I noticed in an article on this site that engineers were seeking a safety waiver for unburned hydrogen in the event of a pad abort. They site that the reason for the waiver is that in the event of a pad abort where the SSMEs are shut down before SRB ignition, then the 3 or 4 pyrotechnic burnoff igniters may have already burned out before igniting post shutdown hydrogen plumes coming from the engine bells.
Why not simply install a second or third set of igniters to provide exended burnoff coverage. If they burn for 8 seconds each, then simply installing two more sets of three and igniting them in sequence will give a much longer coverage time. Surely they are far, far cheaper and safer than pad fire and explosion?
IIRC the waiver is only for this flight. There may be a change to the igniter system already in work for future flights.
What do they use to make the sparks?
I see. It reminds me though of the sparklers you get in a fireworks shop. Is that what is used, but in a larger scale, I mean the same material?
