A little after 3PM today, ET, SpaceX fired up Starship Heavy Booster 9 for a static engine firing test. This caps three days of tests, with a spin prime test on Friday and several tests of the newly-added water deluge system. As usual with these tests, while it looked largely successful, there was minimal official word from the company, except for one thing: the test was intended to light all 33 engines and burn them for five seconds but lasted 2.74 seconds as four engines shut down early.
This short video goes through several views of the test, but the water deluge
does a pretty effective job of reducing the time you can see any evidence of
the engines firing. The concrete looked completely intact after the
test and looking at the video showed no obvious chunks flying or damage to the area, but again, no official word.
SpaceX began the process of fueling the rocket early this morning but encountered an issue when chilling the lines that run to the rocket, and a red team was sent back to the pad to perform repairs. After repairs were completed, the red team departed and SpaceX spooled up their fuel tank farm again.
After a couple of hours of chilling the fuel lines, filling of the liquid oxygen and liquid methane tanks aboard Booster 9 began at T-Minus 67 minutes.
If you look at the booster in the NSF video capture above you can see white frost on the booster from the bottom to around halfway up, then a gap followed by a much narrower band of frost. The bottom section of frost is telling us the liquid oxygen tank is nearly full, while the narrow band at the top is showing the amount of liquid methane in the tank.
An unusual aspect of this test is that SpaceX put up a notice on YouTube that they were counting down to a 2:08 Central time test and covered the test live, as if it were a regular mission. Except for not having a script like they read while going through the mission. It was quiet when there was nothing to be said. Video here.
Having four engines shutdown within a couple of seconds of starting is unsettling to me, but with no information on what the engines were (all "latest and greatest" or just a hodgepodge?) or details on why they shut down, I'll reserve judgement. Losing four Raptor 2 or 3 engines would knock around two million pounds of thrust off the available amount and might doom a full mission. On the other hand, with their philosophy of test, fix, test again, there's really no such thing as failing one of these tests, as long as they learn enough to fix whatever happened. At some point, they need to get 33 good engines on a booster and I think that time is approaching.
Well, for one thing, SiG, this *is* a test facility, and lotsa bugs need to be worked out.
ReplyDeleteWe don't know engine parameters, or the reasons for the shutdowns, but that's what telemetry is all about. They (SpaceX) will reveal what they want to, but they DID say the test was "successful" and hte Booster Bidet seems to be working. You are going to be seeing these tests over and over again until they get it right and all the wrinkles are fixed or eliminated.
Kudos on a successful 29-engine test so far.
Here's hoping they get the engine shutdowns figured out.
ReplyDeleteThere was no rapid unscheduled disassembly, so all is good! It is much easier to analyze the data when everything stays intact.
ReplyDelete29 engines was enough flame and oomph to test the deluge plate thingymabob. Good on them. After-action analysis will be interesting to see what was a success, what was mostly good, what went wrong and what needs to be changed. Will also be interesting to see how much of the new paint went away.
ReplyDeleteAnd, yes, oops on 4 engines, but still, more engines than, you know, BO...
One wonders if the water spray was enough to make ice in some of the engine nozzles before ignition.
ReplyDeleteHmmm. I think the water turns on four seconds before ignition, and doesn't reach full pressure for "a while." At some point, the engines are doing that spinning up they emulate in the spin prime test. Complex situation. I'm not sure the water could get there and the engines still start.
DeleteThe showerheads in the middle are aimed outward, precluding any "water up the schnozz". That's why it spews outward so much. As for "ice"? Not hardly.
DeleteMusk did say once that they could make it to orbit with as many as seven engines out. There is margin and redundancy built into the design. Of course, they will figure out why and fix this issue.
ReplyDeleteAs everyone said, above, it was a successful test in a rapid, wide-reaching test program. Everything is telemetered to Hell and back. The data will be analyzed, conclusions will be reached, things will be changed, and we'll be back at it in no time.
Musk did say once that they could make it to orbit with as many as seven engines out.
DeleteThey could make it to orbit with as many as seven engines out during an empty test flight . Having 26 of 33 engines running is close to 80% - so they lose 20% of their liftoff thrust. Is that normal for a rocket? I think they don't typically have that much margin.
Hit the button too soon.
DeleteYes, I know it's a test and expect they'll get better. In the "Click Bait Universe" of YouTube, I'm tired of people bad-mouthing the Raptors for being unreliable as if it condemns the entire program. They're a remarkable engine, but at the moment they aren't as good as they need to be.
Seriously, as a hypothetical exercise in physics, just how many cow farts are are contained in the methanes tank to run 33 Raptors in a full up orbital Starship launch?
ReplyDeleteEasy to calculate IF you know the volume and density of methane in the average cow fart. I'm *sure* the data is lying around the Interwebbies SOMEwhere.
DeleteSeriously, why bother? EPA might get nervous, or sumptin'.
They did this on NASA Spaceflight during the coverage leading up to the test. Someone went off the microphones for a while and came back with some number I honestly don't remember, but I think he said a year of farting all day. 24/7/365.
DeleteI honestly thought Anonymous' point was to bring up that story.
And it's not cow farts that produce the methane expulsion from cows. It's the first two stomach chambers that start processing the feed, so it's cow burps. Just more spectacular to say 'fart' than 'burp' or 'belch.'
DeleteWell, in this day of Common Core, cow farts can be a unit of measure.
Delete29 engines, is that like herding cats?
ReplyDeleteWhat's the probability of all 29 working as intended, precisely, for the full duration?
Or, (reference to Fractured Flickers)
What dummies they were in the Apollo program to use only one engine first stage.
I know, more than one. But you get the gist.
Delete