Thorp Air Command - T18.net

Hi all
Can I get some comments, corrections or suggestions on my questions below.
I am currently converting John Thorps drawing of the side skins B-593 into a CAD file. I was then going to use that to get the either a full size template printed or possible get the new side skins machine cut.

As I transfer the plan I want to include any service dictated revisions and as much detail as I can so that the machine does all the cutting for me. I hope that by taking the time to get the drawing right on the computer first it will save me from a a few costly mistakes that will waste material.

I have picked up one mandated change and that is for the double row of rivets forward of the spar at the base of the 603 dash frame( from dwg c-580) I think that is the only directive that affects drawing 593

I note that the following items do not show on the original side skin plans but I can probably add these in to save later cutting:
1. A cut out for the Horizontal Trim Tab linkage ( I notice from the member photos that there are a couple of different approaches to this, I still have to determine exactly where to locate this)
2. Inspection panel for Horizontal Stab ( as mentioned in the News letters)
3. Rudder cable holes ( haven't found any reference to these assuming they are mocked up)
4. Optional Splice line just aft of station 179.2
5. Static air source ( One newsletter suggested about 4-5 " in front of STA 149 and at the level of WL38

Are there any other optional extras worth including on the drawing while I am drawing it?
Any suggestions for best locations?

Also I have a couple of dumb novice builder questions regarding this drawing as well.

Regarding the rivet spacing.
The building instructions suggest just using dividers to step out the longitudinal rivet patterns however it is not clear where to start from and the only reference distance I can find is for a 1.5" spacing near the tail however most of the rivets seem to be spaced at a fraction over 2". So I am a bit confused!!

Is the spacing critical at any point ( except for the frames) Can I just evenly space rivets between the frames, or should I set a master rivet and then used a fixed spacing or something else?
Does anyone recall what spacing was used. Would it be worth deviating from the plans and using a closer spacing or non even spacing?

Any ideas or suggestions are welcome.
Thanks
Stuart

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Stug

Hi All
It's taken some time but I think I now have drawing 593 converted to CAD and ready for machine "matched hole" cutting.
Attached is a PDF version which I thought might prompt some last last minute corrections or suggestions.

Stuart

[file]593_Side_Skin.pdf,382,,0[/file]

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Stug

Looks fantastic ! I do have one suggestion. Do one on a "cheap" piece of aluminum 6061 first as a test before using the more expensive 2024.

RB

Yes that was the plan, do a test run on some cheaper material. If the test works out then hopefully it will serve as the template for setting out all the rivet holes on all the frames and longerons.

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Stug

I think what you're doing is a step ahead in building. A little more precise. Not that the original "matched hole tooling" didn't do the job (most of my A/C was built using MHT), I just think this is a step up, just the fact that you can have a computer generate it, cut it and maybe serve a cup of tea with it, is great ! [8D]

RB
NX115RX

Hi all
If all is well then the side skin drawing is complete and I am read to start cutting.
Latest version is attached for those interested
Hopefully I will be doing a test run this week in plastic


[file]593_Side_Skin.pdf,382,,0[/file]

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Stug

If you are using .032 side skins, delete the anti drumming stringers on the sides. We only use these on .025.For the inspection panel backing doublers use the same .032.
I have measured my mod on that virticle doubler, for strenghtening the intrument former, and its rivet row is 7/8in at the top and 1 in at the bottom. Mod the outside doubler mod, to pick up this extra row of rivets.

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James Ball

I finally got around to doing a test run using the CAD side skin drawing to machine cut a single side skin in plastic. It took the machine about an hour to cut, alclad would take slightly longer. It is a bit hard to pick in the photo but the end product looks like it is ready to cleco to the frames and assemble. I am now reasonably confident the drawing is right. The attached picture gives you an idea of how it looks but the 3/32 rivet pilot holes don,t show that well.
I have also been converting the lower skin and deck to CAD drawings as well, i am slowly getting ready to do a big session on the cutting machine.

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Stug