in 1992 the book "Strahlturbine fur flugmodelle I'm Selbstbau" by Kurt Schrekling came out, I absolutely HAD to build that engine, I didn't know a word of German, I didn't have any machine tools, but I simply HAD to.
after a year or two of researching bench-top machine tools, reading text books on turbine theory, and even visiting the Garrett / AirResearch Turbo Charger factory down in L.A. (they were kind enough to share some compressor performance maps / graphs), I started machining, and it was another year or two of "wall parts", but it did become a working engine, ran a couple times in my backyard and once at a BAEM Club meeting (there are still a couple members old enough to remember the event). I am in the process of building a new (good looking this time around) engine mount and display board/box and might even try running it again at another GGLS/BAEM meeting or open house.
and I really need to make another tail cone, in addition to heat discoloration (which will happen either way) it is a cosmetic disaster, I made this one by "metal spinning" except I didn't use a ball-bearing I used metal-on-metal and Yikes! Yeuk! Yeouch! :-( !!!
next up, a second engine based on a Borg-Warner EFR turbocharger, CNC machined from bar stock compressor rotor, cast Titanium-Aluminide turbine rotor (very light weight compared to Inconel), and ball-bearing shaft and housing. With a radial-inflow turbine it should allow a higher compression ratio than the axial flow type in existing RC airplane turbines which should translate to higher fuel efficiency. Whose with me on this, anyone ? !!!
engine number three would be the Holy Grail of turbine builders, a co-axial turbo-fan, but that seems to be a pipe dream, compressor and turbine rotors would need to be designed from the start to be large enough for the fan shaft to pass through, as that's not something you can do starting from a part that was designed for minimum size and mass, and while a 5-axis CNC machined from bar stock compressor rotor is theoretically within the grasp of a home shop machinist, a custom Titanium-Aluminide turbine rotor is simply impossible. But the pipe dream still dreams on
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