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.
So according to this if you need a force that can lift a human and even an extremely ultra-light craft (1500 N) and have a velocity of 200 m/s you can eject extremely small amount of fuel through the nozzle: 0.0007 or less kg per second for as long as you're using 15 MPa pressure which is doable...
Hi all,
I'm writing a technical manual for a starship in a science-fiction series I'm working on, I wanted to check with some folks here to make sure my calculations are correct concerning the ship's engine thrust.
The ship has a fully-loaded mass of 5 million metric tons. Using its...
I'd like to design a ducted fan capable of generating 800 N of thrust. Though I can do fairly high level math, I just really don't even know where to start in calculating (or at least relatively accurately estimating the thrust generated by a propeller, particularly a ducted one (as I understand...
The picture above has thrust density as a column and I am not too sure what that is. Can anyone explain to me what the difference between thrust and thrust density? Thank you for your answers!
I read that a thrust augmentor can significantly increase the efficiency of a jet engine (http://www.pulse-jets.com/phpbb3/viewtopic.php?t=931). Now from my understanding, the thrust agumentor is sort of like a ramjet. Only, in this case, the cold air is being sucked in along with the hot air...
Hello, all -
A question has come back to tickle my brain.
Could a vehicle with less than 1G of thrust manage to escape the Earth's gravity well?
I'm thinking something like Space X's Falcon 9. As it landed, with just a little more thrust, it could go back up again, I would guess. So, if it...
Hi,
I am currently studying aviation engine outputs and to make my study linear in comparative analysis with standard Automotive engines I need some expert help.
Can anyone help me drive precise equations to convert:
1. Engine thrust in Kilo Newton into Horse Power and Watts
2. Engine thrust in...
Trying to remember some basics. I know the thrust of a jet engine. I'm thinking about equivalent HP. I can establish HP at a given speed, but what about while accelerating? I will display my ignorance here :(
Power for static, non accelerating flight:
Power = [Thrust x Airspeed]
Thrust...
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.
Can someone clarify this for me-- how is the motion of the center of mass unaffected by internal forces, as is stated towards the end of the paragraph in the picture I've provided. It seems to me that motion of the center of mass directly affected by these internal forces. Specifically, the...
Homework Statement
Consider an aircraft turbine as in the figure below. In the reference frame of the turbine, air of density ##\rho_0## comes into the turbine with speed ##U_0## through the entrance with cross sectional area ##S_0##. In the combustion zone, air is mixed with the fuel and...
My knowledge suggests when gasses are heated rapidly, they also expand due to the new energy in the gas.
Is it possible to create a thruster that is able to lift 10kg via electric heating?
The thruster would allow cold air to enter the chamber, where it would then be super-heated & ejected as...
Whilst I was thinking of hydrogen combustion jet engines. I thought of a little idea... What if you could create thrust with water vapor the same way you could with the exhaust gas of a jet engine. (NOTE: I have no experience in engineering and I only have a mild interest in it).
If this is...
I am working on a range extender for full size electric aircraft. It is a turbine located under the cowling, protruding only 8 inches. On my full size static model, the turbine can produce 600 watts with the prop blast v measuring 38 mph. If we could fly the plane (we can't, no wings) at 80...
[Mentors' note - this post has been edited to remove some discussion of the EM-drive. See https://www.physicsforums.com/threads/nasas-em-drive.884753/ for our current policy with regard to em-drive discussions]
Hello.
Imagine a closed box with reflecting walls. Inside you have two antennas...
This is not a homework question, I'm just curious.
Suppose you had a sailboat sailing on calm water.
Let's say the sailboat is capable of sailing at 10 knots under the current wind conditions using only its sails.
Now say the sailboat had a small propeller motor that was capable of propelling...
1. Homework Statement
Hi. This is a problem related to designing a RC hover craft. We are given a datasheet for a fan used as thrust.
http://imgur.com/6liZSid Sorry image post no working, url: http://imgur.com/a/6XLwL
We have to approximate the equation to a straight line through the curve...
Hi,
We have a canister at a set pressure (4500psi) full of compressed air. A single stage pressure regulator is fitted to the canister that reduces the outlet pressure to 850psi. The flow from the regulator is then used in a divergent nozzle to create a thrust force capable of lifting a small...
Hello folks! I hope all of you are having a good day.
Here is my question:
How can I calculate the thrust needed by a marine propeller to move a body of about 120 kg? Also, as long we are talking about marine propeller, our propulsion is in water and not in air, so what about the rpm? Are they...
Hello, I was curious about how to calculate how fast the escape velocity of hydrogen out of a tube/cylinder would be. Once end of the cylinder is closed, the other is open, obviously.
Assume the cylinder is full of hydrogen at 1 atm. My thought is that you could use PV=NRT to calculate the...
Homework Statement
The lorry starts from rest with an acceleration of 2 ms-2.
What is the effective thrust is being exerted?
Homework Equations
acceleration=2 ms-2
starts from rest so initial velocity =0 ms-1
The Attempt at a Solution
F=ma
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Does the weight of a propeller have any effect on the thrust provided? For example, if there are are two propellers of the same size same speed but different weight, would the one with more weight have a greater or lesser thrust? also would effect do the number of blades(faces) have on the way a...
Moved this question from the quantum physics section to this section, since... Well it fits this section better since electrons apparently do obey conservation of momentum in the 'classical' sense.
Why not produce thrust in microgravity with electrons? Plenty of harnessable electricity in...
Hi,
First-timer here! I'm designing a physics project that involves pumping a certain pressure of air into an empty bottle.
SETUP: The bottom of the bottle has a small hole through which a thumb tack fits tightly; the top (cap-side) has a valve through which the air is inserted. The bottle is...
I am planning to build a Hero's steam engine or Aeolipile. This is the steam engine invented by the Greeks about 2000 years ago. It is attributed to Hero or Heron (10-70 AD) but was also referred to in 15 BC. My grandfather build one for a show. I have inherited it but rather than try to repair...
Homework Statement
Hi. I'm in high school physics, and as I'm only 2 months in, I still don't know much. We launched a model rocket as an experiment and I need to find the thrust after adding 100g of mass to the rocket's body.
The engine is an Estes A8-3. My teacher told me that its thrust is...
Hello everyone,
I'm attempting to determine the impulse that can be generated by expelling compressed air from a pressure vessel stored aboard a moving craft through nozzles in the nose of the craft. The vessel has a forward momentum of roughly 2,000,000 Ns.
EDIT: For semantics sake, consider...
Hi, I was wondering whether anyone can help with a question I have about the forces acting on a car wheel and the forces the wheel induces on the ground surface.
The way I understand it, a car wheel traveling on a flat surface has the following forces acting on it:
-vertical force due to the...
Greetings all,
I am trying to build a sliding gate operator. I have this wiper motor which says, 24v dc, 64rpm, nominal torque- 4Nm.
Max weight of gate to be 400kg, sliding on a steel rail (Not sure how to consider rolling resistance or Co-eff of friction) . Max pull force to be achieved by...
Hello,
I am trying to build a personal (one-manned) propulsion system that will allow individuals to fly above the trees, preferably fast, and for long amounts of time. I plan to do so using propellers. The power will need to be plentiful and long lasting. These are some options that I am...
I would like to know how does the general equation about propellers thrust look like. How should I calculate the force to be big enough for a lift off? The object (a drone) is located in a spacecraft, which means the gravitational force is 0. Are there more variables that I should concern about...
Good day Geniuses.
im building a drone prototype for an agricultural project.
approx. weight will be 600 lbs, using my own 8 rotor design.
trying to determine rotor size and motor power required to fly such a device at 30 feet.
would also be interested to determine an approximate wind speed...
Homework Statement
I am trying to derive the formula for time varying thrust given that I know the initial mass/volume of water in a water rocket. Knowns will include initial pressure, initial volume of water, and nozzle cross sectional area.
Homework Equations
Bernoullis equation: (p/ρg) +...
Homework Statement
A boat moves across the water at a constant 30 mph towards the west. If the motor is generating a thrust of 500 M then the force of friction on the boat must be...
a. 500 N to the east
b. 500 N to the west
c. less than 500 N to the east
d. less than 500 N to the west...
Homework Statement
vertical rocket start:
F_thrust (simple F)
Δm (fuel consumed per Δt)
m_tot
the relative velocity of the gas w is demanded.
Homework Equations
vgas=v+Δv+w, w<0
m(t)=mtot-Δm*t
The Attempt at a Solution
rocket acceleration.
F-G=m(t)*a(t)
a(t)=F/m(t)-g
first...
Okay, first of all, I'm not very good at maths, so I will have to talk in programmer terms here. I have the following issue:
A small rocket is moving in space, and I want it to move to and stay at a location in space, similar to a quadcopter.
No as far as I see it, I have the following variables...
I'm working on a kinda-sorta confidential device. I would like to know how much psi is required to lift approx. 400 pounds 120m (about 393ft and 8 13/32 inches) into the air. The thing I'm working on is still in the designing stage, so don't worry about the specifics of individual thrusters and...
Hi there. I have come to this forum to try and find someone able of helping me with some (im sure) basic Physics. I'm trying to work out the Physics behind the Prosthetic carbon fibre legs that Oscar Pistorius uses, a diagram would be incredible! I want to know what calculations would be...
Hey everyone,
I have a theoretical problem. I have a box. Rounded off but not greatly aerodynamic. It is 800 kg including propulsion. I have wings with a max of 2.25m long and a max width of about 2m wide. This is the length of the box. I need to know how fast the box needs to go with those...