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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Another slightly 'off topic' topic, but one that will, I hope, interest Jetex enthusiasts:

PVL Penguin

 

Model flyers naturally have a great interest in the old FROG flying models, and Mike Stuart's wonderful website: http://www.houseoffrog.co.uk contains a plethora of plans to enable the replication of many classic FROG models. FROG nostalgia has been well served too, by "FROG Model Aircraft" by Richard Lines and Leif Hellstrӧm which was published in 1989. This marvelous book covers well the history of the founding of FROG by Charles and John Wilmot and Joe Mansour and the development of their innovative products like the prewar Interceptor, the Junior and Senior range of model aircraft after the war (including the World's first all-metal modelaircraft) and the well-respected FROG plastic kits that are still with us.

The book also includes fine compendia of all FROG models, including listings of all the 'Penguins', the non flying (thus the name) scale models moulded from cellulose acetate. The development of these, the archetype of all 1/72 plastic kits. is, however, only briefly described and there has been no book dedicated to the history of these fascinating kits, which even well respected histories of plastic models ignore or misrepresent. And there has been no written history of the little known 'Wimco' Hollows produced by Jetex in the 1960s. Until now.

 Peter, in his just-published book,  covers the genesis of both Penguinsand the troublesome hollows (the progenitors of today's 'vac forms')  in some detail. There is much else  of interest modellers: as well as the many photos and  adverts  ( yes, they are mostly of plastic models, but which who didn't build a few static models in his youth?)  there is, splendidly,  the Jetex connection, as Charles Wilmot and Joe Mansour founded Jetex after they were forced out of IMA soon after the war. 

CWilmot PVL

Above: a previously unknown (1948?) photo of Charles Wilmot with a prototype Jetex model. 

Jetex, as Peter recounts, were soon joined by Bert Judge, who helped produce the early FROG Diesel engines, and the innovation continue.  The somewhat strained relationship between FROG and Jetex is covered (FROG didn't  produce any models for Jetex power, a great shame, the FROG 'Mamba' would have gone splendidly with a Jetex 50).

In short, Peter tackles every aspect of Penguin kits and from their creation to their demise comprehensively, with many personal touches about the idiosyncratic characters involved in the saga and the sad and gradual fading of both Jetex and FROG, and reasons for this are not ignored. There are many unique photos, all except the historical ones in colour, and the text is never less than readable, and the colourful layout is very attractive.  I found Peter's account of his odessy from youthful builder to collector then historian fascinating, and the chapter on model restoration (cellulose acetate is not very stable!) of especial interest.

This  magnificent book -  well more an encyclopedia -  is available from Peter's website: http://frogpenguin.com/ for just 30 Euros.  It  is thoroughly recommended. One thought: a similar book about Jetex is sorely needed. To make it as good as this one, though,  is quite a  challenge!

 

 

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The lack of Rapiers has been a great source of frustration to US modellers, but it has been a great spur to the development of 'Micro EDF', but not everybody has been happy with the status quo, and Chris Sorenson of Maker Research Labs is determined to do something about this, partly because he believes the excitement of rocket planes will be a great way to get youngsters enthused about science and technology.  I have been liaising with Chris for over a year and he and his colleagues have developed a Rapier L-2 analogue that looks most promising.  I received examples of their prototype X-1 and X-2 motors for testing earlier this year.  As Chris has gone public with his endeavours:

https://vimeo.com/209771680?utm_source=email&utm_medium=vimeo-cliptranscode-201504&utm_campaign=28749

now is a good time to publish my results.  I also tested one of the 2017 L-2 LT motors for comparison.

L2-LT march 2017

X1Tests March

The thrust time profile of the L-2 LT ‑ a very useful 125 mN for 18 seconds ‑ is in-line with the many fine flights we have seen with these motors and shows just why they are so popular.  The X-1 motors, of very similar size and weight to L-2s, fired up without problems, and their performance of roughly 140 mN for 12 sec is promising.  A little more duration would be nice, and experiments with the jet orifice diameter and a combustion inhibitor could pay dividends.

Below are the 'empty'  brown X motors with a used Rapier L-2 motors for comparison  

used X1 X2 with L2

Chris is now putting out feelers to scale up production, and is all too aware of the many legislative hoops he will have to jump through before he can bring his product to market.  But his motors do work (see https://vimeo.com/197810434) and if you would like to support Chris's project with its most worthy pedagogic aims please contact him at: Chris@MakerResearchLabs.com.  I have already put Chris in touch with modellers in the US who still have some old Rapiers, and I look forward to hearing about his progress.

 

 

 

 

 

 

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Howard Smith has  just  told me about an exhibition he is organising that I think will be of great Intest to many Jetex flyers.  Here is the poster : 

Dan Dare Ex 1

 

And here are the details:

 

Dan Dare Ex 2

This promises to be a most exciting event!  For those who doubt there is a 'Dan Dare-Jetex connection, this will remind you:

 

DD Spaceship montage 11 15

If any forum member gets there before I do (I don't travel too well at the moment) plese tell all of us about it.

 

Onwards and upwards,

Roger 

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Those who have read my latest postings on the forum will realise that I am now, with a refurbished set of heart valves working as about as well as a mint condition (though antique) Jetex 50 or, perhaps, a new Rapier L-2X,  ready to give Jetex.org the attention it deserves.

 

Folk that I meet on the flying field are appreciative of the website.  This nice - it is there for the free flight rocket flyer - and it is my hope to add to the site and make it an even better resource for those, young and old, who want to fill the sky with smoke trails, and not the thrumming of the latest ARTF drone.

 

I have not been altogether idle during my enforced months of convalescence, and I have put together several new designs, including this 'semi-profile' T-38 Talon:

Talon 1

 

T38 1 

 

T38 2 

T38 5

Above:    My latest models were designed, if that is the right word, by modifying  3-views retrieved from the Internet.  After some manipulation of the flying surfaces, templates were then refined and decorated using 'Paintshop pro'.  

The printed templates were then transferred to (generally) 1/16" light balsa.

 I made two versions of the T-38 in the livery of the USAF aerobatic team (the 'Thunderbirds'): number '1'  to check everything went together OK, (note the square fuselage) and no '3', where the fuselage is 'fleshed out' and a lot more rounded.  

Both await their  'rocket pods' (for Rapier L-2) and  trimming. 

 

Well-known rocket-flyer and 'prime pilot' Andy Blackwell has recently 'beta tested' this design for me:

AB T-38 

Above: Andy was quicker finishing his T-38 Thunderbird (no 2') than I was with numbers 1 or 3!  Here he is after its first very successful and spectacular flight.

 

Next, something for the Francophiles (you know who you are!): 

Mirage 2

 

Mirage 3 

Above: Following the success of my semi-profile F-106 Delta Dart, I couldn't resist trying a  Mirage III.  If it flies as well as the Delta Dart I will be well pleased.  This is 'printed paper over balsa', which allows for a more rounded fuselage.

 

Back to the US: 

CorsairII 1

CorsairII 2 

Above: The Corsair II has all the proportions of a very stable model - large flying surfaces and plenty of fuselage side area.

 

And now for something completely different: 

Cutlass 3

 

Cutlass 1

Above: The Cutlass was let down in real life by its poor engines.  In miniature it presents a challenge, but I'm hoping that my version, powered by a Rapier L-2X, will show what the original could have done for the US Navy.

The Corsair II and Cutlass are printed 'Dark T-shirt' heat activated transfers over balsa.  This allows for a colourful model - note the balsa doesn't show through, but fuselsges are best left with square edges. 

 

Designing and building all (balsa) sheet models was therapeutic, but by this time I was fed up with staring at the computer screen, and hankered after something' stick and tissue' that needed a little more building: 

Hawker Hunter 2 

 

Hunter 1

Above: My original Skyleada Hawker Hunter was wrecked by a Rapier 'blow out' in 2008.  Here it is brought back from the dead and ready for covering.  Note the attention paid to the jet pipe, which looked a little 'naff' on my first one.

 

Here it is again, canopy fitted and ready for airbrushing - not my favourite procedure:

Hunter 2015 blog

Above:  It is covered in white 'Starspan': green Modelspan would have been better, as I hope to finish it in the 'eu de nil' ('duck egg green') of WB188, the first prototype.

 My building skills don't approach those of ubermodellers Mike Stuart, Peter Smart, Richard Crossley et al, but it's the best I can do.

I also cannot build light:  at the moment the Hunter a little over 26g without paint, motor mount or nose weight.  So think '32-34g' ready to fly.  It will probably need all of the 160 mN of thrust an L-2 X can provide.  We shall see.

 

 

Howard Metcalfe, too, has been taking a break from profile models:

HM Cougar 2 

Above: Howard's Cougar.  This is Andy Ray's design.  I do hope it will be finished before the end of the 2015 Flying Season.

 

If any reader is interested in any of the new profile models, I can supply templates that you can print out and attach to balsa, for example:  

Cutlass blog 

 

Or a set of finished balsa parts.  These, though, will cost you £17.50 including postage.

 

So there you have it: I'm all set for the 2015 season.  I would love to hear from you about your own models, especially 'work in progress'.  Please email me with a picture or two and some words.

 

I also hope to meet you on the flying field  - my next meeting is Middle Wallop in mid June.

 

 

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