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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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1answer
485 views

Would it be beneficial to land Falcon Heavy's side boosters on droneships too?

Although the synchronous landing of the Falcon Heavy side boosters looks impressive, they seem to have traveled a long way back to the landing zones. How does this ...
4
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3answers
638 views

Will SpaceX land the first stage for the TESS mission on land or a barge?

I may have the opportunity to watch the upcoming Falcon 9 launch of NASA's TESS mission in person. Because of this, I'm curious whether I'll be able to watch the first stage of the Falcon 9 land back ...
7
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1answer
2k views

Could the SpaceX Falcon 9 Block 5 work without sub-cooling the propellants?

I've been reading about some concerns about the densified (sub-cooled) propellants for Falcon 9 crewed missions in Spaceflight Now's article Lawmakers question safety, schedule for Boeing/SpaceX ...
8
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2answers
1k views

What is the turnaround time for SpaceX's barges?

I believe that currently, SpaceX only has two landing barges - one in the Atlantic (Of Course I Still Love You (OCISLY)), and one barge in the Pacific (Just Read The Instructions (JRTI)). How long ...
5
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1answer
307 views

Why did the “Secretive SpaceX Zuma Launch” make a big “S” or yin-yang shape in the sky?

The Space.com article Strange Sky Spiral May Come from Secretive SpaceX Zuma Launch shows images from this Tweet and this tweet, the second of which was posted by Dr Marco Langbroek (@Marco_Langbroek):...
17
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2answers
650 views

What was the outcome of the launch of ZUMA by SpaceX, to the best of the public's knowledge?

Now, I realise this question is inherently unanswerable due to the classified nature of the mission, and speculation is also not desirable, but that's okay — because we can at least assemble official ...
26
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2answers
5k views

Why did SpaceX retire Falcon 1?

Why did SpaceX retire Falcon 1? Wouldn't it have been more cost effective then Falcon 9 for lighter missions?
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0answers
161 views

Is there any flutter analysis available regarding Falcon's grid fins?

I have never come across any papers which talks about flutter analysis of gridded fins in general, does it not under go flutter behavior or is it technically incorrect to talk about flutter for ...
19
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1answer
3k views

Why are Falcon 9 main engines throttled down and up shortly after launch?

On the official webcast of SpaceX's Iridium-4 mission a "throttle down and throttle back up of the Falcon 9 first stage engines" is mentioned. Why would one throttle down at a crucial time during ...
3
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2answers
181 views

SpaceX's Iridium 4: Explanation of Trail Footage

There is a lot of footage of SpaceX's Iridium 4 mission of 22 Dec 2017. The rocket's vapor trails look very different from those of airplanes, since it gains a lot of height. Anyhow, the result looks ...
4
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1answer
1k views

Why are the new Titanium Grid fins not used on all Falcon 9 landings?

With the Block 4 version of the Falcon 9, one of the new features is the Titanium Grid fins, vs the previously used Aluminium fins. However, not all Block 4 flights have used the Ti vs Al fins. Is ...
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3answers
719 views

Why does one leg open slower than others on Falcon 9 landings?

I had noticed this before, but when landing, the legs do not open at exactly the same time or speed. For the CRS-13 mission, it was really obvious in this video around 50 seconds into the video. ...
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2answers
582 views

Why are CCD cameras still used, not CMOS for live view from the rocket?

I watched the start of the CRS-13 and the view of the engine and other elements of the rocket are shown from CCD cameras in sd. The resolution ok, does not have to be large but why is it still used ...
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3answers
252 views

What fuel is used in the second stage of orbital launch vehicles?

What types of propellant are used in the second stage of multi-stage rockets? For example, the Falcon 9. Is it the same combination as the first stage? I've found plenty of information about the first ...
4
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1answer
117 views

Why is LC39A's TEL enclosed, but the newer SLC40 TEL is not?

After the AMOS-6 explosion on the pad at SLC-40 in September 2015, SpaceX spent a lot of time rebuilding SLC-40, including a very big update on the TEL (Transporter/Erector/Launcher). Whenever they ...
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1answer
230 views

Could a Falcon 9 booster return to Earth with its payload safely in an emergency? [duplicate]

Suppose that during the boost phase a Falcon 9 lost enough engines that it could not deploy its payload into a useful orbit or trajectory. Are there some scenarios where it could conceivably return ...
5
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1answer
3k views

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 ...
4
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2answers
441 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 ...
10
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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?
25
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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 ...
17
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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?
3
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1answer
648 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 ...
9
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2answers
521 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 ...
0
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1answer
134 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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0answers
65 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
65 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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0answers
149 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 ...
4
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1answer
262 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? $\hskip 3.4 cm$...
3
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2answers
380 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 ...
12
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2answers
438 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?
20
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1answer
6k views

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
1k views

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 ...
3
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1answer
528 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 ...
8
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1answer
671 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 ...
13
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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 ...
6
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1answer
564 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?
7
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1answer
2k 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 ...
5
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1answer
811 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 ...
16
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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 ...
24
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2answers
12k views

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
339 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
666 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
7k views

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
1k views

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 ...
3
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2answers
203 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
167 views

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
423 views

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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0answers
121 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.