These two relatively simple turbocharger derived turbojets were the first two successful turbine engines that I designee and built. They both ran relatively well. At the time, the idea to making a turbojet from a turbocharger core was totally new and unique. I learned a lot from the development of these two engines. Both engines were small and produced only about 10-15 lbs of thrust.
Both engines used centrifugal compressors, single external can combustion chambers, annular inflow turbines, and compressed air impingement starting.
The first engine used low pressure fuel vaporizer tubes (40 psi diesel) and a total loss lubrication system. The second engine incorporated high pressure fuel injection (kerosene) and a semi-recirculating oil system. The biggest lessons that I learned were in cold starting sequence and fuel pressure variations from compressor back pressure.