# Tag Info

44

I wonder why nobody ever proposed a space launch system like Starship. What exactly do you mean by "like Starship"? Systems like Starship have been proposed before, although differing in the details, going back to Von Braun's mid-1950s Mars expedition concepts. Starship is ambitious in several ways, but it's more evolutionary than revolutionary. ...

43

The squat end of the spectrum has little to do with solids versus liquids and everything to do with aerodynamics. Spherical tankage is most weight-efficient, so you'd expect squat stages in cases where aerodynamics don't dominate such as your Mars Ascent Vehicle (flying where atmospheric drag is on the order of 1% what it is for Earth ascent) or the Apollo ...

40

Fundamentally, it's because of economics. There simply wasn't any demand for a large rocket between today and the space race. Let's analyze what (I think) makes the Starship concept special: Size: Starship is one of the biggest (if not the biggest) rockets ever constructed. Reusability: One of Starship's core design goals is to be reusable comparable to ...

36

I think you got it wrong: R-7 launches sometimes are also postponed due to weather. Just to name few examples: 18 December 2018, 9 March 2018, 22 April 2016 - Kouru; March 22, 2016 - Baikonur, 2 october 2011 - Plesetsk. These are just few examples of Soyuz launches delayed to weather conditions. R-7 is actually not especially structurally strong, it's a bad ...

33

It’s a sense of scale issue. As much as the struts might look like flimsy bits of drainpipe, those rockets are around 15 meters wide, and the struts are more like the heavy steel beams used to hold up entire buildings. So yes, they’re just really strong.

33

What actual engine are they talking about Organic Marble has identified it as the S5.2/9D21. in what way is it "not a very good missile engine"? The old Soviet engine on the Scud-B uses a propellant combination, kerosene/IRFNA, common for military missiles in the 1950s-1960s, but now considered obsolete, which yields a poor specific impulse (233 seconds ...

29

Why hasn't the small-lift launch vehicles completely replaced by the medium and heavy-lift launch vehicles? Because small launchers can provide several things: A small launcher is much cheaper than using a large launcher to launch a single small satellite. a dedicated launch, instead of having to share a launch which reduces your choice of final orbits a ...

28

This question is based on several serious misconceptions. R-7 launches never get postponed due to weather. Actually, they do. "The launch of the Soyuz 2-1A modernized carrier rocket, scheduled for Wednesday evening, has been put off again, this time due to bad weather conditions at an altitude of more than 11 kilometers," the source said. The only ICBMs ...

22

For Delta IV Heavy, according to Spaceflight101: The CBCs functioning as boosters are attached to the central core using thrust struts that interface with the interstage section of the launcher to transfer loads from the boosters to the rest of the vehicle. Additional attachment points reside in the base of the vehicle right above the engine heat shields. ...

21

Rockets (even old designs) are capable of delivering a nuclear weapon anywhere on Earth. Governments don't want this technology to fall into the wrong hands. Publishing a design takes a lot of effort. The complete design for a rocket easily exceeds a million drawings and hundreds of thousands of pages of supporting documents. For an old rocket, all of that ...

20

Supplemental answer: Scud missiles were powered by the S5.2/9D21 engine, burning inhibited red fuming nitric acid and kerosene. Thrust is 132 kN, Isp is "2285 Nskg" or ~233 seconds. Sources: 1,2,3

20

Is there any current launch system that could get a 75,000 kg object to geostationary orbit? No. (Starship/Super Heavy can, of course, do anything, but it's not a current launch system.) If not, am I correct in assuming the Saturn V could have gotten such an object there? No. According to the Silverbird calculator, a Saturn V could get about ...

19

I've tried to write it down, but then I've changed it into the following scheme. That way it is much cleaner. Note that the scheme doesn't include the recent Soyuz-2.1v vehicle. It seems like it is not "based" on R7 anymore. The conic boosters and core stage of R7 are no longer present.

19

The NASA Spaceflight article Japanese sounding rocket claims record-breaking orbital launch describes JAXA's use of its SS-520-4 sounding rocket to put the Tricom-1R cubesat (43201, 2018-016A) into orbit. While there was an issue related to communications during the ascent, the satellite is currently in a 1572 x 189 km orbit. This is probably the smallest ...

19

In general, umbilicals are provided from the launch pad to the vehicle for any services that need to be provided after the vehicle is installed on the launch mount, and to remove hazardous gases from the vicinity of the vehicle. Consider that vehicles can sit on the pad for long periods if problems occur during the countdown. Many different consumables may ...

18

Really what it means is "Category 3" certified, with an additional review of a self-destruct situation to prevent breaking the nuclear payload. Category 3 is also what is required to launch humans, and in fact the final milestone in the Commercial Crew is to rate the system Category 3. It is required for any kind of sensitive launch. Note that man rated ...

17

Rockets can use different systems for attitude control (control thrusters, fins, gyroscopes, TVC, ...). Since you ask for the seconds after liftoff, the relevant system is TVC (Thrust Vector Control). TVC basically means that the engines themselves can gimbal to change the direction of the thrust. This can influence the attitude of the rocket by inducing ...

17

Apparently lining up a lot of smallsats for a dedicated big rocket launch is like herding cats. Delays on any of the smallsats delay the overall launch. Hence SpaceX's recent announcement that their planned Falcon 9 dedicated smallsat launches will launch on schedule regardless of whether all the satellites are ready. https://spacenews.com/spacex-says-...

15

Juno 1 had a payload of 11 kg to LEO from a start mass of 29 t. Diamant-A had a start weight of 18.4 t, payload 100 kg to LEO. Black Arrow had a start weight of 18.1 t, payload 100 kg to LEO. Vanguard, start weight of 10 t, payload 9 kg to LEO. Lambda 4S had a start weight of 9.4 t, payload 26 kg to LEO. Caleb was an air-launched missile ...

15

Suborbital sounding rockets cost about 1/100 as much as an orbital launcher. Black Brant XII, one of the most advanced sounding rockets in use, can take 100-400kg payload into space for \$600K. For a Falcon-9-based sounding rocket approach to make any sense, you'd have to describe a single payload that delivered as much science as 100 individual 100kg ... 15 They already have one. The Falcon 9. Earlier this month a single Falcon 9 put 64 smallsats on orbit. It was arranged by a rideshare company, Spaceflight, at prices that small launch vehicles would have a hard time competing with, starting at \$300,000.

15

A ICBM rocket launched from a submarine should leave the water as fast as possible. Therefore the rocket has to leave the water vertically. The rocket is blown out of the submarine by using compressed air, it is ignited in air, not in the water. The rocket is stored in vertical position within the submarine. To be launched successfully, the rocket is ...

14

Don't take random youtube videos as fact. That part of that video was incorrect. The unmanned SpaceX Dragon has three pairs of computers used for flight control (so six flight control computers), and has 54 processors in all. The Falcon 9 launch vehicle has another 30+ processors. See http://aviationweek.com/blog/dragons-radiation-tolerant-design. Orbital's ...

14

While I have no specific knowledge of Falcon 9's fairing, it is common for compartments of space vehicles to be purged or pressurized slightly above ambient while on the pad to keep contamination out of the vehicle. After launch, vents allow the pressure in the compartments to drop in a controlled fashion as ambient pressure drops. To get a feel for how ...

14

I can provide details only for the Space Shuttle. 1) Up to 155,000 feet - the approximate altitude of SRB separation - the end of first stage flight. Here are example wind plots (from here) [Note the error on the Y axis label - it should be meters, not km] a. Jet stream winds and associated wind shear b. Sinusoidal variation in wind with altitude c. ...

14

Before I start my answer: This is not a rockoon anymore, since there is no balloon part. It's just a quirky air launched rocket. My answer: No. What you are doing is: Phase 1: Climb with a plane Phase 2: Descend with a plane Phase 3: Climb without a plane So yes, Phase 3 climb will begin with higher speed. However, since it's all energy that was gained ...

13

SpaceX is proposing launch vehicle, as a first stage, and a second stage that would transit to Mars. Interplanetary Space Transport (ITS). The final size is not really confirmed, and they should actually build it before we compare it, but using chemical rockets, it is quite a bit larger than a Saturn V. The Saturn V used 5 F-1 engines with around 1.5 ...

13

Orbital Sciences likes solid rockets. They've produced the Taurus/Minotaur all-solid booster. And, in its three-stage configuration the Pegasus is all-solid. Ignoring that kerosene-fueled launch platform of course.

13

Helium is used as a pressurant and purge gas. While no longer a "modern" launch system, the Space Shuttle made extensive use of helium to pressurize various systems and can perhaps serve as an example. Prelaunch pressurization of the External Tank liquid oxygen and liquid hydrogen tanks (on the order of 100 lbm of He for each tank) During standby ...

12

We can't even directly rebuild a Saturn V at this point (without tons of new R&D) because the tools and manufacturing processes no longer exist and we've lost the institutional knowledge of the people who built it that have since retired: Why not build Saturn V's again? Copying a design that we've never built is way more complex than trying to ...

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