Jetex engine

Harden Associates in the UK reintroduced the Jetex concept in the late 70s/early 80s as 'Jet-X' in the 50 and 100 sizes....along with wick and new fuel-which gave some of the original Wilmot and Mansour Jetex motors a second lease on life-but the concept never really got much buy in from the modelling public and faded off the market again. Curiously the Czech Rapier one shot rocket motors seemed to get more support from the modelling fraternity....and somewhat ironically-there is probably more Jetex activity in the US than in the country of origin.

ChrisM
'ffkiwi'

I had a Jetex, or at least my brother did.

I never managed to track down replacement fuse, so I never ended up trying it.  Still got the tin of fuel pellets.

Didn't risk sending them with the motor when I sold it on ebay a couple of years back.  I think it went to the U.S.  I sometimes wonder why I sold it, but I never would have used it.

All I remember is the frustration of never being able to get it to fire.  Fuse was always the problem

My experience was similar-the fuse and successful ignition of the fuel pellet- was always the weak point of the Jetex system.  In recent times SAMS models in the UK offered a NiCd powered hot wire probe ignition system for Jetex-but it was quite pricey-....essentially it was a wire probe which glowed red hot and was poked through the jet efflux hole to ignite the fuel pellet and then withdrawn fairly quickly before the gas pressure built up...

Here's the big brother of all Jetex motors..the Scorpion [added in edit: sorry I can't get the photos to load]

Today, I might be able to get a flight in. Were experiencing unusually warm weather in these parts and I hope the wind isn't problematic. I'm aware of the igniter you mention and I've tried for a few years to search for it with no luck. My buddy Dan just gave his Scorpion away as he just couldn't locate fuel for it.
My success in getting it too light is due to scraping the pellets with a X-acto knife. I do this with the pellet in the casing. You need to make certain that none of the powder escapes. This is what really kicks off the ignition. The other thing I found is that preheating the exit nozzle slightly without lighting the fuse assists. The fuse can quench itself out because of the cold metal. The fuse as I mentioned before on here is a coated wire. You must be extremely careful when bending it, coiling it, etc. If the coating fractures, it causes a gap which can also prevent ignition, this can be problematic where the screen comes into contact.

Man....if at ALL possible, please get some video of the action!

Today I was able to get that flight. Unfortunately, it wasn't without issue. I test glided the plane many many times prior to trying it powered. I must have a slight warp in the wings which I will try and remove tomorrow. When launched at about a 30 deg angle the plane would stall and bank left fairly quick. I tried bending and twisting the wing . I successfully got the engine lit 3 times first time every time which I feel is monumental for me.

I wasn't able to get any flights in due to others using the field so I had to wait until all activity was over. Being a nice day, there was lots of flyers using the field.The sun was setting quick and I was losing light. I did get some video but it may need a little editing . New Years day is the next attempt and I hope to have these problems resolved by then.

Ken, I'm enjoying the %&#@ out of this thread. I've had
a lurking interest in Jetex engines since the seventies.
Thanks.
Bob

Bob, Roddie peaked my interest in this some time ago on here when he posted his book of models. Without looking, I only remember the book being turquoise in color. There were a few Jetex plans within it. I sourced the book from Ebay due to not being able to locate the one my dad gave me. I was about 9 years old when my dad gave me the Jetex I used yesterday. I find it incredibly amazing that all these years have passed with this stuff sitting in a cabinet and I got it to work. My dad probably purchased the Jetex engine about 1960. I did go to the hobby shop with him and I'm guessing it was 1977-78 and we bought a new Jetex Psst.50 with all the accessories. I don't have fuel for the Psst as I recall it was brownish tan in color and came in a black and yellow package which I think had lettering Telasco corp on it with the Jetex logo in a circle. The Psst is a aluminum cased engine that the older Red Spot Jetex fuel doesn't work in. It fits the casing but it burns too hot. I do have quite a variety of the newer engines and fuel that Kiwi Chris mentioned above which is the Jet-X which Bob Davis of Davis Diesel supplied. While my flight didn't quite perform as I would've liked it yesterday, it certainly brought me back to when I was a kid again. I'm looking forward to New Years Day ( Keeping fingers crossed for good weather) .

Never had a lot of luck with Jetex. Fussy to start and oh so short of a run time. The last one I used I simply gave up on the fuse and screen and just heated the whole thing with a blow torch until it ignited. Seemed to work just as well.
Actually had a plane crash and the Jetex "exploded" on impact. Not much of an explosion to be sure but I was impressed all the same. Jetex "50" if I recall.

Oh, and Jetex, take a picture BEFORE you start it for the first time as it will never look as good as it did in the package.

Roddie, my dad built me the profile Firebird car. I haven't been able to find it but it's in a candy box with my Pinewood Derby car with a new Jetex mounted on it. I've learned quite a bit with the Jetex mostly being self taught but there were a few things I've read which have assisted greatly. I lit the engine last evening first time every time. I have only a little amount of fuse and I want to make it count. Today, I took out the Powermax Jet-X I own. This engine surprised me as it seemed to offer a bit more thrust regardless of what I've read claiming the opposite. I have a fair amount of Jet-X fuel but only a few pellets for my original Jetex. The Jet-X doesn't use the screen like the older engine and seems to be easier to ignite.

The Mig will be tried on New Years hopefully. One thing I think that was happening with the plane I tried last evening was the slight warp combined with the fact I only used one pellet. Under power the plane was ascending like it should but as soon as the power lessened, it would stall and bank left usually hard and fast. I twisted the wing today with a little heat so will see if it stays.

Hope I don't get thrown out of the bar for this one, but for someone
who can't access Jetex type engines, some of these models just scream
for the Estes A, !/2A and 1/4a rocket motors. I have no idea what the
burn time is for a Jetex motor is though.  
Also, where do I get asbestos paper?
Bob

Hello friends, hello Roddie !! ... what you show there is very beautiful! .... I agree with Kim ... if there are videos, it would be great to share them friend !!

then I went to my corner of memories and here I have my Jetex ... a long time ago I asked in this same forum what it was. ... :-)
Well, I share with you photos and discover something amazing! ... a legend dedicated to the former owner of this Jetex, which made me laugh out loud! ...
That dedication says:
Dumbo, (nicknamed by his big ears), buy a turbine of these and place it in the back (behind) to go to Rufino (city where the former owner lived), from Jeta, (by mouth). Bye and good luck.

Then it reads like this:
Dumbo, buy a turbine of these and put it in the behind to go to Rufino by mouth. Bye. Good luck.





dedication representation:

Ken that's good to hear your having some fun with the jetx and hopefully the next fight will take to the next level . Mauricio Thats crazy !!

I knew we'd talked about this before.
https://www.coxengineforum.com/t7651-wanted-jetex-50-motor?highlight=jetex
Shows my memory's going.  I recalled selling it on ebay.  Turns out it went to Darron (AMCGUY) right here on CEF.
Never heard if he got his project with the Jetex completed.

Rod.

asked where do I get asbestos paper?

I know a tongue in cheek ask....but I gotta respond anyway....If you are smart, you don't!

There are a few ways to fire / heat proof areas of our craft....black high temp RTV is surprisingly heat proof but not fire proof...so put a layer of metal foil over the RTV

I was, and still am a low educated chemist, ordnance, and explosives guru
dabbled only in Estes model rockets...bucket list was shooting with big boys

never played JetEx but had friends that did.....when their pellets ran out we experimented with carbide my dad had for a miners lantern....5 lbs of the stuff....dd water and it makes pressure and acetylene a flammable gas .....all we ever did was soot up the garage.....

https://www.thenakedscientists.com/forum/index.php?topic=24417.0

https://www.rocketryforum.com/threads/acetylene-propellant.72944/

we did have interweb then

My fellow club member Rob has been a long time member of the Maryland Delaware Rocket Association. I've asked Rob to see if making fuel is a possibility. Rob is into full scale model rockets such as this https://www.youtube.com/watch?v=uxgMhHOaUSY    My son and I were invited to witness this launch with Rob and it has left a everlasting memory that I will never forget as this was scary and cool simultaneously. Throughout the day, my son and I helped assemble some of these giants on multiple saw horses making them ready for launch. The end of that day was complimented with what was called the "Nike Drag Race". We were hiding behind a large sod pile watching this event as there were 4 of them  lined up in a row about 20" apart. Rob said keep in mind 2 things happen in this hobby, it works or it explodes.

        Rob explained that Jetex formulas not only changed with regular frequency, but it was also closely guarded in terms of chemical compositions. Most of Rob's engines aside from the sugar motors are more like the shuttle solid rocket fuel. This would not work in the Jetex engine casing as it's too hot and powerful. Ebay has instructions for making Jetex fuel pellets and I'm just hesitant to purchase.

To date, it still is a problematic fuel to source. On Jetex.org, it's explained in detail as to why it's difficult to make, find, and produce. This still leaves the issues of the problematic fuse that's not available.

You can make fire resistant paper instead of using asbestos paper. Mix borax (alum) with water, then dip the paper in solution, then dry. Repeat this several times and you have a flame resistant paper.