All Questions
34
questions
3
votes
0
answers
201
views
Does Starship run on Slushies?
Cryogenic slush (a mixture of liquid and solid) can potentially store propellants at higher density than cryogenic liquid. For instance, hydrogen slush is 16-20% denser than liquid hydrogen. https://...
- 22.9k
9
votes
1
answer
713
views
How is SpaceX planning to avoid fuel sloshing on IFT3?
SpaceX is about launch IFT3 and during IFT2, the booster exploded probably due to sloshing and an engine having something block its fuel supply.
What has SpaceX changed to avoid fuel sloshing?
- 80k
7
votes
4
answers
5k
views
Why is fuel cheap compared to rocket?
The fuel for a Falcon 9 (SpaceX) costs around \$200,000 per launch, while the launch itself costs \$62,000,000.
Safety precautions, rocket shell and rocket engines cost a lot. But why not fuel?
CommunityBot
- 1
-4
votes
1
answer
239
views
How does SpaceX prevent fuel from cluttering together in zero G [closed]
What is the solution to stop fuel inside starship collecting in center of the tank during zero G flight? Here is a rough sketch of starship with rudimentary diaphragm system to control flow of fuel ...
- 5,884
5
votes
1
answer
274
views
Why did the June 2016 SpaceX launch run out of propellant?
In other words, what caused SpaceX to miscalculate the amount of propellant required to safely land the booster. They had landed successfully on the drone ship in April. So what went wrong here? What ...
- 15.4k
2
votes
1
answer
290
views
Why do the Falcon 9 fairings have soot on them?
On nearly every SpaceX webcast since 2020 they explain that the Falcon 9 booster has soot on it because, during the entry burn, it flies through its own exhaust plume very quickly depositing the ...
- 12.4k
4
votes
2
answers
9k
views
Calculate Falcon 9 CO2 emissions
Falcon 9 uses Merlin 1 Kerosene based engines. Are there 4 Merlin 1 engines? This seems simple to calculate:
Number of Merlin Engines x Merlin 1 fuel capacity(gallons) x Kerosene to CO2 Production.
...
- 601
4
votes
1
answer
2k
views
Why doesn't the Merlin 1-D use higher LOX to RP-1 mixture ratios?
So I've been screwing around with CEARUN, which is the chemical equilibrium with applications program created by NASA. I've been using it to calculate theoretical Isps for rocket engines using RP-1 ...
10
votes
3
answers
3k
views
Why do $\text{CH}_4$ (Raptor) engines produce less soot than RP-1 (Merlin) engines?
SpaceX's Merlin engine, which burns RP-1 and LOX, has soot visible after the first stage lands. Many articles on the web say SpaceX's Raptor engine, which burns methane and LOX, is clean. ...
35
votes
3
answers
8k
views
What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket?
News piece: NASA supports SpaceX plan to fuel rockets with astronauts on board.
The move is criticized by many as unnecessarily dangerous.
From what I understand though, it shouldn't be necessary - ...
17
votes
3
answers
3k
views
Why don't Raptor engines use CH3Cl instead of CH4?
The boiling point of CH3Cl is -24 degrees Celsius, whereas the boiling point of CH4 is -160 degrees Celsius.
The density of CH3Cl is 2.3 g/cm3, whereas the density of CH4 is 0.6 g/cm3.
CH3Cl is polar, ...
- 2,745
4
votes
2
answers
552
views
How could a hydrazine and N2O4 cloud (or it's reactants) show up in weather radar?
Question: How could a hydrazine and N2O4 cloud (or it's reactants) show up in weather radar?
Tweet:
This is what an ‘anomaly’ looks like on weather radar.
Tweet (with GIF):
Dragon's static fire ...
- 13.1k
15
votes
3
answers
6k
views
Is the supercooled LOX used in Falcon 9 Full Thrust a first?
One of the changes made to the Falcon 9 v1.1 Full Thrust was using supercooled liquid oxygen at 66 K (-340 F) as well as chilled RP-1.
I've seen various claims that this is a first in the industry. ...
- 149k
21
votes
2
answers
23k
views
Why will Starlink satellites use krypton instead of xenon for electric propulsion?
The press kit for the first Falcon 9 Starlink launch and deployment of the first 60 satllites scheduled for May 15, 2019 says:
With a flat-panel design featuring multiple high-throughput antennas ...
- 149k
11
votes
4
answers
3k
views
Why RP-1 and not Methane for Falcon 9's Merlin engines?
I've seen methane described as the best of both worlds---the worlds being hydrogen's energy density + pain-in-the-ass factor and RP-1's lower energy density + ... ease of use?
And this has me ...
- 11.6k