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View Full Version : Jetex kits (maybe B/G convertible)


blackshire
08-11-2019, 02:23 AM
Hello All,

The Vintage Model Company (see: www.vintagemodelcompany.com ) offers replicas of classic F/F (including Jetex) model airplane kits. The Jetex series (see: www.vintagemodelcompany.com/jetex-powered-models.html ) can also use the Czech-made, single-use, Rapier model jet motors (see: www.google.com/search?source=hp&ei=xb1PXaXrI4mr0gKAu7LwCw&q=Rapier+model+jet+motors&oq=Rapier+model+jet+motors&gs_l=psy-ab.12...2884.13227..15707...0.0..0.157.2730.0j24....2..0....1..gws-wiz.......35i39j0j0i131j0i67j0i20i263j0i22i30j0i22i10i30j33i299j33i22i29i30.YAcv9hQA2HM&ved=0ahUKEwjl4cCLoPrjAhWJlVQKHYCdDL4Q4dUDCAs ) instead of the reloadable Jetex/Jet-X motors, and:

The Rapier motors are (were?) paper-cased, clay nozzle-equipped, zinc-sulfur rocket motors whose propellant grains are so formulated that they burn slowly, producing low thrust for longer periods of time than do most model rocket motors. Like model rocket motors, the Rapier motors are (were?) made in various thrust-time combinations. (Perhaps a slow-burning black powder formulation might also provide Rapier-type performance [hint, hint, Estes and Quest... :-) ].) At least some of the above-linked Jetex kits might also--perhaps if equipped with a long, stable booster--be able to be flown as vertical takeoff model rocket boost-gliders (or maybe even as rocket gliders, in a few cases). Their replica of the Skyleada Vulcan (a scale model of the prototype, pure-delta-winged Avro Vulcan jet bomber) should glide very well.

I hope this information will be useful.

Brent
08-11-2019, 08:08 PM
The V1 looks interesting. Prices are in euros?

Ez2cDave
08-12-2019, 09:55 AM
https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=4299.0

blackshire
08-16-2019, 04:11 AM
https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=4299.0 Thank you--I *thought* I had read that about the Rapier motors some years ago, but I wasn't positive. I have a shrink-wrapped (like some sausages) pack of green Rapier motors, which are a bit narrower and longer than Estes 13 mm mini motors. If one of the model rocket manufacturers would produce similar model jet motors, there is a market for them (some people make their own model jet motors, using--in some cases--"watered-down" sugar rocket propellant formulations [the "Incredible Five Cent Sugar Rockets" are even physically very similar to the Rapier motors, having rolled gummed-paper cases and simple modelers' clay nozzles]), and:

There are, surprisingly, still Jetex/Jet-X fuel pellets (jealously hoarded and sparingly used by F/F jet modelers, including at jet model meets). Also, the classic Jetex plane kits are still made by multiple companies (they offer "Retro-Repro" duplicates of the Keil-Kraft, FROG, and other Jetex kits), so if Estes, Quest, Klima, or another model rocket maker offered Rapier-type jet motors, there are plenty of kits that could use them.

blackshire
08-22-2019, 01:35 AM
The V1 looks interesting. Prices are in euros?On my screen, the website https://www.vintagemodelcompany.com/jetex-powered-models/page/1/?scroll=500 gives the prices in pounds sterling (£), which is no problem with PayPal, which they do accept (see: https://www.vintagemodelcompany.com/ordering.html ). I suppose it's possible that my connection just "defaults to pounds sterling" and also can be displayed in euros, but if so, PayPal also supports transactions in euros.

astronwolf
08-22-2019, 07:19 AM
If one of the model rocket manufacturers would produce similar model jet motors, there is a market for them ....
If Jetex-type products had any market viability, you'd think that during the 60+ year span of model rocketry that this would have been tried and maybe caught on. But that didn't happen.

blackshire
08-22-2019, 08:14 AM
If Jetex-type products had any market viability, you'd think that during the 60+ year span of model rocketry that this would have been tried and maybe caught on. But that didn't happen.Guess what? (I'm not being sarcastic, as I just came across the following this morning.) A new Jet-X product line--including kits and motors--*is* being developed (see: https://jetxus.wordpress.com/ ). Their paper-cased, single-use J-1 motor is 1/2" in diameter and 2-1/2" long. Videos on the above-linked Jet-X website show the motors and models in action, and there are also photographs, as well as descriptive text.

astronwolf
08-22-2019, 08:31 AM
A new Jet-X product line--including kits and motors--*is* being developed...
That's nice, but it kind of side-steps my point. You suggested "one of the model rocket manufacturers" take up the torch for Jetex.

jadebox
08-22-2019, 08:49 AM
Maybe someone can develop a really tiny and lightweight thrust-vector control system for those motors. :-)

stefanj
08-22-2019, 09:10 AM
The Jetex revival page that Blackshire points to mentions a crowdfunding effort.

Who would be onboard? I'm wavering.

5x7
08-22-2019, 09:23 AM
Guess what? (I'm not being sarcastic, as I just came across the following this morning.) A new Jet-X product line--including kits and motors--*is* being developed (see: https://jetxus.wordpress.com/ ). Their paper-cased, single-use J-1 motor is 1/2" in diameter and 2-1/2" long. Videos on the above-linked Jet-X website show the motors and models in action, and there are also photographs, as well as descriptive text.

Don’t hold your breath that site has been out there for years. And it ironically says the previous venture failed because there is no market. Be aware the there is an Aerotech C3 and D2 in 18mm with a 10 second burn time so there are alternatives to jet-X vaporware.

blackshire
08-22-2019, 09:30 AM
That's nice, but it kind of side-steps my point. You suggested "one of the model rocket manufacturers" take up the torch for Jetex.So? I only mentioned them as possible producers of model jet motors because they already produce not terribly dissimilar products, single-use paper-cased black powder model rocket motors. I don't care *who* produces model jet motors; I just want to be able to purchase them (and kits, too, although they are of secondary importance, since replica Jetex kits are already available elsewhere) from a manufacturer.

blackshire
08-22-2019, 10:08 AM
Maybe someone can develop a really tiny and lightweight thrust-vector control system for those motors. :-)I was thinking about that, too. (The jet motor mount tube could also--in some model configurations, such as ones in which the motor mount was inside a larger-diameter pod [as in this Veron Fouga Cyclone model: https://www.vintagemodelcompany.com/fouga-cyclone.html ]--be angled in pitch and/or yaw, in order to tilt the thrust vector accordingly.) Constantly-immersed (in the exhaust plume) jet vanes should be feasible, because the exhaust temperature, while high, isn't too high to use metal, or coated metal, or maybe graphite. Also, the burn time, while longer than that of a typical model rocket motor (it's approximately 12 seconds), isn't long enough to burn vanes away. Also:

"Tap contact" jet vanes (whose flat sides would intermittently contact the exhaust plume--Goddard's later rockets used these), or "jet tabs" (they're on shafts parallel to the motor axis, which intermittently rotate, bringing the jet tabs into contact with the exhaust plume--BAC planned to use these on the Skylark sounding rocket), would have even briefer exposure to the jet motor's exhaust plume. Jetavators (gimbal-mounted, rotating circumferential rings--a jetavator is a short length of an open cylinder, surrounding a rocket nozzle) could also be used, for example, in a scale model of a Polaris missile. The Polaris first stage had four fixed nozzles, each with a jetavator surrounding it. As well:

A jet model plane equipped with a micro R/C system could use servo-actuated jet vanes or jet tabs to steer the model during its period of powered flight. One lightweight possibility that I'd thought of could be used in Vintage Model Company's reproduction Veron Fouga Cyclone jet sailplane kit (see: https://www.vintagemodelcompany.com/fouga-cyclone.html ). It could utilize jet vanes or a movable motor mount tube to provide thrust vector control during powered flight. (Axion makes two-channel motorglider models that work similarly; they use rudder control for left-right turning, while a throttle-able, fuselage top-mounted electric motor/pusher propeller [with a slightly raised thrust line] provides pitch control.)

blackshire
08-22-2019, 10:29 AM
Don’t hold your breath that site has been out there for years. And it ironically says the previous venture failed because there is no market. Be aware the there is an Aerotech C3 and D2 in 18mm with a 10 second burn time so there are alternatives to jet-X vaporware.Unless the videos on their website (at least one of which dates only to last November) were shot using models powered by Rapier motors, the Jet-X J-1 motor is already in existence, although not in quantity production yet. Also:

Depending on how much those long-burn Aerotech C3 and D2 18 mm motors cost, I'd be perfectly happy using them. (After World War II, especially in England, many large Jetex-type target aircraft were available as military surplus. It wasn't terribly different from the Aerotech Phoenix R/C rocket glider. The target had, if memory serves, swept wings and tail surfaces, a pod-and-boom fuselage [the boom was a dowel or an arrow shaft, I think], with a circular opening in the rear of the pod fuselage, into which a large Jetex-type motor had been fitted.)

Ez2cDave
08-22-2019, 10:48 AM
https://www.jetex.org/index.php/jetex-forum?view=topic&catid=8&id=4

https://sites.google.com/site/jetexpropulsionlab

Dave F.

blackshire
08-22-2019, 10:54 AM
The Jetex revival page that Blackshire points to mentions a crowdfunding effort.

Who would be onboard? I'm wavering.I will be. Jet-X plans to produce their own kits (and they've already tested them, as their website's videos and still photographs show). Also, since Vintage Model Company already sells "Retro-Repro" duplicates of classic old (Veron, Skyleada, etc.) Jetex model kits, there are already such models that could use Jet-X's J-1 motors. Their J-1 motor is similar in size to Dr. Z's Rapier motors (which are no longer made, although some are still in stashes here and there), whose motor mounts, in turn, are easy to retrofit into Vintage Model Company's Jetex kits (and Jet-X's J-1 motor mount is very similar to the Rapier motor mount). Also, speaking of very small jet motors:

Sam's Models, from whom I bought Rapier motors years ago, carries Derek Knight's tiny (32 mm, 24 mm, and 18 mm diameter) EDF--electric ducted fan--units (see: http://www.samsmodels.com/electric-flight-ducted-fan ). One model rocket-related application of these that comes to mind is a small-scale model of the Harpoon cruise missile, using an 18 mm EDF in the missile and a 13 mm or 18 mm model rocket motor in the booster, which could be parachute- or streamer-recovered (as could the EDF-powered missile as well).

blackshire
08-22-2019, 11:51 AM
Also, Roger Simmonds' Jetex.org website (see: https://www.jetex.org/ ) sells several new-design Jetex/Rapier model kits, which could also use the Jet-X J-1 motor (they also sell a hand-held electric igniter [which is a veterinary device]). His site also contains numerous old and new articles, images, and model plans.

blackshire
08-22-2019, 12:01 PM
https://www.jetex.org/index.php/jetex-forum?view=topic&catid=8&id=4

https://sites.google.com/site/jetexpropulsionlab

Dave F.Thank you--I helped Dr. Edward Jones (he's deaf) get a supply of parallel-wound paper tubes for Rapier-type test jet motors several years ago. His propellant formula at the time even included red gum from a particular Australian tree (I forget which species), but he achieved long, smooth, even-thrust motor burns. He and others have been tinkering to optimize the thrust-time curves, for a family of motors (Dr. Z. had also developed a family of Rapier motors of different sizes, thrust levels, and burn times).

britroc
09-17-2019, 07:40 AM
Also, Roger Simmonds
could also use the Jet-X J-1 motor (they also sell a hand-held electric igniter [which is a veterinary device]).


ooooh poor ol' hoss !

blackshire
09-17-2019, 10:35 PM
ooooh poor ol' hoss !Judging by its size (it's a roughly fountain pen-size device, with batteries sealed inside its plastic case; the folded-wire heating element protrudes about half an inch or less [the one I ordered with my Rapier motors is stored away at the moment]), I think it's used on rams and/or billy goats.

Gelding of horses is done with a crimping device that is applied to the spermatic cord (as well as removing the testicles), which is not always done--even today--under anesthesia, instead using only sedation and a lip twitch for restraint, with the horse standing. (Only the English-speaking world seems to have a "stallion behavior problem." In France, Germany, and other countries, stallions aren't kept in isolation except when bred; they are ridden and driven, and they also pull farm implements [including with geldings and mares, sometimes even when the latter are in season], instead of living alone--it's no wonder that those secluded stallions are so poorly socialized. People in the English-speaking world, assuming that "stallions have one-track minds," keep them in a manner which ensures that they will become that way.)