Pluto balloon rockets.

[cinder1992]

I don't meat to be rude, but
manned_flight+Fuel_leak+exploding_balloon=ohshi...


wait, did I just contradict myself?

 

[insane_alien]

there's a buouancy module for orbiter in existance so why not try it anyway.

 

[Lunar_Lander]

As Andy44's posted video shows, such things had been tried under the name Rockoon in the early days of spaceflight. With the then new polyethylene balloons they thought it might be worth hanging a Nike rocket below. Upon firing, the rocket was shot through the balloon, by the way! (The foil was just 1.5 mil, so no problem there)

But a big rocket would probably not be possible. Also the sole advantage of altitude would probably not be that big compared to airspeed + altitude, like in the X-15 and the Pegasus.

 

[tylor2000]

I like creative problem solving.

If there was a way to use the hydrogen as fuel or compressing it down afterwards so it would sink instead of rise.

There are several problems with compressing it, but if the rocket's initial thrust could e used to power a change of state compressor(or whatever)......and how much energy would that take anyway?

If you constructed the balloon a certain way so that it was meant to exploded but in the opposite direction of the rocket's intended vector in some preplanned orientation then it might actually be used to give extra energy to the rocket. We could call that stage 0, or -1.

We could construct the balloon to be at least partially surrounding the rocket so when the rocket fires the initial acceleration could be used to condense the gas or to orientate the balloon so it explodes behind the rocket. For every force there is an equal and opposite force, ect,

and so goes the possibilities......

 

[Notebook]

Someone else dropping things from ballons:

http://www.senkyo.co.jp/ists2008/pdf/2008-a-42.pdf

N.

 

[docabn]

Even a hydrogen balloon would still be huge. It might work and still be reusable if the balloon was essentially a giant torus with the rocket suspended in the center. How you would get the balloon on target is beyond me perhaps solar powered propellers. Once at altitude, the rocket fires, the guy lines would be on some sort of automated pulley system that causes them to slacken and tighten to keep the rocket oriented as it powers up and once the rocket clears the torus the lines snap and break. I think it might work but I think it would be horribly clumsy.
I’d also be very suspect of how large a device could be lifted this way. The attachment is the crudely draw idea of what this might look like. If anyone can figgure a way for this to work it would be pretty awsome.

Disclaimer: I’ve searched the internet and could not find anything, but I could swear I’d seen this concept in some sci-fi book or magazine. I’m pretty sure this is not entirely my original idea.
EDIT: This http://www.theregister.co.uk/2009/04/17/doughnut_ballutes_go_to_mars/ but in reverse. ( the picture is of a Mars lander concept) This could and should (if not already done by someone be added to orbiter as I think this is one of the better concepts for landing heavy objects on planets with atmospheres).
I knew I'd seen this somewhere.

 

[RisingFury]

If there was a way to use the hydrogen as fuel or compressing it down afterwards so it would sink instead of rise.

There are several problems with compressing it, but if the rocket's initial thrust could e used to power a change of state compressor(or whatever)......and how much energy would that take anyway?

dA = p(V)*dV

Assuming you're compressing it slowly, so heat gets lost...
p(V) = p1*V1/V

dA = p*V/V'*dV
A = P*V*Integral(1/V'*dv)
A = p*V*Log(V/V2)

V is the initial volume, V2 is the compressed volume.

The initial volume can be calculated easily:

Fg = Fb (Buoyancy)
m*g = V*Rho-V*Rho' (Rho is density of air, Rho' is density of hydrogen)
m*g = V*(Rho-Rho')
V = m*g/(Rho-Rho')

I'm not gonna write out the equation to calculate the density of air and hydrogen at high altitude, because I don't have good data for how temperature changes with altitude...

The question is, how much do you want to compress the balloon? To the point where it can't carry the rocket anymore and the whole thing starts to fall?
To the point where after the rocket's release, the balloon still falls?

If you constructed the balloon a certain way so that it was meant to exploded but in the opposite direction of the rocket's intended vector in some preplanned orientation then it might actually be used to give extra energy to the rocket. We could call that stage 0, or -1.

Even if you could get a big enough balloon that would really explode under pressure and not just burst and leak gas, the explosion would never be violent enough to push the rocket anywhere.

We could construct the balloon to be at least partially surrounding the rocket so when the rocket fires the initial acceleration could be used to condense the gas or to orientate the balloon so it explodes behind the rocket. For every force there is an equal and opposite force, ect,

and so goes the possibilities......

If the rocket was inside the balloon and fired it's engines, the balloon would get torn to shreds and leak out with a gentle wizz.

If you put a lot of pressure inside of a non-stretchable balloon, you will increase the density inside it and make it heavier. The balloon would lose the ability to lift weight.

p*V=m/M*R*T
p=m/(V*M)*R*T
m/V = Rho
p=Rho/M*R*T
Rho = p*M/(R*T)

As you can ses from the equation, if the pressure rises, density rises.