Reply to: Aren't Space Rockests Rubbish

[NotAllThere]

Try reading
The Fountains of Paradise by Arthur C Clarke
or
The Mars Trilogy by Kim Stanley Robinson

They've nicked your idea!!

The technology to build a space elevator may be developed in twenty years or so.

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

[TimberWolf]

I could simulate the flight for free at the gym: Strap on some 100 kilo weights and get on the vibrating machine thingy (this can take fillings out). After a few minutes turn off the lights and jump into the pool. Float around for a bit (you might want to take off the weights at this point) and get back onto vibrating machine, turn on ipod for screaming noises, get in sauna and after 30 seconds ignite big petrol bomb. For a successful trip, you obvious don't need a petrol bomb.

[HairyArsedBloke]

Branson - "Never trust a hippy" It's true now as it was then.

[Churchill]

Somehow, I really don't find that very reassuring...

Why?

The technology is proven.

[Churchill]

God preserve us, you'd have to be brave to ride that thing... the bearded twat can't even run trains properly.

The guys who build the things (Scaled Composites) are very, very bright cookies.

[Churchill]

I don't think sh!te will do the job. You'd need a lot of dried cowpats to launch a rocket.

Instead, couldn't we put lots of hose pipes up cow's bottoms to gather the methane and pipe that into the top of the rocket, then light the bottom (so to speak) of the rocket.

One mega cow-fart-launched firework to the moon. A Frisian Fart Blaster.

Yup CH4 is your saviour!!!

All hail the mighty fart!

[RichardCranium]

So the energy required to launch that lot is...

Your sums is sh!te!

I don't think sh!te will do the job. You'd need a lot of dried cowpats to launch a rocket.

Instead, couldn't we put lots of hose pipes up cow's bottoms to gather the methane and pipe that into the top of the rocket, then light the bottom (so to speak) of the rocket.

One mega cow-fart-launched firework to the moon. A Frisian Fart Blaster.

[TimberWolf]

So the weight of the package is 1kg for the payload plus 3 kg for the fuel plus the weight of the craft to carry the payload and fuel...

So the energy required to launch that lot is...

Your sums is sh!te!

My calculation was for the miniumum amount of fuel, you can use as much as you like. For example firing ballistically or climbing a ladder does not require you to carry fuel with you. As you say, with a rocket you also need fuel to carry the fuel to carry the fuel and integration is required. Rockets are by no means fuel efficient, wot I said.

[Churchill]

Don't forget 9 tenths of the energy needed to get the satellite in orbit is kinetic (its orbital speed) with only a tenth potential (its height). So most of the energy given to the rocket from earth must be to push it tangential to the earths surface, not straight up. If you push straight up, it will come back down when you turn off the power. In fact any ballistic path (fired in any direction like a cannon) will return to earth unless escape velocity is reached (which would need more energy, and a rocket that won't come back).

It's amazing not only how old the technology is (though to be fair you can't change the laws of physics) but how ineffficient rockets are. To get 1Kg orbiting at 100km only needs 31,816,706 Joules. Which is about what's contained in 3 kg of petrol. I hope I got my sums right there, but it is small. Admittedly a substantial proportion of these losses may be inevitable since we have an atmophere, unless a Jacobs ladder or somesuch is used instead of brute force.

I'd also like to see more use made of the atmosphere (contains fuel in the form of oxygen and reaction mass to push with), and perhaps rail guns too. Though this would need work on high temperature materials since the atmosphore will make things rather toasty, though it does on the way down too.

So the weight of the package is 1kg for the payload plus 3 kg for the fuel plus the weight of the craft to carry the payload and fuel...

So the energy required to launch that lot is...

Your sums is sh!te!

[OwlHoot]

.. I'd also like to see more use made of the atmosphere (contains fuel in the form of oxygen and reaction mass to push with), and perhaps rail guns too. ..

And natural height to start with, so you miss the thickest part of the atmosphere and get a several mile head start. I wonder if that's why the Chinks are so interested in keeping Tibet - lots of high peaks to site launchpads on. If only our daft Government was so far-sighted.

[TimberWolf]

I went to an excellent presentation from Virgin Galactic a while ago when they made some of these very points. They won the X prize by looking at things totally differently, they launch a craft on the back of a high flying conventional(ish) plane. I was very impressed.

I think the Virgin spaceplane is rather modest in what it achieves though, probably similar to what a WWII V2 rocket could manage? It just goes up (60 miles or so?) and comes down again. It's an advance on rockets, but getting into orbit (or the moon) is light years away from what it currently achieves.

[Spacecadet]

It's quite simple to avoid all that CO2 waste.

Next time they send up a rocket just feed out a length of rope on the way.

Tie it up to a big rock on the moon and then just get the astronauts to climb up in future.

They could probably do something clever with pulleys to help lift heavy stuff.

Try reading
The Fountains of Paradise by Arthur C Clarke
or
The Mars Trilogy by Kim Stanley Robinson

They've nicked your idea!!

[Peoplesoft bloke]

Just perusing the NASA website while bored. It struck me that space rockets are just big tubes full of explosives in fact no material improvement over 2,000 year old Chinese fireworks.
Surely we can do better.
Personally, I'd go with ground laser powered plasma jets, possibly combined with scramjets.
And furthermore, just how much CO2 do these rockets actually produce? Is each rocket launch responsible for the future deaths of billions of cuddly polar bears? I suspect it is. Can someone from the Guardian or similar please quote me on this? I am a scientist after all (B.Sc.)

I went to an excellent presentation from Virgin Galactic a while ago when they made some of these very points. They won the X prize by looking at things totally differently, they launch a craft on the back of a high flying conventional(ish) plane. I was very impressed.

[TimberWolf]

Just perusing the NASA website while bored. It struck me that space rockets are just big tubes full of explosives in fact no material improvement over 2,000 year old Chinese fireworks.
Surely we can do better.
Personally, I'd go with ground laser powered plasma jets, possibly combined with scramjets.
And furthermore, just how much CO2 do these rockets actually produce? Is each rocket launch responsible for the future deaths of billions of cuddly polar bears? I suspect it is. Can someone from the Guardian or similar please quote me on this? I am a scientist after all (B.Sc.)

Don't forget 9 tenths of the energy needed to get the satellite in orbit is kinetic (its orbital speed) with only a tenth potential (its height). So most of the energy given to the rocket from earth must be to push it tangential to the earths surface, not straight up. If you push straight up, it will come back down when you turn off the power. In fact any ballistic path (fired in any direction like a cannon) will return to earth unless escape velocity is reached (which would need more energy, and a rocket that won't come back).

It's amazing not only how old the technology is (though to be fair you can't change the laws of physics) but how ineffficient rockets are. To get 1Kg orbiting at 100km only needs 31,816,706 Joules. Which is about what's contained in 3 kg of petrol. I hope I got my sums right there, but it is small. Admittedly a substantial proportion of these losses may be inevitable since we have an atmophere, unless a Jacobs ladder or somesuch is used instead of brute force.

I'd also like to see more use made of the atmosphere (contains fuel in the form of oxygen and reaction mass to push with), and perhaps rail guns too. Though this would need work on high temperature materials since the atmosphore will make things rather toasty, though it does on the way down too.

[HairyArsedBloke]

It's them rockets that are making holes in the Ozone layer that is letting in all that global warming.

If we didn't have rockets we would be able to drive more and there wouldn't be all them chavs either because there wouldn't be any Sky TV for them to watch all day when they should be working.