
...
The Cruiser wing panels did not have the short nose rib sections between each main rib either
...
The Cub type wing had the concave type false spar and the nose of each rib had the individual brace members. These wings also utilized the short nose rib sections, forward of the main spar, between tha main ribs."

John Scott

John, missed your post, looking for that quote now. Thank you!

If it weren't for the fact that I have two J3 cub ribs and a 12 and 14 rib, I would have never considered this, however the two j3 line up pretty good as do the 12 and 14, but the 14 and 12 are slightly larger at the cord that the j3, however they donīt perfectly line up to the original piper drawing as the j3 is slightly small and the 14 is slightly larger cord. Only the 12 lines up the closes to the drawing... I guess this is all has to do because of the jig differences... 4% is very subtle expect at stations where the cord is thickest at station 18.9... right now from my notes, j3 is 7.53 and 7.56 inches and the 12 is 7.68 inches and the 14 is 7.74 inches... :/

mike mcs repair
03-17-2013, 08:42 PM
...
....I have two J3 cub ribs and a 12 and 14 rib, ....

the -18 (j3 too???) is longer or shorter behind rear spar in aileron bay by about 1/8" than a -12/-14....

JimC
03-17-2013, 08:43 PM
By cord, are you referring to the chord (the distance between the leading edge and the trailing edge)?
Is it different between the 3 and 12 ?

SpainCub
03-18-2013, 02:43 AM
Hi JimC, By cord thickens I was referring to camber thickness on the airfoil. 10740
To answer your question, yes there are differences hence my questioning if the j3 and the 12/14 weren't different, the old USB 35B and USB 35B Modified, it's hard for me to gestimate as the difference is slightly more then half of what it should be in modified vs standard 35B camber thickness. 7.74 - 7.53 = 0.21 inch vs the +0.308 inch where the standard 35B should have 7.392 inches the modified is 7.7 inches, and non of the ribs measure on or the other...


Mike, these are full ribs, and their cord length is almost identical only thing that makes them different is slight bends along the entire rib and it is less than 0.067 of an inch when I convert form millimeters :P and I pace a heavy DM board on them to measure.

These are supposed to be all original Piper ribs, but been in Europe, I'm almost certain that some repairs where made that could have change the ribs all together, all airplane where wrecked at one time or another and surplus parts where used to spring them back to life. :D

JimC
03-18-2013, 07:50 AM
I overlaid an AutoCad drawing of the leading edge skin (from printed dimensions on the Piper Drawing) over the photo of the nose rib that was posted above. Both had issues and neither matched the Piper Drawing.

The PDF print of that was 153 megabytes, so I can't post it here. So, I just took a photo of the screen. It may be too large to post as well.

The three small green circles near the upper surface represent one problem area. The Piper drawing called for that ordinate to be 4.036" (the bottom circle). It should have been 5.036 (the top circle). The Piper draftsman drew it as the middle circle (and the nose rib appears to match the error in the drawing, giving a concave upper surface near that point- oops). When drawn by dimensions, the height of the nose radius point is also off by a little over a tenth of an inch.

Longwinglover
03-18-2013, 08:23 AM
That's not a Piper nose rib; it's Dakota Cub. Who does a Piper nose rib match the drawing?

John Scott

JimC
03-18-2013, 09:03 AM
I was well aware that it is a Dakota rib. I used it because it was also used earlier in this thread and because it is wrong.
I haven't been out to the airport to pick up a Piper rib to compare it to the drawing (which contains inconsistencies as well) -- the coordinates and dimensions listed on the Piper leading edge skin drawing don't match the drawing linework and don't match the Piper rib drawing. These drawings are all typical of our drafting tolerances and shortcuts in the days before we had Cad software.

My hunch is that Piper was building to jigs, not drawings.

mike mcs repair
03-18-2013, 11:51 AM
I....

My hunch is that Piper was building to jigs, not drawings.

Yup theres a video on youtube showing the ribs being made

mike mcs repair
03-18-2013, 12:31 PM
Yup theres a video on youtube showing the ribs being made

at about 11:00 mark


http://www.youtube.com/watch?v=Q6q1VKsTeKQ

qsmx440
03-18-2013, 05:08 PM
Thanks Mike. I never seem to tire of watching that. After some new phase in building I go back and look at it again and learn something new in the details that I had missed before I tried making a part.

MainlandCub
03-20-2013, 04:10 AM
I was well aware that it is a Dakota rib. I used it because it was also used earlier in this thread and because it is wrong.
I haven't been out to the airport to pick up a Piper rib to compare it to the drawing (which contains inconsistencies as well) -- the coordinates and dimensions listed on the Piper leading edge skin drawing don't match the drawing linework and don't match the Piper rib drawing. These drawings are all typical of our drafting tolerances and shortcuts in the days before we had Cad software.

My hunch is that Piper was building to jigs, not drawings.

The Piper ribs have the same "discrepancy" as the Dakota rib shown in Jim's picture. I am elbow deep in new Piper rib nose repair sections and second hand ribs at the moment and they are all like that with that concave appearing section along the top. I purchased a Univair nose rib and it is different again.

I have chosen not to worry about it too much: Before the internet and everyone chatting about these sorts of discoveries and the Northland CD I just used to rebuild the aeroplane with the parts to hand and go out and fly it and it flew like a Cub. A jig was made by selecting the best looking Piper rib and drawing around it with a pencil. So, I have decided not to fret too much and just get on with it.

Andrew.

skywagon8a
03-20-2013, 05:59 AM
My hunch is that Piper was building to jigs, not drawings.
I agree with JimC,
It is not unusual, in prototype construction, to make the drawing from the first part. Then sometimes the engineers refine the drawing. Yet they still build subsequent parts from the original fixture. Thus the parts really never match the drawing. This may not be so likely to happen now in the computer age, but back then things were different.

SpainCub
03-20-2013, 06:00 AM
A jig was made by selecting the best looking Piper rib and drawing around it with a pencil. So, I have decided not to fret too much and just get on with it.

Andrew.

My point exactly, there was debate, but when I took measurements the discrepancies where all over the map, thus the conclusion that moving from jig to jig changed some of the ribs in less than 2% of the chamber thickness all together. :D

JimC
03-21-2013, 10:27 AM
I found the Piper error of 4.036 vs 5.036 at the location of the concavity to be the most interesting. That goof did actually hurt the performance of the wing.

SpainCub
03-22-2013, 02:08 AM
Hi Jim, are you referring to a station between station 44.100 and 50.40? I am not following the station you are referring to? changing 4.036 to 5.036 or vise versa only affects upper camber profile of the air foil, would it not? Sorry I think I need some coffee... :D

JimC
03-22-2013, 11:10 AM
I'm referring to the upper surface ordinate at Station (abscissa) 3.15
The draftsman mislabeled that ordinate as 4.036 when it should have been 5.036
He drew the ordinate at 4.81, and that is what the Dakota rib is built to.

Kerri-Ann's upper surface ordinate at Sta 3.15 is 5.040 (a difference of 0.004), which is good 'nuff fer guvm't work.

SpainCub
03-22-2013, 04:03 PM
Cool, got it!!! What I sis when I drew it up was make ordinates according to the 104%, so I took the 35B airfoil and added the 104% to that, which is what should have been intended (I believed) and I come up with 4.92 (4.731 * 1.04.) I did not catch that on Kari-Ann's drawing. Probably why I did not have to add another ordinance to smooth the curve out, but who know. I will send you my DWG if you like... or send me the picture of the dakota rib and I can line it up. I have not been out to the hangar to get my ribs out and take some reference pictures with a ruler but I will try that ASAP and compare it using original piper ribs.

JimC
03-22-2013, 07:35 PM
Check my post #35 for a photo of a photo of the Dakota Rib laid over Kerri-Ann's drawing and with my copy of the leading edge skin done from coordinates from Piper DWG # 10631 (and another drawing whose number I don't recall). For Station 3.15, the lower small green circle is where 4.036 would fall, the upper small green circle is at 5.036, and the intermediate small green circle is at 4.81 (which is what the Dakota Rib is built to).

I've also tried to attach here, a copy of part of DWG # 10631 with the bad coordinate outlined by a black rectangle. That coordinate should be 5.036 instead of 4.036. However, I couldn't do so, because the upload software won't do anything larger than 620x280, and I can't fit the bitmap drawing into that aspect ratio. I was able to attach it as a jpeg.

E-mail me at jrccea1 at gmail.com
and I will send you a copy.

I would like a copy of your drawing as well. A DXF file would probably be most likely to be compatible.

JimC
03-23-2013, 10:09 PM
I would like to edit my previous post, but can't. Piper Leading Edge Skin Drawing# 10630 has some good coordinates. Sta 3.150 upper surface is called out as 4.936", but only 4.990" will fit (this is in lieu of the 5.036 that I used instead of 4.036" as taken from another Piper drawing in my previous post). Most of the rest of 10630 looks pretty good, but the leading edge radius is 1.5436" instead of the 1.125" and 1.000" that Keri-Ann or I used previously. More to come.

SpainCub
03-26-2013, 01:38 PM
Here is a comparison of the Wag Aero 2+2 vs the data from JimC and myself. Jim's is in blue and the ordinates come from the image above, I took the 35B data and added 4% to that and is in yellow.

http://i1309.photobucket.com/albums/s633/jemo07/Wag-Aero-vs_JM_JIMC02_zps545b3747.png

Well, as you can see JimC's data is closer to Wag-Areo and as soon as I can get some volunteer to send in pictures of Piper Ribs or Dakotas or D&E (am I forgetting anyone) that have been take as parallel as possible to the and have a ruler in the picture, I can line them up and see how they differ. Also, if someone has their J3 drawings form Wag Areo and they care to take a picture of the nose rib drawing with a ruler under it, that would help. My set of plans is in a box I currently can get to... had a friend invade my hangar and I donīt have access to a lot of my stuff at the moment. :D
Regards,

JimC
03-26-2013, 07:44 PM
The Pioer drawing doesn't specify the leading edge radius. I like yours better than mine, so changed my nose radius to match yours.

MainlandCub
05-23-2013, 04:43 AM
What do you guys with autocad plots think happens behind the Rib STA 18.900 upper ordinate? I know the Rib STA 25.200 upper ordinate is lower, but the tracing I have of a Piper rib shows and upper curve increasing past the Rib STA 18.900 upper ordinate before descending down towards the Rib STA 25.200 ordinate.

However the best fit through the known ordinates from Piper drawing 13814 with a loose piece of cap strip doesn't follow the tracing of the Piper rib. I don't think I will be following the tracing of the Piper rib, but I was curious what your plots showed.

I am looking at Piper drawing 13814 when quoting the Rib stations.

Thanks,
Andrew.

JimC
05-23-2013, 09:34 AM
The digital copy of 13814 that I have is 'warped' with mid-chord being roughly 0.15 inch too high relative to the leading and trailing edge so that neither the upper or lower surface can be constructed by tracing. Consequently, it would need to be reconstructed from the printed stations and ordinates. I would do that, but not all of them are legible on my drawing. Anyone have a list of them?

For example, the ordinate at 12.600 is 7.3?0. What is the ? digit?

The ordinate at 25.200 is 7.4?0. What is the ? digit?

The ordinate at 37.880 is 5.7??. What are the last two digits?

I don't have the ordinate for Sta 50.400 or any of the stations and ordinates aft of there.

With those in hand, it would take me a couple of hours to accurately reconstruct the drawing and extract the high point.

As an aside, the station called out as 9.45 on this drawing is called out as 9.4375 on other Piper drawings.

Bugs66
05-23-2013, 09:48 AM
You can easily measure the printed drawing to verify if accurate. If a CAD wizard wants to contribue a fresh drawing that would be welcome! ;) I will host it on my site.

Fyi... The DWG was provided to me by a fellow member (thanks!) and is posted on my site in links page:
http://www.supercubproject.com/links.aspx

JimC
05-23-2013, 10:01 AM
I've already measured enough of 13814 in AutoCad this morning to tell you that it is NOT accurate.

BTW, the drawing labled as 13814 on the link site is NOT 13814. It is one of Kerri-Ann's rib drawings overlaid with a leading edge skin drawn by me based on Piper Leading Edge Skin Drawing # 10630.

The high point on the link drawing is at Sta 19.019 and the ordinate is 7.852.
I wouldn't put much faith in either number.

skywagon8a
05-23-2013, 05:41 PM
The digital copy of 13814 that I have is 'warped' with mid-chord being roughly 0.15 inch too high relative to the leading and trailing edge so that neither the upper or lower surface can be constructed by tracing. Consequently, it would need to be reconstructed from the printed stations and ordinates. I would do that, but not all of them are legible on my drawing. Anyone have a list of them?

For example, the ordinate at 12.600 is 7.3?0. What is the ? digit?

The ordinate at 25.200 is 7.4?0. What is the ? digit?

The ordinate at 37.880 is 5.7??. What are the last two digits?

I don't have the ordinate for Sta 50.400 or any of the stations and ordinates aft of there.

As an aside, the station called out as 9.45 on this drawing is called out as 9.4375 on other Piper drawings.

This is from Piper drawing 13814 from the Northland CD.
Leading edge = 1.77
9.450 = 0.000 / 6.920
12.600 = 0.031 / 7.390
25.200 = 0.176 / 7.480
37.800 = 0.283 / 5.770
50.400 = 0.220 / 3.290
56.700 = 0.126 / 1.780
59.850 = 0.076 / 0.983
63.000 = 0.000 / 0.164

JimC
05-23-2013, 06:28 PM
Thanks.

Would you confirm the Station 37.800 please?
The drawing I have seems to read 37.880.
I'll post the station and ordinate of the upper surface high point tomorrow.

skywagon8a
05-23-2013, 06:41 PM
Yes, It is 37.800.

JimC
05-23-2013, 07:12 PM
In your list, there is a missing station and ordinate at roughly about station 44.100. Do you have that station and ordinate?

Also at either station 31.5 or 31.3. The ordinate at that point is 6.760.

JimC
05-23-2013, 08:23 PM
The high point on Piper drawing 13814 appears to be at sta 19.346, ordinate 7.701.
Consider this preliminary till I double check it tomorrow.

MainlandCub
05-24-2013, 03:55 AM
STA 44.100: .265 & 4.640
STA 31.500: .246 & 6.760

So it looks like it does not rise further past the STA 18.900 upper ordinate. (except for .001") That is good to know.

Andrew.

skywagon8a
05-24-2013, 04:37 AM
In your list, there is a missing station and ordinate at roughly about station 44.100. Do you have that station and ordinate?

Also at either station 31.5 or 31.3. The ordinate at that point is 6.760.

44.100 = 0.265 / 4.640
31.500 = 0.246 / 6.760

JimC
05-24-2013, 06:33 AM
Thanks, guys.

JimC
05-25-2013, 11:12 PM
Well, I finally finished redrawing the US 35B mod based on dimensions from a legible copy of 13814 that was redrawn without change June 15, 1951, compared it to leading edge skin drawing 10630, and extracted the camber line and chord line for the 35Bmod. Noticed several interesting things.

The upper surface of 13814 is drafted wrong in front of Station 1.580. The drafting doesn't match the listed.dimensions and is too low.

The chord line is rotated 1.755 degrees more than the old NACA reference line. Therefore all the old NACA data referenced to the angle of attack needs to have 1.755 degrees subtracted from the angle of attack to match current reference conventions.

The leading edge radius is 1.498 inches (1.50 inches).

The Station labled 37.800 should perhaps be 37.880 to match other drawings and to better match the listed ordinate of 5.770 (it calculates as 5.782).

If I were to let all the listed Piper coordinates float by up to 0.0005 inch, I could slightly improve the fit, but I don't think it is worth the effort.

SpainCub
05-26-2013, 03:58 AM
Great progress Jim!
I have been busy working on the fuselage 3d for the Wag Aero 2+2, as soon I am done with that (many little mods here and there to get it just right) I will redraw the airfoil. Do you have the updated station data to make sure I use those and get the airfoil redrawn.

All the best.

JimC
05-26-2013, 07:06 AM
I do.

I'm cleaning up the Acad drawing this weekend and will email you a copy in a couple of days.

Jonnyo
04-02-2019, 12:13 PM
Hello Darrel,

The link to the airfoil data (after only 6 years ) is no longer working. Any leads on other good sources ?

thanks,

Jonny

skywagon8a
04-02-2019, 12:38 PM
Hello Darrel,

The link to the airfoil data (after only 6 years ) is no longer working. Any leads on other good sources ?

thanks,

Jonny
Is this what you are looking for? http://www.supercubproject.com/drawings/pdfs/A3310184.pdf

This drawing is from Bugs66's web site: http://www.supercubproject.com/

flybynite
04-02-2019, 12:47 PM
I found this:

https://m-selig.ae.illinois.edu/ads.html

Seems to be the root directory containing links to the airfoil data that Darrel linked to. Darrel no longer frequents this site. He has moved on to restoring a Curtiss.


Wayne