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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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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 ...
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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 ...
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1answer
61 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 (...
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1answer
107 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 ...
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1answer
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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?
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1answer
120 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 ...
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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 ...
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2answers
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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. ...
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1answer
162 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 ...
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2answers
239 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, ...
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1answer
73 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 ...
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1answer
139 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 ...
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1answer
193 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 ...
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0answers
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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 ...
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2answers
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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 ...
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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 ...
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1answer
199 views

How do you shut off a Merlin-like rocket engine quickly? How quickly can it be done?

After about 36:17 in part 1 of this recording of SpaceX's Hans Koenigsmann's talk at IAC 2018, he narrates the propulsive landing of a Falcon 9 first stage, and ...
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1answer
627 views

What flame is SpaceX's Hans Koenigsmann describing in his presentation?

At 35:46 in part 1 of this recording of SpaceX's Hans Koenigsmann's talk at IAC 2018, he says something like: The green stuff that you see is TEA-TEB, that’s the ...
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Does anyone know how the Flight Club website simulates Falcon 9 launches?

Does anyone know how the Flight Club website is able to provide falcon 9 launch simulations? Given the estimated weight, fuel mass, thrust, ect, how are they able to provide a graph of how it could ...
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213 views

Is it possible to calculate Max-Q without having to input an altitude

Is it possible to calculate max-q based on just upwards velocity instead of specially inputting a given altitude/air density? Based on this graph of Falcon 9 launches till MECO below "Air Pressure vs. ...
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1answer
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3* Tonnes Unaccounted for in Falcon 9 FT Weight Wikipedia Calculation?

On the Falcon 9 FT Wikipedia page, the fully fuelled weight of Falcon 9 is only 546 300kg instead of 549,054kg as stated on SpaceX website. 546,300 kg - Wikipedia ...
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1answer
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What is the Kerosene/LOX mixture ratio of the Block 5 Falcon 9?

as the title would suggest, does anyone know a calculation or solution to finding the current mixture ratio used on the latest block 5 configuration? This would be easier if so many people did not ...
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Does anyone know how to calculate the KG per second of RP-1 and LOX from the 9 Merlin 1D engines?

as can be seen from the title, I have been through at least 1,000 chrome tabs in the last few hours trying to find some form of definitive answer, but I've found absolutely nothing. Could anyone help ...
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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 - ...
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Does the downrange position of an ASDS vary, depending on payload mass?

SpaceX in its recovery attempts can either do a Return To Launch Site (RTLS) or land downrange on an ASDS landing barge. The Telesat 19V and 18V payloads were some of the heaviest payloads on the ...
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Falcon fairing half - between separation and parachutes deployment

How does Falcon fairing half behaves in atmosphere before parachutes deployment? What is its free fall attitude in atmosphere? Is the fairing's attitude stable (with some wobbling, but without ...
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1answer
117 views

Would having the Falcon fairing reconnect be possible/beneficial?

I understand that many of the problems with recovering the two pieces of the Falcon 9 fairing deal with the weird aerodynamic patterns of the descent. It is by no means an aerodynamically sound object ...
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1answer
267 views

Why doesn't SpaceX deploy some module to cover whole fairing like a rain coat just before sea landing? [duplicate]

In order to avoid fairing to get wet in water, why can't SpaceX just deploy something such that when fairings separate from the Falcon 9 then from inside some raincoat type waterproofing to just cover ...
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4answers
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Why can't Falcon 9 fairings touch the water?

SpaceX is spending considerable effort to catch Falcon 9 fairings into a giant net on a ship. I am aware that salt water ruins almost everything in the long run, but the fairings are a composite ...
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1answer
303 views

What makes it so hard to precisely land a fairing?

SpaceX currently tries to land their fairing halves on a boat with a net attached to it. So far they had no success but landed nearby, although quadrupling the net area. They first tried with this ...
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0answers
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Nature of “the silky black 'highly flame-resistant felt'” on Block 5 Falcon 9's, and its intended functions?

The Teslarati article SpaceX Falcon 9 Block 5 rocket’s drone ship return captured in stunning detail [gallery] and accompanying photo spread shows many interesting details of "SpaceX’s first West ...
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1answer
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What is the minimal TWR of Falcon 9 booster right before touchdown?

A big point about Falcon 9 booster landing is that they need to stick the landing on the first try; they can't just hover and adjust position because even fully throttled single Merlin engine provides ...
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Will SpaceX delay launches, if the landing site weather is unacceptable?

With the initial landing attempts, it was not a big deal, twas all an experiment and they only reused Block 1-4 boosters once at best. So holding a launch because of weather at the landing site ...
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1answer
254 views

How do rockets “blow” smoke rings? Did “smashing through Max-Q” really do this?

The Teslarati article SpaceX delivers largest commercial satellite in kick off of Falcon 9 marathon includes several beautiful photos, of the Telstar 19V launch, including the one below. It shows ...
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Dragon 2 in-flight abort test - what will happen to the booster?

SpaceX is planning to do an in-flight abort test of the Dragon 2. I imagine that at max-Q the Dragon will start its own motors to fly slightly faster than the booster (and move sideways). Suddenly ...
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What holds SpaceX’s rocket in place in this launch?

On a recent launch video, the gantry is at an angle and only loose tethers are attached as the rocket is prepared for launch. What is keeping it upright and in place at this point? The engines haven'...
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3answers
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Why are these Falcon 9 1st stage bodies (apparently) wrapped in black plastic for transport?

The Teslarati article SpaceX’s third Block 5 rocket heads to Texas test site as launch marathon nears includes the image and caption below. Is this an unused rocket body being transported for launch, ...
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Why does the Falcon 9 use RP-1/LOx and not LH2/LOx?

Why does SpaceX use RP-1 in the first and second stages of their rockets? In my view at least the second stage could use hydrogen as it currently is not being reused. I am aware that you have higher ...
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1answer
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Why does the 2nd stage of Falcon 9 need compressed He tanks?

It is well known that the rapid disassembly of Falcon 9 static testing started with the rupture of the composite fibres of the copv He tanks. But what is the need to have the composite tanks ...
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3answers
543 views

Will reusable rockets be financially viable?

While the vertical landing of rockets by SpaceX is certainly a significant achievement, there seem to be many who say that reusability is not actually financially viable. Apparently, it is far too ...
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1answer
99 views

How far apart do both SpaceX half fairings splash down?

Inspired by this question: How far apart from each other (both in space and time) do the two halves of a Falcon fairing land? I'd also be curious to know what's the error margin they have on this. ...
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1answer
178 views

What are these tiles inside the Falcon 9 fairing?

The three photos in SpaceX's recent tweet about attempting to recover the GRACE-FO/Iridium-6 fairing halves included a close-up of the inside of the fairing: [] What do those black tiles with the ...
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1answer
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How does SpaceX decide which half of the Falcon 9 fairing to catch?

Question: How does SpaceX decide which half of the Falcon 9 fairing to catch if they are only going to catch one half? Is one half more expensive and/or well instrumented than the other? Images from ...
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1answer
831 views

How much does a current F9 fairing-half weigh?

Question: How much does a current F9 fairing-half weigh? Is this resting on something, or is it really floating this high in the water? Images from this SpaceX tweet: Falcon 9 fairing halves ...
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Why is the first stage from the Falcon 9 SES-12 mission not recovered?

Youtube video here At 4:13 minutes into the Iridium-6/GRACE-FO NASA Launch, the commentator mentions: The first stage is not going to be recovered, so there won't be any views from the drone ship ...
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What are these circular structures around the rocket?

Youtube video of the Iridium-6/GRACE-FO NASA Launch (Falcon 9 SES-12). Edit 31 May: Too bad they have changed the content of the video (and still call it 'live'), so that you can no longer see the ...
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1answer
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Should SpaceX have 2 versions of the Falcon 9 rocket (cargo-only and human-only)?

I am learning that having a human rated Falcon 9 rocket is very difficult. Would it be better to have 2 versions of the Falcon 9 rocket? I figure a human-only version would be easier to design with ...
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1answer
287 views

Do Falcon 9/Heavy Block 5 boosters need landing legs? Or can they land back on their launch mounts?

At 2017's International Astronautical Congress, Elon Musk claimed that SpaceX could master propulsive landing without landing legs. The assertion was that Falcon 9's ...
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1answer
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Will Falcon 9 block 5 successful launch speed up production of BFR?

I was just wondering that as Spacex has just launched it's final variant of Falcon 9 block 5 successfully, so now will it speed up the process of building BFR rocket ?