These times depend on intermediate details.
Such as, what are the flowpaths of each propellant? Short/long, is one regen
cooling something? What are the action times of the valves, including
statistical distributions and slight stick behavior etc.
Worst case: the LOX is regen cooling, its valve gets a bit inconsistently
sticky due to cryo behavior and takes a bit of time to operate nominally
anyways, no regen cooling channel precooling (so some boiloff will happen), etc.
George William Herbert
Sent from my iPhone
On Aug 1, 2016, at 10:14 PM, Kristin Travis <theeblueorchid@xxxxxxxxx> wrote:
Hello,
I'm working on the Portland State Aerospace Society liquid fuel engine and
I'm wondering about the ignition sequence for main valve timing.
It's a LOX/ethanol pressure fed system. We have a LOX centered pintle
injector and we plan to use a GOX/ethanol spark torch igniter similar to
Robert Watzlavick's design. http://watzlavick.com/robert/rocket/
At the injector, I've heard we need to lead with LOX so that fuel can't pool
in the engine and create a hard start. I've been digging in the archive and
online and I can't find specifics.
Does anyone have thoughts about how much time should elapse between stages of
the ignition sequence? Specifically how much time should pass between
injecting the LOX and the ethanol into the combustion chamber?
Would this be the correct sequence?
close fuel vent
close lox vent
open nitrogen valve
start igniter spark
open GOX igniter valve
open fuel igniter valve
check igniter pressure
open main LOX valve
open main Ethanol valve
Thank you,
Kristin Travis
