You could buy some second hand hot-air ballon propane burner assemblies which are designed to do exactly this (shoot a jet of flame) using a pilot light that won't go out (and is also re-ignitable from a piezo spark ignitor.

The down side is that they consume around 20l of propane per minute and have extremely high BTU ratings - expensive audience burns, anyone?
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One of the few remaining Mk1 owners... #00015