What is Jet: Definition and 327 Discussions

Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1, which are produced to a standardized international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B, which is used for its enhanced cold-weather performance.
Jet fuel is a mixture of a variety of hydrocarbons. Because the exact composition of jet fuel varies widely based on petroleum source, it is impossible to define jet fuel as a ratio of specific hydrocarbons. Jet fuel is therefore defined as a performance specification rather than a chemical compound. Furthermore, the range of molecular mass between hydrocarbons (or different carbon numbers) is defined by the requirements for the product, such as the freezing point or smoke point. Kerosene-type jet fuel (including Jet A and Jet A-1, JP-5, and JP-8) has a carbon number distribution between about 8 and 16 (carbon atoms per molecule); wide-cut or naphtha-type jet fuel (including Jet B and JP-4), between about 5 and 15.

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  1. D

    Efficiency of a Jet-Powered Rotor Engine

    If we make an engine/rotating machine with the use of jets placed around the circumference of a wheel, then how to find its efficiency? This could be something like an Aeolipile (Refer Wikipedia for the same) but without steam.Instead we can use petrol for combustion.Would that make a good engine?
  2. N

    Rocket engine vs jet engine efficiency

    Which are more efficient, Rocket Engines or Jet engines, and why? It would make sense that rocket engines are more efficient because they aren't effected by air pressure but I have been told by some people that actually Jet engines are more efficient so I am confused. If you know of any link...
  3. N

    Can a Jet Engine be Created Using a Traffic Cone Design?

    Would it be possible to make a working jet engine by simply having a structure like two metal cones stuck tip to tip (traffic cone shaped)? The idea is to get it going fast, inject fuel in the middle, have the fuel auto ignite due to compression heating in the front cone, and than use the back...
  4. A

    Why don't we put particle accelerators in a Jet?

    the velocity of the jet will add to the velocity of the particles , so they will be have greater velocity right?
  5. N

    How Do I Make a Grossly Overexpanded Rocket Nozzle Exhaust Jet Stable?

    I have a question regarding the design of rocket nozzles. I am not an engineer nor a physicist but I am involved in amateur experimental rocketry and I was curious regarding grossly overexpanded nozzles. According to Wikipedia a grossly overexpanded rocket nozzle (very bottom of the...
  6. Caolan

    Jet accelerating in problem with Constant Acceleration

    Homework Statement A jet plane is cruising at 300 m/s when suddenly the pilot turns the engine up to full throttle. After traveling 4km, the jet is moving 400 m/s. What is the jet's acceleration? known: x0 = 0m, t0 = 0s, v0 = 300 m/s x1 = 4000m, t1 = ?, v1 = 400 m/s Homework...
  7. B

    Very Basic Thermodynamics, H20, and Jet Engines

    Dear Physics People, I am a religion teacher with a background in philosophy and theology. I haven't taken a physics or calculus in some years, so there is a lot of information that I'm missing in my head. So here's the deal. Airlines spend millions of dollars on fuel a day (around $32...
  8. D

    MHB What is the velocity of the jet?

    A propeller plane and a jet travel 3000miles. The velocity of the plane is 1/3 the velocity of the jet. It takes the prop plane 10 hours longer to complete the trip. What is the velocity of the jet. Let \(\mathbf{v} = \frac{dx}{dt}\) and \(dx = 3000\). The \(dt = t - t_0\). We can always...
  9. W

    What Determines the Force of a Water Jet on Different Surfaces?

    To experiment with conservation of linear momentum I did lab where a jet of water is shot at a flat plate and a hemispherical cup. After simplification the final equation for the theoretical force came out to be F_t= \dot{m}V(1-cos \beta) where \dot{m} is the mass flow rate of water and V...
  10. M

    Data Needed for Impinging Jet Research

    llo, I am looking for some good reliable data of radial and axial velocities of an impinging jet on a perpendicular plate for Reynolds number of between 10,000 and 60,000. I am about to conduct my own experiment using an LDA to measure velocities but am looking for some good data to compare...
  11. S

    Impact of a Fluid Jet Experiment

    Homework Statement We recently did an experiment involving the impact of fluid jet on both plane and cupped surfaces. See the diagram attached for the experimental set up. We were asked to 1) verify the conservation of momentum and 2) calculate the discharge coefficient of the nozzle from...
  12. W

    Compressed oxygen for jet engine (?)

    as jet engines lose there productivity at altitude due to thining air/oxygen , why isn't injecting compressed air directly along side the fuel a good idea ? , is this already being done ? would /does this not increase ceiling height and allow sub orbit levels or possible leave atmosphere...
  13. Z

    Jet Engine performance in Cold Weather

    Hey guys. I was studying up jet-engines and their performances with varying ambient temperatures and found myself stuck on something that is probably very trivial. What I've read online and in my notes is all generally the same - that as temperature falls air density rises and as such more...
  14. M

    Entrainment and Jet Diameter Growth

    Hello, I am looking for some help in understanding jet diameter growth due to entrainment. I have an impingement plate positioned approximately 20 cm from the nozzle exit. Is there an equation or information that will allow me to figure out how a free jets diameter grows the further it gets...
  15. B

    Uniform Circular Motion A Jet Pilot

    Uniform Circular Motion "A Jet Pilot" Hi, my apologies if this has been posted before. I was just wondering if someone could help look over this question for me and confirm if I did it correct or not. It is a written homework rather than online so I can't check my answer to see if I did it...
  16. M

    Laser Doppler Anemometry and Impinging Air Jet

    Hello, I have to conduct a literature review in regards to Laser Doppler Anemometry and Impinging Air Jet. I am doing a project and it is to compare real velocity data obtained from LDA to CFD data and was wondering if anyone had any good books they could recommend for me to read or good...
  17. MarkFL

    MHB Where can the water jet spray?

    Consider a water jet that sprays from ground level on flat ground. The jet can spray at any angle $0<\theta<\pi$ along some horizontal axis, that is in one vertical plane. The jet sprays water at a velocity of $v_0$. Ignoring drag, find an equation that describes the boundary between where water...
  18. D

    Will a Jet-Powered Rigid Link Reach a Steady State?

    I have a mass (m) at the end of a rigid link of length r, pivoted at the red circle (below). m is acted on by a force (F) which is always normal to the surface shown (thrust from a jet say). My question is will this system reach a steady state, ie will it have constant angular velocity or...
  19. 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...
  20. edward

    Jet Man aka Rocket Man flies with WWII B-17 bomber

    Jet Man aka Rocket Man flies with WWII B-17 bomber. https://www.youtube.com/watch?v=tVjIIdMlhio
  21. M

    Finding max. velocity of jet w/ constant and/or changing acceleration

    Homework Statement You must evaluate the relationship between fuel consumption and the attainable velocity of a new jet fighter. Given that: Force of jet= A(r(t))4/3 A: constant determined by the fighter model in the class being considered and the drag force on the plane r(t): the...
  22. T

    What is slowest speed a commercial jet can travel?

    At Stewart airport in Newburgh New York a small commercial commuter jet leaves and lands in Philadelphia, Pa one hour later. The total distance is about 150 miles. Can small commercial jets travel at an average speed of only 150 miles/hour?
  23. F

    Could a jet engine be run on nuclear power?

    I know people have designed nuclear rocket engines, but is there any reason you couldn't have a nuclear thermal jet engine? Simply take a conventional jet and swap out the combustion area with a small reactor? Could the same idea work at higher speeds with a nuclear ramjet, or scramjet equivalent?
  24. B

    How to calculate a centrifugal pump for a jet boat.

    I am building a jet boat as a project this year. I am going construct the impeller my self but don't know what dimensions I need to make it to get the most out of the engines without over loading them. Here's what I have to work with: The power source is going to be approximately 90 hp at...
  25. S

    Human powered wings with jet pack

    Hi guys, i was thinking recently people are trying to fly flapping huge great wings with no success, whilst others are flying with jet packs, so what i was thinking was adding them together. flapping smaller sets of wing assisted by a small jet pack say 2 RC jet engines producing 80-100lbs of...
  26. F

    Why dont jet engines work without a spiner in the center of the blades

    Just trying to complete my physics coursework on bloodhound ssc. Could anyone help to answer the question: why don't jet engines work in supersonic air without a spinner in the centre of the blades ? Thanks.
  27. V

    Speed of Jet Plane - Solving the Problem

    Problem: You see a jet plane flying and you think that it is flying at a constant altitude h. Say you hear the sonic boom at a time t after the plane passes directly overhead. Show that if the speed of sound v is the same at all altitudes, the speed of the plane is v_s=hv/sqrt(h^2-v^2*T^2)...
  28. 5

    Radius of a curvature for specific force on a seat in a jet

    The question is: What is the minimum radius of curvature of a jet, pulling out of a vertical dive at a speed of v, if the force on the pilot's seat is 7 times his weight? The way I thought to answer this is just to say that, 7 mg, the net force on the seat will be equal to the...
  29. F

    How to calculate pressure and flow rate of an air jet?

    Hello, I have a box with a hole directly connected to a blower inside. I can use the air sent by the blower to give a thrust to the box, in order to move it. I can say the the box is in a room, so open air around the box. The thrust should be 35 N and I have to calculate the pressure and the...
  30. V

    What is the net pressure force on a pressurized jumbo jet flying at 10 km?

    Problem: The fuselage (body) of a 747 jumbo jet is roughly a cylinder 60m long and 6m in diameter. if the interior of the plane is pressurized to .75 atm, what is the net pressure force tending to separate half the cylinder from the other half when the plane is flying at 10 km, where air...
  31. A

    How does the angle of the plate affect the fraction of liquid that flows up?

    Homework Statement A horizontal water jet produces a wide sheet of parallel-flowing liquid that strikes an inclined plate and then divides, with a fraction of the liquid flowing up the plate and the remainder flowing down the plate. The figure shows a section of the flow. All surfaces of the...
  32. R

    Suction caused by an air jet acting on a plate, why?

    Homework Statement We set up in a lab a vertical pointing air jet giving a constant output and gradually increased the height of the plate above the jet whilst measuring the force upon it as imparted by the jet using a Newton-metre. At a big distance the air jet was imparting an upthrust on...
  33. M

    Several questions involving a homemade miniature jet engine.

    Hey guys. I am new to engineering and I came to this because I wanted to make my own miniature jet engine. I have a limited knowledge of physics but I wish to broaden it through this idea. Now I know that this was made before for RC models, but I want to actually make one so I understand how...
  34. M

    Achieving VTOL with jet engine instead of rocket engine

    Jetpack International's T-73 achieves vertical takeoff with an actual jet engine as opposed to the rocket engines used by the majority of jetpack models. This allows it to have longer flight time (9 minutes as opposed to 30 seconds). Some fighter planes also manage VTOL with a jet engine, the...
  35. B

    Testing a 100lbf Jet Engine: Blast Shields

    Hey guys. As the title reads, I am a part of a research project and we will soon be testing a 100lbf jet engine. We take safety very seriously and want to take all the proper precautions in order to ensure everybody involved will come out of the experimentafely in case something goes wrong...
  36. P

    How Do You Calculate a Jet's Average Velocity and Change in Velocity?

    Homework Statement A jet is flying at 600 mi/h in a direction of 45 degrees North of West. 2.5 minutes later it is flying at 450 mi/h in a direction of 30 degrees North of East. a) Sketch a vector diagram labeling Vi, Vf, and ∆V. b) Calculate the average velocity vector in unit-vector...
  37. H

    Centripetal acceleration A jet flies in a vertical circle

    Homework Statement A pilot, whose mass is 96.0 kg, makes a loop-the-loop in a fast jet. Assume that the jet maintains a constant speed of 225 m/s and that the radius of the loop-the-loop is 2.064 km. What is the apparent weight that the pilot feels (i.e., the force with which the pilot...
  38. rmattila

    Why aren't jet pumps used as main coolant pumps in PWRs?

    Once again reading reports of PWR main coolant pump seal issues, my mind started to wander.. Is there some obvious reason, why jet pumps are not used as PWR main coolant pumps? This would eliminate the non-isolable leak issue and enable a more flexible pump arrangement.
  39. P

    Can a jet of steam be used to heat drinks quickly?

    hello..i was reading some where that a jet of steam releases latent heat when it condenses.this idea can be used to heat drinks quickly.. i understand that on condensation 1 kg of steam at 100 C should release 2300000 Joules of heat but what should be the conditions for this to happen?what...
  40. O

    Helicopter Flight and Jet Pack Adventure

    A helicopter carrying Dr. Evil takes off with a constant upward acceleration of 6.0m/s^2 . Secret agent Austin Powers jumps on just as the helicopter lifts off the ground. After the two men struggle for 12.0s , Powers shuts off the engine and steps out of the helicopter. Assume that the...
  41. AnTiFreeze3

    Plausability of a Plasma Jet Electric Thruster

    I frequent this website occasionally, but most of the projects on it aren't nearly as outreaching as this one appears to be. http://www.kickstarter.com/projects/2027072188/plasma-jet-electric-thrusters-for- spacecraft ?ref=category It's basically a group of 3 scientists trying to raise...
  42. M

    Lift required to sustain a refueling jet

    Homework Statement A jet is refueled in mid-air by a tanker. The fueling boom enters the aircraft at an angle of 30 degrees from its flight path. The fuel flow rate is 20kg/s at a velocity of 30m/s with respect to the two aircrafts. The density of the fuel is 700kg/m^3 What is the additional...
  43. O

    What Acceleration Does a Jet Need to Alter a Pendulum's Position?

    Homework Statement A pendulum has a length L = 1.47 m. It hangs straight down in a jet plane at rest, as shown by the dotted line in the figure. Then the jet accelerates uniformly, and during that time, the pendulum moves to the equilibrium position shown by the solid line, with D = 0.39 m...
  44. D

    Calculating Bird Flock RCS for Comparable Detection to a Fighter Jet

    A fighter jet has 1 m^2 rcs and is located at 200nmi. Where would a flock of birds with 0.0015 m^2 rcs should be located in order to have the same detectability?
  45. A

    Bernoulli's Equation- on a jet nozzle

    Homework Statement A jet of liquid of density ρ surrounded by air flows vertically downwards from a nozzle of area Ao. The stagnation pressure of the jet at exit from the nozzle is po and the surrounding air is at pressure B. The acceleration due to gravity is g. If the jet flow is...
  46. R

    How to calculate a jet pump thrust force?

    hi everyone In order to calculate the thrust force of a jet pump , what must I know and what is the formula used? thanks :)
  47. K

    Calculating Jet Pressure at Nozzle orifice

    Hello, So i am using this 3HP pump for which the head ranges from 6 meters to 14 meters. Discharge being 19.1 LPS to 10.4 LPS respectively. I am using a 2" pipe to carry the water upto a height of approx. 3 meters, which is then routed into a jet manifold containing number of jet nozzles...
  48. I

    How to Calculate the Length of a Quasar Jet?

    Hi there, I have got a real quick question. From where am I supposed to calculate the length of the jet ? http://i42.tinypic.com/w72929.jpg
  49. C

    Where are the alternators in jet planes?

    In jet aircrafts where are the alternators, how are they connected to the jet engines? Is it using belts? Are they on the wings? Thank you Regards
  50. S

    A 1600 kg jet engine is fastened to the fuselage of a passenger jet

    Homework Statement A 1600 kg jet engine is fastened to the fuselage of a passenger jet by just three bolts (this is the usual practice). Assume that each bolt supports one-third of the load. (a) Calculate the force on each bolt as the plane waits in line for clearance to take off. (b) During...
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