Rocket engine performance: photo, performance, video
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Rocket engine performance: photo, performance, video

Rocket engine performance: photo, performance, video

Space exploration is one of the most amazing events that was held by mankind. Moreover, a great deal of surprise is the complexity of this process.

 

It is no secret to anyone that space exploration is complicated by many problems that need to be solved and overcome. For example, airless space, the problem of re-entry into the atmosphere, the problem with temperature, orbital mechanics, cosmic debris and micrometeorites, solar and cosmic radiation, logistics in zero gravity, etc. But perhaps the most difficult task is the problem of tearing a spacecraft off the ground. Here we can not do without the rocket engine, which we will discuss below.

 

It may seem to many that the rocket engines are simple. On the other hand, rocket engines are just as complex that, in fact, only 3 countries in the world are engaged in delivering people to orbit.

Photo 1

When people think of a motor or engines, they associate it with rotation. For example, a gasoline engine produces auto rotational energy, thereby moving the wheels. The motor carries the rotational energy to drive the disc or fan. The steam engine does the same for the steam turbine to rotate.

 

It is worth noting that the rocket engines have fundamental differences. The basic principle of their movement is the well-known principle of “Newton”, “for every action there is its own equal reaction”. The rocket engine ejects mass in one direction, and moves in the opposite direction due to Newton's principle.

 

The concept of “ejection of mass and motion on the Newton principle” from the first time will be difficult to understand. Rocket engines seem to work with pressure, noise and fire, rather than “pushing things.” Now consider a few examples in order to get a complete picture of reality.

 

If you ever fired a weapon, ideally, a shotgun of the twelfth caliber, then you know what a recoil is. When you shoot from such a weapon, it gives you a shoulder. Such a push is a reaction. A shotgun is capable of bulking about 30 g of metal in one direction at high speed (more than 1000 km per hour), and the impact in the shoulder is quite noticeable. If you were in roller skates or were standing on a skateboard, then a shotgun shot would work like a jet engine, as a result, you would roll in the opposite direction.

nuclear rocket engine

If you once observed how a fire hose works, you notice that it is not easy to hold it (often firefighters hold it together or three of them). The principle of operation of the hose is similar to a jet engine. He throws water in one direction, and people use force to counter this reaction. If they suddenly miss the hose, it will rush around everywhere. If firefighters were standing on skateboards, then the fire hose would disperse them to a very impressive speed.

 

You can also take as an example a balloon, which, having inflated and released, it will immediately begin to fly around the room, emitting air - the same principle of operation of the rocket engine. In this case, you release air molecules from the balloon. Many believe that air molecules have no weight, but they are not. As soon as you let them out of the ball, it will fly in the opposite direction.

 

Another scenario that would help explain action and opposition is space baseball. For example, you went into spacesuit into space next to your spaceship, and you have a baseball in your hand. If you throw it, the body will react in the opposite direction from the ball. For example, its weight is 450 grams, and your body with a spacesuit is 45 kilograms. You throw the ball almost half a kilo at a speed of 34 kilometer per hour. So, you accelerate a half-kilogram ball with your own hand, in such a way that it picks up speed of 34 kilometer per hour. As a result, your body reacts in the opposite direction, but its weight is a hundred times the ball. So, it takes 0,34 km per hour (one hundredth of the acceleration of the ball).

If you are planning to create more traction from a baseball, you have the 2 option: increase acceleration or increase its weight. You can throw one ball after another, or throw the ball heavier, or throw the ball faster. However, this is not all.

RS-25 rocket engine

As a rule, a rocket engine throws out eye-shaped weight under high pressure. The engine ejects a lot of gas in one direction, in order to get a jet motion in the opposite direction. The mass comes from the weight of the fuel burning in the rocket engine. The burning process accelerates the weight of the fuel in such a way that they exit at high speed from the rocket nozzle. The fact that the fuel passes from a liquid or a solid in the process of burning does not affect its mass. If you burn 1 kg of rocket fuel, you get 1 kg of exhaust in the form of hot gases at high speed. As a result, the burning process will accelerate the mass.

 

Traction

 

The concept of thrust is called the "power" of the rocket engine. Thrust is measured in "pounds of thrust" (US, 4,45 Newton = 1 pound thrust) and in Newtons in the metric circuit. A pound of thrust is the amount of thrust required to hold one pound object (0,454 kg) fixed relative to the gravity of planet Earth. Earth gravity acceleration - 9,8 meters per second.

 

One of the problems of rockets is that the fuel weight is usually 36 times the payload. Because, besides the fact that the engine needs to lift weight, the same weight contributes to its own lift. It turns out that in order to put a tiny person in space, a rocket of enormous size and a lot of fuel will be needed.

Orion Spacecraft Launch

The speed of chemical rockets is from 8 to 16 thousand kilometers per hour. The fuel burns for about 2 minutes and produces about a million pounds of thrust at the start of the 3,3. Three main engines of the space shuttle, for example, burn fuel for 8 mines and produce approximately 375 pounds of cords each during combustion.

 

Next we talk about fuel mixtures for solid-propellant rockets.

 

Solid-fuel rocket engines are the very first man-made modifications. They were first invented in China hundreds of years ago and are successfully used to this day. The red flare of rockets is sung even in the national anthem, which was written in the early 1800's). We are talking about small combat rockets, working on solid fuel. They are used to deliver incendiary devices or bombs. As you can see, these rockets have been around for quite some time.

 

The idea of ​​a solid-fuel rocket is quite simple. You need to create something that could quickly burn, but at the same time not explode. In this case, the powder is not suitable (it consists on 75% of nitrate, 10% sulfur and 15% coal). Explosions in the rocket engine are not needed - it is necessary that the fuel burned. You can change the mixture to 24% coal, 72% nitrate and 4% sulfur. Instead of gunpowder, you get rocket fuel. Such a mixture will burn quickly, but it is not explosive, unless, of course, it is properly loaded. We give the classic scheme:

rocket engine circuit

Left - rocket before ignition. Solid fuel is shown in green. It is made in the form of a cylinder with a pipe that is drilled in the center. When ignited, the fuel begins to burn along the pipe wall. Gradually, as it burns, it burns out to the body until it is completely burned. In a tiny rocket or in a small rocket engine, the burning process can last for about a second or even less. In a large rocket, the fuel will burn for at least two minutes.

 

Solid Rocket Configurations

 

In the descriptions of solid-propellant rockets you can often find the following:

 

“The fuel for rockets consists of ammonium perchlorate (oxidizer, by weight - 69,6%), polymer (binder mixture - 12,04%), aluminum (16%), iron oxide (catalyst - 0,4%) and epoxy curing agent (1,96%). The perforation is made in the form of an 11-terminal star located in the front segment of the engine and in the form of a double-truncated cone in each of the other segments, including and final. Thanks to this configuration, high traction is provided during ignition, and then, through 50 seconds after the start, it decreases by about a third, preventing overvoltage of the device during the period of maximum dynamic pressure.

 

This plan explains not just the composition of the fuel, but also the shape of the channel that was drilled in the center of the fuel. You can see the perforation in the form of 11-final star in the photo:

Photo 2

The whole point is to increase the surface area of ​​the channel, and accordingly, to increase the burnout area, resulting in increased thrust. As the fuel burns, the shape changes to a circle. This form in the case of the space shuttle gives a serious initial thrust, which in the middle of the flight becomes a little weaker.

 

Solid fuel engines have 3 important advantages:

  • low cost;
  • simplicity;
  • security.

 

Although there are disadvantages of 2:

  • engine can not be turned off or restarted after ignition;
  • inability to control thrust.

 

Disadvantages mean that the type of solid-propellant rockets is suitable only for short-term tasks or acceleration systems. If you need to control the engine, you will have to resort to a liquid fuel system.

 

Fuel rocket

 

Robert Goddard in 1925 year tested the first engine running on liquid fuel. His engine used liquid oxygen and gasoline to operate. He also sought to solve many fundamental problems in the design of a rocket engine, including cooling strategies, pumping mechanisms and steering mechanisms. Such problems make liquid fuel missiles so complex. All this he successfully managed.

 

The main idea is as simple as possible. In most oil-fueled rocket engines, the oxidizer and fuel (for example, liquid oxygen and gasoline are pumped into the combustion chamber). There they burn, creating a stream of hot gases with high pressure and velocity. These gases pass through a special nozzle, which makes their speed even greater (from 8 thousand to 16 thousand kilometers per hour), and then exit. Below is a simple diagram that demonstrates this process clearly.

Photo 3

The diagram shows the complexity of a conventional rocket engine. For example, a normal fuel is a cold liquid gas of the type of liquid oxygen or liquid hydrogen. But one of the serious problems of this engine is the cooling of the nozzle and the combustion chamber, so at first cold liquid circulates around the overheated parts in order to cool them. Pumps must generate high pressure to overcome the pressure in the combustion chamber burned by the fuel. This cooling and pumping makes the rocket engine similar to an unsuccessful attempt at sanitary self-realization. Now we will consider all the variants of the combination of fuel used in liquid-fuel rocket engines:

  • liquid oxygen and liquid hydrogen (main engines of space shuttles);
  • liquid oxygen and gasoline (first Goddard missiles);
  • liquid oxygen and kerosene (used in the Apollo program in the 1 stages of the Saturn-5 stage);
  • liquid oxygen and alcohol (German-made V2 rockets were used);
  • nitrogen tetroxide / monomethylhydrazine (used in Cassini engines).

 

Prospects for the development of rocket engines

 

In addition to our usual chemical rocket engines that burn fuel to produce thrust, there are many other ways to get it. Any system capable of pushing mass. If you are planning to speed up a baseball to enormous speed, you need a viable rocket engine. With this approach, the only problem is the exhaust that stretches through space. It is just such a small problem that engineers prefer gases to burning products.

 

Most rocket engines have extremely small engines. For example, orientation engines on satellites do not create much traction. Sometimes they are almost never used to fuel - under pressure, nitrogen gas through the nozzle is released from the reservoir.

engines of orientation of the American spaceship Apollo

New designs must accelerate atomic particles or ions to high speed, so that the thrust becomes as efficient as possible. But for the time being, we will make electromagnetic engines and wait for what Elon Musk has come up with with his SpaceX.

 

What is the best rocket engine today?

In appearance, the engine is difficult to say how good it is. We have to look into the boring numbers of indicators of each engine. But what indicators to pay attention, because there are so many of them?

 

More powerful

 

Most likely, the more powerful the engine, the better it is. A large rocket provides greater payload, space exploration is faster. But if you look at the leader in this area, then we are waiting for some disappointment. The highest thrust among all engines, 1400 tons, has a sound accelerator, Space Shuttle.

Photo 4

Despite all their might, solid-fuel boosters can be safely called the symbol of technical progress, since constructively they are only a steel (or composite) cylinder with fuel. In addition, such accelerators have become irrelevant in the 2011 year, which undermines the impression of their success.

 

Those who follow the new SLS super-heavy rocket know that new, more advanced solid-fuel boosters have been developed for it, the thrust indicator of which is 1600 tons, but it is not known yet when they will launch this rocket. In addition, the concept of “taking more segments with fuel to make more traction” is an extensive way of development, and if necessary, you can put more segments and, accordingly, get more traction, redistribution has not yet been achieved, and there are no prerequisites that such a path will lead to technical excellence.

 

The second in terms of tons in 793 is the RD-171М liquid engine produced domestically.

Photo 5

It may seem to many that he is truly the best. But where is his success? Okay, the Energia rocket ended its existence during the collapse of the Soviet Union, and Zenith died as a result of political relations between Russia and Ukraine. But why then does the US not buy this seemingly remarkable engine from us, but give preference to half the size of the RD-180? Why is the RD-180, which began as a “half” of the RD-170, now produces more than half the thrust of the RD-170, namely 416 tons? Unclear.

 

The third and fourth place in terms of thrust is occupied by engines from missiles that no longer fly. This is a UA1207 solid fuel engine installed on Titan IV (thrust - 714 tons) and an F-1 engine (thrust - 679 tons). Even with such outstanding performance indicators, they could not live to this day. Maybe some other indicator is more important?

 

More efficient

 

What indicator is responsible for engine efficiency? If a rocket engine burns fuel to accelerate a rocket, then how effectively it does it depends on the amount of fuel costs that will be needed to reach the orbit / Mars / Moon, Alpha Centauri. To assess this effectiveness in ballistics, a special indicator is used - specific impulse.

 

The remote impulse demonstrates how many seconds the engine will be able to develop traction in the 1 Newton per 1 km of fuel.

 

In the best case, the champions are in the middle of the list, if we sort it out by specific impulse, and F-1 with solid-fuel boosters are far behind. But this is not the most important characteristic, as it turned out. You will be convinced of this, having got acquainted with the leaders of the list. With the 9620 seconds index, a little-known HiPEP electro-jet engine is located on the 1 spot.

Photo 6

Immediately it is worth noting that the HiPEP engine was created for a closed probe project designed to study the moons of Jupiter and work on it was carried out in the 2005 year. According to official sources, on tests a prototype of this engine developed a specific impulse in 9620 c, while consuming 40 kW of energy.

 

In second and third place are the electrojet engines VASIMR (5000 с) and NEXT (4100 с), which demonstrated their characteristics on test benches (they have never flown before). And the engines that flew into space (for example, the series of domestic engines SPD from the OKB "Torch") have indicators up to 3 thousand of seconds.

Photo 7

Why then did these engines fail to crowd out the rest? To do this, consider their other indicators. The thrust of electrojet engines is measured in grams, so they cannot work in the atmosphere. To collect a super-efficient PH on such engines will not work. They require kilowatts of energy in space that not all satellites can afford. Therefore, electric propulsion engines are used, as a rule, only on geostationary communication satellites and interplanetary stations.

 

But, if we discard electrojet engines, then who will be the leader in specific impulse among the number of chemical engines?

 

With the index 462 with the leaders will be KVD1 domestic production and the American RL-10. And if KVD 1 flew only 6 once in the composition of the Indian GSLV rocket, then the RL-10 is an efficient and respected engine for the upper stages and upper stages, which has worked perfectly for many years. In theory, it is possible to assemble the entire PH from such engines, but the eleven ton 1 engine thrust means that at the 1 and 2 they will have to be placed in dozens, and there will not be anyone willing to do that.

 

Is it possible to combine high specific impulse and high thrust? Chemical engines have rested against the laws of our world (physics prohibits the burning of hydrogen with oxygen, which has a specific impulse greater than 460). There were atomic engine projects, but the matter did not go beyond the projects. However, in general, if humanity could cross a high specific impulse and a high thrust, then space would become more accessible. What other characteristics can assess the engine?

 

Tense

 

The rocket engine ejects weight (working fluid or combustion products), creating cravings. The greater the pressure in the combustion chambers, the greater the thrust, respectively, in the atmosphere, and the greater the specific impulse. An engine that has a higher pressure in the combustion chamber will be more efficient than an engine with a low pressure on the same fuel.

 

Having sorted the list of engines according to this indicator, the first place will be taken by the USSR / Russia - we have tried in every way to make efficient engines with the highest possible performance. The first three places were divided among themselves by a family of oxygen-kerosene engines based on RD-170: RD-191 (259 atm), RD-180 (258 atm), RD-171М (246 atm).

In fourth place is the Soviet RD-0120 (216 atm), which occupies a leading position among hydrogen-oxygen engines and flew 2 times on the Energia launch vehicle. The fifth place is also taken by our domestic engine - RD-264, working on the fuel pair asymmetric dimethylhydrazine / nitrogen tetraoxide on the Dnepr launch vehicle working with pressure 207 atm. The sixth place is taken by another American engine, the Space Shuttle RS-25 (203 atm).

 

More reliable

 

No matter how promising the engine was, if it explodes through time, there is no benefit from it. Relatively recently, Orbital decided to abandon the use of NK-33 engines that have been stored for decades. They had high performance, because the accident on the test bench and the incredible beauty of the engine explosion on the Antares PH at night cast doubt on the feasibility of operating these engines in the future. Now the Antares RN will change to the Russian-made RD-181.

Photo 8

The reverse is also true - an engine that is not distinguished by outstanding indicators of thrust or specific impulse, but which is characterized by high reliability, will be popular. The greater the history of the operation of the engine, the more statistics, and the correspondingly more bugs on it caught on accidents that have already happened. The RD-107 / 108 engines on the Soyuz keep their pedigree from the engines that still launched the first satellite and Y. Gagarin, and, despite the modifications, have fairly high rates today. But in many ways it pays for high reliability.

 

More accessible

 

An engine that you cannot buy or build is not of high value to you. Such an indicator cannot be expressed in numbers, but this will not make it less important. Often, private companies can not afford to buy expensive engines, and are forced to make their own, albeit simpler. Despite the fact that they do not shine with their indicators, these are the best engines for developers. For example, SpaceX's Merlin-1D engine has pressure in the combustion chambers of the entire 95 amt, a milestone that Soviet engineers switched to the 1960s, and in the USA, to the 1980s. But on the other hand, Max can produce these engines at his own production facilities and receive, at cost, in the necessary quantities, tens of years a year, which is very decent.

Photo 9

 

TWR

Since we have already started talking about the Spacelines “Merlines”, then it is impossible not to mention such an indicator that in every possible way SpaceX fans and PR people in every way are thrust-to-hand. This is an indicator of the ratio of engine thrust to its weight. According to him, the Merlin engines are ahead of everyone (they have more 150). The SpaceX website states that this makes the engine “the most efficient among all previously created,” and this information is rapidly spread by fans and PR people on other sites. In addition, in the English Wikipedia there was even a small war, when this indicator was placed wherever possible. As a result of such a stir in the engine comparison table, such a column was completely removed. Unfortunately, in such a statement more PR than truth. The pureness of the engine in its pure form can be obtained unless on the stand, and when launching a rocket, the engines will be less than 1% of its weight, and the difference in engine weight will have absolutely no effect. Despite the fact that an engine with a high TWR will be more technologically advanced than a low engine, it is more likely a meta-tension and technical simplicity of the engine. For example, in terms of thrust ratio, the F-1 (94) engine significantly exceeds the RD-180 (78), but the pressure in the combustion chamber and the specific impulse F-1 will be significantly lower. Therefore, to raise the figure of thrust on the pedestal, as the most important characteristic for a rocket engine, is simply naive.

Photo 10

Cost

 

This indicator is largely due to availability. If you make the engine with your own hands, then it is quite possible to calculate its cost price. If you buy, then this figure will be indicated explicitly. But, unfortunately, according to this indicator it is impossible to build a beautiful table, since the cost price is known only to manufacturers, and the cost of sale is also not published often. In addition, time affects the price, if RD-180 in 2009 was estimated at 9 mln. $, Today this cost has increased to 11-15 mln. $.

 

Conclusion

 

In fact, the rocket engines do not have one indicator by which one could clearly understand which one is the best. If you try to derive the formula for better pressure, you get the following:

 

The best rocket engine is such an indicator that you can buy / produce, while it will have thrust in the required range (not too small or not too big) and will be so effective (pressure in the combustion chamber, specific impulse) that its cost will not be too heavy for you.

Photo 11

Finally, it is worth citing examples of engines that, according to experts, are among the best:

  • RD-170 / 180 / 190 series. If you are from the Russian Federation or you can buy Russian engines and you need high power engines on the 1 stage, then this family will be an excellent option. Efficient, with excellent performance and an excellent indicator of reliability, these engines are at the peak of technological progress.

Photo 12

  • Be-3 and RocketMotorTwo. These are the engines of private companies that engage in suborbital tourism and are in space for just a few minutes. But this does not prevent them from admiring the beauty of the latest technological solutions. The BE-3 hydrogen engine throttled in a wide range and restarted, with a pull up to 50 t and an unusual open phase transition scheme, created by a relatively small team - it deserves respect. Experts admire the simplicity and beauty of the RocketMotorTwo hybrid engine with gaseous oxidizer and solid fuel.

Photo 13

  • F-1 and J-2. The most powerful engines in their classes were in the 1960's. Yes, do not love the engines that give them such beauty can not be:
  • RD-107 / 108. Despite its low performance - 60 atmospheres in the chamber and 90 tons of traction, as well as an outdated drive, the engine is highly reliable, and in terms of cost it is close to “a lot of stupid media. These engines, without any doubt, will last for 10 years, and set a record for longevity. It is unlikely that you will find an engine that will have such a glorious history.

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