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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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Falcon 9 Merlin engine thrust vectoring

One of the ways that the Falcon 9's attitude is controlled is through thrust vectoring of the main Merlin engine(s?). In images of older thrusters i've seen hydraulic or electric linear actuators to ...
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2answers
402 views

How does SpaceX phased array system work to keep track on the rocket

I have heard that SpaceX uses some kind of phased array system. I guess, this is reasonable because the speed of the rocket makes usage of any movable parts impossible. However, I am not an engineer ...
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1answer
2k views

How does the Falcon 9 achieves horizontal flight control [duplicate]

Landing of a rocket seems impossible with vertical flight control only. How the rocket achieves horizontal flight control with engines in line with the booster?
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1answer
5k views

Falcon 9 design: Why is the cargo fairing so much wider than the lower parts?

Why does the cargo fairing have a much larger diameter than the lower part of the rocket? Of course a larger diameter lets thicker payloads fit. But then the first, inter, and second stage could have ...
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2answers
1k 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
564 views

What's this chunk that fell off Falcon 9 second stage?

Just after T+3 minutes during today's SES-11 launch I noticed a small chunk fall off the end of a "boom" on the Falcon 9 second stage. What's the boom and what came ...
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2answers
491 views

Falcon 9 maximum point-to-point landing range

Has anyone here ever done enough back-of-the-envelope math to come up with a rough estimate of the maximum landing range of the F9 first stage? I'm talking unladen-swallow-quality math here -- trying ...
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1answer
131 views

Is there some reason why ORBs don't land in a cylindrical cage? [duplicate]

Just watched Elon's video on How Not to Land an Orbital Rocket Booster (ORB), and I just look at that and wonder why they don't build a large metal cylindrical cage on the landing platform so if it ...
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58 views

Is this equation for NEP thrust correct?

I have bolded the part that I am most interested in checking, because I am not sure if the formula is valid. I have been using Excel to find the thrust, power, etc for a NEP mission. I have been ...
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0answers
60 views

What is the mechanism principle of the grid fins in F9? [duplicate]

What is the mechanism principle of the grid fins in F9? or how to design the mechanism for the electricity grid fins? or how to design a electricity folding wing like the grid fins in F9?
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144 views

What accounts for the signal delay from cameras on the Falcon 9?

On the last few webcasts, SpaceX has shown video from both ground tracking cameras and the on-board camera side-by-side, and there's a noticable delay between the two, with the on-board camera being ...
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1answer
244 views

Did I see the Formosat-5 F9 2nd stage nozzle vibrate at about 2Hz at SECO-1?

Did I see the F9 2nd stage nozzle vibrate at about 2Hz at SECO-1? It looked like the bottom of the bell vibrated in an elliptical shape. Did I imagine that? Has this happened before? $\hskip 3.4 cm$...
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2answers
340 views

I don't understand the speed readings for stage 1 on CRS-12

I don't understand the speed reading for the CRS-12 misson's stage 1. While being around an altitude of ~100km the minimum speed that is shown in the webcast for stage 1 is ~1600km/h. If the speed ...
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2answers
407 views

Falcon 9 Range Safety

Does the KSC Range Safety Officer (RSO) have the ability to abort (destruct) the Falcon 9 first stage on its return to launch site? If so, at what point(s) in the trajectory does this ability exist?
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1answer
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What made the Earth appear to be flat during the recent SpaceX launch?

During the recent SpaceX CRS-12 launch which was broadcast live on YouTube, it appeared at one point as if the horizon of the earth was completely flat. What caused this to happen?
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3answers
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Why can Falcon Heavy bring 4.2 times as much mass to Mars than F9, but only 2.7 times as much to LEO?

In Wikipedia's article SpaceX Falcon-Heavy the section titled Capabilities has a table comparing maximum payload masses to Falcon 9 for different payload destination. The current numbers there are ...
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2answers
6k views

Why won't SpaceX launch a rocket for a month?

The last launch of a Falcon 9 (Intelsat 35e) took place on July 5, but the next launch of a falcon 9 (CRS-12) won't take place until August 10. Elon said that SpaceX still had 12 launches to go this ...
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1answer
482 views

How do the F9 grid fins extend and rotate?

How do the F9 grid fins extend and rotate? When the vehicle launches they are flat against the surface of the vehicle. As the first stage begins reentry, the fins extend and start 'flying' the ...
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1answer
578 views

Why is the gas jet from Falcon 9's cold gas thrusters so clearly visible?

If I open the valve on my nitrogen bottle there is a terrible noise but the gas jet is totally invisible. On some Falcon 9 launches, the gas jets are very visible both on ground and in the low ...
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1answer
2k views

Does SpaceX put Falcon 9 2nd stages carrying geostationary satellites into a temporary sub-orbital trajectory before the second burn?

I watched the latest SpaceX launch of Intelsat 35e on 05 July 2017 carried by their Falcon 9 rocket into geostationary orbit, and noticed some confusing telemetry data. Telemetry just before the ...
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1answer
529 views

Why are the cells on grid fins square in shape?

What is the reason for the square shape of the cells on grid fins such as those on the Falcon 9 landed by SpaceX, on missiles, or other places?
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1answer
742 views

When will the first use of the SpaceX rocket grabber be on an ASDS?

SpaceX has been caught developing a thin flat robot to drive out on the ASDS deck and grab a landed stage. Some are calling it the SpaceX Roomba (Xoomba?) others are campaigning for the name Attitude ...
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1answer
729 views

Merlin Engine Stoichiometry

As evidenced by the bright exhaust plume at launch, the billowing black smoke rolling out of the flame trench during static tests, the wispy grey effluent from the Merlin Vacuum engine, and the layer ...
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1answer
1k views

What do the Teeth on the SpaceX Falcon Mod4 do?

Can someone explain the purpose of the 'teeth' seen in the last picture of this answer? Do they have a specific name? They look too far up to be used to grab anything since the rockets land ...
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2answers
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How are the SpaceX Falcon 9 Mod 3 and Mod 4 grid fins different?

Elon Musk tweeted "Flying with larger & significantly upgraded hypersonic grid fins. Single piece cast & cut titanium. Can take reentry heat with no shielding." These have been commonly known ...
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1answer
304 views

Do the SpaceX ASDS orient themselves in a particular direction before a landing? Is there a “landing ellipse”?

The SpaceX Autonomous spaceport drone ships have longer and shorter direction, both for the flat, apparently land-able area, and total footprint in the water. The ships have vertical projections at ...
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2answers
585 views

What are these thirteen purple grape-like things inside this tank?

I am not sure this is a view of the inside of a liquid propellant tank, and even if was, not sure if it belongs to a Falcon 9 per se. But there are places for fourteen round objects at the far end, ...
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2answers
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What is the “emergency crush core”?

In his tweet Elon Musk said: "Rocket is extra toasty and hit the deck hard (used almost all of the emergency crush core)" What is he talking about?
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2answers
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What happens if the Falcon 9 launches with its grid fins open?

Let's suppose that the grid fins of the Falcon 9 remain open and the rocket still launches. This is probably never going to happen because the SpaceX team is exceptionally good, but I am trying to see ...
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2answers
2k views

Does SpaceX name individual boosters?

They name launches, usually after the payload, or just launch number, like "Falcon 9 flight 20, also known as Orbcomm OG2 M2" They named their drone ships some very fancy names. Still, are there ...
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2answers
194 views

Has F9 landed on ships in both the Atlantic and Pacific oceans?

Watching the CRS-11 hosted webcast starting at T -00:08:24 got me thinking about SpaceX launches on both the Atlantic and Pacific coasts of the US. Have there been ...
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0answers
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SpaceX CRS-11 landing pad debris identification

After sending CRS-11 into orbit to rendezvous with the space station, the first stage of the SpaceX rocket Dragon landed on Landing Zone one. In the video released subsequently you can see two pieces ...
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2answers
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SpaceX CRS-11 landing smoke color is weird

So a couple of minutes ago, the Falcon 9 of CRS-11 just landed and I noticed that the "smoke" color was a little different. It is more "red" compared to landings from other missions. CRS-11 (weird ...
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112 views

Falcon 9's description of component mass [closed]

What is the component mass of SpaceX's Falcon 9 or any descriptions that could tell the component mass of SpaceX's Falcon 9.
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1answer
488 views

Why did Falcon 9 boosters numbers skip B1027? What happened with it?

Looking at the list of Falcon 9 launches I noticed the booster numbers jump from B1026 to B1028. Anyone know what happened to B1027? Was it scrapped during manufacturing for some reason?
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1answer
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Why is the development of the Falcon Heavy difficult, when two of three cores are reused?

Elon Musk said that the integration of the Falcon Heavy was "shockingly difficult". I can absolutely believe that. But at the same time, SpaceX is reusing two "flight proven" boosters for the Heavy. ...
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1answer
323 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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1answer
993 views

How many kilo's of nitrogen does Falcon 9 load for its first stage cold gas thrusters?

Watching the video of the 1 May NROL launch, I was surprised at the frequency and apparent size of the cold gas thruster firings. Does anyone know approximately how many kilograms of N2 are required ...
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SpaceX rocket strange velocity

In SpaceX launch on May 1st, 2017, we get to see the full flight path of the first stage rocket of the falcon 9 from launch to land: It accelerates to around 1685m/s ...
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5answers
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Why does the Falcon 9 require a helium pressurization system?

The Space Shuttle was designed in the seventies and did not require a helium pressurization system. Why does the Falcon 9 require one? What are the advantages/disadvantages?
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0answers
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How much fuel is necessary for 2nd stage of Falcon 9 rocket to land?

What is the fuel mass nedeed for the 2nd stage of Falcon 9 rocket to land, how much compared with its total fuel mass that it has? Or how much delta-v is necessary? Would it be able for Falcon 9 to ...
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2answers
271 views

Why is the Falcon 9 upper stage tumbling so much after separation? (SES-10)

Immediately after separation, the upper stage of Falcon 9 seems to head 30 or so degrees sideways. What causes that? Is it a problem or a feature? Separation occurs at 4:40 in this video of the ...
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2answers
696 views

How does Falcon 9 mitigate re-entry pressure?

I was reading this question about Falcon 9's re-entry Max Q, which states that the Falcon 9 has a re-entry pressure 3 times higher than during launch. I was shocked, because SpaceX takes precautions ...
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2answers
414 views

SpaceX NROL-76?

According to SpaceX's website, it does not announce a NROL-76 launch in mid-April. However according to other sources such as the NRO and spaceflightnow announce that a Falcon 9 will launch the ...
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1answer
2k views

Why does the CRS-8 Falcon 9 rocket appear to be swaying before launch?

I just saw the video from the YouTube channel SpaceX Edits titled SpaceX B1021: The First Rocket to Fly Twice (a supercut of highlights mentioned in the Pod Bay, and noticed the Falcon 9 for the CRS-8 ...
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2answers
490 views

SpaceX Falcon expected life span (how many reflights?)

When SpaceX first announced their plans to develop a re-useable first stage, what was the envisioned life span of an individual booster in total launches before retirement (expected typical and ...
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1answer
177 views

What support equipment is necessary to maintain a falcon 9 booster during transport after recovery?

This file photo shows a Falcon 9 first stage being transported by truck after landing. There is some equipment at the end of the truck, which includes dials, knobs, and an exhaust stack, which ...
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Do each of the fairing halves now use thrusters post-deployment? How does that work?

From Reddit Recap of the Elon Musk and Martin Halliwell press conference with lots of new info, March 31, 2017 (presumably not related to April fools day in some time zones?) Fairing and future ...
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1answer
493 views

Why not use a rotorcraft drone or quadcopter using GPS navigation to live stream SpaceX booster landings on the droneship?

In droneship landings of SpaceX boosters, many times in live streaming, the video has stopped because of vibration in the droneship caused by the 1st stage landing of a Falcon 9 rocket. Would it be ...
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2answers
1k views

What's behind the design of SpaceX grid fins?

These grid aerobrakes/drag control moving surfaces, have been used for a while on various aerodynamic designs, and presumably they provide a turbulent airflow, which in some way is more predictable ...