Imagine I'm a time traveller or someone, who has been transported to an alternative reality. Against all odds I established myself as a respected inventor, teacher and noble in one of the local nations.

Since it is pretty much my buisness to train engineers and scientists to "invent" new things here, I've recently finished building a small fleet of hydrogen airships. These and hot air balloons have become my main contribution to the military, apart from artillery and guns. Despite my interventions, most of the fighting is still happening in the ancient and medieval way: tight infantry formations and cavalry.

So, the last campaign was a great success. The airships allowed us to do reconnaissance, harrassment of enemy forces and to perform air raids. Airship armaments include bombs, splinter bombs, firebarrels, poison gas bombs, boulders, diseased rats, archers and whatever nasty things we can come up with. Unsurprisingly this made the war quite easy.

However I like to be ahead of the enemy. So how could they challenge my air superiority? Projectile Launchers are an obvious idea and were tried. However, nighttime air raids targeting the weapons, enemy pioneers and construction efforts proved to be an effective countermeasure. Even though, ballista bolts aren't that effective at bringing down airships. The British had to use a combination of explosive and incendinary ammunition to take down German airships in WW1. Additionally staying above their range is a decent strategy as well.

So unless someone gets their own aircorps, be that copycat airships or flying beasts, my airforce is pretty much unstoppable, or isn't it?

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    $\begingroup$ It looks looks like your world is already build and you're asking how events in your world will play out. This is entirely up to you. $\endgroup$
    – sphennings
    Mar 15, 2020 at 21:26
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    $\begingroup$ There is a high chance of people defecting with an air-ship. They have a high range, can defect to any country on the continent and could effectively become war-lords of their own patch of land somewhere. Or they become sky-pirates, or let themselves be bought by another nation. If someone can give a single of you captains more gold than you can give every one of you captains, they will be bought off. $\endgroup$
    – Falco
    Mar 16, 2020 at 9:50
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    $\begingroup$ History has shown many times over that the greatest threat to hydrogen airships is the hydrogen. Virtually everything you list is far more likely to kill the airships operator and crew than any enemy on the ground. And the second greatest threat is the weather. Several of the early 20th century’s great powers experimented with helium warships, but all such programs were abandoned primarily because of the losses to and other vagaries of weather. $\endgroup$ Mar 16, 2020 at 13:37
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    $\begingroup$ Airship, like any thing else we mean to fly, are still bound by physics, particularly the size of your ship versus the load you plan to carry ... Trying to embark on an airship enough boulders to make a significant impact on anything on the ground would require a really massive airship! The ratio of density versus effectiveness of a boulder makes it a poor choice of weapon. $\endgroup$
    – Hoki
    Mar 16, 2020 at 17:46
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    $\begingroup$ What do you call an airship that hasn't launched yet? A target. Your bases are your weakest link, second only to your hydrogen tanks. $\endgroup$
    – CaM
    Mar 16, 2020 at 18:58

8 Answers 8


Perhaps you overspent on the wrong weapon

WWI taught us that early (WWI-era) air warfare, while romantic, has serious drawback when used against ground troops.

  • The greatest strategic impact of airship warfare in WWI was diverting massive amounts of labor and materiel to air defenses instead of ground combat forces.
  • The greatest operational impact of air warfare in WWI was scouting and signalling, not direct combat against ground troops.
  • Both fixed-wing and airship tried tactical attacks against ground troops in WWI. These were generally considered failures - aircraft carried too little firepower to be decisive, and could not deliver that firepower accurately. The king of battle in WWI was artillery, not air power.

Also, note that early airships could indeed fly at night, but had terrible problems navigating accurately. They depended upon celestial navigation, so clouds got them lost fairly easily. Several raids dropped their bombs on the wrong cities entirely, or on farmland when they simply could not find their targets.

Since you say...

Dispite my interventions, most of the fighting is still happening in the ancient and medieval way. Tight infanterie formations and cavalry.

...it looks like you expended too few resources on artillery and machine guns, which will have a much greater tactical impact against ground forces. Your modernized ground forces are apparently too weak to be decisive (or you wouldn't have this problem.)

While your air force is unstoppable in the air, it's ground facilities are vulnerable to attacks that the air force's limited tactical capability is likely incapable of stopping.

Meanwhile the diversion of vast quantities of war materiel and labor to build your impressive air corps has, for your description, apparently weakened your ground forces.

This makes both your ground and air forces vulnerable, despite your technological advantage. You overspent on the air force instead of more artillery and guns for your ground forces.

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    $\begingroup$ Yes, this was an important factor in WW2 as well - there were a number of German weapons that were technically superior but horrendously expensive, such as the V2. $\endgroup$
    – pjc50
    Mar 16, 2020 at 11:55
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    $\begingroup$ +1 I’m pretty sure though that by “hydrogen airships” the OP meant blimps and dirigibles, not airplanes. So things would actually be much worse than even what you describe here. $\endgroup$ Mar 16, 2020 at 13:50

Airships aren't that effective as war platforms.

They are slow, can be spotted from afar (yes, even at night, unless you choose a moonless and starless night which makes things difficult for navigation), their path is somewhat predictable unless you equip them with noisy engines.

Adopting guerrilla tactics and never having much in any one place that can be targeted from above would be an effective defense. Large movements of troops would be spotted by airships, but that's not a very large advantage against guerrillas.

The enemy could largely ignore the airships and concentrate on the ground troops, which would be (often) forewarned and forearmed, but can still be ambushed and harassed in other ways.

However... Thai lanterns.

Observing that the hot air above a fireplace goes up is enough to make people suspect that hot air rises by the sole fact of being hot; from there to Thai lanterns the road isn't long. Earth Thai lanterns are designed for neither height nor endurance, but both are achievable.

Now, swathes of Thai lanterns going every which way, each trailing a long, light, sticky tail of combustible material (twine soaked in pitch?), could play merry hell with airships filled with flammable hydrogen. Once a tail is attached to the ship, when the lantern plays out the fire will reach the ship's balloon, and wetting the balloon or having someone climb on the outside are both very difficult propositions. It's not easy to set an airship on fire using projectiles, true, but using tinder...

Normally an unencumbered hydrogen balloon could rise higher than a Thai lantern, but a war balloon is far from unencumbered, and it is slow.

Thai lanterns are inexpensive and lots of them can be fired in waves, almost simultaneously, using several possible inexpensive devices.


This guy here has run a lot of experiments with Thai lanterns. Granted, they don't have much lift; an average-sized 40 L balloon develops around 0.08 N of force, and with G being 9.81, that translates in a paltry 1 gram of payload every 5 liters of heated air volume.

Still the same guy showed that a hotter fire and, obviously, a larger balloon allow more powerful lifts (he measured up to 1N, or 100 g of payload, using a 500 °C "flame" and a 270 L balloon).

Since the payload goes up with the volume, everything scales in the same manner. The efficiency goes up with larger volumes though, because heat is lost through the outer surface of the lantern, and that goes up with the radius squared rather than the radius cubed. So, larger lanterns will have the same ascensional speed (if fully loaded) and the same lift ratio, but I expect them to have more endurance.

Twine can weight as little as 40 grams per 100 meters, and pitch or other flammable and sticky substance shouldn't add more than, say, other 40 grams. Length also scales better, since we don't use thicker twine for larger balloons.

By pre-heating the air in the balloon (basically, light a fire, run a tube into the fire and blow hot air into the balloon, while preventing it from taking off), it ought to be possible to achieve a strong initial lift and time the release of the balloon to maximize the chances of collision with the incoming airship, thus needing less twine.

The largest paper lantern ever made had a volume of 1,086 m^3, or about one million liters; using the lowest figure for the lift (5 L for one gram), that gives 200,000 grams - or 200 kilograms - of lift. Granted, that lantern had a radius of five meters or more, so it would be expensive to build and really difficult to launch. But an airship is much more so on both accounts, so it might be worth it to deploy a line of "vertical launchers".

That kind of lift would even allow a suicide archer to fly nearer the airships and cover the remaining distance using fire arrows, greatly increasing the chances of setting fire to an enemy vessel.

  • $\begingroup$ The lift of one of those lanterns is ridiculous (that's why they are made of thin paper AND rise slowly). The weight of the greased line will soon restrict them to too-low altitudes even if they rise at all. You should prove they can lift a reasonable amount of twine soaked in pitch. $\endgroup$
    – Mindwin
    Mar 16, 2020 at 18:03
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    $\begingroup$ The first hot-air ballonos were by the Montgolfier brothers. These were build around 1870, and were large paper balloons, without a heat source. Instead they were heated over an open fire. $\endgroup$
    – CSM
    Mar 17, 2020 at 22:20
  • $\begingroup$ To put the suicide archer in perspective: you ride a balloon with no altitude or directional control, have to be launched nearby the target with the right wind directions to pass it close enough with your shorter-ranged arrows, telegraph your arrival beforehand meaning you can be shot down by the archers on the airship and then you launch fire arrows which have a notoriously low chance of working (which is why you use volleys of many archers rather than one). I would call it the suicide balloon rather than a suicide archer. $\endgroup$
    – Demigan
    Oct 26, 2021 at 9:14

Someone gets their own air corps.

Someone captures one of your downed airships. Maybe they shot it down and retrieved the scraps or maybe it suffered mechanical failure or maybe it was caught by wind and ran out of fuel. They captured some airmen too. Someone is no dope: they treated your captured airmen like visiting royalty. It is easy for the airmen to get used to that. They release one of them who has family back home as a goodwill gesture. The others like that, and like their new digs, and decide to stay.

The hot air balloon piece is not that tricky. It is easy to reverse engineer. Someone has a lot of very clever people living in their country. Some of them have a gift for airborne weaponry that exceeds your own. They remember the splinter bombs.

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    $\begingroup$ espionage will soon delete any technical advantage. Especially with the loose-lips security measures of the medieval era. $\endgroup$
    – Mindwin
    Mar 16, 2020 at 18:05
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    $\begingroup$ Also attacking the ground support facilities for the airships/balloons could render them ineffective. Destroy the hydrogen production facilities, tie-down masts, balloon winches, etc. Can be done with small parties of saboteurs. $\endgroup$
    – Arluin
    Mar 17, 2020 at 18:25

Chinese War Kites

Granted, these things are mostly apocryphal and while the Chinese definitely invented kites, there's not a lot of good evidence that the popular image of the Chinese War Kite ever existed. What are they? Supposedly, China had developed the means to build extraordinarily large kites to the point where, when supplied with a capable ground crew controlling the kite, a person could ride the kite. Possibly even with weapons. And this apparently took place even as far back as the Roman Empire. There also legends that these existed in Japan and were used by the famed thief Goemon. While I'm not sure whether to believe that these events happened, I do think that these events could happen - that is, kites aren't that hard to build and it's possible to get enough lift it a properly constructed kite against a strong enough wind to lift a person.

Now, what is clear is that these kites were really dangerous to the point that they stopped being used. This is no doubt because flying using only a kite is a really stupid idea, if the wind drops, you're dead, not to mention that there was very little in the way of understanding about aerodynamics back then, so the designs were more trial and error of what worked and what didn't.

That said, necessity is the mother of invention, and war is also a great motivator when it comes to inventions. It's possible that your opponents would learn to master the art of kite-flying warriors and respond to your hot-air balloons by sending up batches of their own warriors or saboteurs to your hot-air balloons and airships with the intention of slicing apart the envelopes or cutting the cables to bring the whole airship down.

And even if they couldn't master the art of sending up people, Fighter Kites are also a possibility. If they attached knives or razors to the strings of kites and flew them into your airships and balloons, they could try using that to cut large gashes through them. This is actually a more practical solution then using Chinese War Kites, so it'll be more likely used.

  • $\begingroup$ Even if the wind doesn't drop, how were they supposed to land???? $\endgroup$
    – Blueriver
    Mar 16, 2020 at 14:02
  • $\begingroup$ They have a ground crew holding the strings that were supposed to gently real them in. $\endgroup$
    – Halfthawed
    Mar 16, 2020 at 14:09
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    $\begingroup$ This idea, plus a sticky, combustable line from the thai lanterns, could be combined to create a wall of fire lines which are lit once contact with the balloon is made. I've flown box kites by anchoring them for a long time once they are airborne given the correct conditions. Just need a ground grew ready to light things up once contact is made to the airship. Could even play out line as the airship moved to keep things attached while the fire burned upwards. $\endgroup$ Mar 17, 2020 at 21:17

Airships are not a very good way of projecting air superiority. Even with powerful engines to counteract winds, they are still very much at the whims of weather. An area with perpetual strong winds or a mountainous geography would make simple helium airships wholly ineffective.

As for "primitive weapons" which could counter your balloons:

Trained birds

Falconry is an ancient tradition. Even primitive cultures with only slings and spears could conceivably use falcons or other birds of prey as their hunting partners. These birds have sharp claws, sharp beaks, and are far better fliers than your simple airships. A large bird could probably tear quite a big hole in an airship's skin with its sharp claws and beak. I imagine that training them to do so could be a bit tricky, but once trained, they could be highly effective weapons.

Alternatively, if you have time-delayed incendiary devices, you could train suicide birds (maybe pigeons) to land on your enemies airships and blow them up.

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    $\begingroup$ Airships are capable of handling winds at least up to their maximum airspeed and are in reality the toughest things in the air. For example as early warning America used air patrols around the northpole, but when weather and storms became too severe the only things still able to fly were the airships. Your birds would also barely be able to scratch the surface. And even if they did airships are not balloons, airships use a multitude of compartments of gas to fly. This is why WWII airships could lose 50% of their gas and still make it home $\endgroup$
    – Demigan
    Mar 15, 2020 at 22:04
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    $\begingroup$ @Demigan the level of technology described in the question does not lead me to believe that the airships and hot air balloons used are at a WWII level. Since the question does not describe aircraft or other inventions such as motors, I understood them to be pre-WWI equivalents $\endgroup$
    – Dragongeek
    Mar 15, 2020 at 22:09
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    $\begingroup$ As for "easy to set on fire", while hydrogen is flammable it requires the right mixture of air and hydrogen to really be set ablaze. This is why in WWII it would take entire drums of incendiary ammo and wait times inbetween to let the hydrogen and air mix before the airships caught on fire. Airships dont pressurise hydrogen into their cells as that makes it heavier, this means hydrogen will not spew out but mix slowly. And even then you need to puncture enough cells simultaneously to get the quick fiery death you want. $\endgroup$
    – Demigan
    Mar 15, 2020 at 22:10
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    $\begingroup$ If the airships are loaded with heaps of splinter bombs, poison gas, infected rats and fire barrels, I think a solid hit in this section could easily kill the whole crew. Be it with a trebuchet, a ballista or a bird with an explosive payload. $\endgroup$
    – Falco
    Mar 16, 2020 at 9:55
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    $\begingroup$ Trained birds, like soldiers, are expensive. Train them to carry (in their talons, so they can let go of it easily) a bomb with a sticky bottom, set it on top of the envelope, and return to base so they can do it again. Thermite might also be more effective than explosive. $\endgroup$
    – Matthew
    Mar 16, 2020 at 17:07

Your airships have to land at some point to refuel and re-arm. So they sneak spies into your bases and attack your airships, fuel supplies, munitions, food & water supplies, and pilots while they are on the ground.


They start a guerilla war. They spread their force and raid every small town with as much close combat warfare as possible. From high in the sky you can't assist your friend dueling a foe. Your chance of hitting the wrong one is just as big.

Your airbases are not safe from raids either, unless they have walls.

Next to that, they do see you coming, but you can't find their raiders when you come to aid a raided town, since they hide in farms and start using some camouflage, so you're having a hard time seeing them from the sky, while they wait for your airships to fly over.



If I wanted to attack a, what did you call it?

Hydrogen airship

I'd tie a bunch of explosives to a bunch of balloons and send them up as soon as I see you coming.

The first time I did this, I imagine that it would cause quite a stir. If one of your captains pilots airship commanders actually decided to hit one of my mines, the resulting Hindenburg like fireball would persuade the rest to avoid the mines at all cost.

The resulting confusion would not be unlike the Battle of Salamis IMHO. Airships would be turning in uncoordinated and awkward ways to avoid these mines, hitting each other, injured air ships, and mines.

Once your fleet becomes aware of the mines, they lose some of their effectiveness. But it will keep your ships at bay, at least for a time. I must also remember to stagger the launches of my balloons, such that shooting at the balloons carries the risk of detonating a mine.

However-- at night? That blob? It's a mine. Ohh! Cloud dead ahead? Mines. Foggy? Have some more mines.

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    $\begingroup$ Air is big. It's not as big as space, but there's still quite a lot of it. Good luck getting any of your mines into contact with an airship. $\endgroup$
    – Mark
    Mar 17, 2020 at 23:07

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