Propulsion Definition and 291 Threads

Propulsion is the action or process of pushing or pulling to drive an object forward. The term is derived from two Latin words: pro, meaning before or forward; and pellere, meaning to drive.
A propulsion system consists of a source of mechanical power, and a propulsor (means of converting this power into propulsive force).
A technological system uses an engine or motor as the power source (commonly called a powerplant), and wheels and axles, propellers, or a propulsive nozzle to generate the force. Components such as clutches or gearboxes may be needed to connect the motor to axles, wheels, or propellers.
Biological propulsion systems use an animal's muscles as the power source, and limbs such as wings, fins or legs as the propulsors.
A technological/biological system may use human, or trained animal, muscular work to power a mechanical device.

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  1. T

    Exploring Asymmetry Momentum Transfer for Space Propulsion

    Momentum Drive =============== Just playing with some ideas on rocket propulsion in space based on asymmetry momentum transfer. Any reason why this is not workable? :-p 1. Let m1 = 100 kg robot arm at one end of a cylinder; m2 = 100 kg robot arm at opposite one end of the cylinder; m3 = 10...
  2. A

    Looking for a Rocket Science Book Without Deep Mathematical Details?

    Hello, I've always been interested in space and space flights and have often wondered how rockets are lunched into space, how their trajectories are defined, how they are sped up (like gravity assist), how they are slowed down (like the complicated trajectory of the Rosetta mission etc . . . I...
  3. M

    Designing Powerful Water Guns for Distance Propulsion

    Good morning, I always walk on egg shells posting what is probably a redundant question on a forum. I have been reading for two days and there is a ton of physics information out there on the subject but most of it doesn't truly address the mechanics of what I am looking for. In a very...
  4. K

    What Type of Thrusters Are Best for a Lightweight Aerial Descent Platform?

    i need to design a light weight platform(capable of carrying 60-100kg weight) with some kind of thrusters so that it can go down smoothly through air from about 5-10m of height to ground level. can anyone tell me what kind of thrusters i should use??
  5. A

    Blade Runner -- Prosthesis propulsion question

    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...
  6. praveenpandiyan

    Rocket Propulsion: Calculating Specific Impulse for Return Mission

    well. I have this question. That my rocket is launched from mar in an return mission to earth. To calculate specific impulse of the rocket. Should i consider mar or Earth gravity and if why!? Help me with this
  7. S

    Rocket Propulsion: Explaining How Hot Gases Propel Rockets

    Hi i am doing a project on the future of solar energy. While reading up on rockets and how they are propelled to escape velocity i noticed all references only tell us that the hot gases propel the rocket up. Could someone explain exactly how this happens. What i mean is does molecule collision...
  8. G

    Jetski propulsion analysis (fluid dynamics)

    Homework Statement [/B] http://imgur.com/TQf2TNP http://imgur.com/TQf2TNP Diagram for the porblem For this problem, you may assume the following: • The mass flow rate of water through the jet pump is always the same. • The combined mass of the rider and jetski is 450kg • The time dependent...
  9. T

    Exploring the Feasibility of Road Downhill Propulsion Systems

    Having recently taken up road downhilling, I want to investigate the feasibility of producing a personal, wearable thrust driven propulsion system. Doesn't have to be terribly powerful, controllability should be via twistgrip maybe. I'm drawing pictures of an ergonomically-designed frame which...
  10. S

    Guess propulsion type by its noise

    Could you define what propulsion type this one vehicle uses by noise it makes?
  11. phion

    Non-Chemical Propulsion Alternatives for Space Launches

    I'm attempting to do a term paper about the above title. There are a lot of potential alternatives to chemical rocket launches in the works; some realistic, and some not very. My hope in creating this thread is to gain some insight into what exactly these alternatives are (I'm sure I've missed a...
  12. L

    Water Propulsion Device - geometry configuratiton optimization problem

    Dear physicist, I am designing a device that will use firetruck/hydrant water pressure (~150 psi) and fire hose (5" diameter) to lift up a device in the air and into a burning room. Please advice me and help understand how water flow, pressure and areas influence thrust. My goal is to input...
  13. N

    Can Magnetic Forces Propel a Model Boat on Water?

    Homework Statement I need to find a way to propel a model boat using magnetic forces, without the use of battery or electrical power. Homework Equations Unsure (I am in grade 4) The Attempt at a Solution I have looked into the use of 9V batteries, and use of an electric circuit, but...
  14. C

    What is the propulsion behind UFOs?

    I am new to the board although not young or new to science. I was wondering if there were any serious discussions relating to UFO propulsion. It seems like a lot of UFOs move by a skipping motion, skipping short or large distances, sometimes 20-100 miles or so in an instant. They are not...
  15. T

    Oxygen Needed for Combustion Propulsion in Outer Space

    if outer space is mostly hydrogen then would oxygen be the only ingredient needed to maintain a combustion type of propulsion?
  16. E

    Can Copper Coils and Iron Pipes Create Electromagnetic Propulsion?

    I am interested to know if a copper coil wrapped around a iron pipe could be used to propel another iron pipe capped at both ends through the larger pipe with the copper coil around it? I am thinking that the larger iron pipe would need to be slotted from end to end and insulated from the...
  17. D

    Inertial propulsion, possible ?

    https://www.youtube.com/watch?v=1VW1y6isl18 Above is an old video of a double inclined pendulum device producing unidirectional motion. Here is a newer but much cruder replication https://www.youtube.com/watch?v=N-JKa4Bexz0 Physicists however put Inertial propulsion in the same...
  18. M

    Most promising form of space propulsion?

    Hello, I'm a second year physics student and I'm interested in new approaches to spacecraft propulsion. I apologize if this has been asked many times - while this interest may be partially inspired by science fiction, I am well aware that the real-life situation is not at all as glamorous...
  19. R

    Constant Acceleration / Deceleration Propulsion

    I'm making research for an article about constant acceleration / deceleration ship propulsion. Now, it's about 30 years since I was solving differential equations so there's no way I could solve, let alone devise, an appropriate differential equation. I'm not even sure an appropriate...
  20. P

    Rocket Propulsion Homework: Calculating Travel Time

    Homework Statement A rocket in outer space has a payload of 4050.0 kg and 1.753·105 kg of fuel. The rocket can expel propellant at a speed of 4.300 km/s. Assume that the rocket starts from rest, accelerates to its final velocity, and then begins its trip. How long will it take the rocket to...
  21. J

    Mystery where propulsion originates

    Compared how much impulse is potentially created by heating up a gas as compared to the impulse created by the laser for the same amount of energy. Find that the gas can get a million times more impulse per energy increase. If the heat source was a heater that only heats things up by radiating...
  22. B

    Propulsion Engineer: Pursuing a Career in the Space Industry

    Hi guys, I'm a mathematics graduate who will be going back to university in 2015 to study mechanical engineering, but have a question that I hope can be answered here. I feel that the financial industry that I'm currently working in is not the place for me, as it's quite soulless and...
  23. Q

    What sort of degree is best for working on propulsion systems?

    Hello I am currently an aerospace engineer at university and was beginning to wonder whether it was the best idea to be an AE engineer. The curriculum involves courses on propulsion systems and the different methods as well as other courses about the actual structure of aircraft and...
  24. J

    Black-Powder Propulsion Senior Project

    I'm working on my senior project. The project I'm working on can be modeled similarly to a gun. I am having some problems finding a way to model pressure as a function of time as a weight/mass moves down a tube after the combustion of black-powder. Any direction in this would be great.
  25. C

    Optimal design, water-wing - single oar propulsion

    Optimal design, "water-wing" - single oar propulsion Good evening, and hello to you all. As you can see I'm new here, so please go easy on me. A while ago I got to learn about the single oar propulsion system used in southeast Asia. The way I see it this is a principle with loads of...
  26. M

    Velocity and mass relation by fluid jet propulsion of a squid

    Several species, including the squid, cuttlefish, dragonfly fish and many microscopic organisms, move themselves around by a kind of jet propulsion. In each case the animal absorbs fluid in a body cavity and expels it through an orifice by contracting the cavity. If a squid has a mass Ms when its...
  27. S

    Protons and electrons. Propulsion.

    I've had this strange theory for a long time. If a free floating proton has a tiny amount of mass, wouldn't excelating it to near C increase its mass or energy nearly infinitely? If this is so, if we run a wire and fire electrons down its length let's say 100 times per second. Then fire...
  28. S

    Rail Gun Propulsion: Perverting a Rail Gun Into a Rocket?

    Is it possible to pervert a rail gun into a rocket? I'm understanding that plasma conducts electricity. If i could supply a rail gun with constant current and send in a constant feed of hot plasma into the rail gun would the machine send out plasma at high enough speeds to be used as a rocket...
  29. D

    How Do Pulse Rifles and Pulse Propulsion Function in Sci-Fi?

    I've heard about pulse rifles in movies and games, but I haven't been able to understand how they work. I know that they have to do something with plasma, but they shoot pulse slugs too. Please explain how they work.
  30. B

    How much propulsion would i need to move my 300 pound hovercraft?

    How much propulsion would i need to move my 300 pound hovercraft?
  31. P

    RC-Blimp propulsion system on larger a larger scale

    Hi everyone, and thanks for reading my very first post in Physics Forums! I have been researching a way to construct a single person aircraft with vertical take-off and landing using a propulsion system similar to that of an RC-blimp. I found a video on youtube that illustrates the principle...
  32. C

    Ionized Air Propulsion: Is it Possible?

    I was simply wondering if ionized air propulsion is possible? I don't know much about it but would it be possible to use UV light to positively charge a large amount of air, then another uv light source below a funnel to negatively charge the air creating air flow ( thrust). Can some one...
  33. S

    I'm looking for some cold propulsion possibilities

    I am coming up with a new wing suit that combines soaring with jet pack propulsion in such a way that even valley dwellers can fly, and possibly commute in this fassion. I fear compressed gas alone will not have enough thrust for long enough. One concept to think of is to charge a...
  34. Eirhead

    Solar Winds, Space-Aged Propulsion & Plasma Beams?

    Solar Winds, Space-Aged Propulsion & Plasma Beams? Hi there I'm educated the field of electrical systems & radio frequency, and I love reading about things like ion drives, hall effect thrusters and VASIMR. One thing I find quite fascinating is how the solar winds accelerate away from the sun...
  35. L

    Rocket propulsion - Differential equations

    Homework Statement Suppose a rocket is launched from the surface of the Earth with initial velocity v_0 = \sqrt(2gR) , the escape velocity. a) Find an expression for the velocity in terms of the distance x from the surface of the Earth (ignore air resistance) b) Find the time...
  36. A

    Engineering Aerospace Engineering and propulsion

    Hello In a few weeks I'll have to chose which degree and University to attend (I am an undergraduate). I was thinking about aerospace engineering, though I haven't really made up my mind yet. At first I wanted to take astrophysics, but once I understood that eventually I would have ended up...
  37. B

    Nuclear Engineers Working in Plasma or Ion Propulsion

    Hello. I am wondering what the job field is like for nuclear engineers that aspire to work in plasma research and implementation or things like ion propulsion, etc. I do not want to work in a plant. Thank you.
  38. A

    Propulsion system used in Space probes?

    What is the power source for space probes and how it is sustained for long flights in space? Also how do space probes reach phenomenal speeds (Helios attained 252,792 km/h !)
  39. spacerock1

    Astronautics specializing in Spacecraft Propulsion: What Major?

    Hello, I'm entering my senior year in high school and I can't decide what I want to major in in college. I am DECENT (not too good) at engineering, but I am good with math, science, and the like. Currently, I want to work with Spacecraft Propulsion after college, especially high efficiency...
  40. N

    Can Intense Light Waves Bend Space-Time to Propel a Vessel Through Space?

    Theoretically is it possible to propel a vessel through space by creating a wave in space time using intense amounts of light to bend space time?
  41. G

    Futuristic propulsion of spacecraft

    I read about ion thrusters. If they had enough energy, is it possible, that the descendants of the current engines fires the ions with relativistic speeds, and a small yacht could go from LEO to Moon and back, with small amount of propellant, in hours?
  42. C

    Air Propulsion Project: Designing a 200lb Wheeled Vehicle with Ducted Fan Power

    For a project I am looking into the possibility for a wheeled vehicle to be powered by a ducted fan. At this stage in my process I am only certain that the vehicle will weigh about 200 pounds and will be powered by a 2 horsepower motor at 2000 rpm and operate on low friction surfaces. I am...
  43. A

    Rocket Propulsion: Question About Relationship of V and M0/M(t)

    Did a question about this a few weeks ago, but I thought I might do another, as I don't quite get, what is going on. The relationship: v=vex * log(m0/m(t)) tells us that a rocket will attain greater and greater acceleration as time goes. However, when I try to simulate this in Matlab I get...
  44. A

    Rocket Propulsion: Understanding the Equation Behind It

    Look at the attached picture, which is taken from my textbook. I don't understand the equation: v = vex * ln(m0/m(t)) If the rocket looses mass at a constant rate, wouldn't that equation then say, that the acceleration decreases as time goes. Since the curve of ln(>1) flattens out. That...
  45. O

    Schools Which major for grad school? Planning to do research in space propulsion.

    Hello all. I'm in need of some advice, and I would appreciate any thoughts you guys can contribute. I will be graduating from RPI this semester with a BS in Aeronautical Engineering. I am applying to graduate schools with the intention of becoming involved in space propulsion research (a...
  46. S

    Thrust to Power Ratios for Modern Propulsion Systems

    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 /...
  47. O

    Maximum thrust - theory of rocket propulsion

    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...
  48. B

    Exploring Jet Propulsion: Building a Replica Model of a Hero's Engine

    hi Im currently studying aeronautical engineering at college and needed some ideas for projects and whether they would be pliable or not My current idea: A replica of hero's engine to show the basic principles of jet propulsion but to spice the idea up a little bit, i was thinking about...
  49. G

    Exploring Propulsion with 1kg Mass & 1J of Energy

    Let's say we have a spaceship with a 1kg mass, and 1J stored in a battery or something. I am going to explore two things we can do with this setup to propel the craft. The first one is simply shooting the mass itself out the back. If we shoot the mass out the back by using that 1J of energy...
  50. S

    Jet vs. Wheel Efficiency: Which is More Effective for Land-Based Vehicles?

    Let's suppose one wanted to move a wheeled, land-based vehicle. Generally, which would be more efficient, and why? Using a jet of air straight out the back (like the Batmobile seen in the 1989 Batman movie) or absorbing most of jet's thrust through a turbine and delivering that force to the...
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