5 ms·

At around 1:54:50, upon full landing thrust, the exhaust flames turn green. I know colored flames from chemistry classes, but I always assumed that was caused b

At around 1:54:50, upon full landing thrust, the exhaust flames turn green. I know colored flames from chemistry classes, but I always assumed that was caused by certain salts. Rocket fuel, to my knowledge, does not contain any of those ingredients. Can someone explain what happened there? Was this planned?

fabian2k 6y ago
I really don't know enough about this, but this might be "engine-rich combustion". Which would also explain why the landing part didn't work.
- luizfzs 6y ago
  "engine-rich combustion" has become my favorite expression
Diederich 6y ago
I think that was caused by the out engine trying to re-start itself using TEA-TEB. EDIT: Correction: Raptor doesn't use TEA-TEB.
rajup 6y ago
Most likely the chemical used to (re)start the engine, triethylborane (TEB) https://en.wikipedia.org/wiki/Triethylborane https://en.wikipedia.org/wiki/Triethylborane.
- handol 6y ago
  I thought the raptor was going to use a spark plug.
- NikolaeVarius 6y ago
  Which it does not use
aazaa 6y ago
Copper and boron, according to Wikipedia, will give green flame: https://en.wikipedia.org/wiki/Colored_fire https://en.wikipedia.org/wiki/Colored_fire But given the extreme conditions, a number of other factors could be at work.
deleted 6y ago
[deleted]
tw04 6y ago
I believe it was burning through the copper liner due to fuel starvation (oxygen rich which makes it SUPER hot) http://photos1.blogger.com/blogger/1613/496/1600/Merlin1C_Chamber.jpg http://photos1.blogger.com/blogger/1613/496/1600/Merlin1C_Ch... Seriously getting downvoted? That's what caused the issue.... Elon already tweeted they had low fuel pressure...
- mulmen 6y ago
  You may be right but Starship uses Raptor engines, not Merlins.
  - tw04 6y ago
    I'm aware, the picture was to show what the liner looks like (approximately), the engines are of similar design. I apologize if anyone thought that was literally the liner in question.
    - mulmen 6y ago
      Ah yeah, lots of confusion re: TEB in other comments. Seems like a lot of people have the Raptor and Merlin mixed up so at least in this context probably have to be explicit.
orost 6y ago
Copper burns green, and the engine contains a lot of copper, so I think we saw a malfunctioning Raptor burning itself up. Other answers mention TEB starter fluid but I don't think that's right, because as far as I know Raptor has spark ignition only. edit: Elon Musk just tweeted that the immediate cause of the crash was low pressure in the fuel tank, so that would make sense, as running oxygen-rich would overheat and melt the engines.

fabian2k 6y ago

I really don't know enough about this, but this might be "engine-rich combustion". Which would also explain why the landing part didn't work.

luizfzs 6y ago
"engine-rich combustion" has become my favorite expression

Diederich 6y ago

I think that was caused by the out engine trying to re-start itself using TEA-TEB. EDIT: Correction: Raptor doesn't use TEA-TEB.

rajup 6y ago

Most likely the chemical used to (re)start the engine, triethylborane (TEB) https://en.wikipedia.org/wiki/Triethylborane https://en.wikipedia.org/wiki/Triethylborane.

handol 6y ago
I thought the raptor was going to use a spark plug.
NikolaeVarius 6y ago
Which it does not use

aazaa 6y ago

Copper and boron, according to Wikipedia, will give green flame: https://en.wikipedia.org/wiki/Colored_fire https://en.wikipedia.org/wiki/Colored_fire But given the extreme conditions, a number of other factors could be at work.

deleted 6y ago

[deleted]

tw04 6y ago

I believe it was burning through the copper liner due to fuel starvation (oxygen rich which makes it SUPER hot) http://photos1.blogger.com/blogger/1613/496/1600/Merlin1C_Chamber.jpg http://photos1.blogger.com/blogger/1613/496/1600/Merlin1C_Ch... Seriously getting downvoted? That's what caused the issue.... Elon already tweeted they had low fuel pressure...

mulmen 6y ago
You may be right but Starship uses Raptor engines, not Merlins.
- tw04 6y ago
  I'm aware, the picture was to show what the liner looks like (approximately), the engines are of similar design. I apologize if anyone thought that was literally the liner in question.
  - mulmen 6y ago
    Ah yeah, lots of confusion re: TEB in other comments. Seems like a lot of people have the Raptor and Merlin mixed up so at least in this context probably have to be explicit.

orost 6y ago

Copper burns green, and the engine contains a lot of copper, so I think we saw a malfunctioning Raptor burning itself up. Other answers mention TEB starter fluid but I don't think that's right, because as far as I know Raptor has spark ignition only. edit: Elon Musk just tweeted that the immediate cause of the crash was low pressure in the fuel tank, so that would make sense, as running oxygen-rich would overheat and melt the engines.