A giant balloon - zeppelin

Now that you guys have killed my supergun idea [tears...], what about
a giant balloon/zeppelin that could fly upwards of 50KM in the
stratosphere. Then it could launch an orbital space plane from under
its body (after detaching). The Zeppelin could be built to be either
manned or unmanned autopilot. It would save on the amount of fuel
necessary for the OSP to carry.

Ex: Zeppelin 150 meters long, 40 meters diameter, using helium and gas
engines. OSP: 20 meters long.

Ciao.

garfangle wrote:
Now that you guys have killed my supergun idea [tears...], what about
a giant balloon/zeppelin that could fly upwards of 50KM in the
stratosphere.

Such a great idea it's been in test for some years 8-)

http://www.jpaerospace.com


-george william herbert

garfangle wrote:

Ex: Zeppelin 150 meters long, 40 meters diameter, using helium
and gas engines. OSP: 20 meters long.

You're going to have to do a lot better than that. The volume of air
that such a zeppelin would displace at an altitude of 50 km has a
mass of 200 kg. So your zeppelin, helium, and OSP will all have to
have a total mass of 200 kg as well.

Jim Davis

In article ,
(garfangle) wrote:

Now that you guys have killed my supergun idea [tears...], what about
a giant balloon/zeppelin that could fly upwards of 50KM in the
stratosphere. Then it could launch an orbital space plane from under
its body (after detaching).

I had basically this idea in seventh grade, and thought I was on to
something big. Then one of my teachers helped me work through the math.
Bummer.

The long and the short of it is, you don't save much by starting up
high. It's velocity that you need much more than altitude. The thinner
atmosphere makes a big difference for small sounding rockets, but not
that much difference for orbital launchers, which spend most of their
acceleration time outside the atmosphere anyway.

Cheers,
- Joe

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"Joe Strout" wrote in message
...
In article ,
(garfangle) wrote:

Now that you guys have killed my supergun idea [tears...], what about
a giant balloon/zeppelin that could fly upwards of 50KM in the
stratosphere. Then it could launch an orbital space plane from under
its body (after detaching).

I had basically this idea in seventh grade, and thought I was on to
something big. Then one of my teachers helped me work through the math.
Bummer.

The long and the short of it is, you don't save much by starting up
high. It's velocity that you need much more than altitude. The thinner
atmosphere makes a big difference for small sounding rockets, but not
that much difference for orbital launchers, which spend most of their
acceleration time outside the atmosphere anyway.

But you do gain a little... and you gain more from being able to optimize
your nozzle for a lower ambient pressure.

Is it enough? That's left to the reader as an exercise.


Cheers,
- Joe

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'

In article ,
Joe Strout wrote:
The long and the short of it is, you don't save much by starting up
high. It's velocity that you need much more than altitude. The thinner
atmosphere makes a big difference for small sounding rockets, but not
that much difference for orbital launchers, which spend most of their
acceleration time outside the atmosphere anyway.

Not entirely true, when you look at the fine points. The altitude per se
doesn't make much difference, but the thinner air is important. That's
not because of drag losses, but because it reduces aerodynamic loads and
heating, and -- very important -- because it reduces back-pressure losses
in the engines and permits their nozzles to be optimized for vacuum
operation. This matters most if you're trying to do SSTO, but it's not
insignificant even for multistage designs.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

he volume of air
that such a zeppelin would displace at an altitude of 50 km has a
mass of 200 kg. So your zeppelin, helium, and OSP will all have to
have a total mass of 200 kg as well.
Touche! Most people don't realize how BIG and LIGHT a balloon has to be to
get to 50 km!
Do a websearch for High Altitude Airships and you'll see that the Army WILL
develop a big semi-rigid blimp to get 400 kg payload [anti cruise missile
radar] to 20 km. And then it'll spend 40 million to buy a fleet of ten by 2010.
So, HAA's are definitely going to happen.
I believe that soon the Army will want anti missile missiles on these blimps
and will make them larger to do so. Killer lasers will always be too big and
heavy for blimp use.
And there will be your high alt launch platform to enable cheaper access to
space by smaller orbital rockets. Your idea is sound and will happen.
^
//^\\
~~~ near space elevator ~~~~
~~~members.aol.com/beanstalkr/~~~

garfangle wrote:

Now that you guys have killed my supergun idea [tears...], what about
a giant balloon/zeppelin that could fly upwards of 50KM in the
stratosphere.

Is that even possible for an airship?

Then it could launch an orbital space plane from under
its body (after detaching). The Zeppelin could be built to be either
manned or unmanned autopilot. It would save on the amount of fuel
necessary for the OSP to carry.

Um, if it could be done, it might simplify nozzle expansion issues
and drag somewhat....but not much more.


Ex: Zeppelin 150 meters long, 40 meters diameter, using helium and gas
engines. OSP: 20 meters long.

Ciao.

I once read a corny military scifi paperback that featured an atomic-powered
dirigible that carried Harrier jets and deployed them from a hook/arm like the
British frigates can use. The idea was to have an aircraft carrier that was
very rapidly deployed and could stay aloft for a long long time. The reactor
was the source for (very) hot air to give lift to the ship, as well as electric
motor power. It might also have had a laser (well, why go halfway?);-)

I don't have the math to figure out if you could ever make a hot air zeppelin
that could lift a reactor, much less a wing of Harriers and etc. ...
considering weight, the reactor could not use conventional shielding, and
somehow I doubt you could make a pile that ran hot enough to give you the BTU's
needed for flight, without itself melting down. Kind of like a slow-speed
version of the proposed project Pluto air-breathing nuclear ramjet. And of
course, this thing couldn't be very stealthy in the infra-red, now could it?;-)

"MSu1049321" wrote in message
...
I once read a corny military scifi paperback that featured an
atomic-powered
dirigible that carried Harrier jets and deployed them from a hook/arm like
the
British frigates can use. The idea was to have an aircraft carrier that
was
very rapidly deployed and could stay aloft for a long long time. The
reactor
was the source for (very) hot air to give lift to the ship, as well as
electric
motor power. It might also have had a laser (well, why go halfway?);-)

Well, can't speak for a squadron of Harriers, but some Zeppelins did carrry
fighters that they could launch and recover.

I don't have the math to figure out if you could ever make a hot air
zeppelin
that could lift a reactor, much less a wing of Harriers and etc. ...
considering weight, the reactor could not use conventional shielding, and
somehow I doubt you could make a pile that ran hot enough to give you the
BTU's
needed for flight, without itself melting down. Kind of like a
slow-speed
version of the proposed project Pluto air-breathing nuclear ramjet. And
of
course, this thing couldn't be very stealthy in the infra-red, now could
it?;-)