Pluto balloon rockets.

[cinder1992]

I've been thinking that there may be a more efficient way to get a rocket into orbit... Balloon power! I'm going to make a modle in a few years (recession ). Discuss if this H-O2 rocket could get to orbit.

here's an Image

RED things are separable

 

[garyw]

if this would work why haven't the rocket designers already tried it?

 

[tl8]

ummm

Do know how much a normal rocket weighs?

Like a Delta II

200 000kg

Now Helium can lift about 1kg per m3.
So that is 200 000m3

That is a balloon about 140m long, and 40m in Diameter, that basically means it will be as wide as the rocket is tall...

 

[Hielor]

Look at how big dirigibles had to be just to lift a small gondola with a few people in it. Determine what volume of helium you need in order to lift 1kg of payload. Then calculate what volume of helium you would need in order to lift a ROCKET.

 

[garyw]

wouldn't the rocket break at the mid point due to the pull of the ropes?
I know that rockets like the Delta II have very particular pressurisation requirements on they can rupture.

 

[tl8]

However, if all you want to do is lift a couple of kg to orbit, then a balloon might be cheaper

 

[cinder1992]

I see your point. I WAS going to use hydrogen as the lifter... then I remembered the Hindenburg. Imagen what a rocket engine would do to a one millimetre thick balloon...BOOM! So if I'm gonna make an orbital model... it's using helium.

@tl8: the rocket would be on it's side, thus nullifying the tall/wide thing .

BTW do any of you know an equation to determine how high this thing will go before levelling off/bursting?

edit: I was being stupid when I responded to the tall/wide thing, sorry.

 

[tl8]

I meant the diameter of the balloon is the height of the rocket...

The thing is huge, and the Delta II is really quite small in rocket terms

 

[Eccentrus]

I thought that the hindenburg used to be 100 meters long?

 

[cinder1992]

1+1-1=/= -1

the length of the Hindenburg has nothing to do with the rocket. I was
commenting on how it blew sky-high when the hydrogen ignited.

urr, just realised something... the current fusion reactor design produces a
LOT of helium, and we are at the threshold of a breakthrough in nuke-fusion
power. where's that gonna go huh :lol:? +0.5 for balloon.

And although the ballon would be large, it would be re-usable. looks like a
win-win-WIN scenario to me. +1 for balloon.

but the ascent speed would be HIDEOUSLY slow, making it only economical
for transport/exploration missions. -1 for balloon.

in summary, 0.5+1-1=0.5. still a positive number.

 

[RisingFury]

You wouldn't really gain all that much...

Most of the energy goes into velocity and not int height... I haven't done any meaningful calculations, but I would say 20 times as much energy goes into velocity.

 

[insane_alien]

but the main point is you miss out most of the nasty atmospheric drag and stuff, not that you get a height bonus(athouh that helps too)

 

[IthyStPete]

True, but you wouldn't have to spend all the energy getting through the dense lower atmosphere.

 

[Andy44]

[ame="http://www.youtube.com/watch?v=N8KrEvT-wYQ"]YouTube - FARSIDE rocket-balloon launch from Eniwetok Atoll[/ame]

 

[RisingFury]

IIRC, Pegasus was the first fully commercial rocket to reach orbit. But it did so by being dropped off a cargo plane.


That may work for small rockets, but once things get big, it will be more expensive and complicated to build your balloon then to just launch off the ground.

 

[TSPenguin]

The biggest disadvantage is the lack of control over the baloon.
It would take a long time until it rises, completely floating wherever it wants to go. It might easily float to a point where you can't reach your desired plane at all.
Then you have to wait an undetermined amount of time until the rocket has the correct orientation to be dropped (you would need to drop it if you plan on reusing the baloon at all. Simple the winds created by the rocket exhaust would brake a baloon) quite low again, creating lots and lots of unpredictable stress on the rocket before it can fire. And then the hassle to retrieve the baloon an repair it from all over the world...

My take is that it would work and actualy save a little. But it is highly risky, you can not simply abort and have a whole new horizon of failures that can occur.

I think, launch from a carrier plane to LEO and beeing taken from there via space tug is much more feasable.

 

[Notebook]

Looks a bit like cinder1992's drawing:-
http://i89.photobucket.com/albums/k207/Notebook_04/img030.jpg



N.

 

[cinder1992]

Uh...Huh. I see what you mean. but with all that wind taken into account, it CAN work to the advantage of the balloon, the prevailing winds here alow a stable launch (off plain) to the ISS.

 

[Notebook]

To be honest, I'm not sure how a rocket like Europa would take to being launched horizontally. Besides the propellants having voids along the top of the tanks, might make fuel delivery a problem! They had to hold it down on the launcher for three seconds till it delivered full thrust, not sure how your ballon would like that. Or would you drop it at -3seconds?
Then the trajectory. Would it try to keep localy horizontal, or some pitch up till it gets some horizontal velocity?

N.

 

[agentgonzo]

I WAS going to use hydrogen as the lifter... then I remembered the Hindenburg.

I'd use a hydrogen lifter instead of helium as it has 4 times the lifting power and is a lot cheaper than helium. Yes, the hindenberg caught fire and destroyed itself, but that was (partly) because it was landing in bad weather and a static spark arced to the ground igniting the hydrogen.

In your scenario, you'd be using the balloon as a use-once launcher as the rocket exhaust would wreck the balloon anyway (and there'd be no easy way to get it down after dropping the ballast (rocket)) so durability/landing wouldn't be an issue. The germans flew many many zeppelin flights using hydrogen before the Hindenberg caught fire and if properly managed and launching in only good weather, it shouldn't be an issue.