Be an Aeronautical Scientist: Make your Own Jet Engine for a few Pennies.

Step 4 Getting it right.

People that do this properly use proper tools, but it is possible to get it right with just a hammer and an inappropriate spiky thing.

If your fuel is meths (recommended), and you're using a pasta sauce jar, then the hole needs to be about 10-12mm across.

When I prepared a new jet, with a roughly circular hole about 10mm across, it nearly worked. It lit, went foosh and then RRR for a second.

A couple of minutes prodding at the edges of the hole with a screwdriver made the hole about 11mm across, and it ran well. Really well.

But I forgot to video it!

Never mind, I put the flame out and let the jar cool for a few minutes, then tried again. Yipee! It worked!

Comments

[andy55551]

is there a way so it doesn't brake at the end?

[skatattookid]

i keep mine water cooled and also wrapped the glass in duct tape so if it does break its easy to clean up without getting cut. you can also just drill a hole in a can of broth and just use that.

[BrianRandleas]

That was my thought on using a metal can as well. A beer can or soda can pierced from the bottom instead of "Popping the top" should work as well. If you can find a way to pull the bottom into a cone shape that should also give better results if your wanting even negligible thrust. If you are using a metal canister you should also be able to lay it on it's side. More important than the shape of the flame is the air to fuel mixture you are obtaining.

[Kiteman]

Some people recommend standing the jar in cold water, but I would like, one day, to make a metal version, maybe with water flowing round heat-transfer pipes...

[orangetj]

or possibly have a undamaged lid freeze the jar with the meths inside and then swap lids? but then again it might get hot fast and break sooner

[ELITE-01]

I haven't tried this specifically,
but just as a reference to something I have done, unintentionally,
Rap a jar containing a candle in a cold, wet rag. The glass breaks pretty quickly, large cracks, some shattering, the works. so i'd assume that cold liquids, of any kind, with hot glass is a no go. 

[Aldeas]

Have you looked up the heller/lockwood version of the valveless pulsejet? That version uses a u shaped arrangement of the tube with and expanded combustion chamber to set up the harmaonic combustion pulse. one guy ran a gocart on one of these things using propane as a fuel.

[BitBoink]

Ya I remember SRL (Survival Research Laboratories) did a pulse cart back in the 90's. The pipe was glowing bright orange-hot right behind his head if I my memory serves well ... was insane looking!

[Zaphod Beetlebrox]

I wonder if it work with a pop can. Or would the hole be to big.

[Kiteman]

I tried once, it just went woosh.

[Kiteman]

Although, you can get taller, narrower cans these days...

If you try it, let me know what happens.

[Zaphod Beetlebrox]

Thanks. saved me some experimenting. If I get one working I'll post a pic.

[sceincedude11]

were do you get meth

[somebody12345]

From a drug convention! (just kidding)

[franklinonline]

ask the police and youl be in jail because they think you mean methathetimene

[Kiteman]

Meths is used to clean paintbrushes, so try a DIY store, and as a fuel for small stoves, so try a camping store.

You'll be more likely to get it if you use its full name, methylated spirits or denatured alcohol.

Many shops will refuse to sell it to people who appear young, or who look like they might drink it, so don't be offended if they refuse to sell it to you, just go back with a responsible adult to ask nicely and explain it's for a science project.

[the_mad_man]

I've never seen purple metho before. the only metho I've ever seen is clear

[Kiteman]

In the UK, the purple is to show it is undrinkable.

[the_mad_man]

makes sense, i think petrol is purple as well

[Kiteman]

Apparently, petrol is actually yellowy-brown, but I have seen kites sold as "petrol" coloured that are actually a shade of purple.

[the_mad_man]

confusing

[mgfsniper]

How much Methylated spirits do you add to the jar???

[mmv5004]

Since you are only burning the vapors that escape from the hole, all you need is enough to coat the sides; then you can dump the rest out.

[Kiteman]

That will only give a short run - try a couple of spoons-full.

[Kiteman]

I didn't measure it - about half an inch deep?

[mgfsniper]

ok thanks

[yamahayzfr1extreme]

cant we make it move???? i mean add tiers and place the bottle horizontally so that it moves in front...................

[mmv5004]

You can do this trick with plastic bottles too. Anything from little 500ml bottles up to 5 gallon water cooler bottles. They are much lighter so if you lay them on their side they can really get moving, but if you stand them up the heat will eventually melt them.
I had a chemistry teacher back in high school who used to do this a bunch; I should write an instructable building on this...

[Kiteman]

Feel free to try!

[firepup104]

Whats fun is putting a ton of fuse and firecrackers in a jar then lighting it off

[iac]

I F***ing love church bells going of in the background !'
Not quite Hallaluya (sp?), but it'll do..

[cowscankill]

is there anything else besides meth you could use? and whatis meth? that illegil drug in america?

[Hightechk]

Lol I thought the same thing

[Pink_wolfie]

¬_¬ Metholated Spirits, not Methadone...

[Kiteman]

Methylated spirits (check wikipedia).

Basically it's alcohol, so you could try any easily-vapourised flammable substance. Maybe acetone? pulse jets with a fuel-feed system can use just about any flammable liquid, even vegetable oil.

[juanjomf]

In Uruguay is blue alcohol.
are sold in gas stations where gasoline throw your car if you have questions.

[NachoMahma]

. Is that the same stuff we call Denatured Alcohol here in the Colonies? I think it's mainly ethyl alcohol (ethanol) with some methyl alcohol (methanol) mixed in to make you go blind if you drink it.

[lukeyj15]

Methlyated spirits is an undrinkable alcohol. So denatured alcohol will work as will anything with an alcohol content of 70+% or so.

[Kiteman]

Yes. I understand that there is a brand of de-icer in the states that is almost pure denatured alcohol. Heet? The colour may be important - one colour is denatured alcohol, the other is as flammable as water.

[caarntedd]

Our's is clear down here. I've tried to drink it out of curiosity (wondered what it tasted like). Not good. I knew it was harmful, but a figured a sip wouldn't kill me. I just had to know. It's a bit like putting a tea pot cosy on your head. Eventually, when you think no one is watching, you just have to try it on.