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Old 06-21-2016, 11:40 PM
DavidQ DavidQ is offline
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Join Date: Aug 2011
Location: Washougal Washington
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Default A model rocket model, K-7 Phantom scratch build

Sure, the Phantom isn't really a rocket. Heck, it has no fins. But, it is in the 1963 catalog and has a K-number designation, so it goes on my list to build the original kits starting from the beginning.

It all starts with a plastic tube. It probably was mylar back then, but as I mentioned on an earlier build, I found some plastic tubes at a Walgreens that were within a few thousandths of an inch with the correct radius.

Of course, I also needed a model of the engine. According to the picture in the instructions - which I got from JimZ's site, as one could have expected, the model rocket engine model was filled like a C engine. But, I had just been launching with my class, and we used A engines. So, I sliced a used A engine case lengthwise, being careful to leave the engine rating exposed. I decided to build it to represent how an A engine is packed.

Luckily, the clay nozzle was almost perfect when I split it, so it was good.

I then used a launch rod to plug the nozzle, and a 1/2" dowel with some tape around it to plug both ends of the half engine casing. Once I poured in some polyurethane resin, I had a model rocket engine model. Before it set up really hard, I shaved of the top surface with my knife.

Then, with some tape, acrylic paint, and a detail brush, I made a mock model engine.

edit: Emphasizing that I didn't split a live engine lengthwise. It would go against everything that I tell my class about safety. And, everything that I hold dear about not burning off my fingers.
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Last edited by DavidQ : 06-22-2016 at 12:17 AM.
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Old 06-21-2016, 11:46 PM
DavidQ DavidQ is offline
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Once I finished the engine and tacked it into place, that was most of the work.

Except I needed an engine block. A green one to match the kits of the day, I think. And, I didn't have one and didn't want to order one. So, using an engine casing trimmed to 3/4" long, and some mint green acrylic paint, I made one. I used a 24mm green engine block that I did have as a color guide.

Then, packing some recovery wadding, a parachute, a nose cone, elastic, etc. the model rocket model was done. It's sitting on my shelf next to my other K-7 Phantom, the later model which I built from a kit - it has fins and looks like an Alpha. It likely will appear in a later build.

You can hardly tell them apart! (Oops! This picture from the catalog has a tube-colored engine block. Later pictures on the hang tag had the darker one, which I must have assumed to be the green one. Oh well. If this were government work, it would be good enough.)
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Last edited by DavidQ : 06-22-2016 at 12:39 AM.
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Old 06-22-2016, 08:35 AM
stefanj stefanj is offline
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Nice project!

Guess: That oversized engine block was one of the old-style balsa thrust rings. Hole drilled through the center.

I made a few for my own "early days of Estes" projects. BT-30 balsa bulkheads that I hand drilled.
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  #4  
Old 06-22-2016, 09:47 AM
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hcmbanjo hcmbanjo is offline
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I saw an original Estes cutaway engine on Ebay a while back:

http://modelrocketbuilding.blogspot...mmy-engine.html

Your engine looks better than what Estes produced. The Estes cutaway engine looks like it was cut in half with a bandsaw!

Great work on your "K" kit builds!
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Old 06-22-2016, 11:41 AM
DavidQ DavidQ is offline
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Quote:
Originally Posted by stefanj
Guess: That oversized engine block was one of the old-style balsa thrust rings. Hole drilled through the center. .

Good call! I missed that. The Phantom instructions clearly call it a "Balsa Engine Block # EB-20". The 1963 catalog even calls an EB-20 a BT-20 engine block, 3/4" long, made of balsa. That also explains why the engine block looks almost like recovery wadding in the B&W photo.

My ignorance about the older engine blocks led me to totally miss that detail. Thanks!

But, I'm not changing it. I really wanted the green engine block.
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