Swordfish, Jetex & Ashley’s Article July 2021 Model Boats

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Swordfish, Jetex & Ashley’s Article July 2021 Model Boats

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12 June 2021 at 12:51 #96079
Chris E
Participant
@chrise
Jetex was always one of those models that had mystique. The catalogues were great & built childhood desire but the models…………

I am sure that Ashleys model is a vast improvement in so many ways on the original. Seeing a Jetex model actually work is great. Well done Ashley!

Ah…………… the memories of Jetex.

I had a Jetex brand speedboat as a kid except that as a kid I couldn't get it to work properly but did anybody?

I remember the fuse that came coiled in a little can but which "cracked" ever so easily making it useless as it stopped burning when it reached the crack.

I remember the difficulty of threading the fuse through the orifice at the back of the motor which helped causing the cracking mentioned above.

I remember the gauze that had a notch that the fuse had to fit round also causing the fuse cracking problem ………… and I remember the gauze clogged so easily and which was a problem for my fingers to clean – if I didn't drop it down the plug hole – don't ask.

I remember filling the bathroom with smoke the first time I got it lit & the trouble that I got into.

I remember the total disappointment at the lack of power – it certainly wasn't a speedboat.

Did anybody get theirs to work any better?
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12 June 2021 at 12:51 #4745
Chris E
Participant
@chrise
12 June 2021 at 13:41 #96080
Chris E
Participant
@chrise
Thinking about it I also remember the thin wire which was in the centre of the fuse and which was supposed to blow clear of the jet hole when the pellet lit ……………… but often didn't meaning no thrust.

As you can tell I never had much luck with Jetex even though I loved the idea!

Perhaps I should mention, for those who have not yet received their copy of the magazine, that Ashley has fitted a small ducted fan to a Jetex design.

Edited By Chris E on 12/06/2021 13:46:22
12 June 2021 at 13:53 #96081
ashley needham
Participant
@ashleyneedham69188
Thanks Chris. I also seem to remember having a Jetex, and as per your experience never got it working.

Theres no doubt about it, they were too fiddly for their intended market.

The Jetex site indicates there must be some sort of following for them and I think (off the top of my head) that either fuel pellets or even complete units are available from a foreign power.

I rather think that mine goes a bit better than the original…and how many were ever actually made?. A bit like the Hobbies Hydro…..a lot of work for not much reward.

Ashley
12 June 2021 at 14:30 #96085
redpmg
Participant
@redpmg
There were Rapier rocket motors available from Czeckslovakia (sp) but are no longer around because of transport rules & regs . They were used by the flyboys to replace the Jetex Units – very simple to use – much superior to a fireworks rocket of course .

Still have a JetX type motor which was basically a copy of the Jetex one – but marketed much later by Ripmax I believe . Also killed off by transport safety regs – pity as they worked quite well compared to the original

Looking forward to reading the article Ashley – was given a small ducted fan with dedicated long nose brushless motor which there was no special use for so far…………

Edited By redpmg on 12/06/2021 14:32:55
12 June 2021 at 15:22 #96086
Charles Oates
Participant
@charlesoates31738
I used to modify the fuel and motor, a common practice in my youth. I'd drill a hole down the middle of the pellets, and make a hole in the gauze disc, then enlarge the exhaust hole a little. The fuze then had a straight line and came out easily. The mods were to power the Dan Dare rockets featured in Model maker in the 1950s. I must have made a dozen different rockets from 1 inch square balsa, and they flew well.

I also tried the modified motor in the little jefex boat, it flew across the pond like mad for a few seconds, then sank in a hissing, steaming cloud. At 12 years old I thought it was fantastic, so much fun that wouldn't be allowed now.

Charles.
12 June 2021 at 18:00 #96089
Paul T
Participant
@pault84577
Another trip down memory lane, as youngsters my friend John and I used Jetex to power some models on the Bridgewater.

John was entranced by these solid fuel motors and had devious little ways to make them burn longer and put out extra power.

Looking back it is obvious that his life and career were formed by playing with these motors.
12 June 2021 at 18:27 #96090
redpmg
Participant
@redpmg
Great childhood memories – especially from Charles . My own experience with Jetex motors was on the first occasion the plane initially flew well then the motor decided to go off on its own – never to be seen again – life lesson was that screws dont hold well in balsa…………..

Never tried the jet boat – they were too expensive for my pocket – must have been fun though ………….

Now even the little pop pop boats are frowned upon as someone might get injured by them – the ones I have are all clearly marked Not a Childs Toy or something along those lines . Similar to schools banning conkers…………
12 June 2021 at 18:37 #96091
ashley needham
Participant
@ashleyneedham69188
This is probably the easiest thing you could make for a "spare" ducted fan…..

Included in the article, a free plan! (sort of) (well, the basis of a plan)

Ashley
13 June 2021 at 10:46 #96101
Malcolm Frary
Participant
@malcolmfrary95515
A lot of years ago one of my less stable workmates got a rocket kit by "Estes". Entertaining if somewhat scary, use involved an electric firing device (basically a filament bulb with no glass envelope and a long piece of wire). The motors/fuel still seem to be available after a quick web search.
20 June 2021 at 00:24 #96260
Philby
Participant
@philby
I also had a jetex motor and tried it on different projects then found Estes rockets later on in life (great fun)

and then I built one of these using aero tech motors

Phil
20 June 2021 at 08:38 #96267
ashley needham
Participant
@ashleyneedham69188
Whoah Phil!!

Thats a serious Jetex and no mistake! No wonder satellite coverage round your area is so poor….

Ashley
21 June 2021 at 11:07 #96303
Philby
Participant
@philby
Hi Ashley

If I remember correctly it achieved 8500 feet

I did like the article in MB this month of the Swordfish which had me thinking R/C on rudder and rocket motor propulsion ?

Phil

Edited By Philby on 21/06/2021 11:09:47
21 June 2021 at 11:34 #96304
Philby
Participant
@philby
Ashley

Sorry for stealing your thread

Final picture this was taken at lift off

Phil
21 June 2021 at 12:07 #96305
ashley needham
Participant
@ashleyneedham69188
Phil. Strictly speaking the Jetex was a rocket motor!

i did try a 3s on the Swordfish and it was like a missile…I only applied 1/2 throttle and had to stop as it was fast approaching the bank. Being very light it flipped over and on recovery emitted yellow smoke from the esc. Luckily that’s all, but the boat and box still whiff of it…

Ashley
21 June 2021 at 13:40 #96308
Richard Simpson
Participant
@richardsimpson88330
Surely Ashley a rocket motor burns fuel with liquid oxygen whereas a jet engine burns fuel with oxygen from the atmosphere?

Therefore the Jetex would be a jet engine?

Edited By Richard Simpson on 21/06/2021 13:41:05
21 June 2021 at 14:49 #96311
Philby
Participant
@philby
Hi Richard

the way I understood the difference between motor and engine was an engine was made up with moving parts.Rightly or wrong

ie

a jetex motor was a sealed chamber where the burning of the fuel pellet created heat and oxygen forcing the gases out of the chamber through the nozzle giving the motor the thrust. The trust on this cannot be controlled

where as a jet engine is forcing compressed air into the burning chamber mixing with fuel causing the gases to expel through the rear of the engine giving a controllable thrust

Phil
21 June 2021 at 16:05 #96313
Chris E
Participant
@chrise
Posted by Philby on 21/06/2021 14:49:35:

a jetex motor was a sealed chamber where the burning of the fuel pellet created heat and oxygen …………………

Phil

Agreed that the only source of oxygen must be the burning of the tablet but that oxygen is then consumed by the burning process to create the horrible smelling smoke that came out of the very small orifice at the back.

I was amused by a post earlier which talked about enlarging the jet hole and modifying the gauze to make the motor more useable. This was a toy and purchased by people for children who knew nothing of drills (& whose parents didn't own any of the very small size required).

The Jetex motors were possibly OK for modellers but not as toys.
21 June 2021 at 17:46 #96320
Richard Simpson
Participant
@richardsimpson88330
As regards the difference between a rocket and a jet, a rocket carries its own oxygen supply whereas a jet uses atmospheric oxygen. Precisely why of course you will never find a jet in space.

If Jetex fuel contains all its own oxygen required for combustion then technically it is a rocket, if it uses atmospheric oxygen then it is really a jet.

Whether you call them an engine or a motor doesn't really alter that. Worth remembering we refer to anything on the roads as a Motor Vehicle, Motor Car or Motor Cycle, not an Engine Vehicle, Engine Car or Engine Cycle so I think it is, as with most English, somewhat irregular.

Interestingly if you look at the technical terminology a 'Motor' is only an electrically driven device whereas the Oxford English Dictionary defines “motor” as a machine that supplies motive power for a vehicle or other device with moving parts. It also tells us that an engine is a machine with moving parts that converts power into motion.

I think the interchangeably is now pretty much accepted.
21 June 2021 at 18:34 #96322
Ray Wood 3
Participant
@raywood3
Hi All,

So my Tesla (I wish ) has 4 motors one on each corner, so It took the dictionary this long to get the definition right for a motor vehicle ??

Actually this is one of the only forums where electrical powered vehicles hasn't be a hot topic !! Nuff said

Regards Ray (Strictly petrol or Diesel )
21 June 2021 at 18:59 #96323
Colin Bishop
Moderator
@colinbishop34627
The concept of: 'horrible smelling smoke that came out of the very small orifice at the back' appears to be associated with the over consumption of baked beans… Or have I misread something?

Colin
21 June 2021 at 19:15 #96324
redpmg
Participant
@redpmg
Electric motors are also pollutants Ray if you consider how electricity is generated in most cases – very few environmental friendly power stations – certainly not here – wind farms form negligible input – and the single Nuclear one endangers sea life and believed to be contributing to the poisonous "Red Tides"as well as the creation of yet more hazardous waste with a half life of 500years – presume thats part of the hot topic .

To add insult to injury distances between some towns here would also make them 'impractical to use
21 June 2021 at 22:19 #96329
Richard Simpson
Participant
@richardsimpson88330
Posted by redpmg on 21/06/2021 19:15:50:

Electric motors are also pollutants Ray if you consider how electricity is generated in most cases – very few environmental friendly power stations – certainly not here – wind farms form negligible input – and the single Nuclear one endangers sea life and believed to be contributing to the poisonous "Red Tides"as well as the creation of yet more hazardous waste with a half life of 500years – presume thats part of the hot topic .

To add insult to injury distances between some towns here would also make them 'impractical to use

That's been my argument against electric cars for a long time! A modern diesel engine is comparatively very clean compared to a lot of solid fuel powered power stations.

Then don't get me on what is required to manufacture batteries and disposing of them when they need replacing!
22 June 2021 at 08:24 #96333
Ray Wood 3
Participant
@raywood3
Hi All,

I'm not a supporter of EV's and could never justify the cost anyway !! I think the popular illusion is created because electricity can't be seen, I have felt 240volts a few times so I know it exists

I'm sure Audi,BMW & Merc have taken a hit from the Tesla sales as they look great and are perceived as cool and if a long journey is required they would take the partner's Range Rover

Regards Ray
22 June 2021 at 08:32 #96334
ashley needham
Participant
@ashleyneedham69188
I believe wind farms generate a substantial portion of our electricity…something at approaching 25% if memory serves.

Ashley
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