Why do rockets have multiple stages

Now the air density is much lower so you can accelerate as quickly as you want and reach whatever speed is needed. A third stage might be used to fine-tune the speed and position the craft in whatever orbit or trajectory is needed.

Furthermore, because the air pressure decreases with altitude, the ideal nozzle shape is not the same at low altitude as high.

An overexpanded nozzle at sea-level can be an underexpanded nozzle at altitude resulting in a very narrow range where it is operating at maximum efficiency. You could design adaptive nozzles but they are very heavy and expensive, and they can't really be made to service the full range. Or, you could have stages with fixed nozzles that are designed to be as efficient as possible over the range of altitudes serviced. Both of which lead to a much more efficient motor and thus less fuel.

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Active 8 years, 10 months ago. Viewed 13k times. Wouldn't a single stage with the same amount of fuel weigh less? Note I would like a quantitative answer, if possible Improve this question.

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Lets take the last stage of the rocket. The study of rockets is an excellent way for students to learn the basics of forces and the response of an object to external forces. All rockets use the thrust generated by a propulsion system to overcome the weight of the rocket.

For full scale satellite launchers , the weight of the payload is only a small portion of the lift-off weight. Most of the weight of the rocket is the weight of the propellants. As the propellants are burned off during powered ascent , a larger proportion of the weight of the vehicle becomes the near-empty tankage and structure that was required when the vehicle was fully loaded. In order to lighten the weight of the vehicle to achieve orbital velocity , most launchers discard a portion of the vehicle in a process called staging.

There are two types of rocket staging, serial and parallel. In serial staging, shown above, there is a small, second stage rocket that is placed on top of a larger first stage rocket. The first stage is ignited at launch and burns through the powered ascent until its propellants are exhausted.

The first stage engine is then extinguished, the second stage separates from the first stage, and the second stage engine is ignited. It can be used both in high-thrust chemical propulsion for fast time-sensitive maneuvers, and The finding opens up a new window to search for exoplanets at greater distances Did Venus Ever Have Oceans?

Now an international This is the first time this detection method has been These rocky worlds have an ultra-thin outer brittle layer and little to no topography.

Such worlds After studying the chemical composition of 'polluted' Scientists have developed a They argue that Algol has many companion stars which have not been detected from earlier