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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

#141

Post by ridgeguy »

boznz wrote: post #136
rwmj wrote: post #20

Earlier quoted context omitted.

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

Wonder why they dont just leave them in space, could make a good chassis or building block for building bigger space stations

The fairing doesn't get carried to orbit. It's dumped as soon as aerodynamic loads are negligible.

Since the fairing has the same energy requirement as the payload (in energy/kg), it's important to get rid of it the moment it's unnecessary. If they took it to orbit (so they could leave in space), it would drastically cut down payload mass.

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

#142

Post by JshWright »

jacquesm wrote: post #130
JshWright wrote: post #86

Earlier quoted context omitted.

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.

In this case they ran out because they were relighting three times as many engines.

No, they have used this profile several times in the past. The past couple droneship landing have used three engines for the landing burn (the outer engines shut down before landing).

The recent "stage that lived" was testing three engines all the way to "0" (which worked fine, apparently).

My guess is the hotter than normal reentry meant the engines were a bit tougher to relight, and they burned through more starter loads than they expected.

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

#143

Post by dingo_bat »

jacquesm wrote: post #130
JshWright wrote: post #86

Earlier quoted context omitted.

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.

In this case they ran out because they were relighting three times as many engines.

But didn't put in 3 times as much fuel? Seems like a simple oversight.

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

#144

Post by ceejayoz »

vkou wrote: post #129
mulmen wrote: post #91

Earlier quoted context omitted.

An airliner is on a building scale and carries a slightly less refined petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets only carry LOX because they go into space where there is no atmospheric oxygen to burn the fuel. Airliners are fully capable of turning themselves into fireballs. It doesn't happen often because we have a lot of experience operating them. The same safety levels are possibl…

> An airliner is on a building scale and carries a slightly less refined petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets only carry LOX because they go into space where there is no atmospheric oxygen to burn the fuel. That's true, but a 747 does not burn its weight in fuel in 397 seconds. A Falcon 9 does. It's the difference between igniting a gas barbecue in your back yard, and igniting t…

> There is no one thing that can go wrong on a 747 that will down the aircraft.

C'mon, that's demonstrably false.

https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981 involved a poorly sealing latch.

https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123 involved a single poorly repaired bulkhead.

https://en.wikipedia.org/wiki/TWA_Flight_800 may have been a spark in the fuel tank.

Plenty of other examples on https://en.wikipedia.org/wiki/Category:Airliner_accidents_an...

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

#146

Post by MertsA »

Stratoscope wrote: post #118
quadyeast wrote: post #39

Is that also why the video feed was not working? SpaceX commentators said it was possibly due to vibration.

The video feed didn't stop working, or if it did, it was only for a brief moment. If you watch this part of the YouTube stream, after it cuts back to the two hosts there is a monitor at the far right center of the video that shows the continuing camera feed of the drone ship landing pad. Only part of the monitor is visible, but after the smoke clears over the next few minutes you can see the empty pad: https://www.yo…

The aftermath of this was the most confusing thing ever. In the screen in the background that they forgot about, right when the smoke clears the crowd started cheering. We also could only see the left half of the barge. It certainly left everyone wondering until the official confirmation.

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

#147

Post by jacquesm »

JshWright wrote: post #142
jacquesm wrote: post #130

Earlier quoted context omitted.

In this case they ran out because they were relighting three times as many engines.

No, they have used this profile several times in the past. The past couple droneship landing have used three engines for the landing burn (the outer engines shut down before landing). The recent "stage that lived" was testing three engines all the way to "0" (which worked fine, apparently). My guess is the hotter than normal reentry meant the engines were a bit tougher to relight, and they burned through more starter…

Hm, I thought they were doing 1-1-3 in previous situations and 3-3-3 in this one?

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

#148

Post by [deleted] »

jacquesm wrote: post #147
JshWright wrote: post #142

Earlier quoted context omitted.

No, they have used this profile several times in the past. The past couple droneship landing have used three engines for the landing burn (the outer engines shut down before landing). The recent "stage that lived" was testing three engines all the way to "0" (which worked fine, apparently). My guess is the hotter than normal reentry meant the engines were a bit tougher to relight, and they burned through more starter…

Hm, I thought they were doing 1-1-3 in previous situations and 3-3-3 in this one?

[deleted]

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

#149

Post by JshWright »

jacquesm wrote: post #147
JshWright wrote: post #142

Earlier quoted context omitted.

No, they have used this profile several times in the past. The past couple droneship landing have used three engines for the landing burn (the outer engines shut down before landing). The recent "stage that lived" was testing three engines all the way to "0" (which worked fine, apparently). My guess is the hotter than normal reentry meant the engines were a bit tougher to relight, and they burned through more starter…

Hm, I thought they were doing 1-1-3 in previous situations and 3-3-3 in this one?

I'm not sure what your sequences mean there, almost every boostback and re-entry burn has used three engines (they always light the center engine first, then the outer two).

Most recent droneship landings recently have used three engines for the 'middle' part of the burn, shutting down the other two before actually landing.

The recent GovSat launch tested a three engine burn all the way down (the first time they have tried that, AFAIK).

There was nothing unusual about the number of relights. My guess is the issue was with the difficulty of the relights.

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

#150

Post by jacquesm »

JshWright wrote: post #149
jacquesm wrote: post #147

Earlier quoted context omitted.

Hm, I thought they were doing 1-1-3 in previous situations and 3-3-3 in this one?

I'm not sure what your sequences mean there, almost every boostback and re-entry burn has used three engines (they always light the center engine first, then the outer two). Most recent droneship landings recently have used three engines for the 'middle' part of the burn, shutting down the other two before actually landing. The recent GovSat launch tested a three engine burn all the way down (the first time they have…

Ah, I thought the outer two were optional and not always used for every landing. Ok, thank you for correcting that.
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