Unfortunately, I don't have the money or time to devote to making a jet at home, but I can give you all some important knowledge that you can apply to any engine you design! This instructable will hopefully teach you how to design your own jet engine! Lets begin with the very basics. I know, I know... I'll try to be quick :)
Oh and WARNING: building and operating a jet engine comes with many hazards. You risk it exploding, loss of hearing, etc. Be careful please! The guidance I give you here isn't everything either. It is advanced basics, but basic never-the-less. I don't take responsibility for anyone's actions based on this instructable.
Phew... enough of that... come on, lets peel this onion!
Step 1: Compress Your Air!
The MOST FUNDAMENTAL way to increase pressure is to form a DIVERGENT duct for air to pass through. A divergent duct starts out with a small opening at the front aka inlet and a larger opening at the outlet aka exhaust. This shape of duct will slow the air velocity down and increase the air's pressure as shown below.
There are three methods of compression that I will discuss. Each uses the divergent duct principle to compress air for combustion. These three are:
* Pulse jet
* Centrifugal compressor
* Axial flow compressor