One of the most amazing endeavors man has ever undertaken is space exploration. A big part of that surprise is the complexity. Space exploration is complicated because there are so many problems to solve and so many obstacles to overcome. You have something like this:
– Space vacuum
– Thermal control problem
– Difficulty getting back into the mood
– Orbital mechanics
– Small meteorites and space debris
– Cosmic radiation and solar radiation
– The logistics of having devices that operate in weightlessness
But the biggest problem is harnessing enough energy to get the spacecraft off the ground. This is where rocket engines come in.
A side, rocket engines are so simple that you can build and test your own rocket for next to nothing. But on the other hand, rocket engines (and their fuel systems) are so complex that only three countries have actually put humans into orbit. In this article, we’ll look at rocket engines to learn how they work and explore some of the complexities surrounding them.
When most people think of motors, they usually think of circular motion. For example, a running gasoline engine in a car generates rotational energy to drive the wheels. An electric motor produces rotational energy to drive a propeller or spin a disc. A steam engine is used for the same thing, namely the steam turbine and most gas turbines.
Rocket engines are completely different. Rocket engines are jet engines. The basic principle that governs a rocket engine is the famous Newtonian principle which states that “for every action, there is always a reaction of equal magnitude and opposite direction”. A rocket engine releases mass in one direction and captures the resulting reaction force in the opposite direction.
This concept of “throwing masses and becoming counterproductive” can be difficult to understand at first, because that doesn’t seem like what’s happening. The rocket engine makes the sound of fire, noise and pressure, there does not seem to be any “disposable”. Let’s take a few examples to get a better idea of the practice:
If you pull the trigger on a shotgun, especially a large 12 gauge shotgun, you know that it has “recoil” force. That is, when you pull the trigger, the gun “throws” your shoulder back with quite a bit of force. This other side of the coin is counterproductive. The gun fires about an ounce of metal in one direction at a speed of about 700 miles per hour, and your shoulder takes the brunt of the reaction. If you are wearing roller skates or standing on an ice rink when you pull the trigger, the gun will act like a rocket engine and you will react by skating in the opposite direction.
If you’ve ever seen a large fire hose spraying water, you may have noticed that it takes a lot of strength to hold the hose (sometimes you’ll see two or three firefighters holding the hose). The fire hose acts like a rocket engine. The hose was spraying water in one direction and the firefighters were using their strength and weight to resist the spray. If the firefighters let go of the hose, it will rebound with terrible force. If the firefighters were all standing on the roller track, the lance would push them back at high speed!
When you blow up a balloon and let it float around a room before all the air in it is used up, you create a rocket engine. In this case, it is the air molecules that are projected inside the balloon. Many people believe that air molecules don’t have weight, but they actually do, but not very much. When you remove them from the bullet nozzle, the rest of the bullet reacts in the opposite direction.
Effects and counter-effects
Imagine the following situation: you are wearing a space suit and you are floating in space next to a spaceship; by chance, you have a baseball in your hand.
If you throw a baseball, your body responds by moving in the opposite direction of the ball. What controls how fast your body moves away is the mass of the ball you throw and the acceleration you apply to it. Mass multiplied by acceleration is force (f = m*a). The force you exert on the ball will be balanced by an equal reaction force exerted on your body (m*a = m*a). So, for example, the balloon weighs 1 kg and your body plus the spacesuit weighs 100 kg. You throw the ball at a speed of 32 m/s. In other words, you accelerate a 1 kg ball with your hand so that it acquires a speed of 32 m/s. Your body reacts, but it is 100 times heavier than the ball. Therefore, it moves away at a speed corresponding to one percent of the speed of the ball, or 0.32 m/s.
If you want to get more power out of your baseball, you have two choices: increase mass or increase acceleration. You can throw a heavier baseball or throw multiple baseballs one after the other (by increasing the mass), or you can throw the ball faster (by increasing the acceleration put on it). . But that’s all you can do.
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