Mass drivers

[paltrysum]

A mass driver, a.k.a. "ortillery gun" according to High Guard, "fires large, solid projectiles at speeds optimised for smashing planetary targets."

But...how close would they have to be to a planet that has a thin or higher atmosphere to avoid the ammo burning up in the atmosphere while enroute to the target?

 

[Randalthor66]

A mass driver, a.k.a. "ortillery gun" according to High Guard, "fires large, solid projectiles at speeds optimised for smashing planetary targets."

But...how close would they have to be to a planet that has a thin or higher atmosphere to avoid the ammo burning up in the atmosphere while enroute to the target?

I think it is more about material and speed than distance. An object can come from parsecs away and smash a planet, so long as it is big enough. I would assume that the weapon engineers of the Imperium have figured out the proper material and mass of each round so they will do what they want. Some rounds could be solid enough to just heat up, but basically stay very solid when they hit. Others could be designed to use the reentry to turn into a big ball of plasma when they strike. It just depends.

I'm not sure of what you are trying to learn here.

 

[paltrysum]

I'm not sure of what you are trying to learn here.

Just wondering if there are specifics on how ortillery must be used. Your idea that advanced materials make it possible is a good one.

 

[AnotherDilbert]

Quite, distance should be irrelevant. Anything that does not manoeuvre moves totally predictable and can be hit from more or less any distance.

A mass driver round does not manoeuvre, so has the same velocity from leaving the weapon until the hit something, including an atmosphere. Whether fired from millions of km away or 50 m away it will behave the same when entering an atmosphere.

 

[Sigtrygg]

Nitpick - If it's fired at a planet it will accelerate towards the planet thanks to the planet's own gravity - so its velocity will not remain constant from leaving the weapon.

 

[AnotherDilbert]

Nitpick - If it's fired at a planet it will accelerate towards the planet thanks to the planet's own gravity - so its velocity will not remain constant from leaving the weapon.

Certainly, I simplified a bit. Gravity at a million km is rather weak.

 

[Condottiere]

The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately 20 m (66 ft) near-Earth asteroid with a speed of 19.16 ± 0.15 kilometres per second (60,000[5]–69,000 km/h or 40,000[5]–42,900 mph).[6][7] It quickly became a brilliant superbolide meteor over the southern Ural region. The light from the meteor was brighter than the Sun, visible up to 100 km (62 mi) away. It was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball.
Due to its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft).[7][8] The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km (16.3 mi), and many surviving small fragmentary meteorites, as well as a large shock wave. The bulk of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact estimated from infrasound and seismic measurements to be equivalent to the blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ) range – 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima.[9]
The object was undetected before its atmospheric entry, in part because its radiant (source direction) was close to the Sun. Its explosion created panic among local residents, and about 1,500 people were injured seriously enough to seek medical treatment. All of the injuries were due to indirect effects rather than the meteor itself, mainly from broken glass from windows that were blown in when the shock wave arrived, minutes after the superbolide's flash. Some 7,200 buildings in six cities across the region were damaged by the explosion's shock wave, and authorities scrambled to help repair the structures in sub-freezing temperatures.
With an estimated initial mass of about 12,000–13,000 tonnes[7][8][10] (13,000–14,000 short tons, heavier than the Eiffel Tower), and measuring about 20 m (66 ft) in diameter, it is the largest known natural object to have entered Earth's atmosphere since the 1908 Tunguska event, which destroyed a wide, remote, forested, and very sparsely populated area of Siberia. The Chelyabinsk meteor is also the only meteor confirmed to have resulted in a large number of injuries. No deaths were reported.

https://upload.wikimedia.org/wikipedia/commons/transcoded/e/e6/%D0%92%D0%B7%D1%80%D1%8B%D0%B2_%D0%BC%D0%B5%D1%82%D0%B5%D0%BE%D1%80%D0%B8%D1%82%D0%B0_%D0%BD%D0%B0%D0%B4_%D0%A7%D0%B5%D0%BB%D1%8F%D0%B1%D0%B8%D0%BD%D1%81%D0%BA%D0%BE%D0%BC_15_02_2013_avi-iCawTYPtehk.ogv/%D0%92%D0%B7%D1%80%D1%8B%D0%B2_%D0%BC%D0%B5%D1%82%D0%B5%D0%BE%D1%80%D0%B8%D1%82%D0%B0_%D0%BD%D0%B0%D0%B4_%D0%A7%D0%B5%D0%BB%D1%8F%D0%B1%D0%B8%D0%BD%D1%81%D0%BA%D0%BE%D0%BC_15_02_2013_avi-iCawTYPtehk.ogv.360p.vp9.webm

 

[Randalthor66]

Just wondering if there are specifics on how ortillery must be used. Your idea that advanced materials make it possible is a good one.

I think they are used like other weapons with plusses and minuses indicated in the rulebook.

The thing about the advanced materials, as indicated by Condottiere, they aren't needed. My examples were for how they could be used to increase the effectiveness and even add other effects, such as greater penetration or wide dispersal. Whatever the deviously brilliant minds of the weapons engineers can come up with.

Question about the Railgun (spinal mass driver): How does the -2% damage thing work? (I assume it means after the multiplier of 1,000, right?) It seems like a simple AP would work better. At Least be easier/quicker. Like every 1DD damage equals AP 2, or AP 5, or whatever.

 

[phavoc]

The original Project Thor rounds were 20ft long sabots with a tungsten rod. Later experiments have been looking at carbon composite aeroshells. There is some capability to maneuver while de-orbiting, but, in theory at least, you only need to make minute adjustments. And, based on the type of round it is, you can't really expect much else.

 

[Condottiere]

Carpet bombing.

 

[Randalthor66]

OK, I did snort-laugh at that.

 

[AnotherDilbert]

Question about the Railgun (spinal mass driver): How does the -2% damage thing work? (I assume it means after the multiplier of 1,000, right?)

You fire a 1DD railgun spinal at a ship with Armour 10. You roll a 3 for damage doing 3000 points of damage. The target ship deducts 10 × 2% = 20% for armour, taking 3000 × 80% = 2400 damage.

This is how Armour works for spinals, since deducting 10 Armour from 3000 damage as with bays would be pointless.

 

[Randalthor66]

You fire a 1DD railgun spinal at a ship with Armour 10. You roll a 3 for damage doing 3000 points of damage. The target ship deducts 10 × 2% = 20% for armour, taking 3000 × 80% = 2400 damage.

Thanks, good to know.