Greetings to all! My name is Blackwidow23. I'm a 15 year old freshman from Chicago, IL.
The purpose of this post is to tell about something amazing that can be done, that I just finished doing.
I am going to tell you how I built a jet engine from auto parts, in hopes of inspiring other young people like myself to give it a go...the sound of
success is amazing.
To begin, I will go over the principals of jet engine theory and operation. If you are strapped for time, skip this part, but I strongly suggest that
you read this or unless you already know this stuff, you will become very confused.
The first jet engine was invented by Frank Whittle of England in 1933 and it was quickly patented. Simeltaniously, Hans Jorchin Von O'hain in Germany
and Gampini in Italy also had the idea, but only Germany and England have the technology to follow through. By WWII, it was being used on the first
fighters such as the German ME-262 and the English Gloster Meteor.
A jet engine operates off of an incredible theory of 6 general steps:
-Spool. A motor of some sort spins a fan.
-Suck. The fan begins to suck in air.
-Squeeze. Fans squeeze the air through a progressively smaller space, compressing it.
-Inject. Fuel, usually a refined kerosene (similar to diesel fuel) is vaporized, injected into a chamber. The compressed air also enters.
-Ignition. A high energy spark ignites the mixture of fuel and air.
-Blow. Hot gases blast out the back spinning a turbine wheel. Here is where it gets REALLY cool: The turbine and compressor are connected by a common
shaft, so the hot exaust gases power the compressor. It self sustains! Here is a good diagram:
Now on to the good stuff.
The heart of this engine is a TURBOCHARGER. It is easy to build off of because it already contains a few parts that are incredibly hard to fabricate,
the compressor and turbine wheels, already connected by a common shaft. The bigger your turbocharger, the higher potential thrust for your engine. A
Now to the part that I built. Here is a list of required parts for a turbocharger based jet engine:
Since there is no room to put a combustion chamber INSIDE the turbo itself, the combustion chamber (combustor) cant be IN the turbocharger. This means
that the first thing you should fabricate is the
This is the tube that leads from the air inlet of the turbocharger to the combustion chamber. This tube needs to be no larger in diameter than the
outlet itself, or you may loose pressure. Keep in mind that the "air half" of the turbo is aluminum and compressed air DOES heat up. This tube
should connect into the center of the combustor.
The next thing you should fabricate is the
This is BY FAR THE HARDEST PART AND IT TOOK ME FIVE TRIES TO GET RIGHT!! So do not give up WHEN it doesnt work the first time.
Your housing must be made of steel or it will melt. Not it might melt, it WILL melt. I learned THAT the hard way. It should be at least twice the
diameter of your turbocharger compressor wheel. Just a rule of thumb. Your air feed should feed directly into it.
Now...for the hardest part of the whole darn thing. The dreaded flame tube. The flame tube is a smaller tube inside the combustor housing that slows
down air into its center and allows it to enter in a controlled fashion. It needs a very specific pattern of holes in it. It will be the hottest part
of your engine. There is really no rule of thumb...its trial and error. You will have to U2U me for details on this...but a quick explanation is that
there are three zones of holes. One at one end, to allow air in to the engine for combustion. One in the middle to complete combustion, and one at the
end to dilute it with air and cool it. There area also holes all along the length of the tube to wrap the flame with a cusion of air and prevent the
fire from ever actually touching the sides of the combustor. Mine is made out of 1/4" thick steel to withstand high temperatures.
Your fuel injector should spray lenghthwise into the flame tube at one end. Fuel pump behind it.
Your spark plug should angle into the path of the fuel to light it.
These should share a common end. It doesnt REALLY matter which, but I would suggest the end thats closest to the compressor.
The flame tube must be centered inside the combustor housing, give at least a half inch of room between the two on ALL SIDES. This is to prevent the
actual housing from heating up. It needs to be sealed, so basically an inner tube centered and sealed inside a larger tube.
The next thing to do is to find a way to feed the hot gases from the flame tube into the exaust inlet back into the turbocharger. I did it like
If |||||||||| is the flame tube and it angles up out of the combustor housing into the turbo.
This is important: You need an oil pump to lubricate the bearings of the turbocharger or it will irrapairably fail. And that is REALLY REALLY BAD!! I
would give it a healthy 60PSI of oil at all times for a standard 3"/2" turbocharger. This is too much oil for the turbo but it wont damage it, you
will just have oil dripping from it all the time. I have a pan below it where all the oil drains, and than the pump just sucks from the pan
After you hook up your oil, hook up your fuel. I use kerosene because its good for jet engines, but that again I've done this before and you should
probably start with propane (no need for a fuel pump).
After all the electrical is hooked up, (spark plug, pumps, fuel injector) you need a spool. I just stick a leaf blower in the turbo inlet.
After its up to about 2000RPM, hit your fuel injector. Get it running, than turn on your fuel pump. Wait two seconds...press the spark plug button or
whatever you have to start the spark plug...and if you did everything right...you will get a loud roar...and when you turn off the spark plug...it
will self sustian!!!!! Slowly add fuel pressure...it will get louder and higher pitched. Voila, a jet engine!!!!!
I encourage you all to try this, the sound of success is OH SO SWEET!