Thrust Definition and 333 Threads

I wanted to use a disco ball motor to rotate an object weighing approximately 125lbs. The motor was rated for 25 lbs. Motors rated for higher weights had much higher costs, beyond what would be practical. It was suggested that using an arrangment like the one described in the attached pdf would...

Does anybody know some ballpark figures for thrust to power, Newtons per watt, ratios for modern propulsion systems, mechanical drive train ie cars trucks, propeller driven craft, boats planes, and rockets. I've found one reference that states the F/P ratio for a DC-9 jet engine is 0.016 N /...

Homework Statement i built a boat for physics class with an electric motor. we are asked to calculate the thrust of the motor and the resistance of the hull using Newton's second law of motion. i conducted an experiment (to collect data in order to find resistance) that required a string...

Hello all, Just wondering if anyone can give me some guidance on this: the problem is an apparent contradiction I've stumbled upon. Some sources (e.g. www.braeunig.us) suggest that maximum thrust is achieved when Pe=Pamb (i.e. exhaust pressure = ambient pressure)l whereas others say that...

Hi I have been trying to figure out the force experienced by individual components of a gas turbine engine. Generally, the thrust of the engine is defined / calculated as the change in the momentum of the fluid. Usual formula is mass flow X (C_jet - C_intake) + the pressure difference in...

Hi there - I built a small electronic turntable with the following components: 1- Arduino 2- Sparkfun easy stepper driver 3- Stepper motor 4- Servocity set screw hub. 5- Thrust bearing from mcmaster-carr (square turntable, found here http://www.mcmaster.com/#swivel-plates/=eltxix) 6-...

I need some information and guidance on how to calculate net lift and thrust produced by wings of an MAV(micro air vehicle) which are flapping and active pitching. I know only about one method which is the Blade Element Analysis, but it is just an approximation and doesn't accounts for...

Hi I am building a quadro-copter, and I'm curious to know how i can calculate the thrust generated by a motor/propeller combo. The motors are brushless electric motors for which i know the max RPM. The propellers are two bladed for which the diameter and pitch are known. Is there a simple...

Homework Statement [PLAIN]http://img714.imageshack.us/img714/8184/rocketj.png I am not sure if the problem has enough information to find. However, i tried some of the works. g=10m/s2( i use gravity as 10 .) Homework Equations No idea... The Attempt at a Solution I am...

i want to know the relation between thrust/rpm. what is the formula to calculate it?

I want to make a quad rotor UAV. i studied a lot but i did not find how static thrust is being calculated. In physics forum i have found an equation which is given below but i can not understand what is 'frac' and 'rho'. Equation is: T=\frac{c_T}{c_p}\frac{P}{nD} Where: P = power (ft-lb/s...

I'm a math guy taking engineering classes more or less for fun, so some of the stuff I should know I probably missed in a basic dynamics class. I feel really dumb that I can't figure this out. I'm in a vehicle dynamics class and I have to calculate the constant thrust T for the following...

For example then talking about the rocket the trust is: F_thrust = u*dm/dt where u is speed of the gases relative to the rocket, and dm/dt rate of change of ejected mass of gases. Now if the rocket is being launched vertically so force of gravity acts upon it and: F_net = F_thrust -...

First of all this is not a perpetual motion machine and is not the previous U Reusable Fuel Transit Drive I designed earlier. This type of transit drive, which doesn't reuse fuel, works in theory by having two combustion chambers and their respective exhaust nozzles positioned parallel to the...

Is there any Advanced concepts , theories out there; Instead of the combustion. We're not limited ; direct conversion of electricity to thrust is here, so if you have any ideas leave it here, *Electricity-conversion- microwave- to thrust (radiation pressure difference) *Electricity-conversion-...

Horizontal water rocket thrust calculations - HELP! Hi All, I want to accelerate a 90kg body at a rate of 2 m/s2 for a period of 1 second using thrust developed from a number of water bottle rocket jets. Based on the drag coeff calculated I believe I need to develop 190N of force. A...

Disclaimer: I'm not a physicist nor do I know calculus, but I'd appreciate a little guidance with a concept I've been thinking about. I know one would usually pay for this kind of advice, but since it's just for entertainment, I'm not asking for any equations to be solved, unless you're in the...

first off, thanks to any that respond w useful info :) the end answer i need to find on the first topic is how many atoms of hydrogen are required to propel a mass of "x" at an acceleration of 1g in space (assuming no gravitic influence) but i would settle for how to figure out what the fuel...

Homework Statement I would like to be able to calculate the energy use per second, to maintain a rocket of given mass, at zero velocity, i.e. hovering, at, say, sea level. Homework Equations I have Thrust = Force times velocity, but can't work out the energy due to the velocity of the...

Dear native English-speaking professionals! I am making up an info table concerning railcar operating loads, and I’m a bit stuck with one term - I’m not sure if it sounds comprehensible enough to an Enflish speaking reader. Here is the part I’m struggling over: "Load description: cargo...

Can sound from any source create thrust?? hi there, since I'm new to this forum, i don't know whether this the place to put up a question like this...! if I'm wrong my sincere apologies let me head to the topic now... i wanted to whether the sound waves created form any source can...

Hey guys! I'm new to the forums here and was after some help for something that I am currently working on. I need help converting cfm to thrust, i have found the formula though i can't get my head around it. Here it is: CFM = Cubic Feet per Minute = Volumetric Flow Rate Mass Flow Rate =...

Hi! I have a question about how thrust is made from a turbojet engine. The most common explanation goes something like "As the fluid gets accelerated there is a net force". I don't think this explanation is either good nor rigorous. The force that accelerates the fluid is, of course, the...

Homework Statement Sam, whose mass is 71.0 kg , takes off down a 51.0 m high, 11.0 degree slope on his jet-powered skis. The skis have a thrust of 210 N . Sam's speed at the bottom is 41.0 m/s . Homework Equations I'm not sure which equation(s) to use. Net Force= ma and some kinematic...

hello a plane would need a thrust to weight ratio of 1 of fly straight up without losing speed but how can a plane in level flight maintain its altitude with <1 TWR since to maintain a level flight you need to have lift = weight so your engine needs to supply enough power to generate...

Imagine there are 2 space-probes in space. Both of them start their engines in the same time. The first space-probe has a very low level of thrust but a very high specific impulse. The second space probe has a very high thrust but a very low specific impulse. Both of them have an equal amount...

This is not my homework this is just a random thought. Say you have a 1 kg helicopter hovering in midair. The question is, given perfect efficiency, how much power is it using to hover? My approach is to think of the given information first. We know that g= 9.8. So you have a 1 kg mass that...

hello guys iam ganesh..iam a mechanical engg student and iam new to this forum and this is my first post here.. these plans are uploaded by eric and technical help given by metiz..take a look at it..

Sorry; this is like soooooooo hard Homework Statement A car with a mass of 1500 kg has en engine which can produce 4000N of thrust. Assume that the air resistance on the car is a constant 500N. If the car starts from rest, how fast will it be moving after 10 seconds. Homework Equations...

can anyone help me out to calculate the thrust when helicopter takes off with mass of fuel?

Can anyone help me? I'm doing a question on aircraft propulsion technology and I'm stuck. The question is: 'If the mass of air through a propeller is 1000 Kg/s, the aircraft's velocity is 100 m/s and the slipstream velocity is 120 m/s, calculate the thrust? Attempt at answer...

Homework Statement What is the average acceleration until burnout of a spacecraft engine creating 53.2MN of thrust with a propellant velocity of 4.78km/s? The initial mass is 2.12x10^6 kg and final ,*** is 7.04x10^4. Homework Equations 0 = m(subscript_f)v(_f) + m(_r)v(_r) The...

Hi everyone, as you can tell from the title, I'm having some trouble understanding thrust. Here's what my textbook says: "m(dv/dt) = -u(dm/dt) [where u is the speed of the exhaust relative to the rocket and dm/dt is negative] Now dv/dt is the acceleration of the rocket, so the left side of...

Homework Statement A polaris missile has a mass of 1.4 x 10^4 kg and its engine has a thrust of 2 x 10^5 N. If its engines fire in the vertical direction for 1 min starting from rest, to what vertical height would it rise in the absence of air resistance? Homework Equations F=ma W=mg...

If a rocket doubles it's relative exhaust velocity while do tripling the "burn rate" of fuel, the thrust... A) doubles B) Triples C) increases 5 times D) increases 6 times E) none of the above! Thrust=dv/dt=lVe(dM/dt)l I just plugged in 2 for V and 3 for dM and 1 for dt giving me 6

Homework Statement The idling engines of a landing turbojet produce forward thrust when operating in a normal manner, but they can produce reverse thrust if the jet is properly deflected. Suppose that while the aircraft rolls down the runway at 150 km/h, the idling engine consumes air at 50...

1. A solid bar of length L = 0.5m and with W = 0.1m weighs 2kg. It also has two constant-thrust rockets attached on either end. Each rocket is small enough to be considered a point mass of 0.25kg. If the bar is initially at rest and in two seconds after the rockets are fired it achieves a...

Greetings, I want build an interstellar probe. Given the power of the laser beam and the mass of a mirrored object a laser is shining on, how does one calculate the thrust or acceleration? Thanks

Homework Statement The first stage of a Saturn V space vehicle consumes fuel at the rate of 47400 kg/s, with an exhaust speed of 2820 m/s. The acceleration of gravity is 9.8 m/s2 . Calculate the thrust produced by these en- gines. Answer in units of N. (part 2 of 2) 10.0 points Note...

Hey guys, I'm a college student looking to build a miniature RC plane based off this picture here: [PLAIN]http://www.kruxor.com/wp-content/uploads/2010/07/SC2_Banshee_Art.jpg As you can see, the thrust needed to lift and mobilize the plane is provided by the two fans on the sides (does this...

Hello, I was trying to find out why net thrust decreases then increases with velocity. I recall there is pressure and momentum thrust, however I can not recall why one of them falls away and the other increases. Is momentum thrust the one that picks up as the mass flow increases with...

Homework Statement The 3rd and 4th stages of a rocket, mass 40kg and 60kg respectively, coast in space with a velocity of 15,000kmh when the 4th stage ignites, with thrust T and causes separation. If the velocity of the 4th stage is 10m/s greater than the 3rd stage at the end of the 0.5...

i need to calculate thrust produced by a propeller whilst flying, using the data show below. all equations i have come across require the propeller induced velocity which is not given. things i know; -propeller efficiency -indicated and true airspeed of aircraft -temp. and pressure at...

Homework Statement A closed tank in the shape of a cube of side root 2 is half full with water and half with oil of relative density 1.2. The tank is placed on a horizontal table and is then tilted about one edge until the faces about this edge are inclined at 45 degrees to the horizontal. See...

If light has momentum, is it possible to have an intense enough "flash light" to provide measurable thrust?

Homework Statement Derive from Newton II the thrust (the force produced by the rocket exhaust) achieved by a rocket motor which ejects material with constant velocity u and mass ejection rate a. Homework Equations The Attempt at a Solution Not sure...I know how to derive vf =...

Homework Statement An airbus A320 jetliner has a takeoff mass of 75,000 kg. It reaches its takeoff speed of 82 m/s in 35 s. What is the thrust of the engines? You can neglect air resistance but not rolling friction. (The force of rolling friction is given by Fr = \mur N Homework Equations...

Homework Statement A landing craft of mass 12,000 kg prepares itself for a Moon landing. When at a vertical distance 160m above the Moon’s surface it’s downwards velocity is 15 m/s. A retrorocket is fired to give the craft an upward thrust to slow its speed to zero as it meets the...

Homework Statement A spacecraft orbits around the Earth at a tangential speed v and a radius R, in accordance with the equation a_{c} = \frac{v^{2}}{R} . a) If the spaceship's engines exert a force parallel to its instantaneous vector of motion, what is the effect on the quantities...

Hello. I am trying to find the thrust chamber flow velocity for a rocket engine, but no literature seems to be able to come up with a solution for this. The best I have found is "Rocket Propulsion Elements" which states that the value probably lies somewhere between 200-400 ft/sec. But in...