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)

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7
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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?
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84 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?
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8answers
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Why isn’t the “JRTI” barge larger?

The barge that SpaceX's Falcon 9 was trying to land on is creatively called "Just Read The Instructions"(hereafter known as JRTI). I've been told that SpaceX is using the barge to avoid a land based ...
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3answers
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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. ...
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2answers
2k views

Has SpaceX re-used a first stage twice yet?

SpaceX has re-used a first stage once, several times now. Has it re-used the same first stage twice yet? If not, has a particular mission been named that will be the first second re-use?
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1answer
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What was the first time a "re-used booster" was used to put a payload into orbit?

In the excitement about SpaceX's Falcon recovery and relaunch development program, it's often forgotten in articles like this one that reusable spacecraft were in regular use far back in the 20th ...
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1answer
115 views

When will the first Falcon-9 send something to the Moon? Will it be iSpace's HAKUTO-R?

The Teslarati article SpaceX customer iSpace updates Falcon 9-launched Moon lander, rover plans says Japanese commercial space company iSpace has provided an updated schedule for its first private ...
7
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1answer
172 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 ...
32
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1answer
27k views

What are the droplets/particles falling off rockets at launch?

In this picture from the AsiaSat 6 launch by Falcon 9 on 8th September 2014, the part of the rocket between the fairing and the engine appears to be surrounded by dust, water droplets or debris: And ...
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2answers
228 views

Falcon 9: Why does F9 first stage always lose Video Link during Entry Burn?

Typically the F9 first stage and the drone ship each lose the video connection once during landing: F9 first stage during entry burn Drone ship during F9 first stage touch down (see here and here) ...
8
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1answer
336 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 ...
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3answers
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How far downrange would a reusable Falcon 9 first stage land (without fly-back)?

Let's imagine a rocket like the Falcon 9 recovers its first stage via a soft landing, but doesn't attempt a return to the launchpad. For the sake of argument, let's imagine that there are no ...
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1answer
619 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 ...
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1answer
261 views

What is producing these strange lights around the Falcon 9 grid fins (Starlink launch)?

Early in the video of the launch of the first sixty SpaceX Starlink satellites we can see that after stage separation the first stage grid fins open. Around that time there are some phenomena I don't ...
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253 views

What (the heck) is this purple donut in the video of the Falcon 9 fairing's atmospheric reentry?

This SpaceX tweet (found in CNET's SpaceX camera captures incredible view of rocket part returning to Earth) shows a video taken by a camera in one half of the fairing on the recent STP-2 mission and ...
15
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1answer
1k views

What is the value of the cross-track angle between the two designated CRS-4 first stage recovery zones?

For the SpaceX Falcon 9 launch on its Dragon/CRS-4 cargo delivery mission to the International Space Station, according to Spaceflight 101, two downrange safety zones have been identified: The SpX-...
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1answer
1k views

How far from launchpad did Falcon 9's first stage go?

On December 21st, 2015 on the Orbcomm OG2 mission, Falcon 9's first stage landed 6 miles from its launchpad. What was the highest altitude reached by the first stage, and how far did it go from the ...
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1answer
3k views

What is the burn time for the F9 boostback / reentry / landing burns?

I'm trying to figure out the timing of the 3 recovery burns and the total fuel reserve needed to perform them. [Answers Inlined] Boostback: [30] seconds of 3-engines at full-thrust. Reentry: [20] ...
3
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1answer
662 views

Falcon 9 - relief valves closing times

From what I understand, prior to the launch, the relief valves are open to allow some of the boiling LOX to evaporate and be replaced with fresh, cold one (we can see oxygen evaporating - and "...
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2answers
3k views

How did Falcon 9 deploy 11 satellites?

Falcon 9 Flight 20 has successfully deployed 11 ORBCOMM satellites into orbit. I can easily imagine a rocket deploying 1 or 2 satellites. But how did Falcon deploy 11 satellites in a single flight? ...
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1answer
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2nd stage speed - with respect to what? (SpaceX webcast of Orbcomm OG2 deployment)

As a follow-up question to this answer by @TildalWave, exactly what frame is used to calculate the "speed" in the inset display of speed and altitude in the SpaceX broadcast of the Falcon 9 launch and ...
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1answer
409 views

DId the Falcon 2nd stage turn around [UPDATED] and point "backwards" before the Orbcomm-2 deployement started?

It looks to me like the camera used for the deployment part of the Webcast shown on YouTube is located near the "bottom" of the payload area (closer to the engine & tanks) - in which case, did ...
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1answer
150 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 ...
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1answer
312 views

How many SpaceX 2nd stages are in heliocentric orbits?

I can think of one particularly famous SpaceX 2nd stage in heliocentric orbit that even has its own website: https://www.whereisroadster.com/ and I know one was used to send DSCOVR towards Sun-Earth ...
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3answers
8k views

Why does the video feed always fail during Falcon 9 landings?

I'm in love with SpaceX and Falcon 9, I watch every live stream and the most special, most amazing, most thrilling part of each launch is the 1st stage landing. Seeing the smoke (or vapor) clear and ...
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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?
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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
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1answer
794 views

What is this 'engine plume interaction'?

SpaceX just released this high-speed footage, writing in the comments: Missions in order of appearance: May JCSAT-14; July CRS-9 launch, stage separation, engine plume interaction, and re-entry ...
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1answer
4k views

Why is the center engine in the Falcon 9 (and Falcon Heavy) Octaweb layout at a different elevation with respect to the outer engines?

Looking at this elevation view of the Falcon 9, the nozzle exit of the core engine in the cluster is in a different plane with respect to the nozzle exits of the surrounding eight engines. Why is ...
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3answers
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What are the differences between a standard Merlin engine and the Merlin Vacuum engine?

I know that there's a difference between SpaceX's Falcon 9 1st stage engines and the 2nd stage engine, since that stage is specifically tuned for vacuum. Wikipedia also says that the Merlin Vacuum ...
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1answer
83 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{...
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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.
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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 ...
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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 ...
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0answers
47 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, ...
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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 ...
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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?
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0answers
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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 ...
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1answer
57 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 ...
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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 ...
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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 ...
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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 ...
5
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1answer
114 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
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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
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1answer
6k views

What's the atmospheric drag coefficient of a Falcon 9 at launch (sub-sonic, large fairing)

While I said just a few hours ago that "There's almost no such thing as a dumb question! this one just might sound like one. I'm making some slides about first principles thinking applied to ...
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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
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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 ...
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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,...
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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 ...
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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 ...

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