Questions tagged [launch]

Questions regarding the takeoff or the liftoff phase of the flight of a rocket and the set of activities required for preparation of the launch vehicle leading to it.

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3
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1answer
96 views

Guidance vs. Navigation vs. Estimation

I'm still confused over what exactly falls under the scope of Navigation, Guidance, and Estimation systems. Say I have a bunch of IMUs and use them to determine my position and orientation and my ...
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1answer
108 views

Find the jump condition of the mass costate of a Launch Vehicle ascent problem solved via an indirect method (Pontryagin Minimum Principle)

I'm trying to solve a trajectory optimization problem for a class of problems like the old Altas-Centaur SLV3 Centaur launch vehicles. Those are a stage and a half design where the 2 LR-87 engines ...
3
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1answer
89 views

Are westward launches more expensive than eastward launches?

Basic question for those who breathe rockets: The earth's rotation imparts to the rocket a free delta V of roughly 450 m/s if you launch straight eastward. If you launch westward instead, for a ...
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1answer
259 views

Has a rocket from a torpedo tube ever reached space?

Are submarine launches horizontal? is a general question and specifies by name two large ICBMs which are likely to need to be launched vertically. Since the large naval submarines usually come ready-...
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0answers
36 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
47 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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3answers
691 views

What are the deal-breakers with a preheated Hydrogen gas tank orbital rocket?

Consider this thought process: In selecting the propellant for a reaction engine, lower atomic mass is better because equipment is largely temperature limited, and lighter gas will get higher ...
4
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1answer
54 views

Are Powered Explicit Guidance calculations done before or during launch?

Space shuttle orbital insertion was done using a powered explicit guidance algorithm. At the surface, the algorithm is simple, as it gives the instantaneous pitch as a linear function of time: $\phi = ...
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0answers
31 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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3answers
90 views

Orbital launches

In the 1950s, many US rockets were capable of reaching the lower limit of LEO altitude. Despite this, no one thought of making the launch vehicle / its payload orbit around earth, even for one ...
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1answer
47 views

Estimating time to engine cutoff?

I'd like to calculate the approximate time left to my stage-1 velocity target. A simple way to do this would be to divide my Delta V by my acceleration. Trouble is... my acceleration changes ...
18
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1answer
3k views

What would have happened if only one Space Shuttle SRB ignited?

The ignite command for the Solid Rocket Boosters (SRB) would not be issued unless all three Space Shuttle Main Engines (SSME) were at least 90% of thrust. The launch would have been aborted if one or ...
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3answers
2k views

How much throttleback to keep acceleration under 3g?

Most rockets generally throttle back when they reach max-q to prevent structural failure. This could be the only throttleback event of the launch. But crewed rockets normally do a second throttleback ...
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73 views

Does space weather affect spacecraft launch schedules?

Does space weather affect spacecraft launches and do scientists check it before spacecraft go to space? I know there is space turbulence and it can influence a spacecraft, but can space weather?
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1answer
65 views

What happens with the upper stage of Deep space launches?

When a rocket is sending a spacecraft to another planet, in general, where does it separate from the upper (last) stage of the rocket? What happens to most of those upper stages? They remain in Earth ...
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5answers
3k views

Does upper atmosphere rotate with earth?

Basic question that I should know the answer to but sadly don't. The lower atmosphere must rotate with the earth because of friction---at least the very bottom of it. But what about 30 miles up? There ...
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0answers
26 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!
4
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1answer
177 views

Simple alternative to Powered Explicit Guidance for orbital insertion?

Say you're playing space ops engineer and want to simulate an orbital insertion---but you're petrified by the calculations needed to get the coefficients of the linear tangent law behind Powered ...
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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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3answers
6k views

Do rockets leave launch pad at full thrust?

Rockets always seem to launch slower than I expect them for the thrust they can produce. Do they really launch off the pad at maximum thrust? Or do they launch at lower thrust until they clear the ...
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1answer
80 views

Do you know a rocket for launching femto and pico satellites smaller than the SS-520?

The question has already been asked here why no one has built a rocket to launch one CubeSat. Why isn't there a rocket to launch a single cubesat? If there "won't be" rockets to ...
11
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1answer
5k views

How many successful Soyuz launches have there been?

From the first Soyuz to the launch vehicles used today, how many launches have been deemed successful?
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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 ...
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0answers
30 views

Antares yaw maneuver: how many degrees?

The Antares rocket begins launch with a very noticeable yaw maneuver that seems to rotate it more than the 1.25 degrees documented for the Saturn V. Am I being misled by perspective? Does anyone know ...
3
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1answer
41 views

Initial Yaw Maneuver: Lean into or away from tower?

Some rockets do an initial yaw maneuver to help avoid contact with the tower. I know the yaw is in the plane of the tower: the rocket either leans into or away from the tower... But which of these is ...
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0answers
38 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 ...
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1answer
66 views

First satellite dispenser?

A rocket upper stage, sometimes called kick stage, is the last stage of a rocket and it is used to deploy satellites in orbit. A space tug is a spacecraft released from the upper stage and it is used ...
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2answers
685 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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1answer
49 views

Do rockets headed to ISS get delta V benefit from Earth's rotation

A rocket on the launchpad moves Eastward with the rest of the earth as it rotates about its polar axis. This means that on launch, the rocket already has a sizable eastward velocity component: ~460 m/...
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0answers
35 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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1answer
78 views

Purpose of Initial yaw Maneuver?

I've read the Saturn V began launch with a short yaw maneuver which lasted from t+1 through t+8.25. The purpose mentioned for the maneuver is to avoid contact with the launch tower. But now that I ...
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4answers
529 views

Delta-V required for lift-off from a planet/ asteroid

How can I find a estimation of the delta-V needed to lift-off from a planet and go into a low orbit around it?
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0answers
30 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
127 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
20 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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9answers
190 views

Number of launches by year, by country

This is a question about how many orbital launches made each year China, then the same question for India and so on for every country that made orbital launches Additionaly, is there any country that ...
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3answers
157 views

What is the number of launches by year?

How many orbital and beyond-Earth launches have been done every year? There is a Wikipedia article: https://en.wikipedia.org/wiki/Timeline_of_spaceflight But it doesn't contain enough data. There is a ...
9
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2answers
545 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 ...
8
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2answers
746 views

US states with most space launches?

Some space launches are made from Florida, some from Texas, some from California and so on. Which US states and territories had the most orbital space launches in all space history? I mean launches ...
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0answers
146 views

First time in orbit by USA state launched from? [closed]

Only five states and territories had launches that got into orbit: Florida, California, Virginia, Alaska and Marshall Islands But when is the first time a rocket launched from each of those that ...
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0answers
57 views

Where can I book a flight for scientific experiment to 100 km high? [closed]

I have just been wondering if is there any company in Europe which launch scientific experiments into an altitude of about 100 km?
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1answer
137 views

Number of satellites launched by decade?

How many satellites were launched each decade? Including satellites of Mars Moon Venus Sun etc Similar question Number of satellites launched per year? Most busy times in space launches by decade?
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2answers
191 views

Most busy times in space launches by decade?

If anyone has the curiosity and time and possibility to run the scripts, I think it's interesting to see the most busy day, week, month and year, by decade. Most busy week of 1960s then most busy week ...
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4answers
10k views

If the ISS had an emergency, how long would it take to get a rocket to it?

If there was an urgent need to launch a rocket to the ISS, how long would it take to have a rocket ready to launch? I am trying to understand what factors take up the time to prepare for a rocket ...
4
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1answer
164 views

What is the longest period of consecutive daily space launches?

What is the largest number of days with at least one space launch every day? Also what is the largest number of days with at least a launch per day on average? For example two launches yesterday and ...
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2answers
2k views

What was the most busy week in space launches?

In the history of space launches, which week has had the most space launches? It would be also nice to know the second and third place. I think its also interesting to ask about most busy month and ...
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8answers
2k views

Where to look for next rocket launches?

Is there any place on the internet showing the upcoming rocket launches? Like the launches next week or next month
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4answers
270 views

Can Oberth bike? Is biking up and down a series of hills a good real-world analogy for understanding either the Oberth effect and/or gravity drag?

When faced with a series of ups and downs while riding a bicycle, I try to pedal like mad near the bottoms to gain as much speed as possible. I do this due to some vague, ill-formed notion that either ...
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2answers
112 views

Number of China orbital launches by year [duplicate]

I've also posted the numbers below as a temporary answer here but I don't know if they are right so I'll also ask this as a question. How many orbital launches did China make every year? I got some ...
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0answers
40 views

Number of India orbital launches per year [duplicate]

I've also posted the numbers as a temporary answer here but the data is incomplete so I'll also ask this as a question. How many orbital launches did India make every year?

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