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?
- 370
-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
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 ...
- 3,746
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 ...
- 3,746
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. ...
- 2,888
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, ...
- 411
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 ...
user39728
3
votes
1
answer
156
views
Could another fuel be used in the SpaceX Starship header tank?
A memory of hexane and water in a separatory funnel brought to mind the issue of helium and LNG in the header tank while the Starship flips and does its powered landing.
There was discussion of the ...
- 1,088
4
votes
1
answer
1k
views
How long does it take to refuel a rocket?
I've been wondering how long the refueling of a rocket, say the falcon 9 takes.
That's it.
- 41
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
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 ...
- 149k
4
votes
1
answer
457
views
What type of propellant does Spacex plan to use in Starship for long duration missions?
For long duration missions such as ones to mars what type of propellant would be best suited?
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 ...
- 201
11
votes
1
answer
16k
views
How much fuel does the Falcon Heavy use? What is the price RP-1?
Does anyone know how much fuel the Falcon Heavy can hold, the RP-1 fuel and liquid oxygen as oxidizer, and how much of that will it use to get to a certain point?
I don't know how i would calculate ...
- 175
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 - ...
- 55.1k
5
votes
0
answers
219
views
What is the droplet size that is desirable for pintle injectors?
The pintle injectors tend to generate droplets after impingement of the fuel and the oxidiser stream and I understand that the droplets will be premixed.
In such a case, even a larger premixed ...
- 4,479
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?
- 73
7
votes
1
answer
2k
views
Could the SpaceX Falcon 9 Block 5 work without sub-cooling the propellants?
I've been reading about some concerns about the densified (sub-cooled) propellants for Falcon 9 crewed missions in Spaceflight Now's article Lawmakers question safety, schedule for Boeing/SpaceX ...
- 1,778
5
votes
1
answer
418
views
Why did the "Secretive SpaceX Zuma Launch" make a big "S" or yin-yang shape in the sky?
The Space.com article Strange Sky Spiral May Come from Secretive SpaceX Zuma Launch shows images from this Tweet and this tweet, the second of which was posted by Dr Marco Langbroek (@Marco_Langbroek):...
- 149k
2
votes
0
answers
525
views
How much fuel is necessary for 2nd stage of Falcon 9 rocket to land?
What is the fuel mass nedeed for the 2nd stage of Falcon 9 rocket to land, how much compared with its total fuel mass that it has? Or how much delta-v is necessary? Would it be able for Falcon 9 to ...
- 2,145
4
votes
1
answer
4k
views
What is the spherical tank in this drawing of the BFS?
The big news in this article is the extremely large carbon-fiber fuel tank. However, the drawing in the article does not show it well. Instead what stands out like a sore thumb in the drawing is the ...
- 149k
6
votes
1
answer
268
views
Can Falcon 9's fuel be ignited by static discharge?
Reading Twitter comments about the recent Falcon 9 pad explosion, some postulated the problem was that a static discharge ignited the fuel as it was being loaded.
Since TEA-TEB is required to ignite ...
- 863
3
votes
0
answers
461
views
What could be wrong in the ground support equipment to cause the Falcon 9 AMOS on pad explosion? [closed]
The AMOS-6 mission Falcon 9 had a RUD (Rapid Unscheduled Disassembly) event on the pad, and it is initially postulated that it was related to fueling the second stage.
We know that SpaceX revamped ...
- 80k
0
votes
2
answers
2k
views
Falcon 9 fuel use [closed]
How much fuel does a Falcon 9 rocket used by SpaceX use, for a trip to the International Space Station?
Any possibility of Teslas batteries being used in the future?
4
votes
0
answers
99
views
What is the icy formation on these rockets? [duplicate]
I've sometimes seen icy formations form and break off of spacecraft. In today's SpaceX launch, there are a couple examples (times based on video) at 51:55 where you can see it growing:
Two similar ...
- 1,144
6
votes
1
answer
511
views
SpaceX Webcast - What is visible in this clip? [duplicate]
I've just watched the SES-9 Launch Webcast and was wondering what is visible at about 37:15?
Does the Falcon 9 have cameras in the kerosene (or LOX) tank?
- 163
11
votes
2
answers
922
views
How long can a vehicle stay fueled before the liquid oxygen gets too warm?
On February 28 2016, Falcon 9 attempted a second launch for its 22nd flight. However, it was put on hold for about 20 minutes at T-01:33 and had its countdown reset to T-11:44, giving a total of about ...
- 306
2
votes
1
answer
372
views
How much fuel remains in a booster such as the one used for Jason-3
Building off of this question, I am curious as to how much (just a simple magnitude of order) propellant remains inside a booster to cause such an explosion? Considering cost, I would expect very ...
- 2,941
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. ...
- 773
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.
...
- 43
13
votes
5
answers
2k
views
What are the challenges in Falcon 9 "full thrust" (v1.2) with densified propellant?
SpaceX has announced an upgrade to their Falcon 9 rocket, achieving greater thrusts with, as far as I can tell, the same rocket motors (at least, they apparently still call the motors "Merlin 1D"). ...
- 1,542
38
votes
6
answers
9k
views
Why did it take so long for methane to be used as a rocket propellant?
SpaceX have put methane on the map as a rocket fuel, but they weren't the first to consider its use. The first experiments in building a rocket engine that uses methane date back to 2007.
Now methane ...
- 128k
8
votes
1
answer
754
views
SpaceX Falcon 9 Reusable first stage propellant for return
How much propellant is required to return the Falcon 9 Reusable's first stage after separation?
- 10.1k