What is Thrust: Definition and 344 Discussions

Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system.
The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust.

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  1. J

    How to Achieve 2500lbs+ Thrust: Ducted Fans, Turbofans, or Other Methods?

    hi what is the easiest way of achieving 2500lbs+ of thrust, is it by using a ducted fan/propellors or turbofans? first i also considered valveless pulse jet engines but i don't know if you can get enough thrust from them. also are there better ways than the ones i mentioned? help and...
  2. M

    Thrust Vectoring - Jet Aircraft

    To go off on a tangent - I am watching a discovery channel program about the F22 fighter. A pilot (who looks about 15) is describing how the aircraft's engine is unique because it can vector thrust for manouverability and can fly supersonic without afterburner. I suppose that's true now that...
  3. S

    Calculate Rocket Thrust Force of 90g Rocket Achieving 80m/s in 3.0s

    A toy rocket, of mass 90g, acheives a velocity of 80m/s after 3.0s when fired straight up. What average thrust force does the rocket engine exert? I dont' know what formula to use for this
  4. K

    Calculating Sam's Jet Ski Coasting Distance and Top Speed

    Homework Statement Sam, whose mass is 75 kg, takes off across level snow on his jet-powered skis. The skis have a thrust of 200N and a coefficient of kinetic friction on snow of 0.10. Unfortunately, the skis run out of fuel after only 10 s. a. What is Sam’s top speed...
  5. J

    Magnitude of thrust of rocket (q50)

    For this question: http://tinyurl.com/ynkshx I just use ma=(3000-800)*20 =44kN to get the answer, and the answer is correct. and haven't make use of thrust=exhause velocity * dm/dt or change in velocity=exhause velocity*ln|initial mass/final mass| So, just want to confirm am I solved...
  6. M

    Wheels, camber thrust and slopes.

    My understanding of 'camber thrust' is that when a wheel rolls with it's axle not parallel to the ground, it will act as a rolling cone and try to follow an arc around the point at which it's rotation axis intersects the ground. I've seen this effect on flat ground for instance being able to...
  7. T

    Calculating Aircraft Speed: Weight vs Thrust

    How do you figure out how fast an aircraft can travel, in Km/H ,if given the weight and the thrust. For example: the aircraft weighs 3,100 lbs and has 20,000lbs of thrust i thought it was 20,000/3,100= 6.5m/s/s which would be 23km/h ? but a 747 weighs around 850,00 lbs and has...
  8. T

    Calculating Thrust & Force During Space Shuttle Liftoff

    At liftoff, a space shuttle with 2.0 x 10^6 kg total mass undergoes an upward acceleration of 0.60g. Find the total thrust force developed by its engines?What force does the seat exert on a 60-kg astronaut during liftoff? Thank you for helping with the problem
  9. S

    What PSI Results from an 8 lb Thrust in a Closed Container?

    If I have a RC electric ducted fan engine blowing at 8 lb of thrust into a closed container, what PSI would it be inside of the container, (when the engine is runny continuously)? Thanks
  10. B

    Offcentre thrust, spinning spaceship

    This isn't really an aerospace problem, just basic physics. Been thinking about hardSF spaceship designs. Could someone comment on my logic and maths? The basic plan has a nuclear powerplant and a habitable section connected by a long tether. the whole contraption spins to provide cetrifugal...
  11. H

    Calculating Flight Angle and Thrust Force of a Gliding Plane with Engine Failure

    Homework Statement A plane of mass 1220 kg has an engine failure when flying with an airspeed of 138 km/h at an altitude of 2960 m on a calm day. It then glides at a constant glide angle (which is the direction of flight below the horizontal) 6.80 degrees towards a safe landing at this...
  12. A

    Thrust Vectoring Design Project - Unleash Your Ideas!

    Hey people, I've started a group undergrad project that involves designing, and probably building I hope, an addition to a small jet engine, for thrust vectoring. I got a few ideas already, but of course a few more from all the jet enthusiasts out there won't hurt. :smile: More specificly we...
  13. V

    Calculate Thrust Force of Aero Modeling

    thrust calculation... am doing an analysis with the aero modelling as part of my project... i need to calculate the thrust force of the aero...i have the propeller diameter and rpm...i need the air velocity that comes out from the propeller to calculate the thrust... but i don't know how to...
  14. P

    How Does Thrust Vectoring Work?

    hi frnds,, i want to present a seminar on thrust vectoring,but apart frm very superficial stuff,i am not getting anything frm d net.can neone help me regarding dis..
  15. X

    Calculating Thrust Force of a Model Rocket

    1. Homework Statement A model rocket of mass 4.8 x 10^2 g accelerates vertically upward at 34.m/s2. Calculate the thrust force applied by the rocket if the air resistance is 2.4N 2. Homework Equations F=ma? 3. The Attempt at a Solution Converted into SI rocket mass = 0.48g...
  16. N

    Can anyone confirm this equation? Prop. Thrust

    can anyone confirm this equation?? Prop. Thrust there are many websites that calculate propeller Thrust, and they never show any formulas for it... and i somehow manage to find the formula from NASA website, but when i compare the result with each other, i get totally different numbers...
  17. B

    Calculate Jet Engine Thrust for 800 kg Jet Takeoff with 4 m/s^-2 Acceleration

    Homework Statement Calculate the engine thrust required to produce an acceleration of 4 m/s^-2 in a jet of mass 800 kg as it takes off along the runway. The air resistance is 500 N Appreciate if anyone can check if I have used the correct equation, and my answer. Homework Equations F - R...
  18. M

    What Torque and Power is Needed to Spin a Propeller at a Given Speed?

    :confused: I am working on a project where I need to understand flight physics. I am having some trouble getting the whole torque vs power vs thrust thang. I'm basing my project off a existing ultralight, the LightSport Ultra from Free Bird Innovations. Here are the specs: 530lbs...
  19. A

    S: Thrust vs Gravity & F22 Raptor

    The F22 raptor has an approximate 2:1 thrust to weight ratio. It can climb vertically and stand on its tail in a hover. Vertical acceleration is given by: Thrust - Drag - Weight = mass * acceleration (aka gravity). The opposing force to thrust involves an acceleration due to the force of...
  20. D

    How does thrust affect takeoff performance for the F-14 tomcat?

    How does thrust work? Another question about top gun, I did some research on the F-14 tomcat and the Max takeoff weight: 72,900 lb, how does this relate to the amount of thrust needed. The turbofans generate 13,810 lbf dry, 27,800 lbf with afterburner (72 kN / 126 kN) each. I don't understand...
  21. C

    Can I Calculate Thrust for Different Pump Sizes?

    Hello All, I am building an ROV and would like to use bilge pumps for the thrusters. I would like to calculate the thrust that a prospective pump is going to create so as to decide which pump to buy. I know that the pump can output 1250 gallons per hour and has a nozzle with a 2" diameter...
  22. Labguy

    How Does Weight and Thrust Affect Rocket Acceleration and Velocity?

    Don't laugh guys, but I'm familiar with a lot of general astronomy stuff but my question will seem very stupid.,:cry: About rockets, etc. I was thinking today (dangerous) and realized I don't know the answer to: Samples: (hypothetical) 1. Space shuttle and all weighs 5 million pounds and...
  23. G

    Finding Maximum Thrust: Flow Rate, Velocity, Area & Pressure

    I've been thinking about how to calculate how to find maximum thrust. But I can't find any equations for flow rate and pressure and area. I know that thrust is a force and force is mass x acceleration. But I don't know how id get an acceleration. There's an exit velocity at the nozzle of the...
  24. kach22i

    Hovercraft Thrust - Velocity verses Static Pressure

    I am trying to get my mind around concept of Velocity verses Static Pressure in simple terms. Using a hovercraft as our topic model, I understand that high static pressure is desired for the lift system, and high velocity for the thrust system. Therefore it's nice two have two systems one...
  25. S

    Formula to calculate Rocket Thrust

    I'm tyring to find the formula that is used to calculate rocket thrust. Thanks Serena
  26. E

    Wheres the reaction in an ice skater who thrust sidewards with parallel skates

    when you walk the reaction of your thrust is the Earth going very slightly in the other sense but how can an ice skater that having the skates perfectly parallel while thrusting pushes sidewards and advances forward besides taking into account that being the skates parallel the longitudinal...
  27. R

    Calculating Thrust from Propellers for Model Airplane

    can anyone tell me how to calculate thrust for a model airplane. i know the propeller size and pitch and also the engine power and RPM. Any help would be much appreciated regards reg_ram
  28. recon

    Find Thrust of Rocket: 1.9x10^3 kg with 2.5x10^3 m/s

    A space-research rocket stands vertically on its launching pad. Prior to ignition, the mass of the rocket and its fuel is 1.9 X 103 kg. On ignition, gas is ejected from the rocket at a speed of 2.5 X 103 m/s relative to the rocket, and fuel is consumed at a constant rate of 7.4 kg/s. Find the...
  29. N

    Solving the Force of Reverse Thrust on Mars' Polar Lander

    Hi guys… there was a lot of arguing in my class when my teacher gave us this one assignment question that I’m not too sure about. It goes as follows… A Polar Lander somewhere above the surface of the Mars is landing with a deceleration of 23m/s^2. If the Lander itself had a mass of...
  30. tony873004

    Calculate Mass Exhausted Per Second from Space Shuttle Thrust

    At launch, the space shuttle’s engines develop 3.0 * 10^7 N of thrust. If the speed of the exhaust gasses is 15 km/s, what mass of gas is exhausted per second? F=ma\Rightarrow m=\frac{F}{a} kg=\frac{kg\cdot m/s^2}{m/s^2} kg=\frac{kg\cdot m/s^{\rlap{--} {2}}}{m/s^{\rlap{--}...
  31. E

    Thrust Vectoring: Explained & Applications

    What is Thrust Vectoring and its applications? Does anyone who can explain it ?
  32. M

    Find Thrust of a Model Rocket Motor

    I was wondering how I could find out the thrust, any any other interesting facts about my model rocket motor, but maily the inpulse/thrust. Here is what I know/can measure: -mass of propelant and whole motor assembly -type of propelant (aswell as full expected reaction of propelant as it...
  33. M

    Calculating Thrust Speed in Space: 10 Tons, 100 kg Thrust

    I am playing around here at home and was thinking about how thrust works. This is assuming we are in space... Let's say I had a mass of 10 metric tons (including the engine) and an engine that produces 100kg of thrust (I don't know if you would refer to it in seconds, minutes, or hours). But...
  34. N

    Impulse thrust calculations from pressure bottle

    Hi, Am wondering how to calculate the thrust and impulse thrust for gas escaping a pressure bottle - ie a scuba tank or the like. My maths is a lil shady so go easy on integration and such. Like say if I wanted 1MJ of energy output - what size bottle at what pressure with what nozzle...
  35. C

    Jet Engines: Momentum, Pressure and Thrust

    I am just about to start my Aero. Eng. degree in a few days time and am currently ploughing my way through all the reccommended reading. A lot of it either gives textual explanations (rather than mathematical proofs or both) or gives a brief description, glossing over anything that may be...
  36. A

    A possible way to produce thrust from ZPE?

    Take two plates of a suitable material, and attach them at one end at a 90 degree angle, such that they form a V shaped assembly. The plates will block some of the vacuum flactuation frequencies inside the V, so a Casimir-like force will appear on the two plates. But since the plates are at an...
  37. wolram

    Calculate Thrust Needed for 300lb Vehicle in 10 Seconds

    Sorry if this question is on the basic side, but i need some way of calculating the amount of thrust needed to propel a vehicle a quarter of a mile in 10 seconds. this vehicle is not built yet, but will be as light as possible, at a rough guess 300lbs with driver.
  38. S

    Calculating Thrust for a 1.5 HP Motor: Tips for Project Hovercraft

    Does anyone know how to calculate the vertical thrust of 1.5 horsepower motor? I need some calculations for a project hovercraft and am wondering how much thrust is needed to lift 200 lbs. Also is thrust affected by fan blade size? Any help is appreciated, Thanks!
  39. K

    Thrust of a rocket at lift-off

    Need help with an ancient A lvl question. Just can't visualise the whole process even though I drew out the diagram A space research Rocket stands vertically on its launching-pad. Prior to ignition, gas is ejected from the rocker at a speed of 2.5x10^3 ms^-1 relative to the rocket, and fuel...
  40. N

    Thrust & Pressure: Physics Simulation for Hovercrafts

    Hi there. I am trying to create a realistic physics simulation for testing thrust based hovering vehicle designs and i am stuck. I understand basic physics like moment of inertia and forces and the like but thrust is something i am having trouble with. Currently if i place a vertical...
  41. F

    How Do I Calculate Thrust for My Hovercraft Project?

    I'm buildind a hover craft for a Physics project. I have built it, and am need ing to calculate how much thrust my leaf blower has to put out in order to lift me up, how do i do that? Same thing with forward movement, how do i figure out how much thrust it will take to move me forward if I'm...
  42. N

    What is the thrust of the engine?

    A rocket is moving away from the solar system at a speed of 6.0 x 10^3 m/s. It fires its engine, which ejects exhaust with a speed of 3.0 x 10^3 m/s relative to the rocket. The mass of the rocket at this time is 4.0 x 10^4 kg, and its acceleration is 2.0 m/s/s. A) What is the thrust of the...
  43. K

    What is the best way to calculate power and thrust for model aero engines?

    Hi I am helping someone with the aerodynamics to program a model aircraft flight simulator however my aero study has been aimed at radio controlled gliders so I'm a bit lacking on the power side of things. We need to relate power and thrust for various model aero engines. I did a static...
  44. M

    Greatest Thrust of All Rocket Engines Constructed

    Hello, I'm interested in knowing which is the rocket engine of all that have been constructed to date that has major thrust The first in my list is the RD-170, that was used in the Energia launch vehicle, and is still used in the Zenith rocket. The RD-170 rocket engine has a nominal thrust of...
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