Hot Air Balloons for Artillery spotting

packhunter wrote:So it seems that all the best fantasy authors are trying their hands at steampunk genre lately. I'm quite certain that RFC could wright something trully epic and amazing if he was to start something up.

Problem he has way too many serries that are still ongoing that starting something new just to play with steam powered machines and magic would slow everything down.

Enter the Safehold serries, they have steam engines now, they have sufficently advanced technology that is indestinguishable from magic. They can easily(if the author chooses) have fleets of airships duelling it out in the ski, while steam tanks roll through the feilds and massive Battleships and Dreadnaughts trade broadsides on the seas.

Well maybee not in the next book or two, but certainly in a decade safehold time.

Tenshinai wrote:

fallsfromtrees wrote:At the beginning of OAR I think there was a reference to gravity being 85% of Earth. This provides no information about the air density, since that depends on the quantity of air. Probably no air generator, as the native plants and animals co-exist along with the Terran imports, so the atmosphere was pretty much the same.

Ooh, lower gravity and overall colder, that´s GOOD conditions for balloons.

If air density is also above earth, then flight could be really easy. Hanggliders or manned kites might be realistic even with just the most simple materials and experimentation.

Randomiser wrote:

fallsfromtrees wrote:At the beginning of OAR I think there was a reference to gravity being 85% of Earth. This provides no information about the air density, since that depends on the quantity of air. Probably no air generator, as the native plants and animals co-exist along with the Terran imports, so the atmosphere was pretty much the same.

Tenshinai wrote:Ooh, lower gravity and overall colder, that´s GOOD conditions for balloons.

If air density is also above earth, then flight could be really easy. Hanggliders or manned kites might be realistic even with just the most simple materials and experimentation.

I'm not really into atmospheric physics, but won't air density be connected to gravity? If surface gravity is lower what would keep the air density up?

fallsfromtrees wrote:

Randomiser wrote:I'm not really into atmospheric physics, but won't air density be connected to gravity? If surface gravity is lower what would keep the air density up?

If surface gravity is lower, then the gradient of air pressure will be lower - that is the rate at which air pressure changes with altitude will be less. The base line however is determined by the amount of atmosphere. An example is in our solar system, where Earth and Venus have similar gravity fields, but the air pressure at the surface is vastly different - 1 atm on Earth, approx 800 atm on Venus. We don't have any information on what the base pressure on Safehold is, although it can be assumed that it is roughly equal to that of Earth, or at least that the partial pressure of Oxygen of Safehold is roughly equal to the current partial pressure here on Earth (about 0.21 atm)

Randomiser wrote:
I'm not really into atmospheric physics, but won't air density be connected to gravity? If surface gravity is lower what would keep the air density up?

SWM wrote:[planetary scientist hat]Correct! An even more extreme example is Jupiter, which is believed to have a solid core only slightly larger than the Earth, but has an enormously massive atmosphere.[/planetary scientist hat]

TN4994 wrote:We can't have lighter than air gases without gravity.

Tenshinai wrote:

TN4994 wrote:We can't have lighter than air gases without gravity.

Say what?

Tenshinai wrote:

SWM wrote:[planetary scientist hat]Correct! An even more extreme example is Jupiter, which is believed to have a solid core only slightly larger than the Earth, but has an enormously massive atmosphere.[/planetary scientist hat]

Yes, but Jupiter also has 2.5 times Earth gravity. And that core is still guesstimated as having far more mass than earth, a quick check says the numbers predict 12-45 times Earth mass.

TN4994 wrote:We can't have lighter than air gases without gravity.

Say what?

SWM wrote:I think that he means that buoyancy is an effect that only exists in a gravitational field.

TN4994 wrote:Any gas is a collection of molecules that are attracted to each other by gravitational pull. These in turn are acted upon by the Earth's gravitational pull. Some more than others.

TN4994 wrote:Any gas is a collection of molecules that are attracted to each other by gravitational pull. These in turn are acted upon by the Earth's gravitational pull. Some more than others.