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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19
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1answer
2k views

What does 'Rocket is in self align' mean?

I've noticed during SpaceX streams (this could happen with other LSPs but I've only noticed it with SpaceX) that shortly after the vehicle goes to internal power the controller says "Vehicle is in ...
1
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1answer
109 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 ...
53
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5answers
12k views

Why doesn't the Falcon-9 first stage use three legs to land?

The immediate thought that would probably come into your mind would be "Because 4 legs is more stable than 3." However that is not always true. 3 legs offer the same or in some cases more stability as ...
6
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1answer
183 views

Does central Merlin have a different specific impulse?

On a Falcon 9 booster, does the central engine experience unique variations of its ISP due to its plume bordering the eight other plumes? If there is any influence, how does the ambient relative ...
3
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1answer
151 views

Is vertical assembly worth the cost (Ariane 6)

Very recently, ESA released a new video showing the proposed Ariane 6 rocket being assembled. This mostly takes place in a large 'moveable gantry' building where the payload is placed on top of the ...
5
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0answers
146 views

What's 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 ...
25
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5answers
9k views

Why doesn't SpaceX land boosters in Africa?

Apart from the obvious answer that it'd take too long to get the booster back across the Atlantic, why doesn't SpaceX leave the main or centre booster in space a little bit longer and guide it to land ...
7
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1answer
128 views

How much of the recovery system does Spacex remove from a Falcon 9 when using it in an expended manner?

Falcon 9s have a limit to how many times they can be reused, and, for the last flight of a booster they don't make it land (in one piece), and instead use all the fuel to help the payload. That way ...
3
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1answer
78 views

F9 - Lift Off from “Landing Legs” [duplicate]

Could it ever be possible for Falcon 9 to lift off from its own "landing legs"? i.e. no strongback, no complex launch pad support, just land somewhere, get a new second stage and a tank of gas and off ...
3
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0answers
85 views

How much do SpaceX's titanium grid fin geometrical parameters measure?

Does anyone know approximately what is the width, length, thickness and depth of the titanium grid fins used in the Falcon9 v1.1? I'm trying to make a 3D model on solidworks but can't find the ...
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0answers
117 views

What is the function of this Merlin engine's tube, and why is it getting red hot?

In the video of the recent SpaceX Starlink launch, one view of the Falcon-9 2nd stage engine shows a cane-shaped tube that glows red hot at the "handle" end and seems to get hotter over time. ...
2
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0answers
124 views

What caused 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 ...
4
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2answers
107 views

Shortest ever F9 2nd stage burn for the largest ever F9 payload? (Starlink Mission's SES-2 burn time of 3 seconds)

According to the SpaceX broadcast the first SpaceX Starlink launch (24-May-2019) is notable for reasons including being the heaviest ever Falcon 9 payload to date. At roughly ...
11
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2answers
374 views

What does this SpaceX tweeted photo show and what causes the pure red and blue color?

This May 4, 2019 SpaceX tweet says More photos from Falcon 9’s 40th successful launch from Pad 40 in Florida and 39th first stage rocket booster landing to date → http://flickr.com/spacex and ...
3
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1answer
210 views

Can we get to Mars today using current rockets/technology?

I was wondering if, using the rockets we have today (I'm guessing the most likely candidate is the Falcon Heavy), we could send at least 1 human to Mars. For arguments sake, let's ignore the fact it ...
3
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1answer
141 views

When Falcon 9's stage 2 engine fires up, does the flame of the engine affect stage 1 in any way?

Are there any specific design considerations that are made over nonreusable, traditional rockets to tolerate the blast from the stage 2 engine? As shown in this moment:
6
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2answers
323 views

Is this Falcon 9 on a drone ship in Port Canaveral really on fire?

The Teslarati article SpaceX’s latest Falcon 9 booster returns to port as NASA hints at “vested interest” shows this tweet about booster number B1056 from Jennifer Krafft Photography: #SpaceX #...
4
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0answers
125 views

Books on Vertical-Landing Vertical-Takeoff (VTVL) of Rockets? or Rocket Design in General?

I am working on a rocket control system design and I am trying to understand the the fundamental principles and concepts to design an efficient controller for recovering and landing the rocket, ...
5
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2answers
281 views

Could Falcon 9 take off without launchpad

As far as I'm currently aware, the Falcon 9 block 5 does not have the capability to retract it's landing legs once they're deployed, however: If F9 landing legs had the ability to retract themselves (...
5
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1answer
434 views

What exactly happened to crew dragon on 4/20?

The crew dragon experienced an anomaly yesterday during testing. It seems that there was some sort of unexpected event that resulted in damage to the crew dragon test article. This unconfirmed video ...
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0answers
95 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 ...
2
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0answers
90 views

What would be payload capacity of reusable Falcon 9 if there was no atmosphere on Earth?

Reading this question and answers, I wondered what would happen if there was no atmosphere, everything else being the same on Earth. What would be the payload capacity to LEO of Falcon 9 in reusable ...
3
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0answers
126 views

Are these two length scales in FH exhaust plumes real, understood, and distinct?

The Ars Technica article We can admit it—we’re dazzled by the controlled fury of the Falcon Heavy includes a beautiful photo of the exhaust plume produced by the 27 engines of a Falcon Heavy launch. ...
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0answers
63 views

SpaceX Avionics [closed]

Just wondering what are some avionics aboard the falcon 9 and heavy. also what are some avionics on the dragon? Just general avionics that play a pivotal role in space travel.
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5answers
4k views

Why does Arabsat 6A need a Falcon Heavy to launch

Is it just me or does a falcon heavy seem like a bit of an overkill to launch Arabsat 6A? Falcon Heavy - GEO payload: 26,700 kilograms Arabsat 6A - weight: ~6000 kilograms Wouldn't some other ...
8
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1answer
359 views

Why is the Falcon Heavy interstage not black?

Falcon Heavy has two side boosters that are essentially standard Falcon 9 lower stage with a nose cone, along with a black interstage, as seen below. (Full size) But the renders that SpaceX shows of ...
3
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0answers
194 views

Falcon 9 Landing Speed

I wanted to know what the fastest speed is that a Falcon 9 can land at and thus the max force the landing legs can withstand. I assumed the mass when landed is 26,000 kg (I once heard that somewhere). ...
3
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1answer
161 views

What's the shortest time to reflight of a Falcon 9 booster?

What has been the shortest time in between the landing of a Falcon 9 booster, and SpaceX reusing them on a different mission?
-1
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1answer
143 views

How are 9 Merlin 1D engines packed and able to fit in a Falcon 9 FT first stage?

It was proved by Pirl in 1969 the most optimal packing of 9 circles in a larger one https://en.wikipedia.org/wiki/Circle_packing_in_a_circle. The radius of the larger circle should be ≈ 3.613r (r is ...
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0answers
91 views

Calculating the height and width of a rocket for drag

While messing around with making a little rocket launch simulator, I seem to have hit a slight wall with finding the relevant information in order to calculate the width and height of the rocket for ...
4
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0answers
166 views

Falcon 9 2nd stage pusher; how far does it continue to extend as it accelerates separation?

I've just watched Scott Manley's video SpaceX's Water Landing Reveals Rocket "Secrets" (or, What We Learned from CRS-16) (again) and he mentions the second stage "pusher" in the center of the view (...
3
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2answers
263 views

Is helium used to power the Falcon 9 grid fins?

Is helium used as a hydraulic fluid to power the grid fins? Or for engine gimbaling? What are the pros and cons of using helium instead of hydraulic fluids?
3
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1answer
157 views

The changes of a throttled Merlin-1d engine

With Merlin-1d being able to throttle down from its full thrust potential, this post about its throttle capability does not mention much of its change in performance. On the Wikipedia page of Merlin-...
5
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0answers
83 views

In landing, how much of a Falcon 9 First stage's velocity is lost to air resistance and how much to retropropulsion?

Thinking about this question I was led to wonder to what extent retropropulsion is used to kill the F9 first stage's full velocity and to what extent it is used simply for course control and landing, ...
7
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2answers
1k views

How many engines are restarted for landing the falcon boosters

For landing the boosters, it is clear that SpaceX is using the center engine, but I suspect that igniting one engine will not be helpful. If they aren't igniting all the 9 engines, how are they ...
4
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0answers
97 views

Falcon 9: how much fuel is left on a booster after stage separation?

If the booster attempts either land or sea landing, how much fuel (RP-1 and LOX) is left in its tanks right after stage separation? Recently, I have heard numbers as high as 30% of its total tank ...
1
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1answer
120 views

Does the Falcon 9 charge its batteries during flight?

I'm wondering if the Falcon 9 booster or upper stage regenerates any electrical power from the Merlin engines or their subsystems, or if the battery systems are perpetually draining while in flight (...
5
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1answer
202 views

Why was the water-landed Falcon 9 B5-B1050 towed backwards for retrieval?

The rocket was apparently recovered by attaching a towing line to the heavy, lower end (with the engines) and pulling at backwards. This seems counterintuitive to me, as this pushes the water into ...
2
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1answer
143 views

What are the four vertical structures surrounding Falcon launch? [duplicate]

This image is on the first page of the Falcon 9 Launch Vehicle PAYLOAD USER’S GUIDE which features Falcon blasting off and four masts with cables attached to their tops. What are they?
4
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1answer
305 views

Why did they not use the Flight Termination system on CRS16 booster?

All US boosters (I assume other nations as well) have flight termination systems. The goal is to try and stop an out of control booster (Big vehicle, full of explosives/fuel/oxidizer) from causing ...
28
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5answers
5k views

Falcon 9: engines stabilize spin

On CRS-16, the landing Falcon 9 booster entered a spin rotation due to a stalling grid fin hydraulic pump. According to Musk, the engines stabilized the spin. How is this possible? The main engines ...
5
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2answers
255 views

If the CRS16 booster was out of control, how did it abort to water?

The CRS-16 missions first stage, seems to have had a stuck grid fin. Apparently a hydraulic pump failed. It was spinning fairly wildly and clearly did not try to land at the pad as it was scheduled. ...
7
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1answer
214 views

What is the circular item that fell off of the returning booster during the CRS-16 mission?

During reentry of the first stage booster on the Dragon Resupply Mission (CRS-16), there was a ring-looking item that floated away from the booster. I would imagine it is some sort of ice debris, but ...
5
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2answers
369 views

What are these flames on the Falcon 9 booster?

When Falcon 9 was on its way to ascend, flames appeared around the bottom of the booster. What are they? It seems to begin around about 20:36 in the video, ...
5
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1answer
104 views

Loading the LOX into Falcon 9 V1.1 and Falcon 9 Full Thrust

It is clear from the spaceflight101.com that there is difference in Launch sequences of Falcon 9 FT and Falcon 9 V1.1. Clearly, Spacex has found a way to load the tank in 30 minutes (falcon 9 FT) as ...
5
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1answer
323 views

How long does the refurbishment process of a Falcon 9 take?

When launching a reused Falcon 9, how much time would it take to refurbish a used first stage in order to get into working condition? NOTE: This question is different as it looks at the time between ...
9
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1answer
314 views

What is the mysterious cube shaped object observed in the Falcon 9 launch? [duplicate]

For today's(November 15 2018) Falcon 9 launch, at around T+ 06:04 into the mission, we can see a cube shaped object flying near to Falcon 9 first stage. This ...
0
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0answers
36 views

Gimballing angle consider for liquid rocket engines [duplicate]

I went through the documents for gimbaling of liquid rocket engines and saw that there is about 20 degrees per second of gimbaling rate (in comments). But I am not able to get, what is the maximum ...
5
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2answers
164 views

what's this fluffy object on the SAOCOM 1A mission's upper stage? [duplicate]

When watching the upper stage of the Falcon 9, I noticed this white or blue tuft: It changes shape a bit as time goes on. That makes me think it is something very light (cotton candy, fiberglass ...
16
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1answer
470 views

Why is the exhaust plume of Falcon 9 upper stage shaped the way it is?

The (single) Merlin 1D vacuum engine's exhaust plume has a symmetric shape, comprising of six distinct "inner" plumes. Why does it have this shape? Is it due to the shape/configuration of fuel ...