Jetex Blog

An online resource covering the technical and historical aspects of small sustained thrust micro rocket motors for use in model airplanes and other craft.

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I recently bought some very nice vintage Tiger kits from a gentleman in Japan:

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Tiger profile kits, made in Japan in the 1960's were nicely presented.
The F-102 Delta Dagger and MiG-19 are I think unique, and well worth replicating today.

Today's modeller has access to many computer techniques simply unknown in 'the old days' so that the parts of an old kit -– and the vast majority of 'Jetex' kits are old and date from the 1950's – can be scanned in, cleaned up and replicated. The trouble is, most of the modellers interested in such kits also date from the 1950's. We have problems getting the best out of sophisticated drawing/painting programs – well I do anyway – and modern modellers who can make the latest CAD or version of Paintshop sing and dance are not interested in granddad's latest antediluvian model. So I struggle on, cutting and pasting on bits here and there until that classic and evocative Jet from 1951 looks 'half right':

 

mig19a

A Hawker P 1081 – the precursor of the Hunter - for Rapier L-2, designed and drawn using a popular 'Paintshop' program. Reproducing the 'eu de nil' pale blue/green caused an outburst of 'computer rage'.

 

But it takes hours, what a young expert can do in minutes takes me hours, and I end up truly pixellated. 'Never again' I say, until I find the next evocative prototype on the Internet.

 

Since first writing this, I have been putting together templates for an Alpha Jet, MiG 19 and an F-106 Delta Dart (which initially I derived from the Tiger Kits F-102 Delta Dagger).

 

Silver/grey is particularly tricky to reproduce - 'Fiffty Shades of Grey' isn't in it as it becomes blue/green  on printing and transferring to balsa with heat transfer paper.  Any suggestions?

 

F-106 Blog

 

Above:  progress so far with the F-106 for Rapier L-2.  All 'profile models' tend to be caricatures, and  note the wings are enlarged, but are the various shades of grey here 'over the top'?

 

 

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It seems strange to me that Jetex stuff is apparently sold on eBay and, by all accounts, posted off to the lucky winner, without the restrictions that apparently apply to Rapiers. I have bought motors and pellets on eBay with good results.

Fuse, though, is definitely dodgy – to buy and to post – and some of the old stuff doesn't burn very well. I am told that Dr Zigmund is 'on the case' so if I hear anything I'll let you know. Meanwhile, I guard the good fuse I do have – the test is to see if it stays lit through a Jetex nozzle – and hope somebody clever comes up with an electric igniter.

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This nice item appeared on eBay recently, but will the fuse (right) still work?

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Another modelling technique Joe Mansour experimented with was 'paper over balsa'. This is a method well suited to profile jets, and, using computer programs not available to the old guys in the 1950's, very colourful models can today be designed and put together very quickly:

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Draken designed by Rob Smith using CAD. Construction is printed paper over Depron and balsa.

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These models make a very good introduction to rocket flying, as they are robust, light, easy and inexpensive to build. Also – a consideration given the nasty weather we have been having – another can be printed off if the first one flies away in a thermal or crashes because of turbulence.

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One of the inventors of the original Jetex motors, Joe Mansour, explored innovative ways of building models – for example the 'Tailored' series with internal motors:

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An original Jetex Tailored Hawker Hunter rescued from eBay and beautifully restored by Ian Hobbs.

 

A feature of these models, the fully moulded balsa fuselage, is not too difficult to reproduce, for example this Draken:

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Draken for Rapier L-2. The fuselage is moulded; the wings and tail are built up.

 

The trick is to use the very lightest balsa available, and I can fully recommend online suppliers like
http://www.slecuk.com/catalogue/sitemap.html

The Draken is a little over 30g – much lighter than an old Tailored model and should fly well, but, what with the weather at meetings we had last year, has not been fully trimmed out.

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Flying small model aeroplanes with rockets is a thrilling activity, one open to all, but in the last couple of years there have been questions about the availability of Rapier motors, and their reliability and performance when you can get them.

Although they are not now sold by model shops like the splendid 'SAMS Models', who nevertheless sell models for them, see: 

http://www.samsmodels.com/acatalog/copy_of_AEROGRAPHICS_KITS.html

Rapiers are still made by Dr Zigmund in the Czech Republic and available in this country. They can be collected at meetings or by personal delivery. The situation is not unlike that of the more powerful motors for model rockets. But, if you want 'em, you can get them, and the latest 2013 batches are well worth having.

The latest L-1 motors put out 100mN for 10 sec, giving my Swedish Lansen (above) a sparkling performance:

The latest L-2 motors are also pretty potent, and so far, I've had no blowouts. So we can build and fly with confidence!

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