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SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

latimes.com

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Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#81

Post by delecti »

vkou wrote: post #48

This is one of the reasons why space travel will never be 'routine'. A million and one things can go wrong, and any one of them can destroy the spacecraft. Compare that to commercial air travel - where a number of unlikely events have to happen, to down an airplane. Some time ago, there was a HN discussion about traveling from continent to continent in minutes, using a sub-orbital hop. I don't know about anyone else,…

One big flaw in your argument is that the payload was delivered safely and successfully. They're making great strides towards making components reusable when they never really were before. That they're not perfect right out of the gate isn't reason to give up hope it ever could be.

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#82

Post by tuna-piano »

std_throwaway wrote: post #19

I bet it didn't randomly lack fluid due to some stupid miscalculation. It's probably more like: "Due to unforeseen circumstances it needed more fluid than expected. But we adjust our numbers and next time we expect more (in the hopes that it will be enough, which it will probably be)."

Two big aerospace companies ran out of fluid recently. Southwest airlines cancelled basically all their flights from Chicago yesterday because they ran out of Deicing fluid. They can use your same excuse! Something tells me Southwest failed at a much easier task, though.

"Southwest has 'multiple glycol deliveries' scheduled for Monday and expects to resume 'close to normal operations' at Midway, she said."

https://www.usatoday.com/story/news/2018/02/11/de-icing-flui...

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#84

Post by Someone »

ashleyn wrote: post #17

Perhaps some rocket scientist can explain why this seemingly-obvious error even happened? Shouldn't it be possible to calculate the precise amount of fuel used, and therefore required?

I’m not a rocket scientist, but the Navier-Stokes equations are nasty; the best we can do is model what happens, assuming that we can exactly predict what will happen, which we can’t. Temperature, pressure and humidity of the air the rockets will fall through will not be exactly known, and all will affect how the rocket moves.

And even the best of modeling will not guarantee that reality will behave as predicted. Suspension bridges, for example, often need some ‘tuning’ to remove resonance after construction.

Bridge engineers, knowing that, often won’t even try to spend time and money to exactly predict bridge behavior. This may be similar: they may just have thought it would be faster or easier, maybe even cheaper to do the experiment than to work on exactly modeling their engine.

(The center engine is different from the others, but it also could just be statistics, with the amount they used giving a probability slightly below 1 of igniting one of these engines, and this being their unlucky day (given that they already have quite a bit of data from earlier launches, that is not too likely, but it is something I would let an engineer look at)

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#86

Post by JshWright »

ashleyn wrote: post #17

Perhaps some rocket scientist can explain why this seemingly-obvious error even happened? Shouldn't it be possible to calculate the precise amount of fuel used, and therefore required?

It's not "fuel" in this case, it's the highly reactive compounds that are used to ignite the engines (TEA/TEB are pyrophoric, so they ignite spontaneously when exposed to air).

The precise amount they'll need depends on how quickly and reliably the engines restart. If the engines take a couple extra shots to light, then you may run out.

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#87

Post by vermontdevil »

rwmj wrote: post #20
huhtenberg wrote: post #3

Has anyone seen any updates on how their fairing recovery attempt went? They had the ship done and seemingly ready back in December - https://imgur.com/gallery/MQcEE

Isn't the fairing just a simple pair of metal casings. Why bother to recover it?

About $5 million and long production time.

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#88

Post by JshWright »

tuna-piano wrote: post #82
std_throwaway wrote: post #19

I bet it didn't randomly lack fluid due to some stupid miscalculation. It's probably more like: "Due to unforeseen circumstances it needed more fluid than expected. But we adjust our numbers and next time we expect more (in the hopes that it will be enough, which it will probably be)."

Two big aerospace companies ran out of fluid recently. Southwest airlines cancelled basically all their flights from Chicago yesterday because they ran out of Deicing fluid. They can use your same excuse! Something tells me Southwest failed at a much easier task, though. "Southwest has 'multiple glycol deliveries' scheduled for Monday and expects to resume 'close to normal operations' at Midway, she said." https://ww…

Interesting, I would have assumed that was a service they just paid the airport for, rather than one the airline handles itself.

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#89

Post by mikeytown2 »

meteor333 wrote: post #61
mikeytown2 wrote: post #54

Earlier quoted context omitted.

Titanium grid fins is a big reason they recovered the 2 side boosters. This launch and landing will be used to fine tune their simulation parameters. The block 5 variant is designed for 10 launches in a row with 24hr turnaround. With service, over 100 launches is the goal.

Wow! that's impressive!

SpaceX has a fairly large collection of graphics cards for simulation purposes see https://www.youtube.com/watch?v=vYA0f6R5KAI and https://www.youtube.com/watch?v=xNqs_S-zEBY

Re: SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines

#90

Post by mkempe »

dogma1138 wrote: post #69
toufka wrote: post #50

Earlier quoted context omitted.

I think they cost on the order of magnitude of $1M each. As I've heard it been put - "Imagine if there was a pallet of $1M in cash falling from the sky. And you knew where and when it would fall. And you'd expect the rate of 'cashfall' to increase to tens, even hundreds of times a year. Would you try to develop a system to catch it?"

Only if the total operational cost of that system would be lower than the amount of cash falling from the sky.

The profit equation is a little bit more complex. Consider that recovered fairings would be used multiple times, not just once each; and the long time to manufacture each new one adds an unwanted scheduling delay.
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