Owain wrote:
"Christian McArdle" wrote
| I've got a New World Royale 600 gas cooker with a self-lighting
| oven - you turn the gas on and the sparker clicks away until
| the oven lights.
| First, how's it do that then?
| Hardly rocket science.

Presumably there must be a similar mechanism on rockets to ignite them? I
can't see NASA sending out for some two-furra-pound gas lighters every time
they want to do a launch.

It varies.
For example, the solid rockets on the shuttle are ignited by a small rocket
motor
mounted in the top.
This is lit by a small pyrotechnic device.
When it lights, it fills the chamber of the rocket with hot pressurised
gas, and rapidly lights off the main engine.

The main engines do almost use gas-lighters.
They are basically really big spark plugs, hooked up to a high power
ignition system.