Armament for airships filled with non-flammable gas

Question

In my Fantasy/sci-fi universe there exists a lighter than air gas, that is non-flammable, while having density similar or even smaller than hydrogen (I will post some questions related to this gas in the future). This gas, combined with light and strong materials used in universe, permits making big airships that can lift big weight, but not making steampunk-looking flying battleships.

The airships carry a light armor on crew areas, ammo storages etc, but the whole envelope is not armored, but divided into many gasbags, like airships in real life were, so piercing a few of them won't bring the airship down. To clarify, these airships are rigid airships, not blimps.

Now, the question is: what weapons are best for airship to airship combat in such scenario?

I was thinking about simple thermobaric warheads for tearing apart envelope and gasbags, coupled with light cannons for precise strikes on ship's vital areas, like engines, armament etc. What do you think? Edit: Some notes on tech level: military tech is similar to what we had on Earth post-ww1 but planes are significantly less advanced than in our world, they are similar to planes that took part in the beginning fights of First World War, and are sometimes used as deck planes for airships. Material tech is more advanced, and makes it possible to build durable drigibles.

Answer 1

You want to hit as many gas bags as you can, so something that spreads out once fired would be better than a single shot.

Grapeshot would be like a cannon sized shotgun, making a large cloud of pellets. Like a shotgun, you have the disadvantage of having to be pretty close because each pellet doesn't weigh much and so will lose momentum and piercing power quicker than a large shell.

Flechettes are like small arrows, and can be bundled together to fire a lot all at once. This has some advantages over grapeshot in that they have more piercing power at a greater range due to their pointed tip and fletching to keep them straight. Being fired out of a cannon, you'd want to use heavier flechettes for increased range and accuracy.

Flak is another useful anti-aircraft weapon that could be used with good effect.
The main version uses a shell filled with high explosives and equipped with a fuse. The shell travels toward the target, then the fuse runs out which sets off the HE, and the shell explodes sending shrapnel in all directions.
A blimp mounted system might use shells with different length fuses, depending on the range of the target. If a flak cannon has an effective range of 1000 meters, you might want the shell to go off at 500 meters, and so a gunner would want to have an assortment of shells to chose from.
A skilled gunner might be able to get the shells to pierce the envelope, and then explode inside, which would cause a lot more damage.
You could use an impact fuse, so that it explodes an instant after impacting the envelope, if there was enough of an impact to actually trigger the shell.
Incendiaries could also be used to ignite the envelope fabric by filling a HE shell with phosphorus or other highly flammable substance. It wouldn't ignite the gas, but it could still burn the gas bags.

Answer 2

Tactics

The most common weapon would be explosive or incendiary missiles - this would devastate your airship's armour and/or burn through it. These are the same missiles used today. These can be fired from any position, ground or air.

However if you don't have missiles, you mentioned cannons. Again, explosive shells seem the best bet to disable an airship - because of weight airships can't have much armour. Remember you don't need to completely destroy it, only break it up a little to reduce it's altitude or become uncontrollable.

This poses a few issues:

1. Airships are quite slow moving and inherently fragile
2. Cannons have limited range
3. The higher you are the further your range.

Therefore, the first thing Airship captains will do is to increase altitude as much and fast as possible when in contact with an enemy target. If it is a battle between two airships, the highest airship wins.

Airship Design

Therefore airships have the best advantage the higher they are to begin with, meaning the less weight the better. That means less armour, as it doesn't really do much in a fight. Altitude wins the day and is your best defence (if there are no missiles...)

Answer 3

Firstly, there's already a lighter-than-air gas with similar lift properties to hydrogen. It's called helium. Despite the higher molar mass, it has virtually the same lift as hydrogen.

As for airships taking each other out, you're probably looking at timed explosive ammunition. Airship envelopes are so delicate, that they're—paradoxically—actually quite resistant to damage from impact explosives: they don't provide enough resistance to set off the charges and are likely to have an explosive or incendiary shell or bullet go right through and out the other side. Something with a timer on it, however, could wreak havoc if you get the timing right. A shell going off inside an airship's envelope would shred a lot of ballonets or gas cells and would at least force the damaged airship out of a fight. A crash would be unlikely, as they would probably still have enough lift to land safely.

TV Tropes actually has a useful notes page about airships that could be very...well...useful to you.

Answer 4

Solvent

putting enough holes in gas bags made with ballistics in mind might actually be really hard.

If you use something that can dissolve the cloth, it might penetrate much more effectively than ballistics.

It's the difference between shooting bubble wrap with an arrow, and spraying it with acetone.

Answer 5

Forced landing weapons.

1. Autonomous grapnel anchors. These can be used for naval boarding operations which would be exciting in the air. In another use, after the grapnel engaged with the target the near side is fired into the ground and an automatic winch winches the captured airship down to where it is out of action - or the ground troops can get at it.

2. Cold gun. This is the opposite of Greek fire, because burning things has been done so much and burns hurt. The cold gun would spray something very cold (maybe a supercooled gas, but maybe just cold salt water* for its high thermal mass). This would not damage the ship or personel but would cause the gas bags to shrink, decreasing lift. The ship would gradually fall out of the air, to be captured intact.

For either method, captured air sailors would be released after each one successfully sang the national anthem of the victor, and like he really meant it, and in tune. And with the dance moves.

*there might still be small fish and shrimp in this cold salt water.

Answer 6

For a slightly unconventional but low-tech weapon, try using birds of prey.

Hawks are quite trainable and have talons sharp enough to shred the outer fabric shell of the enemy airship (razor-edged claw caps can make them even more effective). A projectile weapon will - best case scenario - tear one hole on the way in and another on the way out. A trained hawk can continue to rip and tear into the enemy ship until you call them back. They aim themselves, so they can attack a moving enemy in any direction, aren't significantly affected by heavy crosswinds, and have an impressive range. They're capable of flight at airline cruising altitudes, and will be significantly more maneuverable than a bulky airship. They're reusable, but they will eventually tire so lengthy, large-scale battles will require some planning ahead.

Answer 7

Anti aircraft weaponry is designed to produce large amounts of shrapnel to destroy control surfaces (degradation of structure and handling) and hopefully get pulled into the jet engine air intakes (degradation of propulsion)

Even if your airships have light armour, it will behave in a predictable way allowing weapons systems to be designed to counter it. If you look into the development of fighters post WW1 through to the end of WW2 their gun sizes and capabilities changed over time to bigger caliber rounds, and armour piecing capabilities because the targets were continually evolving - self healing fuel tanks, pilot armour, increased structural strength ...

What you need to imagine is what led up to the designs of your ships - if it is new technology they will have been designed around an existing older tech (hence we call these vehicles airships for example), or they will have been modified to resist the current weapon technology and function better (compare blimps - essentially a minor upgrade from hot air balloons to the hard bodied airships built by Count von Zeppellin for example), to at least over a 50/50 chance of not losing both crew and airship, or much higher if the owner/operators of the airships are not in a situation where the resources required to make them are in short supply

Answer 8

You'd definitely want some sort of chain shot grapeshot and the like would be great for making lots of holes, but chain shot would make large tears that would quickly allow the buoyant gas to escape.

I would expect combat to focus around getting above your opponent, as Flox describes. In addition to greater range, it would allow you to focus on the envelope of the enemy airship. If the weapons are only on the bottom, this would prevent lower airships from returning fire at all. Airships would evolve to be able to raise quickly, and have guns that can shoot downwards. They may also drop bombs on airships/ground targets below them.

Answer 9

Depending on tech-level:

• Anti air missiles that use Shrapnel, such as Hawk or BUK. Shoot one into the vicinity of an airship and watch most of it´s gasbags turned into rags.
• Cannons, loaded with grapeshot. Same principle, but you have to make a fly-by short distance for it to be effective.

Answer 10

Thermobarics will certainly have their uses but in the interests of not having to totally destroying every target, Chain-shot or something like a Rivebow that fires a cutting disc would be quite useful, you can aim at the fabric of the bag or the anchoring lines that attach it to the gondola with equal effect that way.

Answer 11

Flak cannon with a timed burst. Shred the internal gas chambers.

Note that precision timed airbursts were a solved problem by World War One; shells could be set to detonate in the air above the target, on impact, or after impact, and that was due to timed fusing (proximity fuses only came around in World War Two). Firing at a (slowly) moving target from a (slowly) moving platform is more difficult than ground artillery firing at a fixed position, but again that's a largely solved problem because navies had been working on firing at moving targets from moving guns for a while.

The third dimensional aspect (the target could be above or below your own altitude) adds a little more complication, but not much; snipers deal with that issue all the time. All it would require is slightly more math, and once you have the range it wouldn't take many hits to force an airship down.

Answer 12

Fifty caliber Browning machine guns. If those don't do it you need to invent the Vulcan cannon, post-haste.

What's the thickness of the armor, it's composition, and what design strategy does it employ? Tell me what it is and I'll tell you what to shoot at it with. I only need to know one thing...

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In reality you should be putting all of your resources towards advancing flight, because whoever learns first that airplanes are 1000x less fickle than airships (and has the necessary resources to build them) will win the war.

The US had the two coolest aircraft carrying airships ever built, but they both crashed due to weather and killed a bunch of people. TL;DR: build a weather machine.

If I were your adversary, my weapon would be deception. That being, I would appear to match your airship program tit-for-tat, plus a one-up, to make you keep dumping resources into your program.

Answer 13

Incendiary Cannons

Essentially cannon shells filled with napalm. They'd have a small high-explosive charge to ignite and disperse the fuel, carefully delay-fused to explode inside the lifting cells. The goal isn't to set the gas alight, but to make it rapidly expand from the heat, bursting the lifting cells.

The shells would have to be quite large to carry enough fuel, and so would have limited range. The shorter flight-times at close range would also make it easier for the delay-fuses to be adjusted correctly (it would have to be done manually).

This means that our airships will first engage with intense, close-range broadsides. Eventually, one ship will lose critical lift and be forced to lower altitude. Once this happens, the higher airship can begin to back off, slipping out of the lower airship's range while continuing to fire on it from above.

Gravity bombs

Once the losing airship has been forced to the ground, it can be totally destroyed with conventional gravity bombs.

Flak Cannons

These are useful for degrading the firing capabilities of the enemy airship. As pointed out by others, they're not effective against the lifting cells, but they can be targeted at the gondola, where they can sever control lines, injure personnel, and destroy weapons and ammunition.

Sniper Cannons

This is something we don't really have an equivalent for in Earth-tech. Without the speed and maneuverability of heavier-than-air craft, we can expect extended aerial pursuits between airships, as one seeks to avoid or delay engaging the other at close range. These would look a lot like chases between old sailing ships, except that stability and altitude give the two vessels clear lines of sight to each other at all times.

This opens up an opportunity for long-range, high-accuracy weaponry. Imagine something like a sniper rifle, but even higher caliber and velocity. Pivot-mounted to the deck, featuring an extremely long, rifled barrel, and relatively lightweight ammunition. Operated by a single, highly-trained crew-member, it would be fired at the propulsion engines of the enemy craft. Even a relatively small hole in the right spot could significantly slow an airship until repairs could be made, allowing the fleeing party to escape, or the pursuing party to catch its prey.

Guided torpedoes

A moderate range, heavier than air torpedo, featuring wings and a massive high-explosive payload could potentially destroy an airship with a single direct hit.

In order to be practical, such a heavy and expensive weapon would need the most effective guidance system available to an interwar society: a human pilot willing to die for the cause. Desperate, but effective.

Answer 14

Gas Weapons

Something not yet mentioned is gas, a weapon very fitting for the period.

Getting poison gas into the enemy crew-cabin is game over. Even if gas masks are used, the massively reduced visibility is going to severely cripple enemy crew performance.

If the same gas is also corrosive then it could potentially damage very large surface areas of the enemy gas bag, and as it condenses it could even drip down to damage the internal gas bags. Treating the gas bags to resist this kind of attack would have a huge opportunity cost in terms of weight.

Finally, the gas would certainly be heavier than the gas used for lift. This means that any gas inside the enemy gas bag would displace a similar volume of vital lifting gas.

Answer 15

Lasers

I’m going to (semi-)humorously suggest that lasers would be an awesome way to create holes in other airships.

This is a low weight, long distance, perfectly accurate system that is dependent solely upon the amount of energy you have available to burn and the tech level available. Sadly, it wouldn’t work during storms, but do you really want to be in an airship during one of those anyway?

This would also inspire some interesting airship design - likely with reflective/white balloons.