Gemini - 1:12 - Page 3

**thorst** · #21 12-29-2011, 04:34 PM

Quote:

Originally Posted by mspacemike

[...] I take my sketchup drawings and import them into pepakura. From there I then go thru the motions to unfold the more complicated pieces. It is just a frustrum and my drawings were not coming out matching the interior details. So I did my own calculations and found that the sections did not all match, which resulted in creeping errors. That and the radius was not quite right. Did anyone else experience this? [...]

I don't use the software myself, but I think the part's mismatch is due to the division of the conical object into flat surfaces like seen in the last picture of the first post in this thread. This will result in a slightly narrower (or wider) part than the ideal, analytically calculated part (wider if the surfaces are outside of the ideal surface, narrower if inside). The gridsize of the triangulization should influence the quality of the unfolded part strongly, make the single triangulas more narrow and you will get better results, if that's the problem.

And that's a nice project, I'm following closely!

Thorsten

**mspacemike** · #22 12-29-2011, 05:27 PM

I was using the grid to make sure that the right/left sides were matching up, and when they didn't then I got down to brass tacks to figure out why. I will double check my printouts to make sure that the creeping errors did not creep into anything else.

**mspacemike** · #23 01-16-2012, 05:41 PM

I have been working on the positions of the equipment bays. I still have a ways to go with getting them to position correctly on the pressure vessel. As you can see by the first picture, I have the inner liner with the bays marked on it and the outer surface that is supposed to slide over it.
I came across an issue with the recessed section in front of the doors. This is not going to let me slide the surface, so I will have to work something else out. Picture two shows the drawing that gives the overall impression of the pressure vessel. The next four pictures are of the mockup of the pressure vessel as presented by Life Magazine. This gives me lots of detail that can be added to the model. The stringers are shown quite well in the mockup and also in the last drawing showing the stringer cabin section. The very front and back of the pressure vessel has stringers that will not be visible in the model, so that will save time on the construction. I have the heat shield in the back of the first picture, and still mulling over how to get this smoothed over. I have a few ideas that I am working on.

Zathros · #24 01-16-2012, 07:10 PM

This type of accrued intolerance creeps into CAD also. What appears as super fine lines turn into lines that look like they were drawn with Crayola Crayons if you are taking lines or "points" for reference. What are you using for reference? I am just curious if you have some blueprints or dimensions or whatever, just curious. Also, in this thread the word "frustum" was used, and someone asked me over at ZEALOT what the formula and the name for it about 6 months ago. That was the first time I had heard that word used more than once in one year for many decades. Kind of refreshing. Are you going to put in the corrugations? I was hoping to learn a method for doing that. I have the tooling to do it in light gauge steel, but not paper. Thanks.

**mspacemike** · #25 01-17-2012, 10:05 AM

I use some drawings/blueprints that give the dimensions to 0.001 of an inch. I also use a single point of reference to measure from so that I don't accrue the intolerance with my addition/math. I have some drawings that are not found in the pdf's that are on the net. Wonderful resource the pdf's. I did not have these when I started my drawings in 1983. I am working on a method of the corrugations. Delta 7 did it with artwork, and I will also explore this method. In this scale it would be great to have the physical corrugations.

Zathros · #26 01-17-2012, 12:23 PM

Thanks for sharing. This kind of reminds me of some sections of body panels I used to have to fabricate when I restored a couple of old Mercedes Benz cars (450 SLC, 250 C, 280C, 450SL, 230 SL). Lots of cardboard prototypes before cutting and welding in the metal panels sections into the cars. These cars all rust in the same places.

**davelant** · #27 01-19-2012, 10:29 PM

Quote:

Originally Posted by mspacemike

And an extra treat, the first Gemini Paper Model, circa November 6, 1962 from Department 507 at McDonnell Aircraft.

I just saw this and remembered it from when I was a kid and my Dad was working at Mac. I don't know if this makes me happier or the 1/12th scale detail model.

**mspacemike** · #28 01-19-2012, 11:04 PM

Very few of the original engineers were left at Mac from the Mercury/Gemini time when I worked there. But I did get to talk to a few, and to walk in the same buildings and rooms where they built the craft was a thrill. We (the young engineers that wanted to preserve Aviation/Space history) helped to compile a list of those engineers that worked on the projects. The list was quite extensive.

Zathros · #29 01-25-2012, 07:32 AM

Any progress lately?

**mspacemike** · #30 01-25-2012, 09:37 AM

Yes Zathros. I have been doing the drawings for the outer shell to make sure that they match the inner equipment bays. I have also worked on detailing the bay walls, but most of the detail will be hidden with the equipment in place. I will have more pictures in a day or so. I have also been putting more hours at work so that I can get my bills paid. It is tax time again!