Man, that never gets old.
Falcon Heavy - two months and counting.
Anyone willing to place a bet in Vegas about the Heavy launch actually happening before the New Year?
Is there a market for all of these used Falcon 9 boosters or are they just accumulating?
I was once standing at attention at a change of command ceremony where those directly involved in marching around during the process were marching to that tune. I had a hard time keeping a straight face, wondered how many others were having the same problem, and wondered if the music choice was made by someone who knew the somewhat inside joke. The difficulty of keeping a straight face wasn't reduced by the fact that those few involved in the marching were of significantly different heights which required the step size of the shorties to be unusually large and slightly comical.I saw the video with compilations of crashes on Elon Musk's Instagram feed this morning, "How NOT to land an orbital rocket booster". Backed with the music that Monty Python used as their theme, and with a few witty captions, it showed quite a few explosions. It seems like it ended on Instagram before the video was actually over so I'm hoping it's available elsewhere soon.
I've got the book from Apogee about the Saturn V. It goes into great detail (almost millisecond-by-millisecond) of the startup and operation of each engine and stage. Is there something similar for the Falcon/Merlin? How do the generate ullage for the returning first stage? It's in freefall for a lot of the time. Are they using the cold gas rockets for this? I'd really like detailed step-by-step details on the start/restart of the engines, too.
BTW, The Liberty Bell March is one of my favorite pieces of music. In spite of Monty Python's use, it is patriotic music rather than comedic.
Unlikely there will ever be such a document. Pretty much all rocket technology is now governed by ITAR regulations that make it very difficult to publish detailed technical info. Also a lot of what SpaceX does is protected as a trade secret rather than with patents. If you patent something you have to publish it. That makes it available to foreign governments who don't always respect US patents and have a large vested interest in competing with a company like SpaceX. So they go to great lengths to keep it proprietary.I've got the book from Apogee about the Saturn V. It goes into great detail (almost millisecond-by-millisecond) of the startup and operation of each engine and stage. Is there something similar for the Falcon/Merlin? How do the generate ullage for the returning first stage? It's in freefall for a lot of the time. Are they using the cold gas rockets for this? I'd really like detailed step-by-step details on the start/restart of the engines, too...
Unfortunately, the only time I'd heard it before that change of command ceremony and even since was on Monty Python, so it was and will forever be comedic to me. Had they played Stars and Stripes Forever, different story.BTW, The Liberty Bell March is one of my favorite pieces of music. In spite of Monty Python's use, it is patriotic music rather than comedic.
They get "ullage" after the RCS thrusters rotate it around to prepare for the BoostBack burn.
Once the tail is facing more into the airflow (direction of coast), then the fuel settles into the bottom of the tanks. Because while it is up 65-75 km at staging (depending on payload and planned trajectory), I think there is enough thin air to cause some air drag to decelerate it. If not, then they could have some RCS thruster nozzles pointed "down" to provide ullage. Or even some internal fuel line trickery to hold a bit of fuel and oxidizer for the center engine, enough for start-up, but that begins to seem a bit Rube Goldberg-ish if it could not be done simply.
Yes, I don't know every detail on a Falcon-9. Not that SpaceX releases that much. But some are obsessed over every inch of the surface that's visible.... even if WHAT some things they see are known for a fact to be something specific or are popularly speculated to be such-and-such.
I suspect that when they begin the BoostBack burns, that they ignite the center engine first, as they definitely do for re-entry burns and the risky "hot re-entry" 3 engine landing burns. So the gimbaled thrust of the center engine not only steers it, but corrects when the outer 2 start to ignite (and shut down) since they may not do so evenly. If the center engine "burped" during the ignition process due to ullage issues, I do not know if that would risk damage to it (presumably at lowest throttle, around 40%). And it also uses TEA and TEB to begin reignition, which MAY work with gaseous oxygen if the % of gaseous oxygen is sufficient (by then though most of the gas is helium to keep the tanks pressurized). Otherwise, if the center engine would be OK after a burp, then its thrust would ensure ullage for itself and the outer 2 engines to ignite.
In any case, ullage is one of the biggest problems they had to solve for doing boostback burns. To get that booster flipped around so fast, fuel sloshing like crazy, yet making sure the center engine isn't starved of fuel as it ignites as the booster is STILL rotating in pitch.
And for the re-entry burns and landing burns, air drag while pointing engines-down definitely providing plenty of "ullage"
Now targeting October 11 for the launch of EchoStar 105/SES-11 from Pad 39A in Florida.
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