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Orbital Bombardment Calculator
ProudKiwi
http://www.lpl.arizona.edu/impacteffe...cteffects/

Work out how much damage your preferred kinetic weapon would do.

i prefer a small high velocity projectile. Focused massive damage with most effects coming from the air blast. No tectonic plate cracking for me thank you.Grin
 
MarieHawke
Your Inputs:
Distance from Impact: 12000.00 km = 7452.00 miles
Projectile Diameter: 12000.00 m = 39360.00 ft = 7.45 miles
Projectile Density: 100000 kg/m3
Impact Velocity: 100000.00 km/s = 62100.00 miles/s (Your chosen velocity is higher than the maximum for an object orbiting the sun)
Impact Angle: 90 degrees
Target Density: 2356 kg/m3
Target Type: Crystalline Rock

Energy:
Energy before atmospheric entry: NaN x 10NaN Joules = 1.08 x 1017 MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:
The Earth is strongly disturbed by the impact, but loses little mass.
100.00 percent of the Earth is melted
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
What does this mean?


Transient Crater Diameter: 12300 km = 7660 miles
Transient Crater Depth: 4360 km = 2710 miles

Thermal Radiation:
What does this mean?


Time for maximum radiation: 1.54 seconds after impact

Your position is inside the fireball.
The fireball appears 2750 times larger than the sun
Thermal Exposure: 1.40 x 1015 Joules/m2
Duration of Irradiation: 2e+06 seconds
Radiant flux (relative to the sun): 700000

Effects of Thermal Radiation:


Clothing ignites

Much of the body suffers third degree burns

Newspaper ignites

Plywood flames

Deciduous trees ignite

Grass ignites


Seismic Effects:
What does this mean?


The major seismic shaking will arrive at approximately 2400 seconds.
Richter Scale Magnitude: 16.0 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 12000 km:

X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.

XI. As X. Rails bent greatly. Underground pipelines completely out of service.

XII. As X. Damage nearly total. Large rock masses displaced. Lines of sight and level distorted. Objects thrown into the air.


Ejecta:
What does this mean?


Little rocky ejecta reaches this site; fallout is dominated by condensed vapor from the projectile.


Air Blast:
What does this mean?


The air blast will arrive at approximately 36400 seconds.
Peak Overpressure: 3.1e+09 Pa = 31000 bars = 440000 psi
Max wind velocity: 44800 m/s = 100000 mph
Sound Intensity: 190 dB (Dangerously Loud)
Damage Description:


Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.

Highway truss bridges will collapse.

Highway girder bridges will collapse.

Glass windows will shatter.

Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

weee
A starlight sharpshot magical girl!
 
Itharu
Yeah I had fun for about an hour with this thing. I found that if you can make a realitily small object really dense, you can cause far more damage. I've been using it terms of replicating actual projectile weaponry Grin

----------

Your Inputs:
Distance from Impact: 5.00 km = 3.10 miles
Projectile Diameter: 4.00 m = 13.12 ft = 0.00 miles
Projectile Density: 35000 kg/m3
Impact Velocity: 600.00 km/s = 372.60 miles/s (Your chosen velocity is higher than the maximum for an object orbiting the sun)
Impact Angle: 90 degrees
Target Density: 2750 kg/m3
Target Type: Crystalline Rock

Energy:
Energy before atmospheric entry: 2.11 x 1017 Joules = 5.04 x 101 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 2.3 x 103years
Atmospheric Entry:
The projectile lands intact, with a velocity 551 km/s = 342 miles/s.
The energy lost in the atmosphere is 3.33 x 1016 Joules = 7.95 x 100 MegaTons.

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:

Transient Crater Diameter: 1.62 km = 1.01 miles
Transient Crater Depth: 0.574 km = 0.357 miles

Final Crater Diameter: 2.03 km = 1.26 miles
Final Crater Depth: 0.433 km = 0.269 miles
The crater formed is a simple crater

The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 201 m = 659 ft.
The volume of the target melted or vaporized is 0.00158 km3 = 0.00038 miles3
Roughly half the melt remains in the crater

Thermal Radiation:

Time for maximum radiation: 0.00204 seconds after impact

Visible fireball radius: 1.12 km = 0.697 miles
The fireball appears 51 times larger than the sun
Thermal Exposure: 3.39 x 106 Joules/m2
Duration of Irradiation: 14.6 seconds
Radiant flux (relative to the sun): 232

Effects of Thermal Radiation:
-Clothing ignites
-Much of the body suffers third degree burns
-Newspaper ignites
-Plywood flames
-Deciduous trees ignite
-Grass ignites

Seismic Effects:

The major seismic shaking will arrive at approximately 1 seconds.
Richter Scale Magnitude: 5.7
Mercalli Scale Intensity at a distance of 5 km:

VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

Ejecta:

The ejecta will arrive approximately 32 seconds after the impact.
Average Ejecta Thickness: 49.8 cm = 19.6 inches
Mean Fragment Diameter: 34.3 m = 112 ft

Air Blast:

The air blast will arrive at approximately 15.2 seconds.
Peak Overpressure: 323000 Pa = 3.23 bars = 45.8 psi
Max wind velocity: 392 m/s = 877 mph
Sound Intensity: 110 dB (May cause ear pain)

Damage Description:
-Multistory wall-bearing buildings will collapse.
-Wood frame buildings will almost completely collapse.
-Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.
-Highway truss bridges will collapse.
-Glass windows will shatter.
-Cars and trucks will be overturned and displaced, requiring major repairs.
-Up to 90 percent of trees blown down; remainder stripped of branches and leaves.
-Fear the Might of the Imperial Cortharian Fleet
 
TelQuessir
You just simulated the effect of firing a warship class HVR150 onto a ground target.
 
TelQuessir
RG 320 on sedimentary rock

Quote



Your Inputs:
Distance from Impact: 0.01 km = 0.01 miles
Projectile Diameter: 0.32 m = 1.05 ft = 0.00 miles
Projectile Density: 16000 kg/m3
Impact Velocity: 25.00 km/s = 15.53 miles/s
Impact Angle: 60 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock
Energy:
Energy before atmospheric entry: 8.58 x 1010 Joules = 0.20 x 10-4 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is less than 1 month.
Atmospheric Entry:
The projectile lands intact, with a velocity 1.67 km/s = 1.04 miles/s.
The energy lost in the atmosphere is 8.54 x 1010 Joules = 0.20 x 10-4 MegaTons.
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.
Crater Dimensions:
What does this mean?



Transient Crater Diameter: 13.4 m = 43.9 ft
Transient Crater Depth: 4.73 m = 15.5 ft


Final Crater Diameter: 16.7 m = 54.9 ft
Final Crater Depth: 3.57 m = 11.7 ft
The crater formed is a simple crater


The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 1.65 m = 5.43 ft.
At this impact velocity ( < 12 km/s), little shock melting of the target occurs.
Thermal Radiation:
What does this mean?



At this impact velocity ( < 15 km/s), little vaporization occurs; no fireball is created, therefore, there is no thermal radiation damage.
Seismic Effects:
What does this mean?



The Richter Scale Magnitude for this impact is less than zero; no seismic shaking will be felt.
Ejecta:
What does this mean?



Most ejecta is blocked by Earth's atmosphere


Air Blast:
What does this mean?


The air blast will arrive at approximately 0.0303 seconds.
Peak Overpressure: 128000 Pa = 1.28 bars = 18.2 psi
Max wind velocity: 209 m/s = 467 mph
Sound Intensity: 102 dB (May cause ear pain)
Damage Description:


Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Highway truss bridges will collapse.

Glass windows will shatter.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.


Note, "19050" is the density value for depleted uranium.
Edited by TelQuessir on 10-11-2005 00:45
 
TelQuessir
RG1200, similar parameters to above, note drastically increased damage potential

Quote

Your Inputs:
Distance from Impact: 0.05 km = 0.03 miles
Projectile Diameter: 1.20 m = 3.94 ft = 0.00 miles
Projectile Density: 16000 kg/m3
Impact Velocity: 25.00 km/s = 15.53 miles/s
Impact Angle: 60 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock
Energy:
Energy before atmospheric entry: 4.52 x 1012 Joules = 0.11 x 10-2 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 0.6 years
Atmospheric Entry:
The projectile lands intact, with a velocity 12.1 km/s = 7.54 miles/s.
The energy lost in the atmosphere is 3.46 x 1012 Joules = 0.83 x 10-3 MegaTons.
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.
Crater Dimensions:
What does this mean?



Transient Crater Diameter: 89.9 m = 295 ft
Transient Crater Depth: 31.8 m = 104 ft


Final Crater Diameter: 112 m = 369 ft
Final Crater Depth: 24 m = 78.6 ft
The crater formed is a simple crater


The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 11.1 m = 36.4 ft.
The volume of the target melted or vaporized is 8.23 m3 = 291 feet3
Roughly half the melt remains in the crater
Thermal Radiation:
What does this mean?



At this impact velocity ( < 15 km/s), little vaporization occurs; no fireball is created, therefore, there is no thermal radiation damage.
Seismic Effects:
What does this mean?


The major seismic shaking will arrive almost instantly.
Richter Scale Magnitude: 2.2
Mercalli Scale Intensity at a distance of 0.05 km:


I. Not felt except by a very few under especially favorable conditions.

II. Felt only by a few persons at rest, especially on upper floors of buildings.


Ejecta:
What does this mean?



Most ejecta is blocked by Earth's atmosphere


Air Blast:
What does this mean?


The air blast will arrive at approximately 0.152 seconds.
Peak Overpressure: 1.19e+06 Pa = 11.9 bars = 170 psi
Max wind velocity: 840 m/s = 1880 mph
Sound Intensity: 122 dB (Dangerously Loud)
Damage Description:


Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.

Highway truss bridges will collapse.

Highway girder bridges will collapse.

Glass windows will shatter.

Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.



Solid railgun shot from a ship in low orbit thus only causes localised damage and is great for precision strikes against hardened targets.

Explosive (or DPICM equivalent) or nuclear payloads from naval railguns thus can be said as a worthwhile development for increased area of effects in surface bombardments.
Edited by TelQuessir on 10-11-2005 00:42
 
Itharu
Depleted Uranium in a ship vs ship battle is all good and such, due mostly inpart to the effects of heated uranium (ie, it keeps melting anything in it's path when overheated), but with orbital bombardment, wouldn't you most likely want to be using a metal that fits this criteria;

-High thermal tollernace, keeping it from melting in atmospheric transit.
-Aerodynamic, pointed being a good shape design, or frictionless (Astro glide frictionless)
OR
-Dense as hell (to keep it from breaking up in the atmostsphere)
-Somewhat magnetic, (if not then have strips of magnetic material for firing purposes only)

If pure nutrons could somehow be harnessed, I think they could be the second most dense substance that would make for an excellent weapon. (I say nutrons because it can overcome the problems of repelling due to atomic charges)

Just my thoughts on this......
-Fear the Might of the Imperial Cortharian Fleet
 
ProudKiwi
What would happen if someone threw the moon at us

Quote

Your Inputs:
Distance from Impact: 5000.00 km = 3105.00 miles
Projectile Diameter: 3476000.00 m = 11401280.00 ft = 2158.60 miles
Projectile Density: 3344 kg/m3
Impact Velocity: 2.00 km/s = 1.24 miles/s
Impact Angle: 90 degrees
Target Density: 2750 kg/m3
Target Type: Crystalline Rock

Energy:
Energy before atmospheric entry: 1.47 x 1029 Joules = 3.51 x 1013 MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
What does this mean?


Transient Crater Diameter: 1340 km = 835 miles
Transient Crater Depth: 476 km = 295 miles

Final Crater Diameter: 3450 km = 2140 miles
Final Crater Depth: 3.44 km = 2.13 miles

The crater formed is a complex crater.
At this impact velocity ( < 12 km/s), little shock melting of the target occurs.

Thermal Radiation:
What does this mean?


At this impact velocity ( < 15 km/s), little vaporization occurs; no fireball is created, therefore, there is no thermal radiation damage.

Seismic Effects:
What does this mean?


The major seismic shaking will arrive at approximately 1000 seconds.
Richter Scale Magnitude: 13.7 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 5000 km:

IX. General panic. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in ground. In alluviated areas sand and mud ejected, earthquake fountains, sand craters.

X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.


Ejecta:
What does this mean?


The ejecta will arrive approximately 1570 seconds after the impact.
Your position is beneath the continuous ejecta deposit.
Average Ejecta Thickness: 234 m = 766 ft


Air Blast:
What does this mean?


The air blast will arrive at approximately 15200 seconds.
Peak Overpressure: 4.95e+07 Pa = 495 bars = 7020 psi
Max wind velocity: 5660 m/s = 12700 mph
Sound Intensity: 154 dB (Dangerously Loud)
Damage Description:


Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.

Highway truss bridges will collapse.

Highway girder bridges will collapse.

Glass windows will shatter.

Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves

Edited by ProudKiwi on 11-11-2005 02:19
 
MarieHawke

Quote

Your Inputs:
Distance from Impact: 20000.00 km = 12420.00 miles
Projectile Diameter: 12874720.00 m = 42229081.60 ft = 7995.20 miles
Projectile Density: 3000 kg/m3
Impact Velocity: 22.00 km/s = 13.66 miles/s
Impact Angle: 90 degrees
Target Density: 2750 kg/m3
Target Type: Crystalline Rock

Energy:
Energy before atmospheric entry: 8.11 x 1032 Joules = 1.94 x 1017 MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:
The Earth is completely disrupted by the impact and its debris forms a new asteroid belt orbiting the sun between Venus and Mars.


Pwned Sad
A starlight sharpshot magical girl!
 
Itharu
God's Super Asteroid attcks and hits you.....

Quote

Your Inputs:
Distance from Impact: 12000.00 km = 7452.00 miles
Projectile Diameter: 12.00 m = 39.36 ft = 0.01 miles
Projectile Density: 99999999999999 kg/m3
Impact Velocity: 120000.00 km/s = 74520.00 miles/s (Your chosen velocity is higher than the maximum for an object orbiting the sun)
Impact Angle: 90 degrees
Target Density: 2750 kg/m3
Target Type: Crystalline Rock
Energy:
Energy before atmospheric entry: NaN x 10NaN Joules = 1.56 x 10^17 MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.
Atmospheric Entry:
The projectile lands intact, with a velocity 120000 km/s = 74500 miles/s.
The energy lost in the atmosphere is 1.30 x 1022 Joules = 3.11 x 10^6 MegaTons.
Major Global Changes:
The Earth is completely disrupted by the impact and its debris forms a new asteroid belt orbiting the sun between Venus and Mars.


CRITICAL HIT!
-Fear the Might of the Imperial Cortharian Fleet
 
Glacialis
Yes, throwing neutronium is devastating. Sure.

Ten billion metric tons per teaspoon.

Let's pass on that...Wink It's a bit beyond HW-era tech methinks.
 
TelQuessir
The existence of this thread indicates that I wish to discuss orbital bombardment weaponry in the HW universe. Thus the existence of this thread on this forum is dependent on whether that discussion objective is met.
 
MarieHawke
Last craziness...

Quote

Your Inputs:
Distance from Impact: 20000.00 km = 12420.00 miles
Projectile Diameter: 10000.00 m = 32800.00 ft = 6.21 miles
Projectile Density: 16000 kg/m3
Impact Velocity: 299943.00 km/s = 186264.60 miles/s (Your chosen velocity is higher than the maximum for an object orbiting the sun)
Impact Angle: 90 degrees
Target Density: 2750 kg/m3
Target Type: Crystalline Rock

Energy:
Energy before atmospheric entry: NaN x 10NaN Joules = 9.00 x 1016 MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
100.00 percent of the Earth is melted
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
What does this mean?


Transient Crater Diameter: 8950 km = 5560 miles
Transient Crater Depth: 3160 km = 1960 miles

Thermal Radiation:
What does this mean?


Time for maximum radiation: 0.482 seconds after impact

Your position is inside the fireball.
The fireball appears 1500 times larger than the sun
Thermal Exposure: 3.99 x 1014 Joules/m2
Duration of Irradiation: 1.88e+06 seconds
Radiant flux (relative to the sun): 213000

Effects of Thermal Radiation:


Clothing ignites

Much of the body suffers third degree burns

Newspaper ignites

Plywood flames

Deciduous trees ignite

Grass ignites


Seismic Effects:
What does this mean?


The major seismic shaking will arrive at approximately 4000 seconds.
Richter Scale Magnitude: 16.0 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 20000 km:

X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.

XI. As X. Rails bent greatly. Underground pipelines completely out of service.


Ejecta:
What does this mean?


Your position is in the region which collapses into the final crater.


Air Blast:
What does this mean?


The air blast will arrive at approximately 60600 seconds.
Peak Overpressure: 8.32e+08 Pa = 8320 bars = 118000 psi
Max wind velocity: 23200 m/s = 51900 mph
Sound Intensity: 178 dB (Dangerously Loud)
Damage Description:


Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.

Highway truss bridges will collapse.

Highway girder bridges will collapse.

Glass windows will shatter.

Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

A starlight sharpshot magical girl!
 
Itharu

Quote

Glacialis wrote:
Yes, throwing neutronium is devastating. Sure.

Ten billion metric tons per teaspoon.

Let's pass on that...Wink It's a bit beyond HW-era tech methinks.


Heh, I don't think Ten Billion Metric tons per teaspoon is correct.... Quite possibly for a black hole.

Yeah there are problems with collecting neutronium, from a Neutron Star (it mainly being that it is escentially half a black hole), but I'm sure you could manufacture it in one way or another. Maybe through fission leftovers.

Anyways, Tel did mention bombardment being investigated. I found that if you could make a projectile between 4 and 12 meters with a density of about 17000-22000kg/m3, it would keep intact and make a nice crater of about 250-400m, with a depth penitration of about 80m (traveling at around 100m/s entry).

So I'm wondering what's going to be the objective of orbital bombardment? or is it just a deterant factor in space warfair?
-Fear the Might of the Imperial Cortharian Fleet
 
Glacialis
Sorry. 100 million metric tons. Was off by a factor of 2.

Imagine railgun rounds. I'm not sure their size or density, but they will be moving very, very fast. c-fractional is a given. .3c? .5c? .7c?
 
Itharu

Quote

Glacialis wrote:
Sorry. 100 million metric tons. Was off by a factor of 2.

Imagine railgun rounds. I'm not sure their size or density, but they will be moving very, very fast. c-fractional is a given. .3c? .5c? .7c?


Rail gun rounds? Generally you want some uranium moving at about 2500Km/h if possible, which is roughly 600m/s. That's a decent speed. Grin
-Fear the Might of the Imperial Cortharian Fleet
 
Glacialis
That's absurdly slow. We're talking a significant portion of the speed of light.
 
Itharu
Becareful with that. High speeds require high ammounts of energy. Also when approaching the speed of light, you mass begins to creppy towards infinity. And when that happens, you need more energy.

If you want it faster tho, add an extra 0 or two to the 2500 Pfft
-Fear the Might of the Imperial Cortharian Fleet
 
Glacialis
I'm perfectly aware of relativistic effects on matter. Pfft Remember that in the game engine, every meter measured for distance (not ship size) is a kilometer. Put on the 7.1 test package, test out the railguns there and see how long it takes them to cross say, 10,000m in game/10,000km.
 
Slith
I don't happen to know how fast a railgun projectile travels in the homeworld universe, nor how large they are, so I'm randomly stabbing in the dark here.

Quote

Projectile Speed One: 30km/s
Distance from Impact: 1.00 km = 0.62 miles
Projectile Diameter: 1.20 m = 3.94 ft = 0.00 miles
Projectile Density: 19050 kg/m3
Impact Velocity: 30.00 km/s = 18.63 miles/s
Impact Angle: 60 degrees
Transient Crater Diameter: 109 m = 356 ft

Effects of Thermal Radiation: [At 1 km away]
None listed

Air Blast: [At 1 km away]
The air blast will arrive at approximately 3.03 seconds.
Max wind velocity: 15 m/s = 33.5 mph
Sound Intensity: 76 dB (Loud as heavy traffic)
No damages listed


Projectile Speed Two: 300km/s
Distance from Impact: 1.00 km = 0.62 miles
Projectile Diameter: 1.20 m = 3.94 ft = 0.00 miles
Projectile Density: 19050 kg/m3
Impact Velocity: 300.00 km/s
Impact Angle: 60 degrees
Transient Crater Diameter: 299 m = 981 ft

Effects of Thermal Radiation: [At 1 km away]
Much of the body suffers first degree burns

Air Blast: [At 1 km away]
The air blast will arrive at approximately 3.03 seconds.
Damage Description:
Multistory wall-bearing buildings will collapse.
Wood frame buildings will almost completely collapse.
Glass windows will shatter.
Up to 90 percent of trees blown down; remainder stripped of branches and leaves.


From the way these numbers work out, it seems like Railguns wouldn't be as effective as larger calibre, slower moving projectiles. I experimented with even faster speeds than this, but the results were dissapointing. Velocities in excess of 415km/s resulted in the projectile burning up in the atmosphere. Larger size projectiles may alleviate this to some extent.

I have my doubts about these numbers, however. The calculator is designed for extra-terrestrial bodies, such as comets or asteroids. So it is quite likely that purposely designed munitions would stand a better chance of punching through the atmosphere. Another thing to take into account is the atmosphere itself.
 
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