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43

There are some major challenges with this. For starters, the engines of the first stage produce far too much thrust for the last stage, which would require extra structural mass to allow the rocket to hold together, and would not allow manned rockets at all, as humans have fairly tight g-force limits. If you reduce thrust to manage these problems, you're ...


41

The first multistage rocket is much older then one might think. Its from the 14th century CE. Huolongchushui or fire dragon issuing from the water (Chinese: 火龙出水; pinyin: huolóngchushui; literally: 'fire dragon out of water') were the earliest form of multistage rockets and ballistic cruise missiles used in medieval China. The name of the weapon was used ...


36

As with most things space, it all comes down to tradeoffs. The most efficient rocket is one that is purely expendable and has no mass that does not contribute to getting the payload towards orbit. If the aim is to reuse the rocket, you need a mechanism to achieve control in the upper atmosphere, a method to control descent rate and a method to achieve a ...


25

I am referring to rockets capable of taking supplies and humans to other planets. For an interplanetary single-stage rocket with tens to hundreds of tons of payload capability, no existing propulsion system can do the job in a practical way. Chemical rockets lack the fuel efficiency; electric rockets don't have the thrust required to leave Earth's surface. ...


23

Nathan's answer is good and cover almost everything but let me add a last bit: An engine nozzle can be optimized for only one given altitude ambient pressure. This has a great impact on the rocket performance. You probably wouldn't want to drag that heavy, inefficient engine all the way up, even if you could. Some designs attempt to circumvent this issue ...


20

To get a rocket to space, you have to build it to be really light while containing lots of fuel. This is called the mass fraction: In most rockets, more than 90% of the starting weight is fuel, the rest is divided into the rocket structure (engines, tanks) and the payload (the satellite you want to launch). If you build one really big rocket, it starts ...


19

Rockets are basically devices which exploit Newton's Third Law, for every force there is an equal and opposite force. By throwing mass out the back as fast as possible this imparts an equal force that lifts the rocket, engines, payload, and all its own fuel. Single-Stage-to-Orbit can be done, but it's horribly inefficient. This is because of the Tyranny Of ...


18

The SRBs have smaller solid separation motors, 8 on each, which simultaneously fire to push the boosters safely away from the orbiter/ET. Here's a video showing them in action -- they're powerful enough to give the external tank a good scorching. You can see the separation is designed to turn the boosters slightly outward so any remaining SRB thrust takes ...


18

It's possible, but not as easy in real life as it is in KSP. To maintain proper tank pressurization, the crossfeeds have to be pump-driven; the fuel and oxidizer crossfeed lines have to be pretty large to move the required amount of propellant (i.e. on the order of the same power as the core section's engine turbopumps). All this increases weight and ...


17

The burning seems to be after the 5 J-2 engines on the second stage fire. Each J-2 has about 230KLbs of thrust for well over a million lbs of thrust aggregate. ANYTHING exposed to 1 million lbs of LOX/LH thrust is very likely to burn. No doubt they ran some oxygen and hydrogen through the engines to pre-cool them before igniting, (like the SSME does, like ...


16

No, they don't have sufficient thrust when they're jettisoned to catch up with Space Shuttle accelerating away: The SRBs are jettisoned from the space shuttle at high altitude, about 146,000 ft (45 km). SRB separation is initiated when the three solid rocket motor chamber pressure transducers are processed in the redundancy management middle value ...


16

Wings are heavy. They also add mass to the rocket's structure, because it is loaded horizontally when flying with wings rather than vertically as it is at launch. At the time Energia was developed, control systems were not developed enough for a vertically landing rocket. However, now that we have that ability (as Blue Origin and SpaceX have demonstrated), ...


15

Offered as a supplement to the other answers, here are some data about SRBs thrust profiles and operation. Thrust of a SRB is function of the area of the solid fuel burning, as shown below: You can find here how the space shuttle SRBs are filled: The propellant had an 11-point star-shaped perforation in the forward motor segment and a double-truncated-...


15

The SRBs are pretty close to burnout when they separate: SRB separation is initiated when the three solid rocket motor chamber pressure transducers are processed in the redundancy management middle value select and the head- end chamber pressure of both SRBs is less than or equal to 50 psi. A backup cue is the time elapsed from booster ignition. ...


15

Your assumption that rotating the rocket removes asymmetry is incorrect. The total thrust of the rocket can be visualized as a vector. This vector should point at the center of gravity of the rocket. If it doesn't, the thrust will change the direction of the rocket. It's easy to see that a rocket with 1 booster will not have its thrust vector pointing at its ...


15

I would mention works of Konstantin Tsiolkovsy. I think that he was first, who proposed to use multistage rockets for space flights. His most important work, published in May 1903, was Exploration of Outer Space by Means of Rocket Devices (Russian: Исследование мировых пространств реактивными приборами). Tsiolkovsky calculated, using the Tsiolkovsky ...


14

The From the annotated Apollo 8 Flight Journal, in the notes after the 2:36 mark, we see that the interstage separation happens well after the J-2 engines on the second stage are running: If, at staging, the interstage were to stay with the S-IC, there is a danger that any slight rotation of the massive first stage would cause contact between it and the ...


14

Could a slower or smaller rocket take advantage of lift if all the stages had wings? Wings on the first stage can be useful; the Pegasus air-launched rocket has wings on its first stage that provide some lift. In most cases wings aren't worth using on orbital launchers; they add drag and weight that usually isn't compensated for by lift. Wings on upper ...


13

...is the tank within a tank a sound engineering concept for rocket stages? I take this to mean that you are not talking about pressurant bottles or other small devices submerged in the propellant tanks. Instead you mean the large primary propellant tanks. Then, No, this is not a good idea. It doesn't need to be a double-walled, or "dewar-flask" tank....


13

It's always easier to create a new launcher by making a small modification to a reliable existing launcher. Small solid rocket stages are relatively simple and reliable, so building up a launcher from solids is less risky than the stage count might indicate. Small solid stages are also extremely cheap. The Peacekeeper ICBM is a three-stage suborbital ...


13

The major limitation to the performance of chemical rockets is the amount of fuel they must carry to reach high speeds. To reach higher and higher speeds you need to carry exponentially more fuel, because you have to accelerate all the fuel you need as well as the payload. By splitting a rocket up into stages, you can discard some of the weight of fuel ...


13

There actually aren’t that many different stage counts, but the variation comes because different missions have different delta-v requirements, and different propulsion technologies yield different amounts of delta-v per stage. The definition of “half stage” is not totally clear. It’s mostly used to refer to the Atlas and Atlas II strategy of dropping ...


13

As far as I can tell, the most ever used in sequence is 5 on India's ASLV. It only ever succeeded once, though. Wikipedia mentions a possible 5th stage for Titan IVB but I haven't seen actual references to it (possibly it's referring to the Inertial Upper Stage IUS) Seems that as technology progressed the number of stages has been reduced from the common 3-...


12

Any multi-stage rocket design has to obey three rules to achieve good performance: The fuel should have a high specific impulse. A real rocket will achieve a fixed percentage thereof, depending on structural weight and payload. Each stage's payload (which can be another stage) should outweigh the stage's structure, otherwise most of the energy is wasted ...


11

You can see these in the diagram (from here): Which clearly indicates that these are the 4 'siskin' separation (and ullage) motors.


11

If, counting a stage as a unit of a craft that fires, providing thrust, and all thrust cuts off before a different unit in the craft starts to thrust... The Saturn V - Apollo - LEM stack is 6 stages. The Saturn stack of 3 stages, plus the 2 stages of the LEM, and the single stage CSM pairing. In sequence: Saturn stage I, Stage II, and Stage III, then the ...


10

The current launcher with the highest overall system specific impulse is almost certainly the Delta IV Heavy. As far as I can tell from the list of current orbital launchers on Spaceflight 101, it is the only one that uses hydrogen-fueled engines on all stages. All the others use hypergolics or kerosene or solids somewhere in the stack, which all have far ...


10

The additional speed you can gain from this is too small to be of any use. Here is why: First of all, the stage and payload is not designed to withstand acceleration larger than few g, e.g. 5g. That means, ejection of the first stage must take place over an extended amount of time. Let's assume a time of 1s - at 5 g this gives an additional 50 m/s to the ...


10

In general, no; rockets aren't equipped to pump propellant between stages. You load each stage with enough fuel to do its job, plus a safety margin, and if you discard leftover fuel you congratulate yourself for having built a system with reliable performance, and on future missions, you might load a little less propellant and/or take a little more payload! ...


10

According to The Logic of Microspace: Technology and Management of Minimum-Cost Space Missions by Rick Fleeter (Microcosm & Kluwer, 2000), p.130, the de-facto standard mechanism for separating spacecraft from launch vehicles is the Marman ring. The spacecraft and launch vehicle each have a truncated cone structure, the wide side of each fitted against ...


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