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Old 05-10-2021, 02:02 PM
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Earl Earl is offline
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Default Apollo RCS 3-D Model

Last night as I was going through some things on eBay an item popped up at the bottom of the page ('recommendations for you' kind of thing) and one of them was a 3-D printed model of one of the Apollo RCS thruster engines with nozzle. I'm sure many of you have seen images of this Marquardt R4-D reaction control thruster many times before, both mounted on the Apollo Service Module and the Lunar Module in 'quads'.

At first, looking at the listing photos, I thought some of them were of a 'real' thruster engine, but then realized "no, that is the ACTUAL model!".

This person has done a great job on modeling this engine, I think, and I decided to go ahead and get one. About $85, plus shipping, which isn't actually cheap per se, but not totally out of line with the cost of 3-D printed models. This actually will be the first 3-D printed model I have bought.

Link: https://www.ebay.com/itm/3039506849...353.m2749.l2649

The bad news is this is the last one he had. I asked him if he was planning to do more and just how much smaller than full-scale is this (turns out 'just barely' smaller than full scale). He said someone else actually did the design files and that there were a number of different versions of this engine (there are), but that this was the smallest version.

Here is his response on the 'scale' question I put to him"

Well, I don't have a lot of reference material, but I can tell you that there were many versions of this engine. This model is closest to the smallest version: The spec I have says it should be about 12.47" tall and 6.01" in diameter. The height is about right, the mouth of the bell is closer to 5.5 inches. I did not design this, so I'm relying on the designer's numbers here. That's why I say "close to," because the designer obviously had access to more reference material than I do.


And just received another response back that he'll be doing more of them, but it takes 34 hours of printer time to make one!

Below is a graphic I found of the engine, which matches pretty close to his specs, with a nozzle exit diameter of a little over 5.5 inches.

Anyway...I thought it would make a great desk model to have. I always wanted one of these "real ones", but in collectors hands these days they go for many thousands of dollars.

Earl
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Last edited by Earl : 05-10-2021 at 10:57 PM. Reason: Spellin’ fix
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Old 05-10-2021, 11:04 PM
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Earl Earl is offline
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Here are a few of the images of the completed model from the eBay listing.

Lister said he used regular automotive primer as the only 'paint' on the completed model and that was applied just to the thrust chamber and to the two 'plates' above the thrust chamber that the solenoid valves attach to (area where you see the metal nuts). All the rest is the natural color of the 3-D plastic.

Earl
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Point 39 Productions

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