How are space shuttles propelled into space?

[Lynda92]

Hello everyone I'm a physics beginner and just out of interest, I would really appreciate if someone could explain to me how a space shuttle is proplled into space.ie.what forces are involved,how their sizes differ relative to each other and how energy generated to achieve this process.

 

[K^2]

There are several rocket engines attached to the shuttle itself plus two boosters attached to external fuel tank to help it along while the tank is still heavy with fuel. The boosters and later the external tank separate from shuttle before it reaches orbit.

Main engines run on liquid hydrogen and liquid oxygen. The combustion results in a jet of water vapor escaping the nozzles at roughly 3km/s. The reaction force is what pushes the shuttle. Boosters use solid fuel. I don't know the composition, but the principle is very similar.

I don't recall exact thrusts of the engines and boosters, but shuttle lifts off pulling roughly 2G, which means that the force from engines + boosters is roughly 2 times the total fueled weight of the shuttle with the external tank and the boosters.

That's a quick summary off the top of my head. You could get a fairly detailed description from Wikipedia article on Space Shuttle.

 

[Feldoh]

Hi Lynda92,

Welcome to PF!

Your questions is actually a rather complicated one to answer fully. The space shuttle was launched through several phases.

So the space shuttle has three on-board engines. On-board meaning that they are attached to the shuttle and are always there. The fuel for these three main engines is a liquid rocket fuel.

In addition to the three on-board engines there are two solid rocket fuel boosters which are used in the initial stages of take-off. The two solid rocket fuel boosters are named that way because, well, they use a fuel which is a mixture of chemicals in a solid state. Essentially they use aluminum and react it with oxygen and a variant of ammonia as the fuel.

On lift-off all five of these engines are turned on giving the shuttle a thrust of several million pounds. (Like 1 million lbs from the main engines, and another 6 million lbs of thrust from the boosters). This is enough power to life the shuttle and start accelerating the whole thing into space.

Now after a certain point the boosters will run out of fuel. When this happens the boosters are released from the shuttle and dropped into the ocean. This is done for a few reasons. NASA can recover the boosters and re-use them this way. Also, by dropping the boosters the shuttle is significantly lighter meaning that it is easier to accelerate.

Once the boosters have been dropped the shuttle starts to accelerate some more at which point the shuttle is in the outer atmosphere. The shuttle is accelerated in the outer atmosphere because of friction. Flying the shuttle in the atmosphere causes friction which opposes the shuttle movement and also significantly heats it up. (The reason the shuttle turns red on reentry is because of all the heat with re-entering the atmosphere).

 

[Lynda92]

Thank-You K^2 and Feldoh for your helpful explanations,I will definitely read up on the topic.