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Demi John Rocket

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lowga

A.K.A. 'Mr. HoJo'
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I'm seeking additional data on a variant of the Douglas Honest John missile called the "Demi John."

Minimum range for the Honest John was about 10,000 yards. In an effort to reduce this to just 5,000 yards, and give field commanders greater flexibility in using the rocket, a project that became known as The Demi John was undertaken. These rockets had special spoilers mounted near the base of the pedestal adapter between the motor and the warhead.

All test rounds fired suffered failures of one sort of another, and eventually the project was abandoned. I'm interested in modeling this version of the iconic rocket, but can't seem to find any photographs of the missile with these spoilers mounted.

Hoping someone out there can help.
 

lowga

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Love it when digging into the research allows you to answer your own questions. :)

My library yielded a paragraph or two on the Demi John variant from the book "The Rockets and Missiles of White Sands Proving Ground 1945-1958" by George Kennedy. More Internet research turned up a copy of "History of the Basic (M31) Honest John System 1950-1964 by Mary T. Cagle. On Page 127, there is a pretty complete description of the Demi John program, and a single poor quality photograph.

The spoiler plates in the form a collar below the warhead are clearly visible in the shot.

I would love to find more photographs, or detailed drawings of the spoilers.

https://www.scribd.com/document/730...doc_id=73031679&download=true&order=460133099


Demi John Oct 23 1953.png
 

lowga

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Gene Dirk, who is the curator at the White Sands Missile Range archives was very helpful. They've searched their records, and can only locate a single photograph of the Demi John Variant of the Honest John. No date is associated with the photograph.

I used Photoshop to make a good quality enlargement to 200% of the air brakes, and again to 300%. Those are attached here as well.

I'm attempting now to find someone to prototype 3-D printed parts for use on the Estes Honest John kit, and the larger kits from Boyce Aerospace (which is new, and awesome!) or the less detailed Madcow 4.5/5" kit.

The air brake would have the added benefit of limiting the altitude of the models, and keeping them in range for recovery.

Who will be the first to model a scale entry of the Demi John variant? If you beat me to it, please post pics here.
 

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lowga

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Sheree & Alex Boyce have done it again! They've custom made 3-D printed parts to create Demi John models from most of the easily available HoJo kits.

Just today, I received beautiful parts for:

For Boyce Aerospace small 1/24th scale HJ
For the Estes 1/14th scale HJ
For Boyce Aerospace Large 1/9th scale HJ (also the Estes Maxi HJ)

Very reasonably priced as well. Alex designed the "Drag Fairings" for the Demi-John. They are not exact as far as the number of Holes due to the limitation of the minimum hole size that is
printable at 1/24th scale with an FDM printer.

The connecting rods are either thin wire or dowel from a hobby shop (again printing a 1mm rod is impossible on an FDM printer and would not have any strength). The idea to attach is to drill two small holes for the rods on the nose cone above the spin motors and then super glue the rods and drag fairings in place. A drop of super glue where the fairings contact the base of the nose cone (just below the spin motors) and you should be all set.

Here are the CAD drawings that Alex supplied:

Boyce Aerospace Demi-John Missile Parts (2).png
Boyce Aerospace Demi-John Missile Parts.png
 

lowga

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Playing around with some ideas now to build this using the 3-D printed parts from Boyce Aerospace. I want to experiment with making fly-away versions of these air brakes that would separate from the model's airframe on first motion. This would make the model eligible for NAR scale competitions, and ensure safety.

My concern with any kind of permanent mounting is that if one side came off, the model would become very unstable. A fly-away design eliminates that concern.
 
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