On Fri, 22 Nov 2013, Ed Kelleher wrote: > Has TEA/TEB ignition been used before on 2nd Stage? Seems most upper > stages are hypergolic, or augmented spark type ignition. > Apparently it hasn't been used much on American launchers. More or less by historical accident, LOX/kerosene upper stages haven't been common in the West. Low-performance upper stages used hypergolics (no igniter), and high-performance ones used hydrogen (spark or torch igniters preferred). Even the LOX/kerosene first stages generally didn't have *plumbing* for their TEA/TEB igniters, just cartridges in fuel lines, because they didn't have to be restartable. The only Western LOX/kerosene upper stage I can think of is Titan I's second stage, and if that used hypergol ignition, it probably just used a hypergol cartridge, because it wasn't restartable. Henry Spencer henry@xxxxxxxxxxxxxxx (hspencer@xxxxxxxxxxxxx) (regexpguy@xxxxxxxxx)