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-   -   Mercury Redstone K-41 Build (http://www.oldrocketforum.com/showthread.php?t=19188)

PaulK 01-03-2021 09:34 AM

Mercury Redstone K-41 Build
 
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A while back I came across a partial kit, missing the header card, main BT, and chutes. Everything else was there, including the cardstock sheets, fin stock, capsule, tower, dowels, decals. I have some vintage checkerboard chutes to keep it mostly vintage.

After losing my recent #1921 build, thought I'd tackle this instead of building another 1921. The previous owner had drawn out some of the fin shapes on the balsa, but nothing was cut. The only change I'm making to the original design is Kevlar tied to the forward CR.

The two fun parts of this build, are of course the fins, and the escape tower. Cutting the fin gussets (#5) were tough, I cut a few extra and kept the best ones. I resisted the urge to buy the laser-cut set from eRockets, I want the experience on this build, to help building the sealed kit in the future.

PaulK 01-03-2021 09:41 AM

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I had to study the instructions for a long time, walking away, coming back, etc., before I wrapped my head around how to build the fins. I think I finally figured it out. Now that I've built them, the instructions look clear, but they didn't when I started! Fin part #5 was the tough one, it's not obvious how to orient. The expanded assembly drawing helped, showing that part #5 needs to overlap the bottom of the BT.

One other modification, instead of using the cardstock for fin part #3, I cut those out of 1/64" ply - the cardstock is the weak part of these fins, same as on the current #1921 kit

The bevel was sanded on a sanding block, gussets were sanded after assembly using a sandpaper wrapped dowel, as the instructions illustrate. Final touchup was with sanding sticks of various grits.

PaulK 01-03-2021 09:47 AM

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And this is where I'm currently at, fins assembled and mounted, with a couple coats of Aerogloss Sanding Sealer. Elapsed time something like 4-5 weeks for steps 1-8. :o

In case you're wondering Danny, the MMT was built with an engine hook, since that's what the instructions called for. :)

A little further sanding touch-up will be needed on the gussets, then on to Step #9, the escape tower!

erik442 01-03-2021 10:35 AM

Looking good. I replaced fin part #3 on mine with bits of maple wood from a popsicle stick.
I have a Dr. Zooch Redstone that I've never attempted due to the mini size of the wood escape tower.
Those Semroc Saturn 1B laser cut fins you recommended arrived this week. Very nice kit.
Thanks for the tip. It would've taken me forever to cut out all those tiny pieces. :o

dwmzmm 01-03-2021 12:13 PM

Great job on those hard to build fins!

I have one (built around 1970 or 71) and it was (to this day) one of the hardest build. Did ok on the launch escape tower but screwed up the paint finish (sprayed too much white enamel and paint started to run on one side of the Redstone body).

Still have another unopened kit of this model that will be a near future project once I've retired from work and have the time to devote on the build.

dlazarus6660 01-21-2021 06:24 PM

Looking great so far.

KUTGW!

In 1985, I was handed a box full of rockets and rocket parts.
One of the rockets was a pre Damon MR K-47 complete kit unopened.
The header card had a reddish tinge on it.
I held on to it until 2002 and put it on Fee-Bay starting at $9.95.
It sold for around $200.00.
I thought it would be too hard of a kit to tackle even for my skills.
I currently have two MR's, one has plastic fins and the other balsa fins.
I lost the capsule to one MR to a wind and a tree.

ghrocketman 01-21-2021 07:21 PM

That MR kit is K-41, not K-47.
I currently have 2, an opened "builder" kit and a sealed one.
I last built one of those towers in 1981 when I was 11.

PaulK 01-23-2021 06:08 AM

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I just noticed the title is wrong, sheesh! Scott could you please fix the title to "K41"?

Anyhow, the K-41 build continues at a glacial pace. Finished sealing the fins with Aero-Gloss sanding sealer, I lost count but applied probably 5-6 coats with 320 grit sanding after the first couple coats, then 400 grit sanding between coats.

The NC was pretty beat-up, so the exposed section below the shroud took 3 rounds of squadron white/green putty, followed by 3 coats of aero-gloss and 400 grit sanding. There are only 2 parts of the NC that are exposed when done, the area just above the shoulder, and the very top, which I simply brush painted with Testors.

Lastly, I coated the card stock shroud sheet with 3 coats of Krylon UV Crystal Clear Gloss. It's fairly yellowed, but I'm hoping the yellow doesn't show much once the pieces are cut out.

PaulK 01-23-2021 08:35 AM

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Here's the capsule shrouds after clear coat. The yellowing is worse than the photo shows. I tried making a copy, but my Canon all-in-one didn't reproduce the detail. Despite the yellowing, the printing is very good on this, the corrugations and bolts/rivets are quite nice on the large shroud, considering it's small size. I'd be interested to know what printing process was originally used for these. Wouldn't have been enough volume for Web Offset or Gravure, and Flexo often doesn't reproduce fine detail very well.

BARGeezer 01-23-2021 11:32 AM

Quote:
Originally Posted by PaulK
Here's the capsule shrouds after clear coat. The yellowing is worse than the photo shows. I tried making a copy, but my Canon all-in-one didn't reproduce the detail. Despite the yellowing, the printing is very good on this, the corrugations and bolts/rivets are quite nice on the large shroud, considering it's small size. I'd be interested to know what printing process was originally used for these. Wouldn't have been enough volume for Web Offset or Gravure, and Flexo often doesn't reproduce fine detail very well.

Don't know if this is better resolution, but here's a scan of the capsule shrouds and nozzles from YORP's decal and templates page.
https://plans.rocketshoppe.com/decals/SP-41.pdf


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