Tuesday, August 13, 2013

Remembering Jetex (updated...again: new link and photo)

I recently re-found the jetex.org site. This site is dedicated to all things Jetex, including the motors, fuel, model kits, plans, etc. You youngsters, assuming you haven't already resorted to Google, are asking, "WTF is Jetex, anyway?" Jetex motors were the original reloadable solid rocket motors. They were first sold in the late 1940's and were popular in the 1950's and '60's. I'm not exactly sure when the went belly-up. These were really low thrust motors, having a range from 0.35 oz to 6 oz of thrust. The site also discusses the German Rapier motors and models that use them.  From what I remember, these are, or are going, out of production.

I bought a Jetex motor in the mid 1960's or so. I don't have it any more but, from what I see on the Jetex site, I think I had a Model 50. Here is an exploded view of the motor:

The you slid in the fuel pellets (items 3), the nozzle (item 9) was held in place with a spring clip (item 8), and it was ignited with a fuse inserted through the nozzle. I don't remember the gauze discs (item 4).

My main interest at the time was rockets (and it still is) and, with half an ounce of thrust, this motor couldn't lift itself vertically. I never got into building balsa gliders but remember attaching it to simple ones with flat components (hand glider style). I also remember this was mostly a failure...but I had fun. This left attaching the motor to various rolling models. Like I said, it was fun for a young kid.

I don't remember seeing all the plans that are available on the site but have now been poking around. These are a few that caught my eye.

JH-3 Jet Helicopter, by Parnell Schoenky - Reprinted from Model Airplane News, August 1955, pp. 9, 10, 37-39. Plans for this are also available. Hmmm, how about an Art Applewhite-style bi-copter with an add-on fuselage?

Coccinellida by Ian Geddes - From Aeromodeller, November 1956, p 590.

Update: Blog reader Artemi points us to his build. It includes a nice video detailing the process and a launch video. It was stable but the A3-4's delay was too long.

There was also a similar rocket glider from the following decade called the Flying Stovepipe (a plan from Estes). Maybe this is where Estes' designer got the idea? Here's a photo I took at NARAM-50.


M.A. 191 by Paul Del Gatto - From Model Aircraft magazine, August 1954 p. 316. There are several similar models but this is a good example.

These are only a few that caught my eye and could motivate other rocket powered contraptions.