"D" Windows

[Steve Pierce]

Most of the fuselages I have gotten ready for cover have required that the "D" window be replaced due to rust. If you check the price of a "D" window for a Clipper, Pacer or Tri-Pacer part number 11856-00 you will find they list for $168. A J3 rear window is $40. The left side "D" window of a J3 part number 10057-00 was used to make the window for our Short Wings. The right side is too short. Don't ask me how I know. So if you want to save some money buy the LH J3 "D" window, lay your old window over it, cut a section out and weld it back together. I have done this several times and it works just like it did for Piper did 50 plus years ago.

[Gilbert Pierce]

Rex,
I see Steve remembered to put in the additional fabric support above the rear window and rear door. Good.
It's much harder to do once the fabric is in place.

[Hillbilly]

Steve, Is the best place to get the D window Univair? Clyde Smith?

Also please tell me about the Additional fabric support your Dad mentioned in his post?

Tanks - Hillbiwwy

[Gilbert Pierce]

Hillbilly
If you cover your fuselage as Piper did according the drawings-Section B-B of drwg 13925 it is not a problem. However I covered mine with 3 pieces of fabric. The first covered was the belly. Then from top center spine down to the bottom longeron on right side and then from the top center spine to the bottom on the left side. This leaves no seam across the top of the fuselage at the juncture of the vertical tail. Only a seam along the top center spine and up the leading edge of the vertical stab.

If you do it that way you cannot wrap the fabric around the piece of u-channel that forms the butt rib shape above the window frame that has the clamps on it in the previous pictures pictures. There is only 3/8" horizontal surface to glue to. When you shrink this are it will pull loose and the fabric will hang straight down instead of making a sharp 90 and then another sharp 90 where it goes around the butt rib former. We welded a piece of flat stock 4130 about 1 inch wide and the length of the u-channel to provide an extra area to glue the fabric too. You can see this piece clamped to the u channel in the previous post. When completed it is not noticable but gave me additional tummy comfort it was not going to pull loose. Cover it according to the drawing and it is not a problem. I did not want to use an envelope-it was covered with one when I got the airplane and was ugly. I did not want that seam at the base of the vert. stab that runs out to the longerons either so I came up with a way to get around it.
Attached is a picture of the plate welded on Steve's airframe and a picture of my fabric where it makes the 90 and another 90 around the butt rib 3/8 u ChannelFabric support.JPG[/attachment] The picture of the fabric was taken when I realized I had a problem and before I solved it. The Fabric was on shrunk and starting to pull loose due to insufficient area to glue to. On my fuselage I made a plate out aluminum and screwed it with #4 PK screws to the U-channel to provide addional area to glue to after the fact. That solved the problem without removing the fabric. The airplanes Steve has done since then he has welded on this plate so he has adequate surface to support that fabric. After you study the drawing you will see how Piper solved it. I like my way better. The last picture is the FIX above the rear door as taken from inside the airframe after the fabric was completed.[attachment=3:3id3hac6]Fabric.JPG[/attachment:3id3hac6].[attachment=3]

[shelbysautosales]

Hillbilly
If you cover your fuselage as Piper did according the drawings-Section B-B of drwg 13925 it is not a problem. However I covered mine with 3 pieces of fabric. The first covered was the belly. Then from top center spine down to the bottom longeron on right side and then from the top center spine to the bottom on the left side. This leaves no seam across the top of the fuselage at the juncture of the vertical tail. Only a seam along the top center spine and up the leading edge of the vertical stab.

If you do it that way you cannot wrap the fabric around the piece of u-channel that forms the butt rib shape above the window frame that has the clamps on it in the previous pictures pictures. There is only 3/8" horizontal surface to glue to. When you shrink this are it will pull loose and the fabric will hang straight down instead of making a sharp 90 and then another sharp 90 where it goes around the butt rib former. We welded a piece of flat stock 4130 about 1 inch wide and the length of the u-channel to provide an extra area to glue the fabric too. You can see this piece clamped to the u channel in the previous post. When completed it is not noticable but gave me additional tummy comfort it was not going to pull loose. Cover it according to the drawing and it is not a problem. I did not want to use an envelope-it was covered with one when I got the airplane and was ugly. I did not want that seam at the base of the vert. stab that runs out to the longerons either so I came up with a way to get around it.
Attached is a picture of the plate welded on Steve's airframe and a picture of my fabric where it makes the 90 and another 90 around the butt rib 3/8 u ChannelFabric support.JPG[/attachment] The picture of the fabric was taken when I realized I had a problem and before I solved it. The Fabric was on shrunk and starting to pull loose due to insufficient area to glue to. On my fuselage I made a plate out aluminum and screwed it with #4 PK screws to the U-channel to provide addional area to glue to after the fact. That solved the problem without removing the fabric. The airplanes Steve has done since then he has welded on this plate so he has adequate surface to support that fabric. After you study the drawing you will see how Piper solved it. I like my way better. The last picture is the FIX above the rear door as taken from inside the airframe after the fabric was completed.[attachment=3:3id3hac6]Fabric.JPG[/attachment:3id3hac6].[attachment=3]

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[Roger That]

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shelby - I found the original post by Gilbert, but no photos?

[rmalone]

Good advice that I know will pay off when I start my cover job.

[Steve Pierce]

I have to laugh thinking back when we were trying to get the fabric to glue down to that 3/8" channel and the ultimate solution we came up with without removing the fabric.

Univair is the only manufacturer of this part that I know of. Even the other Super Cub fuselage manufacturer, (Airframes, Inc.) buys the "D" window from them.

[Hillbilly]

Wow, thanks for your time Steve. So basically I wont need the fabric support on this restoration because I'll be using an envelope? (cover materials were included when I bought my plane, cant afford not to use it.) - Hillbilly

[Steve Pierce]

You might. I doubt that envelope is made like the ones Piper used. Look at the drawing my Dad called out above for a better discription or I bet JohnW can describe it better than me. Basically there is a piece of fabric that goes behind that 3/8" U channel and another goes over it. I think the strip makes it much easier.