This momentum is used to both lift and propel the rocket. There are no wings for uplift. Any wings are for steering purposes. A rocket is generally much more powerful and wasteful than a jet engine. Most airplanes don't know of any exceptions can not possibly climb vertically, while rockets are built just to do that. A jet airplane is pretty much useless outside the atmosphere, but a rocket will work just fine since it carries its own fuel and oxygen.
Answered by: Yasar Safkan, Ph. A jet engine combines oxygen from the air with fuel at high temperature. There is usually a spark to ignite the fuel vapor, but once the engine begins turning, it will continue running until it runs out of fuel or air. The jet is pushed forward by the hot gas coming out the back, the same way a garden hose pushes back on you when you spray it. The rocket engine, by comparison, is not what's called an 'air-breather'.
Rockets can work anywhere, in vacuums, or in the atmosphere. A good example of this would be the space shuttle, which uses both of main types of rocket engines. The large nozzles you see at the bottom of the Shuttle itself and liquid-fueled rocket motors.
They spray liquid hydrogen and liquid oxygen together, right at the bottom of the cone, which then burns as long as it continues to be fed fuel and oxygen. The rocket, however, doesn't use any air. It will work at any altitude, or in space. The problem is, though, that now, the craft must not only carry fuel The huge brown tank on the belly of the Space Shuttle is the main fuel tank, holding both hydrogen and oxygen.
To lift all that weight requires a LOT of energy, which requires more fuel, which requires more space, and weight; and at a certain point, using liquid-fueled rockets, you start to work against yourself.
You can see how large the Saturn V rockets were compared to the Space Shuttle, and you can compare payloads. People generally believe that a rocket must push on air in order to propel the rocket forward, but that is not the case. The burning of fuel creates gases at high pressure, which exit from the exhaust nozzle and push the rocket forward. As gases exit the rocket, a reaction force thrust pushes on the rocket making it go forward. The faster the gases are expelled from the rocket, the greater the thrust.
Think of how a garden hose creates a force pushing back on the hose as water squirts from it. In fact, jet engines and rockets operate on the same general physics principle. Both eject fuel out the back. The momentum imparted to this exhaust is equal to the momentum gained by the vehicle, thus making the vehicle go forward. One difference between rockets and jets is found in the type of fuel they burn.
Jet engines are air breathers. They take in air which contains oxygen needed for combustion , mix it with fuel, burn it to increase the pressure, and exhaust the spent gases out the back at a high rate of speed. This high-speed ejection of mass propels the plane forward. Rockets do almost the same thing with two exceptions. Unlike jets, they carry their own oxygen along with them and a rocket does not have wings that add lift.
NASA and aerospace giants like Rolls-Royce had tried, and all the projects fizzled out due to soaring costs and major technological challenges. Davis lacked the funds needed to run detailed fluid dynamics simulations to model the engine on a computer, so the duo decided to build a physical engine instead. And when Davis triggered the ignition last year, the Fenris engine worked. Davis claims that test is the first and only time an air-breathing rocket motor has been successfully hotfired.
They just wanted to see if their engine could pull air in one end and belch flames out the other without blowing up. Later this year, Davis and Stegman will run some more advanced engine tests in a decommissioned missile silo in Wyoming.
Unlike the first test run, these will be all about pushing Fenris to its limits and extracting as much power as possible from the experimental engine. Based on his computer models, Davis says he expects to achieve over seconds of specific impulse during the tests, which is a measure of how efficiently a rocket engine uses its propellant.
This would be a monumental achievement given that the world-record specific impulse—held by NASA—is seconds, and most operating orbital rockets have specific impulses around seconds.
If the demos in Wyoming go well, the next big step would be to demonstrate the motor in flight. If he finds a launch partner, Davis says the Fenris engine could fly as soon as The lines around the cone feed kerosene and gaseous oxygen into a combustion chamber, where it is mixed with the air and ignited.
Historically speaking, Davis and Stegman are in good company. The birth of modern liquid-fueled rockets was driven by amateurs like Robert Goddard, Jack Parsons, and Wernher von Braun who cleared the path for the massive state-run rocket programs that followed. But not everyone is convinced that Fenris is a game changer. One concern is that the atmosphere is mostly inert nitrogen—and in a rocket engine that nitrogen acts like a wet blanket.
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