Questions tagged [falcon-9]

Questions regarding the Falcon launch vehicle developed by SpaceX for medium payloads (15,000 lbs) to LEO and GEO (via GTO, second stage cannot inject into GEO direct)

Filter by
Sorted by
Tagged with
4
votes
1answer
80 views

How does the Falcon 9 upper stage settle its propellants?

I understand the upper stage separates with the use of pneumatic pushers, but what settles the propellants in the upper stage tanks so that the propellant is pushed back to the intake? The pushers ...
12
votes
1answer
3k views

Cost per launch to ISS: Starliner vs Crew Dragon

What is the cost to NASA per launch to ISS of Starliner vs Crew Dragon? The Crew Dragon flights uses the SpaceX Falcon 9-FT with the first stage reusable, along with the partially reusable Crew ...
4
votes
0answers
90 views

Will the International Space Station be able to see the Falcon 9 (Inspiration4 launch)

Will astronauts aboard the International Space Station be able to see any part of the Inspiration4 flight of the Falcon 9 during launch and/or during orbit?
7
votes
1answer
1k views

How will the Inspiration 4 capsule deorbit?

Soon the Inspiration 4 mission will launch and the crew will orbit the Earth for three days. How will the crew capsule then deorbit? Will it use the super/regular Draco thrusters?
7
votes
1answer
176 views

Would it be possible for a Falcon 9 booster stage to land after an in-flight launch failure?

We all know that the Falcon 9 is designed for reusability, but there still have been some hull losses. Though this hasn't happened yet, say a Falcon 9 experiences an in-flight failure where four core ...
8
votes
1answer
342 views

Why do recent launch vehicles like that of Space X and Rocket Lab have far fewer umbilicals than before? What has changed?

Launch vehicles using mobile launch pads have many umbilical connections, whereas the ones using TEL launch structure with strongback, don't. Why is that? As seen in the picture, Electron has just one ...
4
votes
1answer
621 views

Which Falcon-9 launches were of a Falcon-9R rocket?

I have heard about Falcon 9 1.1 and Falcon 9 FT, but what is a Falcon 9R? If I understand correctly R = "reusable" which seems to apply to a lot of them. Are the Falcon 9 FT rockets launched ...
2
votes
1answer
151 views

Puzzler; what can we learn about the distance and direction of Earth from this cool SpaceX-tweeted image of Earth and a vacuum nozzle?

The 18-June-2021 Spacex-tweeted below says: View from Falcon 9's second stage Merlin Vacuum engine There is information out there about the approximate exit diameter and length of the nozzle and ...
22
votes
2answers
4k views

Do Falcon 9s get a thorough wash or a fresh coat of paint (they look clean pre-reflight)? [duplicate]

Before/during reflight, the boosters look white and clean, but after, they don't. I'm not sure if that's soot and/or burned paint. I looked but it doesn't seem to have been asked before. RE Is Falcon ...
1
vote
0answers
48 views

Why does the signal get lost every single time a Falcon 9 booster or Falcon Heavy booster lands on a droneship? [duplicate]

SpaceX reuses the Falcon 9 boosters and they sometimes fly back from space and land on land or sometimes at sea. In the sea landings, they land the booster on a floating drone ship(mainly, Of Course, ...
3
votes
1answer
120 views

Moment of inertia data for rocket stage?

I'm modeling a rocket launch and would like to compare my calculated moments of inertia to actual real-world data from other rockets. Any rocket would do, though those similar in size to Falcon 9 ...
6
votes
0answers
95 views

Bumps/nodes on rocket skin: What are they?

I've wondered for a while now what the many bumps and nodes on a rocket's skin are. Picture below for example (red lines mark bumps). Can someone clarify?
5
votes
0answers
83 views

Crew Dragon: How thick is the skin?

Auto body panels are about 20-gauge, or just under 1 mm thick. This is fine for many reasons: thin panels are light for good fuel economy and crumple easily for shock absorption without unnecessary ...
2
votes
1answer
58 views

Dragon Launch Escape: Attitude Control?

I've read the superdracos have a deep throttle range suited for attitude control during powered landings---an old requirement that's long been dropped. This has me wondering: are the superdracos ...
4
votes
1answer
86 views

Crew Dragon: Could launch escape thrust determine payload capacity?

The superdracos in Dragon's launch escape system each produce $\color{black}{\texttt{71.2 kN}}$ (16,000 lbf) of thrust. There are eight superdracos, giving a combined thrust of $\color{black}{\texttt{...
1
vote
1answer
63 views

What is the semicircular puff coming from the Falcon 9 first stage in this picture?

When I was watching the Crew 2 launch this morning, I noticed that while the first stage was coasting up and back down, it kept giving off arc-shaped "puffs". I did not see any corresponding ...
2
votes
0answers
35 views

Dragon launch escape: roll control?

Dragon’s four superdraco pods are positioned well for pitch and yaw control, but not for roll control. So I’m wondering how they’ll control for roll during launch escape—or if they’ll even control for ...
2
votes
1answer
77 views

Dragon launch escape: is nose cone ejected for parachute deployment?

Dragon’s landing parachute is stowed roughly in the nose cone hinge area, and this leads me to believe the nose cone has to open for the chute to deploy. In normal operations, I believe the nose cone ...
1
vote
1answer
60 views

Dragon Superdracos: how much MMH/NTO propellant?

How much Monomethylhydrazine + Dinitrogen tetroxide (MMH/NTO) hypergolic propellant does the Dragon crew module carry and how much burn time does that afford them during launch escape if one is ...
5
votes
1answer
115 views

Do Falcon 9 grid fins lock up during reentry?

Do Falcon 9 grid fins lock up when extended during reentry? Or do they rely on aerodynamic forces to keep them extended once they're deployed? Could the fins flail down during the reentry burn when ...
2
votes
2answers
206 views

Falcon 9 vs Apollo Landing: Key Differences?

So I'm struggling to model a Falcon 9 vertical landing. And because Falcon 9 info is scarce, I'm looking for more public info sources---like the apollo missions. The Apollos did basically vertical ...
3
votes
0answers
54 views

Falcon 9: transonic attitude control on reentry

Attitude control on the falcon 9 is done with engine thrust vectoring, cold gas thrusters, and grid fins. After the reentry burn, when the rocket stage is in the atmosphere, there is a short period ...
3
votes
0answers
54 views

Falcon 9 cold gas thrusters: why in line with grid fins?

The cold gas thrusters of the Falcon 9 are right in line with the grid fins. The grid fins deploy immediately after MECO and stay deployed while the cold gas thrusters fire. And it seems the expelled ...
1
vote
0answers
31 views

Falcon 9 flipover duration

This launch video shows a very gradual stage-1 flipover. The flipover starts right after MECO, before the 3:00 mark, and it continues slowly until just after the 6:00 mark. Or that's the impression I ...
3
votes
0answers
91 views

Why do Falcon 9 grid fins open in piecemeal fashion?

The grid fins on Falcon 9 seem to open in piecemeal fashion: extending a few degrees, pausing, extending a few degrees, pausing, etc. Any reason why this happens? The rocket stage is around 80 km high,...
2
votes
1answer
139 views

How do grid fins actually work? Which aerodynamic mechanism(s) produce the torque on the spacecraft?

I’m trying to model the steering force that grid fins exert on a falcon 9. I know these things are not just grid-shaped fins but actually grids of fins. And each of those fins will experience drag and ...
1
vote
1answer
89 views

State vector update on reentry

The integration errors from IMU state measurements would seem very problematic when you're coming in for a landing, where error tolerances would probably be as small as they could get. This must mean ...
3
votes
2answers
450 views

Ullage control with single engine stage?

How does a single-engine upper stage, like that of Falcon 9, do ullage control before starting the engine? Does it fire its cold gas thrusters? Does it fire the engine at minimum throttle for a second ...
0
votes
1answer
49 views

Ullage control on stage shutdown?

Is ullage control a thing only engine startup? Would a rocket like the Saturn V or Falcon 9 leave an engine running for a second or two longer just for ullage control?
0
votes
0answers
32 views

3g Throttling: Does Falcon 9 kill engines if acceleration over 3G?

I'm simulating a launch and I often hit minimum throttle before I hit MECO (triggered at 15% fuel mass---my reserve for stage-1 reentry). Acceleration then begins to rise to maybe 3.3 g by the time ...
1
vote
0answers
37 views

Falcon 9 landing speed estimate?

How fast is a Falcon 9 stage 1 going when it touches ground? Rough estimates are OK. An upper limit would be helpful too. I'm getting 5.5 m/s (12 mph) in simulation and wondering how reasonable this ...
1
vote
0answers
38 views

Falcon 9 Reentry Burn Duration?

The videos and simulations I've seen suggest the reentry burn lasts 30 seconds. This is followed by the final landing burn and it may be preceded by a boostback burn. I'm interested only in the ...
0
votes
0answers
22 views

Falcon 9 Stage-1 Helium Capacity

Is it known roughly how much helium a Falcon 9 stage 1 carries for leg deployment? Any educated guesses as to what the volume or mass might be? I don't imagine there are pictures of the stage-1 helium ...
1
vote
0answers
219 views

Vertical Landing: Calculating start altitude for hoverslam landing burn

So I've been thinking about hover slam landings. I want to simulate one. This is the best I've come up with so far. It's all high school physics. Am I far off? Scenario Say you're landing a rocket ...
1
vote
0answers
29 views

Falcon 9 Legs: helium just for pushers or also for telescopic cylinders?

For the longest time I assumed the Falcon 9 legs use pressurized helium to extend. But gravity by itself would cause them to extend---so long as you first kick them out from their stowed position. For ...
1
vote
0answers
29 views

Falcon 9: Landing leg helium pressure?

So it seems the Falcon 9 landing legs are powered by a helium precharge. Does anyone know the pressure of that precharge? If no numbers for Falcon 9, is there at least a reasonable range of what the ...
7
votes
1answer
391 views

How did the SpaceX come up with such a disruptive design in the Falcon 9?

Because of the answers to Why has a rocket system like Starship never been proposed before? , now I need to ask something I'd always taken for granted. If Falcon 9 wasn't revolutionary for technical ...
3
votes
0answers
52 views

Falcon 9 Flipover Direction?

Consider a Falcon 9 at MECO. The rocket's close to 30 deg relative to the local horizon, down from the 90 deg it had at launch. Stage 1 separates and flips more or less 180 degrees for the return ...
0
votes
1answer
33 views

Falcon 9: How many engines on first burn in two-burn reentry?

Consider a Falcon 9 two-burn reentry maneuver. My understanding is that the second, final, burn is always single-engine. And I think the first burn can be either single-engine or three-engine. But I'm ...
0
votes
0answers
42 views

Falcon 9 legs: precharged helium?

I've read the Falcon 9 uses helium pneumatics to extend its legs. The separation pushers are also helium pneumatics and I believe those are precharged so no pumps required. Are the leg cylinders ...
2
votes
1answer
210 views

Hover Slam Landing: How is it Done?

I want to simulate a hover slam landing. Is there an overview of the maneuver anywhere? I'm especially interested in the control algorithm used to bring the rocket stage to a halt at just the right ...
3
votes
2answers
167 views

Falcon 9 Max Q on reentry?

Max Q for a Falcon 9 is on the order of 30-40 kPa during launch. What would the number be on descent? Do they allow for greater dynamic pressures in that portion of the flight? Or is the rocket still ...
11
votes
2answers
3k views

What is this line, what is it called, what is the reason behind it?

I started following SpaceX recently. I used to read the updates but now I am diving deeper to learn new things. SpaceX is fascinating and I really like everything about it. But I have question, I don'...
3
votes
1answer
123 views

Can Falcon 9's engines be ignited more than 4 times if there is enough TEA-TEB?

SpaceX's Falcon 9 uses TEA-TEB as a ignitor for its Merlin engines. My question is if the rocket has more TEA-TEB, can the engine be shut down and restarted more than 4 times?
3
votes
1answer
224 views

If a company/agency has already developed a kerolox/hydrolox rocket, is it wise for them to switch to an all-methalox rocket? (to lower costs)

Multiple rockets, such as the Atlas V or Saturn V, have used the combination of a kerosene/liquid oxygen (kerolox) lower stage for higher density and thrust within the atmosphere and a liquid hydrogen/...
2
votes
0answers
50 views

Falcon 9: Stable platform or strapdown IMU?

What type of IMU does the Falcon 9 use? Is it a stable platform aligned with a global frame by gimbals? Or is it a strapdown system fixed to the body of the rocket and therefore aligned not with a ...
1
vote
1answer
178 views

How long is Falcon 9 suicide burn?

My question is How long is a Falcon 9 suicide burn? I assume the answer might vary between rides, depending on the payload lifted and its destination orbit so the time might not be the same for a ...
3
votes
1answer
110 views

What is the inlet and outlet pressure of Merlin LOX/RP-1 turbopump?

I got the inlet and outlet pressure of Saturn V engines turbopumps here, but I couldn't find the turbopump pressure of the Merlin engine of Falcon 9.
2
votes
1answer
102 views

Does Falcon 9 perform static fires before every launch?

Before launching every Falcon 9 rocket, is SpaceX performing a Wet Dress Rehearshal (WDR) and a static fire? If not before every launch then is it doing it before every first launch of a new booster? ...
0
votes
0answers
49 views

How long to flip over stage 1 of Falcon 9?

Curious how fast stage 1 flips over. 180 degrees is a lot of turning. At a rate of 5 deg/s, it would take 36 seconds to flip. This seems very long for the maneuver. A more modest duration of 10 s ...

1
2 3 4 5
13