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could a large 12ft model rocket be used to launch a probe into space, such as a telescope?

- Thread starter Turtle^2
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could a large 12ft model rocket be used to launch a probe into space, such as a telescope?

- #2

Danger

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Welcome to PF, Turtle.

Does "12'" refer to length or diameter?

Does "12'" refer to length or diameter?

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No.could a large 12ft model rocket be used to launch a probe into space, such as a telescope?

People have tried. There are amateur rocket builders who are working on it. First you need a lot of power to get into space - so you'd need a bigger rocket, the bigger the rocket the more power you need, and the bigger the rocket the harder it is to control it. So, pretty big rockets are usually required to put even relatively small things in space.

They need to be big..........

About this big http://www.orbitcast.com/archives/satellite-launch.jpg [Broken]

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- #4

Nabeshin

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A 21 foot tall amateur rocket using just solid propellant reached past the official boundary of space, up to 116km though! So 12 feet isn't THAT far off.

Source: http://en.wikipedia.org/wiki/Civilian_Space_eXploration_Team

Note however that if you want to launch something into ORBIT, or on an escape trajectory, the amount of power necessary increases manifold.

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Probably 4 ballons with the rocket between them, and use a RC/unit with an arduino or raspberry pi to control levelling and launching.

- #6

Drakkith

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You simply get yourself 30 km up in the air and don't need to make it up using the rocket. It makes it easier to get into space, but not to get into orbit. Getting into an orbit requires accelerating from near zero to about 8 km/s for a low Earth orbit.

Probably 4 ballons with the rocket between them, and use a RC/unit with an arduino or raspberry pi to control levelling and launching.

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I am pretty sure that because of thinner air, you will less fuel 30-60km than you use 0-30km

I'm trying to find some data on it. No, I don't expect the answer to be "orbit".

I am worried about stability though. High winds up there. Lower winds at ground level and easier to stabilise yourself once in motion.

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8 km/s where are you getting that figure?.....That's 23 times the speed of sound. The max speed of the space shuttle was 1.3 km/sGetting into an orbit requires accelerating from near zero to about 8 km/s for a low Earth orbit.

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Look here:

http://en.wikipedia.org/wiki/Orbit_velocity

The high velocity is required because that is the velocity needed to be in uniform circular motion around the earth, with gravity

being the centripetal force.

edit/add: http://www.space.com/12127-8-surprising-space-shuttle-facts.html

Here's another something similar:

http://en.wikipedia.org/wiki/Escape_velocity

It's the velocity required for a body to escape the pull of gravity.

(example: you shoot a cannon ball straight up, but it normally falls back down. If you shoot it fast enough (escape velocity or above), then it'll never fall back down

- #12

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8 km/s where are you getting that figure?.....That's 23 times the speed of sound. The max speed of the space shuttle was 1.3 km/s

If you were to use all your kinetic energy at the surface of the earth in 1 instant (time approaches 0 or power approaches infinity), you would need about 8 km/s as an initial velocity. This is the definition of "escape velocity".

- #13

256bits

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Escape elocity for the earth is a little more than 11 km/s.If you were to use all your kinetic energy at the surface of the earth in 1 instant (time approaches 0 or power approaches infinity), you would need about 8 km/s as an initial velocity. This is the definition of "escape velocity".

As drakith stated 8 km/s is needed for a low earth orbit.

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mfb

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[tex]m_{total} = m_{dry\,mass} \exp\left(\frac{8km/s}{v_{exhaust}}\right)[/tex]

The best chemical propellants reach an exhaust velocity of about 4km/s, therefore the exponential is about e

Compare it with real rockets:

The space shuttle could launch about 25 tons into low earth orbit, but required a total mass of 1500 tons -> ratio 1/60. However, that reusable shuttle was not really ideal in terms of "payload to orbit"

The Saturn V was bigger, and with a better ratio: 120 tons payload, 2800 tons total mass -> ratio 1/23

Soyuz-U: 7 tons payload, 313 tons total mass -> ratio 1/45

As you need some systems regardless of size, smaller rockets tend to have a worse ratio. Let's look at commercial rockets:

Falcon 1 (21m height, 1.7m diameter) can launch 0.7 tons with a total mass of 39 tons (1/56), the bigger Falcon 9 with 10,5 tons / 333 tons (1/32) is better. Falcon heavy: 53 tons / 1400 tons (1/26)

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I've heard it stated that the most expensive part of a launch is the first 2 inches!

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I would love to have a link to learn more about that!I've heard it stated that the most expensive part of a launch is the first 2 inches!

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- #18

mfb

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I think what that means is getting it 2 inches off the ground without it malfunctioning and exploding is the most expensive part of the launch.I've heard it stated that the most expensive part of a launch is the first 2 inches!

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