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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3
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1answer
84 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
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1answer
107 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/...
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0answers
38 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 ...
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1answer
95 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 ...
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0answers
24 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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1answer
89 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? ...
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0answers
43 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 ...
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1answer
72 views

Falcon 9 altitude and speed during reentry burn?

After MECO, stage 1 of Falcon 9 does up to three engine burns: a boostback burn followed by a reentry burn followed by a final landing burn. I'm interested here in the reentry burn. How high and how ...
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0answers
51 views

How much lower is max q if launching from high altitude (i.e. mountain top)?

I looked at very simple max q formula: q=1/2 ρv^2 (https://en.wikipedia.org/wiki/Max_q). As air density is lower with altitude, the max q should be lower as well, and also should occur at higher ...
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0answers
34 views

Falcon 9 Angle of attack on return flight?

Do they control for angle of attack on the return flight of stage 1 of Falcon 9? Once it reenters thick atmosphere, aerodynamic stresses would be a concern as during launch, maybe more so because you ...
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0answers
27 views

Falcon 9 Stage-1 Reentry Burn: Throttle Setting, Duration?

How long does stage 1 of Falcon 9 fire its engines during its reentry burn, and what throttle setting do they use? Also, is it known how much fuel is left at MECO? Thanks if you know and can share!
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Does the Falcon 9 stage 1 have cold gas thrusters near the bottom?

I've seen the cold gas thruster pods on the interstage of Falcon 9, and I know that stage 2 has them too, even if there seem to be zero pictures of them on the web (they're the only means of roll ...
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0answers
16 views

Falcon 9 Stage 1 Guidance After Separation?

Does anyone know how stage 1 of Falcon 9 is guided immediately after stage separation? I'm not interested at this point in getting it to a precise landing spot, nor am I interested in the landing ...
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0answers
39 views

Pressure level inside Falcon 9 tanks?

What is the pressure level inside the Falcon 9 liquid oxygen tanks, RP-1 tanks, and helium tanks - at launch? The question is for both stages Related question: Pressure inside a launch fairing - ...
3
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1answer
86 views

How powerful do cold gas thrusters normally get?

Modern rockets like the Falcon 9 use cold gas thrusters for steering on landing approach when the engines are dead. Cold gas thrusters are common in smaller satellites and spacecraft, which way a ...
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0answers
21 views

Falcon 9 CGT Force?

Curious how much force the Falcon 9 cold gas thrusters produce for steering? I've seen numbers in the range of 25--100 lbf, but not sure where in this range (or outside it) the Falcon 9 falls. If you ...
4
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1answer
76 views

Does the SpaceX Falcon 9 first stage fleet, fly in order?

SpaceX by the end of 2020, made it very clear that they have solved the first stage reflight problem. Two cores have flown 7 times. Several are over 4 flights. At the beginning of 2021 they have about ...
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0answers
59 views

Why does Falcon 9 launch with Crew Dragon solar panels facing down?

I noticed in video of the first crewed mission in August that Falcon 9 pitches down with the Dragon solar panels facing down. I'd been expecting the solar panels to be facing up, because sun. Does ...
12
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2answers
704 views

How do they determine dynamic pressure has hit a max?

Max-Q is a key event during launch, and dynamic pressure is closely monitored so they know when a max is hit. But how exactly do they know when Q hits a max? If you track the rate at which Q is ...
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0answers
36 views

Coordinate axes of Falcon 9 on launchpad 39A

Can someone please correct me on the orientation of the Falcon 9 rocket as it sits on launchpad 39A at Kennedy? Looking at the image below, which way should X (red), Y (green), and Z (blue) face? I ...
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0answers
31 views

Orbital Insertion Altitude for Rendevous with ISS

When SpaceX launches a CRS mission to the ISS, what altitude do they target at orbital insertion? If the ISS is 400 km above ground, do they target 400 km at SECO? Or do they target a lower number---...
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1answer
104 views

Rocket dashboard: separation/pyro indicators

I'm curious about rocket dashboards. Separation events are big things and they depend on pyro bolts detonating and linear charges or pneumatic pushers firing immediately afterward. There must be ...
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1answer
132 views

Gimbal Check: Before or After Engine Ignition?

Is the engine gimbal check done before or after ignition? Also curious: How many seconds does the check take? What does it consist of? Do they gimbal each engine separately, or do they gimbal all ...
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0answers
23 views

Falcon 9: SECO target altitude/speed?

Is there a typical target altitude and speed for SECO on a Falcon 9 CRS launch? SECO precedes orbital insertion but there are multiple orbital adjustments afterward, so I also wonder: does Dragon have ...
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1answer
426 views

Is there an acronym for secondary engine startup? SESU?

We have acronyms for main engine cutoff (MECO) and secondary engine cutoff (SECO). Do we have an acronym for secondary engine startup---SESU maybe?
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2answers
559 views

Falcon 9 TVC: Which engines participate in roll control?

Stage 1 of Falcon 9 uses its gimballed engines during launch to control roll, pitch, and yaw. Only the eight peripheral engines can be used for roll control since the center engine couldn't possibly ...
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4answers
3k views

Are SpaceX Falcon rocket boosters significantly cheaper to operate than traditional expendable boosters?

The title pretty much sums it all up. I remember somebody once remarked about the space shuttle program that “the space shuttle was originally designed to be a space truck. But the shuttle is to ...
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0answers
61 views

How soon after launch is pitchover done?

I'm reading conflicting things on the timing of the pitchover. When exactly does it start? Many people write that it's almost immediately after launch, as soon as it's practical. Once the rocket ...
3
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1answer
164 views

Why does SpaceX Crew Dragon not have planned holds?

I watched the launches of SpaceX Crew Demo 2 and Crew 1. I observed that there were no planned holds during the last hour of the countdown. The Space Shuttle had planned holds at T-20 minutes and T-9 ...
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0answers
34 views

What does diiferent colours in orbital path seen in the CRS 21 launch video indicate?

The SpaceX broadcast of Falcon 9 - CRS 21 launch showed the orbital path of the vehicle differently than previous videos. Separate green lines and rectangualar boxes were visible. What additional ...
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0answers
88 views

Does Falcon-9's second stage “blow” into the first stage's top intentionally? [duplicate]

Every time I watch Falcon-9 moments like that at , I wonder: Is it really intentional that the main engine of stage 2 after startup blows directly into stage 1´s top, ...
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5answers
2k views

Using of the rocket propellant for engine cooling

Why does liquid space propellant make a good engine coolant? I was researching the regeneratively cooled nozzle and combustion chamber on the Merlin 1D when I found this out. I do know that the pipes ...
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1answer
112 views

Falcon 9's theoretical horizontal performance

Roughly how fast would Falcon 9 accelerate, and what would its payload's final speed be, if mounted horizontally on an ideal cart? Make simplifying assumptions as needed: massless frictionless cart, ...
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1answer
148 views

How many Crew Dragon spacecraft are SpaceX planning to operate?

NASA has bought six Crew Dragon flights and there is at least one private flight booked for next year. There are currently two flight-capable Crew Dragon spacecraft. Is SpaceX currently building ...
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0answers
156 views

How heavy is SpaceX's Octagrabber?

SpaceX's drone ships have a vehicle that drives under a booster after landing and then clamps onto it to secure it. Photos of it suggest that it has neither ballast nor any way to clamp onto the ...
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1answer
2k views

Is Falcon 9 repainted before reuse?

Before reusing the first stage of Falcon 9, is it repainted? If yes then why?
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1answer
180 views

Can the grid fins affect the rotation of the Falcon 9 descent?

Can the grid fins control the rotation of the Falcon 9 on descent? How would they have to be positioned to stop the rotation? If used to rotate the ship, then how they would they have to be positioned ...
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0answers
37 views

How hot the payload fairing of Falcon 9 can get?

When going up, what is the peak temperature of the Falcon 9 payload fairing? Is it heating uniformly or there is a significant temperature difference between various regions of the fairing?
2
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1answer
195 views

Where does a Falcon-9 get the hottest during launch, and how hot does it get? (aerodynamic heating)

We know there is a Max-Q point1 during a launch, have an approximate altitude, equations for it's pressure value and suspect it lies very near the apex of a rocket's nose. But is there a "Max-T&...
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2answers
200 views

Why Falcon 9 doesn't need heat shield tiles? [duplicate]

The Space Shuttle and the Starship need tiles for termal Protection while reentry. Why Falcon 9 doesnt need them?
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2answers
1k views

Why does the Falcon 9 use turbopumps as well as helium pressurisation system?

Falcon 9 first stage use turbopumps as well as helium pressurisation system. Isn't the turbopumps enough to pump in the propellants to the combustion chamber?
3
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1answer
74 views

How throttle changes affect calculations of thrust?

So, for constant throttle setting equation to calculate thrust looks like $ \ F = \dot{m}_\mathrm e V_\mathrm e + (p_\mathrm e - p_0) A_\mathrm e$ But if we are looking at flightclub.io simulation, ...
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0answers
161 views

Why is the water pumped out of the holding tank a minute before Falcon 9 liftoff?

SpaceX Falcon 9 - starlink mission on October 5. Video : Why is the water discharged at T- 01m:30s from the holding tank far away from the launch pad? This was also ...
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1answer
230 views

What is the Falcon 9 interstage used for?

What is the interstage used for, how big it is and is it deorbiting separately?
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2answers
590 views

What is the return speed of the Falcon 9 booster?

The Falcon 9 first stage detaches at about 70 km high and it descends in about 6 minutes. That means an average descending speed of 200 m/s But what is the maximum speed it reaches on descent? And ...
6
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1answer
381 views

Simulating launch velocity of falcon 9

Help! I finished my numerical simulation of falcon 9 launch in google sheets, where I calculate all the value changes with time. But, when I looked at real launch to compare the values, I got really ...
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1answer
80 views

At what time is the Falcon 9 loaded with fuel?

How long before launch are the fuel and oxidizer loaded into a Falcon 9 rocket? And how much time does it take to load it?
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1answer
84 views

How long it takes for the Falcon 9 payload fairings to reach the sea?

The payload fairings of Falcon 9 are released at about 3:15 min How much time they need to fall and reach the sea? And what is their maximum speed while reentry?
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1answer
83 views

The numbers on the live Falcon 9 videos

In the live Falcon 9 launch videos there are two numbers displayed at the bottom-left corner of the screen. The two little circular and text gauges that have the units under them. I guess they are the ...
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1answer
97 views

Falcon 9 landing stages

I know the first stage of Falcon 9 separates at about 2:30 min and it lands at about 8:30 min But what are the distinct stages of the descent? Like deorbit burns, grid fin deployment, leg deployment ...

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