are you referring to firefly alpha?
m.
Am 02.09.2015 um 20:43 schrieb Ben Brockert:
One of the challenges of multi-chamber aerospikes or other
multi-chamber thruster architectures (like OTRAG) is that if you don't
have every chamber lit when propellant flows into it, an unlit chamber
will hard start when the propellant is lit externally by an adjacent
chamber. If it's built to flight weight, that will destroy the chamber
and likely anything next to it. This has happened on at least one
project here.
So the ignition system in all of the chambers needs to be both very
vigorous and well-interlocked. If it's something like an air-launched
aerospike where you might want to keep trying to launch even if all
the chambers don't come online, then you also need individual
per-chamber propellant isolation valves.
On the other hand, setting off a full chamber of gas-gas even at
stochio inside a liquid thrust chamber will generally do no damage, as
the total mass of propellant is much lower.
So with the addition of a bit more plumbing and a second valve set,
you could start a multi-chamber engine off gas-gas pulled off ullage
in an autogenous or self-pressurized propellant combination, run it
just long enough that any slow chambers will ignite off nearby
chambers, then pop open the main liquid propellant valves.
Probably something no one will ever use, but it came to mind and AR
has been quiet lately.
Ben
