Sciencemadness Discussion Board

SpaceX Starship crash coloured flames

phlogiston - 10-12-2020 at 04:17

I was watching the video of yesterdays spaceX rocket crash, and I noticed the flame turns a bright green moments before the attempted landing.

You can clearly see it in this video: https://www.youtube.com/watch?v=jLo73YkEvpM&feature=emb_...

Just after the 1:00 mark, the main motor flame goes from an indistinct washed out purple/white to bright green. A few flashed at first, but then the whole main engine flame turns green.

And then a fraction of a second before the crash the flame suddenly goes bright red again.

Anyone knows why? Do they change propellant chemistry specifically for the landings? Is there boron or copper or barium/halogen in the propellants?


Swinfi2 - 10-12-2020 at 04:39

I believe they use a boron based hypergolic starter mix, but I'm not sure why it went off like it did

sciece nerd - 10-12-2020 at 04:56

The raptor engine doesn't use the boron starter mix, and the green flame is from an engine problem that caused copper from the engine bell to be burnt off.

simply RED - 10-12-2020 at 05:52

Shut up physicists. Musk and Bezos know how to build spaceships!

Laboratory of Liptakov - 10-12-2020 at 13:27

0:56 starting engine 1.
0:57 starting engine 2.
0:58 starting engine 3. Failing.
1:00 Computer increase thrust for 2 running engines on maximum.
1:01 Engine 1 ... overheating of the nozzle neck, melting of the copper part that dissipates heat from a critical point.
1:02 Engine 1: burnt throat diameter is bigger and bigger.
1:03 Engine 1: loss of thrust 50% or more, almost destroyed throat.
1:04 Computer stopped engine 2 (?) Or his failing. (?)
1:04 Computer starting engine 3 again: Unsuccessfuled.
1:04 Engine 2 is still off.
1:04 Into engine 1 is pumping all fuel.
1:05 Engine 1: In combustion chamber burns unbalanced chemical mixture. Total loss of thrust of last (1) engine. The rocket falls in a free fall.
1:12 Elon Musk strangles a programmer.

MineMan - 11-12-2020 at 14:48

Quote: Originally posted by Laboratory of Liptakov  
0:56 starting engine 1.
0:57 starting engine 2.
0:58 starting engine 3. Failing.
1:00 Computer increase thrust for 2 running engines on maximum.
1:01 Engine 1 ... overheating of the nozzle neck, melting of the copper part that dissipates heat from a critical point.
1:02 Engine 1: burnt throat diameter is bigger and bigger.
1:03 Engine 1: loss of thrust 50% or more, almost destroyed throat.
1:04 Computer stopped engine 2 (?) Or his failing. (?)
1:04 Computer starting engine 3 again: Unsuccessfuled.
1:04 Engine 2 is still off.
1:04 Into engine 1 is pumping all fuel.
1:05 Engine 1: In combustion chamber burns unbalanced chemical mixture. Total loss of thrust of last (1) engine. The rocket falls in a free fall.
1:12 Elon Musk strangles a programmer.


Haha! He’s back!!!

TriiodideFrog - 13-12-2020 at 05:15

Space X used oxygen and methane. Maybe there was some barium or copper impurity?

Vomaturge - 13-12-2020 at 08:15

Quote:
https://www.cnn.com/2020/12/10/tech/spacex-starship-sn8-test...


[Quote]"Fuel header tank pressure was low during landing burn, causing touchdown velocity to be high & RUD, but we got all the data we needed!" Musk said in a tweet.


I agree that it probably cooked off some copper inside the engine. I'm no rocket scientist but I'm thinking there's a part (fuel injector?) that's cooled and shielded by a stream of fuel or oxidizer. According to wikipedia, the landing engine is powered by gas-phase methane and oxygen. If the propellant flow drops, the gases wll be burnng closer to that copper injector and it's going to melt. Not that it matters much, since low propellant flow basically causes the rocket to free fall into the landing pad...

Morgan - 13-12-2020 at 08:17

The nozzle looks quite copper clad in these photos.
https://wccftech.com/spacex-starship-prototype-test-key-thin...

[Edited on 13-12-2020 by Morgan]

Laboratory of Liptakov - 13-12-2020 at 11:45

Not that it matters much, since low propellant flow basically causes the rocket to free fall into the landing pad....:D...Anyway, all will destroyed....:D

Interesting news. I guessed something right, not something. The drop in fuel pressure caused excess oxygen, which burned the combustion chamber and its throat. Like when steel is cut with a sharp oxygen flame. A very expensive copper alloy was cut here. Resetting the engines was intentional, but engine 3 (middle in the video) failed to start at all...:cool:

ordenblitz - 13-12-2020 at 19:17

Man that sure looks more like a boron green than a copper green.

Morgan - 14-12-2020 at 04:02

That green copper nozzle effect brought to mind this copper coupling reducer used in a jam jar jet.
https://youtube.com/watch?v=GIstWmvSkbA