Hot Air Balloons

Tenshinai wrote:

TheOneLogician wrote:Just a lot. How hard would be be right now for either Charis or Siddermark to produce hot air balloons for either reconnaissance or bombing of high clusters of Church manufacturing?

First balloons on Earth were made with 18th century tech.
They have more like 19th century tech.

So probably doable. Don´t expect big bombing raids though, because airships are a lot harder than balloons.

While "doable", balloons not tethered drift with the wind, and are vulnerable to rockets, therefore impractical at current weaponry available.

SciFi90 wrote:
While "doable", balloons not tethered drift with the wind, and are vulnerable to rockets, therefore impractical at current weaponry available.

If too close to the ground, they do make rather big targets, don't they....

Without some means of propulsion, they do indeed drift.

Don

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captinjoehenry wrote:Observation would be really really easy just make a hot air balloon. Bombing not so much as you would need to guide the balloon over the target and that requires power of some sort and steam engines are heavy.

There was plenty of lightweight steam engines even in 1850s. The Stringfellow engine, for example:

http://www.douglas-self.com/MUSEUM/TRAN ... mplane.htm

He was able to have 1 Hp per 13 pounds of engine own weight (including water)

So, as I mentioned before many times - the steam-powered airships are perfectly possible on Charisian current level.

Laenole wrote:
snip

What are the physical properties that make propane the fuel of choice? LPG can be liquefied at 100F at 177 pounds per square inch (psi). Set quantities (like a cylinder full) of natural gas must be transported compressed (CNG) or cooled to its liquid state (LNG). LPG is 3.5 more efficient than CNG according to Wiki propane page. LNG must be kept at around -260F at around 1 atmosphere.

snip

Laenole
“All that glitters is not gold”

FWIR. some experimental submarines have used hydrocarbons and LOX with stirling engines whose cold end would evaporate the LOX for use, producing higher efficiency.

This should be another topic, but I don't know how to start a topic from within a topic yet.

DDHvi wrote:

Laenole wrote:
snip

What are the physical properties that make propane the fuel of choice? LPG can be liquefied at 100F at 177 pounds per square inch (psi). Set quantities (like a cylinder full) of natural gas must be transported compressed (CNG) or cooled to its liquid state (LNG). LPG is 3.5 more efficient than CNG according to Wiki propane page. LNG must be kept at around -260F at around 1 atmosphere.

snip

Laenole
“All that glitters is not gold”

FWIR. some experimental submarines have used hydrocarbons and LOX with stirling engines whose cold end would evaporate the LOX for use, producing higher efficiency.

This should be another topic, but I don't know how to start a topic from within a topic yet.

You just start a new topic then make a reply in the old topic with a link to the new topic.

Balloons wouldn't be workable as either reconnaissance or offensive platforms because you can't steer them at will, into enemy territory and then back to base, full circle, regardless of wind conditions. Considering what the church does to heretics you really don't want to end up setting down in their territory. Especially if you've just blown something up.

I don't know how high zeppelins can go as a practical matter. Theoretically, with no payload at all they should be able to reach a height where the air outside matches the density of the gas inside, so depending on payload mass the actual height will be less. From what I remember Safehold is slightly smaller than Earth. That means air density would fall off more rapidly with altitude. You'd have to run some specific numbers to know if the effect was significant or not.

At the heights they've historically flown though, massed rifle fire from the ground could punch enough holes to cause noticeable leakage (and force them down). Hydrogen is potentially explosive but requires a spark; bullets passing through canvas, mylar, or whatever the gas bag is made of, probably wouldn't spark but I imagine there's still a remote chance of it with each hit. If you can switch to helium that risk goes away but it also lowers your maximum cruising altitude.

Not that any of this stuff really matters. Whatever advantages a fleet of balloons or a squadron of zeppelins might give Charis would be outweighed by public reaction. Even within the Empire. They've only gotten people outside the inner circle to accept Merlin and Nimue's skimmers by calling them hikousen, mystical vehicles used by the archangels and the original seijins. Father Paityr isn't going to convince anyone flying machines are within the bounds of the Proscriptions, no matter what creative BS he comes up with to support the idea. And people outside Charis who are questioning whether the jihad is God's war, or just Clyntahn's, will re-evaluate that view in light of proof the Charisians really are dabbling in Shan-Wei's unclean knowledge.

ecortez wrote:Balloons wouldn't be workable as either reconnaissance or offensive platforms because you can't steer them at will, into enemy territory and then back to base, full circle, regardless of wind conditions. Considering what the church does to heretics you really don't want to end up setting down in their territory. Especially if you've just blown something up.

I don't know how high zeppelins can go as a practical matter. Theoretically, with no payload at all they should be able to reach a height where the air outside matches the density of the gas inside, so depending on payload mass the actual height will be less. From what I remember Safehold is slightly smaller than Earth. That means air density would fall off more rapidly with altitude. You'd have to run some specific numbers to know if the effect was significant or not.

At the heights they've historically flown though, massed rifle fire from the ground could punch enough holes to cause noticeable leakage (and force them down). Hydrogen is potentially explosive but requires a spark; bullets passing through canvas, mylar, or whatever the gas bag is made of, probably wouldn't spark but I imagine there's still a remote chance of it with each hit. If you can switch to helium that risk goes away but it also lowers your maximum cruising altitude.

Not that any of this stuff really matters. Whatever advantages a fleet of balloons or a squadron of zeppelins might give Charis would be outweighed by public reaction. Even within the Empire. They've only gotten people outside the inner circle to accept Merlin and Nimue's skimmers by calling them hikousen, mystical vehicles used by the archangels and the original seijins. Father Paityr isn't going to convince anyone flying machines are within the bounds of the Proscriptions, no matter what creative BS he comes up with to support the idea. And people outside Charis who are questioning whether the jihad is God's war, or just Clyntahn's, will re-evaluate that view in light of proof the Charisians really are dabbling in Shan-Wei's unclean knowledge.

TLs are already convinced that Charis is dabbling in unclean knowledge...steamships, Merlin's pistols, percussion caps and much more. Adding one more item to the list isn't really going to change the equation much one way or the other.

Actually what would interest me more than balloons would be heavier than air flight...steam powered airplanes. But we are a way from seeing that.

Don

ecortez wrote:BFrom what I remember Safehold is slightly smaller than Earth. That means air density would fall off more rapidly with altitude. You'd have to run some specific numbers to know if the effect was significant or not.

I don't think so. IIRC (and Wikipedia agrees) scale height of an atmosphere is based on temperature, gas composition and gravity. The size of the planet is only relevant as it affects the gravity, and Safehold's gravity is earth normal. (And a lower gravity means a slower decline in pressure with altitude.)

Safehold is colder than Earth, but the difference must be very tiny - it's clearly not as cold as Earth during the last glaciation, and that was only ~5 degrees Celsius colder than today at its peak.

EDIT: removed unnecessary quoting

n7axw wrote:TLs are already convinced that Charis is dabbling in unclean knowledge...steamships, Merlin's pistols, percussion caps and much more. Adding one more item to the list isn't really going to change the equation much one way or the other.

Actually what would interest me more than balloons would be heavier than air flight...steam powered airplanes. But we are a way from seeing that.

Don

Yeah, but a lot of people aren't buying the accusations of Charis violating the Proscriptions. Years of Charisian propaganda consistently telling the truth while the Church often exaggerates or lies means only the most fanatically devout are likely to take them seriously. And besides, hasn't the Church adopted the same innovations and declared them all permissible? Certain developments however - like electricity, flying vehicles, or energy weapons - you couldn't even pretend were not major violations. You'd have to be ready to denounce the Writ and tell everyone the full truth if you intended to use them openly.

cralkhi wrote:... a lower gravity means a slower decline in pressure with altitude.

Safehold is colder than Earth, but the difference must be very tiny - it's clearly not as cold as Earth during the last glaciation, and that was only ~5 degrees Celsius colder than today at its peak.

You're right. I got that mixed up. Higher gravity causes the atmosphere to settle more closely to the surface resulting in a steeper pressure gradient. Colder temperatures have much the same effect. This could potentially offset the lower gravity. Atmospheres are complex and dynamic systems though, temperature trends and circulation patterns at different levels won't necessarily be the same from one planet to the next. You'd have to model Safehold's climate and I doubt enough information has been provided to do that.