Made all those changes, what do people think?
Quote from: Colds7ream on 01/16/2012 03:29 pmMade all those changes, what do people think?I'm still picking my jaw off the ground from Wayne Hales response, there was an article? I also vote for drafting Wayne Hale to clean up Wikipedia!
There are still some grammar mistakes: "entered the orbiter at the an umbilical disconnect" -> "entered the orbiter at the umbilical disconnects" for one. Otherwise its quite good.
From the article..."In addition, an oxidizer post, which had been intentionally plugged, came loose inside an engine's main injector and impacted the engine nozzle inner surface rupturing a hydrogen cooling line allowing a leak and resulting in a premature engine shutdown due to increased propellant consumption."
QuoteFrom the article..."In addition, an oxidizer post, which had been intentionally plugged, came loose inside an engine's main injector and impacted the engine nozzle inner surface rupturing a hydrogen cooling line allowing a leak and resulting in a premature engine shutdown due to increased propellant consumption."Actually, a 0.1" diameter, 1" long gold-plated pin, used to plug an oxidizer post orifice was what was ejected. The oxidizer post itself did not detach. Three nozzle cooling passages were breached.
Quote from: DMeader on 01/16/2012 05:01 pmQuoteFrom the article..."In addition, an oxidizer post, which had been intentionally plugged, came loose inside an engine's main injector and impacted the engine nozzle inner surface rupturing a hydrogen cooling line allowing a leak and resulting in a premature engine shutdown due to increased propellant consumption."Actually, a 0.1" diameter, 1" long gold-plated pin, used to plug an oxidizer post orifice was what was ejected. The oxidizer post itself did not detach. Three nozzle cooling passages were breached.Fixed! Thanks!
The design for the SLS features the RS-25 on its core stage, with four different versions of the rocket - Block 0, I, IA & II - being installed with varying numbers of engines (3, 4, 4-5 & 5 respectively).
"Each engine would have to undergo a flight-readiness firing (FRF) before installation (the so-called "Main Engine Test" that NASA conducted with each new orbiter and prior to STS-26)." From a quick google, it looks like Shuttle FRF was with the engines mounted in the orbiter (ie not "before installation").
Was each new-build engine from Rocketdyne not test-fired at Stennis before installation for first flight? (With the obligatory reconditioning/rebuild in between, of course.) But "FRF" might be reserved for the (6? 7?) done by the Orbiters themselves? -Alex
Quote from: alexw on 01/17/2012 05:32 am Was each new-build engine from Rocketdyne not test-fired at Stennis before installation for first flight? (With the obligatory reconditioning/rebuild in between, of course.) But "FRF" might be reserved for the (6? 7?) done by the Orbiters themselves? -AlexI swapped 'before installation' to 'before launch' - that better?
This is definitely a nit, but the nozzle and MCC were constructed differently - the description of brazed stainless steel tube wall is accurate for the nozzles, but the MCC used Narloy-Z copper alloy material and the cooling passages for the LH2 were machined slots in the Narloy-Z liner, electroplated over after machining with a copper layer jacketed by electrodeposited nickel, with the whole assembly then jacketed in a Inco 718 structural shell.
Personally, I found it fascinating that breaching a fuel line resulted in a LOX ECO (rather than a fuel ECO), and why that happened.
Thanks! I made some changes to incorporate this information, what do you think?
When there is a fuel leak, the engine recognizes that there is a drop in chamber pressure, and compensates by opening up the lox valve to return to commanded pressure. So generally a fuel leak will cause the engine to run lox rich, and hot. Also, there is always more propellant margins for fuel than for lox, because a lox rich cutoff is a bad day.
By the way, would anyone happen to know where I can find a NASA-made diagram of the throttle settings through launch (i.e. the thrust bucket) please?
Quote from: Colds7ream on 01/22/2012 08:19 amBy the way, would anyone happen to know where I can find a NASA-made diagram of the throttle settings through launch (i.e. the thrust bucket) please?Is this the kind of thing you were looking for?
Would it be allowed on Wikipedia if you reproduced that diagram with matlab, excel or other tool and quoted the above as the source?
Quote from: DMeader on 01/16/2012 05:01 pmQuoteFrom the article..."In addition, an oxidizer post, which had been intentionally plugged, came loose inside an engine's main injector and impacted the engine nozzle inner surface rupturing a hydrogen cooling line allowing a leak and resulting in a premature engine shutdown due to increased propellant consumption."Actually, a 0.1" diameter, 1" long gold-plated pin, used to plug an oxidizer post orifice was what was ejected. The oxidizer post itself did not detach. Three nozzle cooling passages were breached.Why was the plugging done in the first place? Was this method a routine procedure to fix what, exactly?
"It had become common practice to deactivate main injector LO2 posts when they were determined to be life-limited because of manufacturing or operational damage. When a post life-limit was reached, a pin was inserted in the LO2 post supply orifice that shuts off the LO2 flow through the post, reducing high-cycle fatigue loading."
I would think that closing off some of the injector orifices might lead to bad things (combustion instability for instance) but apparently, it had become fairly common practice up until that point. I imagine there is probably more information on L2.
Quote from: DMeader on 01/23/2012 04:43 pmI would think that closing off some of the injector orifices might lead to bad things (combustion instability for instance) but apparently, it had become fairly common practice up until that point. I imagine there is probably more information on L2.Combustion instability, etc was tested for. However, one of these posts did become dislodged on STS-93 and punctured one of the regen jacket lines on the nozzle.