[freeztar]

Thanks for the explanation Alex, it's an interesting idea.
My first thought is "Why aren't we employing this method already?". I can only assume that there is a logical reason for not using this method, else space agencies would be using it. Perhaps the amount of balloons needed is impractical? Not enough lift? I'm not sure, but it would need some number crunching to verify the possibility.

I think I'll stop here and go check out xubuntu.

[Giles Corey]

I shall propose a Magenetic Acceleration Cannon to deliver our package to the moon!
That or a giant sling shot is about equal in the chance of success...At this stage at least.

[freeztar]

Originally Posted by Giles Corey

I shall propose a Magenetic Acceleration Cannon to deliver our package to the moon!
That or a giant sling shot is about equal in the chance of success...At this stage at least.

I think we've all come to the consensus that a rocket is the best way to go.

If you think of a better/cheaper way, then we're all ears.

[alexander]

I think we've all come to the consensus that a rocket is the best way to go.

except for me, i voted for a boomy boosty thingy if i recall correctly.

Why aren't we employing this method already?

Because for the amount of mass they are sending into space, the balloon method would be impractical. second reason is that it is not as simple as using an already built platform. Lastly it has been used in russian space program and xprize, they use planes, i propose high altitude balloons for environmental reasons. also, remember that we are not sending a 2 tonn craft up into space, we need to make it as small and light as we can possibly make it

[freeztar]

Originally Posted by alexander

except for me, i voted for a boomy boosty thingy if i recall correctly.

Oh, right. A "boomy boosty thingy".
What exactly were you referring to?

We're still going to need some kind of rocket to take us to the moon. Is that what you were referring to?

Because for the amount of mass they are sending into space, the balloon method would be impractical. second reason is that it is not as simple as using an already built platform. Lastly it has been used in russian space program and xprize, they use planes, i propose high altitude balloons for environmental reasons. also, remember that we are not sending a 2 tonn craft up into space, we need to make it as small and light as we can possibly make it

Good point. So I wonder how much lift those balloons can provide?
(freezy heads off to google)

edit: ok, found this site: Balloon Lift

For Hydrogen:

diameter=24 volume(L)=204976.4 lift(gr)=228550.5 lift(lb)=503.87

That's a lot of lift, but I suspect our module will be much heavier than that.

[Janus]

Originally Posted by alexander

certainly, you as a space person, should be aware of where the majority of chemical energy of a rocket is spent. right, to accelerate the craft over the first 10000feet. the air is dense here, and it takes lots of energy to propel a vehicle through it. This is why for a very long time, russians, in their Buran project, were working on creating a flying shuttle launch platform, because the energy saving is termendous, so, you need less fuel, which means less weight and ability to use a smaller craft. This is also why the original x-prize used a plane to launch the "runner" (i think they called it) which had the rocket booster that then accelerated the craft to where it needed to go...

I suggest a similar design, only instead of a plane, it would be cool to use high altitude balloons, and thinking about the weight of the craft, most likely multiple high altitude baloons, to get the craft to over 10000feet, in fact to something like 100-120 000 feet prior to using rocket boosters to then break the earth's pull... I'm a math person, but i'm not a rocketry person, so i can not give you precise figures, but maybe someone with rocketry experience can, but it would be a hefty amount of fuel that would take you 35km up.... though it's still miniscule compared to the totel distance that is needed to travel, methinks its the biggest friction barrier for the mission

i think i'll stop here and go start working on changing over my linux install to xubuntu on my mac (dont worry it's a dual boot)

Okay, using the launch model I already have ready in orbiter, it is pretty easy to figure out if this is practical or not.

At an altitude of 35km, my model has used 43487 kg of fuel, the remaining mass being 54294 kg.

So how much hydrogen would it take to lift this mass to 35 km by balloon?

It takes about 0.6 kg of hydrogen to lift 1 kg of mass, so this gives you a mass of 33120 kg, for an apparent savings of 10367 kg (not counting the weight of the balloons themselves.)

But, here in lies the rub: My model has an upward velocity of over 1 km/sec when it hits that 35 km. A balloon would not have this velocity. So how much of that 10367 kg was used to get that 1 km.sec? You can't count this as part of your savings.

So instead of figuring out how much fuel is used when you pass the 35 km mark, you figure out how much fuel it would take to just get the rocket to a altitude of 35 km with no vertical velocity when it gets there. This worked out to be 29385 kg of fuel. This left a remaining mass of 68394 kg. This would be the mass a balloon would have lift, and you would need 41038 kg of hydrogen for your balloon.

Slight problem here, this is more than the fuel you would burn by rocket.

Quick note: My model is based on what it would take to deliver and land a payload of just a bit over 100kg to the moon's surface.

[Turtle]

Originally Posted by alexander

except for me, i voted for a boomy boosty thingy if i recall correctly.


Because for the amount of mass they are sending into space, the balloon method would be impractical. second reason is that it is not as simple as using an already built platform. Lastly it has been used in russian space program and xprize, they use planes, i propose high altitude balloons for environmental reasons. also, remember that we are not sending a 2 tonn craft up into space, we need to make it as small and light as we can possibly make it

Not an impractical idea to be sure. >> Air Force Explores Balloon-Assisted Launches

Maybe kites? Sorry...had to say it.

[DougF]

interesting link Turtle, I didn't know they were thinking about this type of launch.


you know that would have to be the worlds largest kite.

[Turtle]

Originally Posted by DougF

interesting link Turtle, I didn't know they were thinking about this type of launch.


you know that would have to be the worlds largest kite.

Air Force Explores Balloon-Assisted Launches

...Powell turned to the work of space science pioneer James Van Allen, who developed the concept of balloon-assisted launches at the University of Iowa in the 1950s. Van Allen, discoverer of the Van Allen Radiation Belt, used a rockoon to explore cosmic ray intensity, auroral particles and the Arctic magnetic fields. The rockoon system carried rockets via balloon to heights of 1,500 meters, and from there they were launched to altitudes of up to 75,700 meters. ...

Just to clarify, it has already been done. Rockoon to the Moon!! I love it. Way to go Jim Van.

Problem with the kite is that no matter the sail area, as you climb higher the air thins and you loose lift. I just like attaching ideas to kites. I like saying kite. Ohhh....Rockite!

[freeztar]

If what Janus has calculated is true (and I'm only saying "if" because I have not checked the numbers myself), the balloon-assisted launch idea is not a good one for a lunar mission. I'm sure that it can find use for the purposes listed in the article Turtle posted (small, lightweight satellites), but for a lunar trip it seems impractical and more expensive compared to a traditional rocket approach, as discussed earlier in this thread.