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SpaceX's Falcon Heavy Center Booster Lacked Ignition Fluid To Light Engines and Land On Platform (latimes.com)
An anonymous reader quotes a report from Los Angeles Times: The center core booster of SpaceX's Falcon Heavy didn't land on a floating sea platform as intended during last week's first test flight because it ran out of ignition fluid, company Chief Executive Elon Musk said Monday. Musk took to Twitter on Monday morning to give a few more updates on the Falcon Heavy's first flight. After liftoff, the rocket's two side boosters touched down simultaneously on land, eliciting cheers and applause from the crowd of SpaceX employees gathered in the company's Hawthorne headquarters, as seen on the launch livestream. Those two boosters, which were used in previous launches of SpaceX's workhorse Falcon 9 rocket, will not be reused again, Musk said in a post-launch news conference last week. But the center core booster ended up hitting the Atlantic Ocean at 300 mph and about 328 feet from the floating platform where it was supposed to land. Musk said Monday that there wasn't enough ignition fluid to light the outer two engines of the booster "after several three engine relights."
Not sure the point you are trying to make here... It was a test flight. The first time they have had to slow down a booster from this sort of burn, with the longest set of three engine burns so far.
Turns out the current build doesn't have enough igniter fluid. But they captured that data, and can now correct for it.
It is exactly the same thing that happened with the early test landings of the Falcon 9 boosters, where they weren't sure how much hydraulic fluid they would need. Now they know, and now they land the Falcon 9 boosters with an incredible success rate.
They can't just calculate exactly how much they need of these things, because the atmosphere adds a highly dynamic variable. They can take a very educated guess, but as the landing is automated and corrects for a wide variety of conditions, this is one of those "we have to do it to see... and we might not even get it right the second... or third... or fourth time."
FFS, America, USE METRIC !
The ignition fluid in question is TEA-TEB https://en.wikipedia.org/wiki/Triethylborane#Rocket, a mixture of triethylborane and triethylaluminium. This is a common ignition fluid for rockets which burn RP-1 (rocket grade kerosene), since RP-1 is hard to ignite. The two are mixed because one of the two has really dependable ignition while the other one burns more cleanly. This sort of ignition system has been in use since the 1960s, but SpaceX is the first to use the TEA-TEB ignition system to ignite a rocket engine while the rocket engine is moving quickly *downwards* into the atmosphere. Experiments will sometimes work, and sometimes won't. They are obviously figuring out just how much TEA-TEB they need.
To save people video watching:
In the post-flight press conference, Musk said that the titanium grid fins are hard to manufacture and expensive and they currently don't have many, so he was very pleased to get these ones back. Also, the titanium grid fins are larger, and the side boosters need the bigger fins because the nose cone (rather than blunt end) reduces the effectiveness of the fins.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
The payload went into the wrong orbit. Don't forget that.
A fabulous, deep, funny book on rocket fuels and the crazed chemists that developed them is called "Ignition!", by John D. Clark and forward by Isaac Asimov. Example text:
"Recommended lab attire for working with this volatile compound: Running shoes."
Ignition! has been long out of print. Thankfully archive.org has a copy here: https://archive.org/details/ig...
The target orbit was one that went at least to Mars orbit. There were no requirements that it only go to Mars orbit. They burned to depletion to demonstrate the amount of second stage performance available after a 6 hour coast (that being a requirement of some defense launches).
Sure, but this is a TEST flight, so I would argue that it's more important to start with a smaller payload. That way you can work down from safe to probably safe and have less risk of losing the test vehicles.
Well, it's less risk to the test vehicle but the more your final configuration deviates from the current configuration the higher the risk of some unexpected side effects. When you can count the number of tests on one hand with fingers to spare it's better to fail on the first test and say that's what tests are for than fail on the second test and raise concerns that it has hidden flaws that might kill missions at random. Despite all that Elon Musk said to manage expectations they did not send a $100 million dollar rocket out there to blow up an equally expensive pad on a 50-50 or 2/3rds chance. They've extensively tested every component and subsystem they could find, simulated it a million times with computers and it would have passed with flying colors.
This is the final integration test, not the first test. The rest is that X factor, what haven't we taken into consideration. Are our assumptions, models and formulas flawed in some way. He can't really lose talking it down, if it blows up on the pad well space is hard. If it works, he's pulled off some amazing feat. So I'd want something very close to the production model flying, as long as the odds remain good you'll get your test data. And in that respect this was an entirely insignificant failure, they got telemetry on everything right up to the final impact. Making this part of the mission fail-safe wouldn't really have any big benefit. Just downsides in redesign, if this was what they thought was the right amount.
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