What is Rocket: Definition and 1000 Discussions

A rocket (from Italian: rocchetto, lit. 'bobbin/spool') is a projectile that spacecraft, aircraft or other vehicles use to obtain thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket. Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space.
In fact, rockets work more efficiently in space than in an atmosphere. Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets rely on momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, spin, or gravity.
Rockets for military and recreational uses date back to at least 13th-century China. Significant scientific, interplanetary and industrial use did not occur until the 20th century, when rocketry was the enabling technology for the Space Age, including setting foot on the Earth's moon. Rockets are now used for fireworks, weaponry, ejection seats, launch vehicles for artificial satellites, human spaceflight, and space exploration.
Chemical rockets are the most common type of high power rocket, typically creating a high speed exhaust by the combustion of fuel with an oxidizer. The stored propellant can be a simple pressurized gas or a single liquid fuel that disassociates in the presence of a catalyst (monopropellant), two liquids that spontaneously react on contact (hypergolic propellants), two liquids that must be ignited to react (like kerosene (RP1) and liquid oxygen, used in most liquid-propellant rockets), a solid combination of fuel with oxidizer (solid fuel), or solid fuel with liquid or gaseous oxidizer (hybrid propellant system). Chemical rockets store a large amount of energy in an easily released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks.

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  1. P

    Calculations on a fireworks rocket?

    So I'll soon be writing an assigntment on the physics and chemistry behind firework rockets and that's why I'm here! I've already prepared for the chemistry part but when it comes to the physics part then I am a bit lost. Bare in mind that I'm supposed to learn something new (myself) and explain...
  2. Benjamin Fogiel

    A rocket burns out at an altitude h above the Earth's surface

    Homework Statement A rocket burns out at an altitude h above the Earth's surface. Its speed v0 at burnout exceeds the escape speed vesc appropriate to the burnout altitude. Show that the speed v of the rocket very far from the Earth is given by v=(v02-v2esc)1/2 Homework Equations KEf-KEi=Ui-Uf...
  3. Rick16

    I How to develop the rocket equation?

    I am referring specifically to chapter 3.2 in John Taylor's textbook Classical Mechanics where he develops the equation of motion for a rocket, but not in enough detail for me. Taylor first writes down the change in the momentum of the rocket as dP = P(t + dt) - P(t) = (m + dm)(v + dv) - mv =...
  4. T

    Forces - Space Shuttle Takeoff Calculations

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  5. S

    Force and acceleration of a rocket

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  6. S

    I Multistage continuous Rocket Eqn

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  7. S

    Why are rockets tethered before takeoff

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  8. TheKracken5

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  9. Z

    Model Rocket Launch: Maximum Height, Time, and Duration Calculations

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  10. I

    Solving for Angle to Destroy Rocket Launcher

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  11. Julian Erickson

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  12. DracoMalfoy

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  13. G

    I ##F=\dot{p}=\dot{m}v+m\dot{v}## and Galilean invariance

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  14. S

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  15. P

    B Condensate around rocket spin? Why?

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  16. MathematicalPhysicist

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  17. Roy S Ramirez

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  18. S

    I Could a Smoke Detector Serve as a Sail for Spacecraft Propulsion?

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  19. Islam Hassan

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  20. granzer

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  21. G

    Maximizing rocket velocity - shoot fuel at once, or slowly?

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  22. L

    Relative velocity of exhaust in Ideal Rocket Equation

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  23. isukatphysics69

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  24. K

    When should the drag coefficient of a rocket peak?

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  25. D

    I Why do rockets turn horizontally so soon after launch?

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  26. TaylorLL

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  27. P

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  28. F

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  29. M

    Newton's Second Law Rocket Problem

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  30. N

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  31. Spinnor

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  32. BlackholeGirl

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  33. D

    A rocket needs to hover stationary over the ground

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  34. M

    B Finding the mass of gas ejected by a rocket

    I ran into this problem and need some guidance. Here's the question exactly as it appears in my sheet: "A 500 kg rocket is set for vertical take-off. If the exhaust speed is 1,000 m/s, the mass of gas ejected per second to supply the thrust needed to overcome the weight of the rocket is:"...
  35. Specter

    Finding the net gravitational force on a rocket....

    Homework Statement The Earth has a mass of 5.98 x 1024 kg and the moon has a mass of 7.35 x 1022 kg. The distance from the centre of the moon to the centre of the Earth is 3.84 x 108 m. A rocket with a total mass of 1200 kg is 3.0 x 108 m from the centre of the Earth and directly in between the...
  36. U

    How can I calculate the required thrust for my model rocket design?

    Hi, I am currently working on a Hybrid Rocket which uses fuel grain as 3-D printed ABS and oxidizer as N2O, but i need to calculate some basic parts such as required thrust to reach specific altitude. I want to calculate the required thrust to reach 1.5km for 10kg rocket with 7cm radius. It will...
  37. E

    Rocket momentum through a cloud of particles

    Homework Statement A cylindrical rocket of diameter 2R and mass M is coasting through empty space with speed v0 when it encounters an interstellar cloud. The number density of particles in the cloud is N particles/m^3. Each particle has mass m << M, and they are initially at rest. Assume each...
  38. K

    Lift coefficient of rocket at vertical flight

    Hi, I am looking into aerodynamic parameters for rockets (ogive nose, cylindrical body of different diameters, four fins at bottom) and have a question about the lift coefficient. If a rocket is launched vertically, with zero incidence angle and wind, would that result in a very small lift...
  39. P

    I Is it possible to use the vacuum to launch a rocket?

    Hey I'm new to Physics. I have a question. Is it possible to use the force generated when air entera a vacuum tube to launch something into space? Can anybody throw some light on this in simple words please. Thank You.
  40. T

    Deriving the relativistic rocket equation

    Homework Statement so i read morin's derivation of rocket equation propelled by photons now i want to try for relativistic mass ejection but i am having some problems let subscript e denote quantities of ejected material and subscript of r denote quantities of rocket Homework Equations ## P =...
  41. chandrahas

    Can Smaller Rockets with Less Fuel Mass Lower the Cost of Space Travel?

    Rockets are quite expensive and it takes about 2000 to 10000 dollars to place 1 pound into orbit. So I was wondering: Is the size or the fuel mass of a rocket a big concern or will it be of no help economically if we make smaller rockets with less fuel mass for the same amount of payload...
  42. C

    Rockets approach: time they meet w.r.t. rocket A?

    This is an IB problem from November 2017. Two rockets are separated by 6E8m (2 sec x c, or two light-seconds), w.r.t. Earth, and are approaching Earth from opposite directions. Rocket A approaches from left at 0.6c. Rocket B approaches form right at 0.4c. According to Earth, when do they...
  43. karush

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  44. T

    Regression rate of fuel in rocket nozzle

    So we have: stability for n < 1 instability for n > 1 I assume to get the time growth, I have to integrate the above first eqn. However I also get ln(δpc) at the LHS from the integrating. However the above equation for time growth removed that ln(δpc) and thus I can't...
  45. Dr Wu

    B Discovering the Correct Rocket Mass Ratio: A Guide for Beginners

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  46. yrjosmiel

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  47. I

    A rocket moving vertically -- Find the cosmonaut's weight

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  48. Franz Rojas Ayala

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    Greetings All! I am not sure if this is the correct place to post this, but I think that since rocket fuel is considered a chemical reaction, this sections seems appropriate. Right, to the topic. Me and my team from the spaceflight society are looking forward to building a hybrid rocket fuelled...
  49. M

    I on my rocket engine thrust equation

    I have been working on a rocket engine and I have cad models and everything and I am getting ready to build it. Then, I was running over the numbers one more time and I realized that the thrust I was getting was completely different from what I should have been getting. The big problem is the...
  50. J

    Calculating Water Rocket Height from Hangtime | Formula and Explanation

    Homework Statement We are doing water rockets and I don't know how to calculate the height it went from it's hang time. It's total hang time was 7.35 seconds, and I know it's vertical acceleration was -9.8m/s^2 from gravity, and I'm assuming I need to first find out it's initial velocity, since...
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