space shuttle take off like airplanes

[Parag]

why dont the space shuttles just take off from the ground off a runway? it seems easier than the massive fuel and disposable rockets. 747s take off and can fly almost into space with huge amounts of weight, i know the engines wont work without air. but they dont weigh all that much. just a thought i have had for a while now. i would feel alot safer taking off in a airplane than a rocketship.

[The Stig]

I'm just going to give you the short answer because I really don't want to explain the physics. Space shuttles are VERY VERY heavy, so they need a LOT of force to propel them upwards. Then, they need to escape the Earth's gravitational field and the most efficient way to do that is by going the opposite direction of gravity (aka straight up).

[NavyDood]

http://quest.nasa.gov/qna/questions/...tle_Launch.htm

[Steve Dallas]

My dream for humanity is that someday we build a Space Elevator. We are actually not that far off from having the technology to do it. It would need to be someplace near the equator. If this was done, the cost of getting into space would be minimal, because all the power could come from the station in orbit at the top of the elevator.

[Camaro_Corvette]

Massive amounts of physics involved, but I think you get the gist(sp?) of it now.

[DGthe3]

Originally Posted by Parag

why dont the space shuttles just take off from the ground off a runway? it seems easier than the massive fuel and disposable rockets. 747s take off and can fly almost into space with huge amounts of weight, i know the engines wont work without air. but they dont weigh all that much. just a thought i have had for a while now. i would feel alot safer taking off in a airplane than a rocketship.

A 747 gets nowhere near space. They fly at about 6 or 7 miles above sea level. The edge of space is about 10x higher than that, and they shuttle orbited at about 3 or 4 times that.

The rockets in the shuttle weren't disposable. After the boosters detatched they fell into the ocean, were recovered & reused on a later mission. The orange external fuel tank for the shuttles main engines was disposable though.

As for why the shuttle takes off vertically vs horizontally, you have to understand that the shuttle, boosters, and fuel tank weigh about 5 times as much as a fully loaded 747. To get the lift required to get such a beast off the ground using wings you would need to have an aircraft substantially larger than the 747, which would again make it heavier requiring a larger aircraft and so on. Assuming it does get off the ground, in order to reach orbit at some point it would have to change over from using the lift of its wings to the thrust of its engines due to the thinning atmosphere. When you change the orientation like that, you have to make everything stronger again, which adds more weight. In the end, to have a single stage to orbit spaceplane that could reach orbit without jettisoning booster rockets or fuel tanks you would have to either make the payload (the stuff you're sending into orbit) so tiny that its not practical, or the spaceship would be so massive that it might require things like a 20 mile long runway carved out of bedrock, and simply building it could cost more than the entire 25 year shuttle program.

That said, there has been a 2 stage airplane-rocket combination that has gone sub-orbital (~60 miles). The airplane took off conventionally, carrying the small 2 man rocket up with it. The rocket was then released and took off, reaching the edge of space.

As for safety ... don't worry too much. Things can just as easily go catastrophically wrong when lifting off horizontally as vertically.

[trooper182]

QUESTION:
Why must the shuttle be launched vertically?

ANSWER from Ed Mango on April 3, 1998:
The answer is in the physics. In order to get an object to orbit the earth, it must be travelling at over 17,000 mph. Using today's technology, the only way to generate enough energy to get the shuttle to orbit is with engines that are more powerful then jet engines. Those engines use fuels like liquid oxygen, liquid hydrogen and solid fuels like in a bottle rocket. The Space Shuttle generates about 6,000,000 pounds of energy (thrust) to get the orbiter to orbit at the right speed. There are no known wheels, tires or runways that can handle that much energy. So, we designed the shuttle to launch vertically.

[2ndgenz28]

Just turn the top secret rail gun into a launcher to shoot it into orbit like a balsawood rubber band powered airplane.

[Nessal]

Actually, if I'm correct, the shuttle actually doesn't travel straight up.

[Steve Dallas]

Originally Posted by Nessal

Actually, if I'm correct, the shuttle actually doesn't travel straight up.

You are mostly correct.

Initially, the Space Shuttle was pointed directly up. The shuttle would roll and this roll would place the rudder facing down while the shuttle would change angle from straight up to about 60 degrees in relation to the ground while still in our lower atmostphere. That angle continues to flatten out as it must in order to enter an orbital path.

In order to achieve orbit, it needs to achieve orbital velocity, but that velocity needs change from going straight up into a direction that is tangential to the earths surface.

Rocket science is just that...it's complicated. So many factors are taken into account. Getting to a high altitude quickly is important because of the drag the atmosphere can cause. So though it's not going straight up, it's still going at an angle that will minimize the time spent in the lower atmosphere where drag is an issue. It's one reason that they don't throttle up the engines until later in flight...because the shuttle couldn't take the pressure generated if you were at full throttle.

Virgin Galactic launches its suborbital spacecraft from beneath a plane going horizontally. I haven't seen a mission profile for these craft, but I'm pretty certain they stay fairly level...They just drop from the plane carrying them at high altitude, and are able to accelerate from there.

You can see how the shuttle arcs into space in this video:

[CamaroSkooter]

Originally Posted by 2ndgenz28

Just turn the top secret rail gun into a launcher to shoot it into orbit like a balsawood rubber band powered airplane.

...and watch as the crew and payload turn to mush from the ridiculous G-Forces

Originally Posted by Steve Dallas

You can see how the shuttle arcs into space in this video:

When you can no longer see a contrail, is that when the shuttle has reached space or is it just in the upper atmosphere at that point?

[Steve Dallas]

Originally Posted by CamaroSkooter

...and watch as the crew and payload turn to mush from the ridiculous G-Forces



When you can no longer see a contrail, is that when the shuttle has reached space or is it just in the upper atmosphere at that point?

I'm not 100% sure on this, but I would guess that it's still the upper atomosphere. Contrails are water vapor, and the upper atmosphere wouldn't have enough density to form a control. At least, that's my guess.

Also, the white cloudy trail you see early in the launch isn't contrail, but rocket exhaust, so I'm not sure if and when an actual contrail happens.

[DGthe3]

Originally Posted by Steve Dallas

I'm not 100% sure on this, but I would guess that it's still the upper atomosphere. Contrails are water vapor, and the upper atmosphere wouldn't have enough density to form a control. At least, that's my guess.

Also, the white cloudy trail you see early in the launch isn't contrail, but rocket exhaust, so I'm not sure if and when an actual contrail happens.

The huge cloud right at launch isn't exhaust, but it is water vapour. Prior to launch, they begin spraying water beneath the shuttle. When the engines ignite, it turns to steam. I remember hearing that they do this to dampen the roar of the engines.

But in the exhaust itself, some of it is water. After all, the main engines burn hydrogen and when you burn hydrogen you get water. Not sure what exactly the main engines burn but I'm sure they produce some water vapour too.

[wylde1]

Originally Posted by DGthe3

The huge cloud right at launch isn't exhaust, but it is water vapour. Prior to launch, they begin spraying water beneath the shuttle. When the engines ignite, it turns to steam. I remember hearing that they do this to dampen the roar of the engines.

But in the exhaust itself, some of it is water. After all, the main engines burn hydrogen and when you burn hydrogen you get water. Not sure what exactly the main engines burn but I'm sure they produce some water vapour too.

I second this. Not to mention that at the exit of the nozzle and some ways past that, there is so much heat and pressure that any moisture in the air is immediately vaporized causing more steam.

The shuttle with it's boosters produces about 37 MILLION horsepower. that's so much HP that if you spread it in a 1 inch thick layer it would cover Germany.