"Bob Martin" wrote in message ...

The highest chemical engine Isp I've seen is about 520-530... it was done
using a three-propellant engine (of which one propellant was fluorine).

I'm familiar with the high Isp tri-propellant engines (and their
problems), but I was particularly curious about how far current,
favored fuels (specifically hydrogen-oxygen) could be pushed.

Mike Miller, Materials Engineer