Military Blimps and Dirigibles Coming Back.

[Ocklawaha]

Looks pretty real and beautiful to me Stephendare, frankly majestic in the air!

Love that historical "tell all" name too, USSLZ FREEDOM PHOENIX

OCKLAWAHA

[buckethead]

I've lurked in this thread for a while now. I really don't have much to offer other than to say that lighter than air freight solutions as well as passenger fare has been long over due.

It's idea was well ahead of it's time. To provide stable, reasonably quick and reliable service at a fraction of the fuel costs seems like a no brainer.

IMO, it is the future platform for entry into space. What could be more logical than to float into space? Space Mining, here we come.

I would support any responsible initiatives to get Jax and area into the mix.

[Captain Zissou]

Buckethead, i don't follow your theory. As you got high and higher you would lose lift based on the atmosphere being less dense until you would have zero lift upon entering space itself.  Are you saying for the zeppelins to be launch points for spacecraft or spacecraft themselves??

[Ocklawaha]

All images of the USS LZ AKRON.

OCKLAWAHA

[BridgeTroll]

The Macon had this capability also...

[buckethead]

Buckethead, i don't follow your theory. As you got high and higher you would lose lift based on the atmosphere being less dense until you would have zero lift upon entering space itself.  Are you saying for the zeppelins to be launch points for spacecraft or spacecraft themselves??

No, but a hybrid blimp/rocket seems to solve many problems. They could be launch platforms as well, but stability would pose may challenges, one would think.

Does anyone know the operational ceiling for a blimp/zepplin/derigible/lighter that air craft?

[buckethead]

So if testing on such has been done, I wonder why NASA isn't all over it.

Instead of 3B per launch (not sure if that's accurate) it could be a 30M launch.

Beam me up, Scotty.

[NotNow]

World record for unmanned lighter than air is currently about 175,000 ft.  Manned record is almost 70,000 ft.  The problem is loss of lift in less dense atmosphere.   Record setting craft had ultra thin (3.4 micrometers) skin. The density of the helium must lessen with the density of the atmosphere around it, creating a larger area of gas needed for lift.  That is why the old photos you see have balloons that look almost empty on takeoff.  The balloon or dirigible will not reach escape velocity by itself.  I'm not sure what other ideas may be on the drawing board.

[Ocklawaha]

World record for unmanned lighter than air is currently about 175,000 ft.  Manned record is almost 70,000 ft.  The problem is loss of lift in less dense atmosphere.   Record setting craft had ultra thin (3.4 micrometers) skin. The density of the helium must lessen with the density of the atmosphere around it, creating a larger area of gas needed for lift.  That is why the old photos you see have balloons that look almost empty on takeoff.  The balloon or dirigible will not reach escape velocity by itself.  I'm not sure what other ideas may be on the drawing board.

Add to that that escape velocity is 7 miles per second. Not highly likely a blimp or zeppelin will do that. Take a moment to float off into space with me:

http://www.youtube.com/v/rL1oU6fH25w&hl=en&fs=1&color1=0x402061&color2=0x9461ca

ALBEDO 0.39

Maximum distance from the sun: 94 million 537 thousand miles

Minimum distance from the sun: 91 million 377 thousand miles

Mean distance from the sun: 92 million 957 thousand and 200 miles

Mean Orbital velocity: 66000 miles per hour

Orbital eccentricity: 0.017

Obliquity of the ecliptic: 23 degrees 27 minutes 8.26 seconds

Length of the tropical year: equinox to equinox 365.24 days

Lenght of the sidereal year: fixed star to fixed star 365.26 days

Length of the mean solar day: 24 hours and 3 minutes and 56.5555 seconds at mean solar time

Length of the mean sidereal day: 23 hours and 56 minutes and 4.091 seconds at mean sederial time

Mass: 6600 million million million tons

Equatorial diameter: 7927 miles

Polar diameter: 7900 miles

Oblateness:  one 298th

Density: 5.41

Mean surface gravitational acceleration of the rotating earth: 32.174 feet per second per second

Escape velocity: 7 miles per second

Albedo: 0.39

OCKLAWAHA

[buckethead]

Ock, I don't hope to compete with your ability to understand data and complex issues.

It does seem that the escape velocity you refer to of seven miles per secon is based on a ground launch.

If I could get to 200,000 feet using lighter that air technology, it seems that it would require less velocity to escape gravitational forces. I clealry am no engineer.

If an object was placed in a "stationary" position, relative to the earth and sun, outside of the atmosphere, would it fall to earth at the same rate as the same object would fall from 50,000 feet?

I guess what I'm asking is: At what point do the effects of gravity due to the mass of earth begin to decrease?

[Dog Walker]

"If an object was placed in a "stationary" position, relative to the earth and sun, outside of the atmosphere, would it fall to earth at the same rate as the same object would fall from 50,000 feet?"

Can't be stationary to both and the "rate" of acceleration would be the same (Physics 101), but falling from four times the distance the "speed" would be much higher when it hit the ground. (Yes, ignoring the air resistance which is dependent on the shape of the object.)

[NotNow]

Escape velocity is a standard.  outside of atmospheric forces, any mass must have momentum to defeat gravity.  The constant pull of gravity extends a lllloooooonnnnngggggg way.

[Dog Walker]

Just as boats can't float above the water no matter how light they are, balloons cannot float out of the atmosphere either.  And atmospheric density falls of geometrically, not arithmetically.  Try breathing at the top of a 10,000 foot mountain and you lungs will tell you about the difference.

[Dog Walker]

The astronauts on the space station are not floating around because they are "outside" earth's gravity field.  They are still well within it, but they are not resisting it, they are actually falling with it around the earth.  Their sideways velocity keeps them from falling into the earth.  That's the 7 miles per second escape velocity.  You get a little bit of the same effect when you go down in a fast elevator.

For the shuttle to get back to earth, they actually slow down by firing the rockets backwards so that they are pulled back to earth and stop falling around it.

[buckethead]

Thanks for all the insightful responses.

I'm gald to actually have the opportunity to consider these plainly obvious facts.

As you were posting, Dog Walker, I was contemplating exactly what you were writing.

Astronauts are not "weightless". It is the same effect as the training they recieve in a 747 diving from high altitude.

If they did not have momentum, they would fall back to earth. I had not considered any of this before.

The Science channel has failed me!