1/12 Scale Little Joe I (was: Anyone care to ID this component?)

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James Duffy

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Here's a bit of a project that has been in progress for the past couple of months (or the past 15 years, depending on perspective). Anyone care to venture a guess as to what type of rocket is coming together here?

That's a standard 12" ruler in the foreground for reference. Total mass of this assembly is in the neighborhood of 6.5 ounces/184g.

James

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hcmbanjo

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I know what it is, the fin shape gives it away. But, I'll let everybody else play along -
Pretty impressive rivet and bolt work there.
 

James Duffy

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Little Joe?
Bingo! This is about the eleventy-fourth Little Joe model I've built over the years. The model you see is being constructed at 1/12 scale and will stand in excess of 4' tall when complete. Here's a photo of the stacked boilerplate also under construction, as well as airframe sections for the primary model.

James
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MaxQ

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Bingo! This is about the eleventy-fourth Little Joe model I've built over the years. The model you see is being constructed at 1/12 scale and will stand in excess of 4' tall when complete. Here's a photo of the stacked boilerplate also under construction, as well as airframe sections for the primary model.

James
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Nice.
One of my favorite subjects.

Is this flying or static?
 

burkefj

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Very nice James. BTW, I saw that a lot of your dvd content is now on youtube, are you tapering off on the video production now and just releasing it to the public?

Frank
 

Micromeister

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Here's a bit of a project that has been in progress for the past couple of months (or the past 15 years, depending on perspective). Anyone care to venture a guess as to what type of rocket is coming together here?

That's a standard 12" ruler in the foreground for reference. Total mass of this assembly is in the neighborhood of 6.5 ounces/184g.

James

James:

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James;
Is it possible to reveal the method used to create the rivet pattern? I'm guessing the Skin is either thin Styrene or Polycarbonate.
 

James Duffy

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Is it possible to reveal the method used to create the rivet pattern? I'm guessing the Skin is either thin Styrene or Polycarbonate.
Sure, there are no secrets in this dojo. You are correct, the skin is .010"-thick styrene sheet, and the pattern is embossed into the sheet using a laser-cut pattern. First, the rivet pattern is created in Adobe Illustrator, then a laser cutter is used to cut that pattern into a sheet of 1/8"-thick acrylic sheet. A sheet of .010" styrene is taped into place on the pattern, and the resulting sandwich is placed on a light table. The pattern of holes created by the laser cutter is clearly visible, and a small round point embossing tool is used to create the rivet dimples. Once all of the rivet details are in place the styrene is trimmed to size referring to the trim marks on the acrylic pattern. The finished styrene sheets are then applied to the balsa & plywood fins or the plywood airframe tube using 3M Type 90 spray adhesive. I have dozens of these acrylic pattern sheets, each created for a specific portion of the model. The process is simple (assuming that you have access to Illustrator and a laser cutter), although admittedly time consuming.

The embossing tool is used in scrapbooking, apparently, and my wife was happy to let me use it. A ballpoint pen would probably work as well in place of this tool.

James
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kjohnson

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You may get away without having a judge telling you to make the model 4 inches taller this time around. :)

kj
 

hcmbanjo

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The process is simple (assuming that you have access to Illustrator and a laser cutter), although admittedly time consuming.
James

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When those results are achieved, a time consuming operation are well worth it.
The "UNITED STATES" stencil font always struck me as a little different.

Sheesh, Little Joe I rivets and koa body ukeleles!
Can't go wrong with that combination.
 
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AlphaSigOU

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When those results are achieved, a time consuming operation are well worth it.
The "UNITED STATES" stencil font always struck me as a little different.

Sheesh, Little Joe I rivets and koa body ukeleles!
Can't go wrong with that combination.
They should be the 45-degree 'stencil' lettering commonly used by the Air Force and Army. Navy uses a 60-degree 'stencil'. (The degrees are for the corners of the lettering.) Still, it is an outstanding bit of craftsmanship!

EDIT: On a second look at the photos, it is the correct font! When you look at LJ1 photos from a distance the 'blanks' in the stencil tends to blend in!
 
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James Duffy

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Another photo of the aft thrust structure of the model, along with a shot of the equivalent structure on the prototype. There's still a bit of paint and detail work yet to go...
IMG_1665.jpgljbooster-3.jpg
 

James Duffy

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Here's another progress photo of the painted thrust structure installed on the model. There is still much detail work yet to be done...
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TheAviator

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Here's another progress photo of the painted thrust structure installed on the model. There is still much detail work yet to be done...
View attachment 279875
Looks incredible, James! I'm not that familiar with the original Little Joe. It looks like you have two of the Algol mounts covered; were there LJs flown with only two Algol motors?

What's the diameter of the Recruit throats? Any chance of putting a 10.5mm Ultra motor in there? :p

How is the thrust structure built? More styrene sheet or cast resin?

Thanks for the information on this fantastic build. I look forward to hearing the report from the WSMC!
 

James Duffy

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Looks incredible, James! I'm not that familiar with the original Little Joe. It looks like you have two of the Algol mounts covered; were there LJs flown with only two Algol motors?

What's the diameter of the Recruit throats? Any chance of putting a 10.5mm Ultra motor in there? :p

How is the thrust structure built? More styrene sheet or cast resin?

Thanks for the information on this fantastic build. I look forward to hearing the report from the WSMC!
The Mercury Little Joe boosters were flown with either two or four of the "big" Castor/Algol motors, and were always flown with four of the small Recruit motors. The particular round shown here (LJ-1A) flew with two Castor and four Recruit motors, so the other two large engine mounts are buttoned up.

The thrust structure parts are mostly laser-cut acrylic with some additional styrene bits. The additional detail yet to be added will probably be done using custom photoetch parts. The nozzle assemblies are also yet to be done. All six nozzles will be vacuum-formed, and the four Recruit mounts are 13mm. Still trying to decide what sort of motors will go in the main 29mm engine mounts.

James
 

Glideroc

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Looks incredible, James! I'm not that familiar with the original Little Joe. It looks like you have two of the Algol mounts covered; were there LJs flown with only two Algol motors?

What's the diameter of the Recruit throats? Any chance of putting a 10.5mm Ultra motor in there? :p

How is the thrust structure built? More styrene sheet or cast resin?

Thanks for the information on this fantastic build. I look forward to hearing the report from the WSMC!
Algols weren't fitted to Mercury Little Joe. Castor/Pollux only. Right? And very nice scale work.


California Dave
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James Duffy

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Algols weren't fitted to Mercury Little Joe. Castor/Pollux only.
Sounds right, now that you mention it. I seem to recall that the motors were all Sergeant variants, and different thrust profiles were given different non-military designations.

James
 

James Duffy

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Some weeks ago I was asked how the "UNITED STATES" markings were applied to the model. The markings were applied to model #2 today, so I took the opportunity to snap a few photos of the process to share.

First, the graphics for the markings were created in Illustrator, printed on standard paper, and checked against the model for size and location. With that verified, that file was used to cut a mask out of frisket film on a laser cutter. Frisket film is a low-tack masking material used by airbrush artists, and can be found in the hobby section of your local Hobby Lobby.

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The masks are cut from the sheet using scissors, and trimmed to make them easier to handle.

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The backing paper is peeled away and the frisket is positioned on the model. The material is clear, so it doesn't show up too well in this photo. (I've also reached the point in my life where magnification is pretty much required for precise work like this.)

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In order to protect the model from overspray some plastic drape material is taped into place, and the airbrush is loaded with Tamiya semi-gloss black acrylic paint (WARNING: I have no idea how the frisket material would hold up to the solvent in lacquer or enamel paints, so be sure to test first before using that combination.) A few layers are built up on each of the masked locations.

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The masking material is removed, and the finished markings are in place! The finished airframe section is then compared to the one completed a few weeks ago.

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More later,
James
 
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burkefj

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Very nice James, thanks for sharing how you did that. I really need to break down and get an airbrush....

Frank
 
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