The Turbocraft U-22 Turbo-Jet was an interesting little idea cooked up by a US company several decades ago.
Although it looked really impressive and rather cute, there are no recorded instances of the engine actually running.
Indeed, one only has to look at the array of tiny combustion chambers seemingly made from old soda-siphon CO2 cartridges to realize that this engine was built for one thing only -- to look good.
It was advertised extensively in such publications as Popular Mechanics and Popular Science, and had a price tag of $189.50. That's one expensive paper-weight but I guess it would make a lovely lamp-stand.
The compressor section (pictured at left) appears to be a very simple and crude radial (centrifugal) unit with incredibly thick vanes and no real difuser as such.
Note also that each of the tiny combustion chambers has its own glowplug for ignition purposes and that the airflow from the compressor to these chambers must be incredibly turbulent due to the sharp angles involved.
Even crazier was the use of a spraybar in front of the compressor where
the air and fuel were mixed prior to being compressed!
Although this particular example has a discolored tailpipe which indicates that it has at least got hot, the lesser and uneven discoloration of the combustion chambers clearly indicates that it didn't run "as advertised."
The last one of these I saw sold on eBay for over $400 so they probably have quite a significant appeal to collectors.
If anyone has ever seen one of these engines run or has any more information on their manufacturer or distributors then please let me know