Dirigibles: Feasibility as (Effective) Aircraft Carriers

Question

The flying aircraft carrier has been in the imaginations of many a writer and engineer, but to date the only true flying aircraft carrier has been USS Akron (and to a lesser extent, her sister ship, the USS Macon). Neither lasted long enough to see war.

In my story, however, the Evil Empire of XXXXXX is about to shatter the tense peace of an alternate, post WW1 Europe by a launching a surprise (or, to some, not so surprising) invasion of the continent. As required by all evil empires, they have constructed a superweapon. Key to their conquest is the use of a massive fleet of dirigibles (~50) designed to keep aircraft close to the front and right behind the empire's advancing armies.

The main focus of their invasion is an mid-sized, neutral country that lies in between the alternate europe and the empire. Within this country are a massive array of helium mines with the potential to let the empire build limitless amounts of their flying dirigible aircraft carriers. Capture the mines, and the rest of the continent will bow to their war machine. Fail, and the war will slip from the empire's favor.

But will it really?

With no later than 1931 tech, would the empire's dirigibles be an effective fighting platform?

Parameters:

• dirigible design copies from the USS Akron
• aircraft are similar to the F9C Sparrowhawks used by the USS Akron, but optimized beyond its real world application as a strict reconnaissance vehicle
• the issue with weather has been ̶ i̶g̶n̶o̶r̶e̶d̶ resolved
• in terms of fighting strength, the empire represents the axis powers circa WW1
• in terms of fighting strength, the neutral country at the center of the invasion is comparable to Belgium circa WW1
• air defense and weapon technology are also restricted to 1931 or earlier

Answer 1

helium mines

Helium is generally produced by extracting it from natural gas. There simply won't be any helium mines.

But the biggest issue here is that you only need the helium for airships and they're simply not going to be used when competing technologies (aircraft) advanced and developed into more effective weapons systems.

No helium mines in the first place, but no helium requirement anyway.

The effort to generate Helium is also greater than the effort required to produce other materials.

With no latter than 1931 tech, would the empire's dirigibles be an effective fighting platform?

No.

Your problem is a simple one : the size of an airship required to support one fighter is enormous and all you get is an awkward, large, slow very attractive target for the enemy to focus on.

Also keep in mind that the first jet aircraft engine was developed in 1937 and patents had been filed in 1930 and serious design research papers in the later 1920s. The airship was essentially dead long before 1931.

The absolute limit for an airship is one based on removing all the air and replacing it with a vacuum (nothing) - you can't get more buoyancy than that (ignoring the material required to contain this vacuum).

That limit is 1.28 grammes of lift per liter of air removed.

So how heavy is a fighter aircraft ? Well it's one pilot at least, some fuel, bullets and a machine gun (or light cannon), wings, etc.

A typical late WW1 fighter like a Sopwith Camel was about 420 kg empty and about 659 kg loaded. Let's be fair and day we need something like 750 kg per plane including pilot.

That means for every plane we need some 586,000 liters of volume. That's a sphere of some 586 $m^3$ or about a sphere of 10 meters diameter or cube of about 8.4 meters side.

For every plane !

And your FC9 Sparrowhawks were twice are heavy ! That means you need twice the volume which is some 25% extra per linear dimension.

And that ignores the weight of engines, fuel, crew and compartments required by the airship itself.

And on top of that you need recover the aircraft. That's really difficult. For a functioning aircraft carrier airship you need to be able to easily take off and land. You also need to be able to resupply the aircraft, which means lots of heavy fuel and ammo as well as replacement parts and some kind of maintenance deck.

That's a real problem as these all add to the size and mass.

And the larger it is the bigger the target it !

And airships are slow. Unlike sea based aircraft carriers they're hard to defend. You can't just surround them with a cordon of defensive ships. A gunner on the ground can take you out easily. Now Zeppelins could climb above anti-aircraft fire, but technology advances and if you are faced with a high flying enemy you will develop effective weapons to defeat them.

The alternative.

Aviation developed the way it did because there are easier solutions than airships that are more effective.

Long range multiengine aircraft and the ability to carry drop-able fuel tanks to extent fighter range all proved effective in the long run. By WW2 these were the ways to go.

So technology quickly overcomes the airship.

Note in particular that if you're an attacking army wanting to deploy fighters and bombers forward as you advance, the technique is to either take over enemy airfields and airports or operate from fields and roads. Both these tactics have been used effectively.

You don't need an airship, you need a supply chain to support your advance. You need cargo aircraft to resupply. And, again, aircraft rapidly developed to be better at this than airships.

The further beyond 1931 tech you get the more the airplane technology becomes more effectives. Better wings, better engines, better materials, better fuel systems. The ability to build bigger multi-engined aircraft. Even better communications (radio) means you can use your force more effectively.

Likewise the more advanced the technology for flight becomes, the more advanced the air defense technology becomes. Better fighters and anti-aircraft (and anti-airship) weapons will also be developed. This make slow moving and large targets like airships extremely vulnerable. Because they're also storing aircraft they're even more attractive targets and would be heavily attacked (just as aircraft carriers were in WW2).

air defense and weapon technology are also restricted to 1931 or earlier

This is reality-check and that's not a realistic restriction. No one is going to restrict the development of these systems to allow airships to gain the upper hand.

Quite the contrary.

They're going to realize that they need these technologies to defend against airships. So rather that restricting develop, airship carriers would actually accelerate the development of these other technologies.

Answer 2

Another massive problem, apart from speed and vulnerability already mentioned (which are shared by ships acting as aircraft carriers to a large degree) is landing aircraft on the bloody thing.

Both the USSR, UK, and USA experimented with airborne aircraft carriers and abandoned the idea as being impractical and too dangerous for the crews.

The USSR even went so far as to test the concept in combat, fitting some heavy bombers with a number of small fighter aircraft during WW2 and using them as escorts for bomber attacks on German held positions, or to attack well defended targets with bombs where the larger bomber was deemed unlikely to penetrate the defenses.

All experiments ran into the massive problems of getting the smaller aircraft back on board safely, using various forms of hooks and catching mechanisms. While they could work, they did depend heavily on extreme pilot skill, very calm winds, and incredible luck even under those conditions and more than a few attempts failed, resulting in crashed aircraft and dead pilots.

As a result, all these experiments came to naught, and the few remaining prototypes were either scrapped, became museum pieces, or were converted to other duties.

For one way missions, where landing back on the mother ship isn't planned, the concept can work. Launching a manned aircraft from another flying platform has been done successfully many times, it's pretty routine and no harder than launching a large missile (the main problem is keeping the pilot of the smaller aircraft happy during a potentially long transit to the launch area).

Some wikipedia links giving ideas: flying mother ships flying aircraft carriers

Answer 3

Airships are probably not necessary to support 1910-style ground operations.

Armies still move at the speed of a walking soldier, or at best the speed of a truck on back country roads. The support elements of an aviation squadron should be able to keep up, leapfrog airbases close to the front. Every couple of days, the aircraft take off from one airbase and land at another closer to the front.

Airships might be necessary to support 1939-style ground operations with 1920s-style technology.

Blitzkrieg was not just about tanks. It was about highly mobile columns of all arms. Integration was not up to modern standards of combined arms, but it was understood that the infantry had to keep up with the tanks, and they couldn't do that by walking.

But trying to implement Blitzkrieg with 1920s-era technology is going to run into problems. Radios are bulkier and less reliable. Tanks and trucks break down more often. And so on.

One problem is that aircraft have lower speed and range. Blitzkrieg requires aircraft for tactical recon and tactical air support. Your flying aircraft carriers could help make recon available to the tip of the spear. However, it could be useful to have the aircraft available for recon, defensive counter-air, and dive bombing. A key element of the early Blitzkrieg successes was the Stuka with a responsive close air support doctrine.

Answer 4

By 1931 the Schneider Trophy was at its peak: the Supermarine 6 could fly at more than 500 km/h.

With those speeds a dirigible is just an easy target floating mid air.

I think they would not be such a formidable weapon: too slow to effectively support faster aircrafts, effectively hampering fast deployment of troops.

Answer 5

Doubtful - the Akron-class simply lacks the lifting capacity to carry an entire expeditionary squadron of fighters, once you add in the weight of fuel, ordnance, spare parts, pilots and mechanics, their water and food and lodging, etc.

Remember that even the much larger Graf Zeppelin and Hindenburg-sized airships carried very small passenger loads on long-range trips. While their rather luxurious travel accomodations were heavy, the ammunition and fuel for expeditionary power projection and close air support are even heavier.

Also remember that carriers are themselves targets, so a good strategy is to avoid being located by the enemy. However, that causes all kinds of fresh problems with precise navigation (especially when cloudy) and with secure, reliable, over-the-horizon communication between the carrier and the fighter group when the enemy does something unexpected.

Answer 6

With no latter than 1931 tech, would the empire's dirigibles be an effective fighting platform?

Definitely no.

Other answer already showed why they won't be such a good idea because of logistic reasons, unnecessary costs and unavoidable critical manouvres.

The other main reason why they won't work is because they would have been an easy target for the 1931 state of the art: 550km/h planes and air-to-air rockets.

Someone might say that it's critical to aim something travelling at 500+km/h. Well, of course it's not easy, but the stuka dive bombers were able to hit the target with a bomb, diving at 500-600km/h. In any case the difficulty is to produce something that can fly fast, not slow: if these airship aircarrier were used extensively and become a serious menace, the opposing force would have developed a "slow-enough" plane equipped with some big-caliber/slow-rate machineguns and/or dedicated explosives.

I'd go with something similar to an Hawker Hart Demon, a '31 fighter/bomber, already equipped with Vickers machineguns. Since it's based on a bomber plane it won't have issues to carry some additional wheight (the aforementioned rockets). The speed is not an issue, it can cruise at 300km/h, therefore if needed (i doubt) it could easily reduce the speed to 200-250km/h and that's for sure a not-critical speed to aim something as big as the Akron. These rockets were able to shoot down fighters while launched by other fighters, it's just not reasonable to think that an Akron could be hard to be aimed at or could evade the rocket once launched in its direction. Not only, they have 6+km range, therefore they can be used "en masse" against an Akrons fleet, outranging other AA weapons, and they will hit something sooner or later.

Obviously the Demons should be escorted by other, faster, fighter planes but they won't be an easy prey (they can still fight back). On the other side, if the Akron's fighters air superiority is not unbearable for the not-imperial air forces, the Akron's fleet will be a really easy target.

Unless some fictional tech development they won't stand a chance, and that's why they were dismissed as air aricraft carrier (and as attacking vehicle in general).

Answer 7

I'm going to suggest an alternative to airships which also takes advantage of 1920-30 era technology: rockets.

The chief reason to want a flying aircraft carrier is essentially to extend the range of the aircraft (particularly with the relatively weak engines of the period), but using rocket power provides many of the same benefits. JATO rocket assist for aircraft take off was used during WWII, but the essentially technology was developed much earlier (Robert Goddard, the German VfR group and the Russians all had vigorous experimentation on liquid and solid fuel rocket technology during this period). The Luftwaffe also was using rockets to boost training gliders into the air during the 1920's.

It actually took America until 1941 to develop JATO assist

The advantages of rocket assist are allowing the aircraft to take off with a shorter runway, or alternatively take off with a much heavier payload or fuel tanks. The short field performance will allow tactical aircraft to be based in unexpected places to support the advancing army, while the ability to take off at the maximum take off weight provides the ability to maximize range or bomb/cargo load for bombers and transport aircraft. Delivering a large transport plane full of food and ammunition to a leading column can certainly give the ground commander much more flexibility and provide unexpected problems to the defenders.

All these advantages require little modification to the aircraft of your force (essentially some internal strengthening of the fuselage and wings, and some modification to the landing gear to handle the extra stress), and once JATO assist becomes common, aircraft designers will make allowance in their designs for this.

If you want to provide a real "Rocketpunk" flavour to the setting, aircraft could be designed to actually take off as rockets, and unfold wings at the top of a ballistic arc, while engines and propellers will be designed much like "assisted gliders", which start and stop the engine in flight according to need, and have propellers which fold away to minimize drag when not in use.

Stemme S-10 in flight with propeller extended. When the engine is stopped, the propeller is retracted behind the spinner cone. Imagine this taking off under rocket power and swinging the wings out and starting the engine for a "rocketpunk" fighter

Answer 8

They could work, but they wouldn't be super efficient at their job. They'd be easy to take out and they aren't bringing much to the table. Carrier based aircraft are generally at a disadvantage against ground based craft because they have engineering limits imposed by the length of the runway or weight issues - a water based carrier is going somewhere land based craft generally can't, which is why we accept the compromise. Having a carrier hovering over the land makes that compromise unnecessary.

From a strategic perspective the best use you would get out of them would be extending the flight range of the onboard aircraft - they wouldn't function like a water based carrier in this scenario. You wouldn't carry logistics or repair stuff beyond some duct tape and glue - you carry fully loaded planes up to your capacity, move forward at high altitude at night, launch your planes right before dawn and then hightail it as quickly as possible to the rear. Then land, so you can reload and do it again. This would give you the ability to hit targets further into enemy territory, and coupled with strategic surprise could be a pretty good first strike weapon.

If you are really an evil empire and don't care about your minions, you could use your flying carrier to do something that a ground base simply can't do. Instead of heavy aircraft, load your carriers up with https://en.wikipedia.org/wiki/Rotor_kite which comparatively weigh basically nothing, require way less maintenance and are easy to 'fly'.

You could have a couple of small bombs attached to each and you just drop a bunch of them over the front lines. If they make it back, fine. If not? Who cares. They are ridiculously cheap compared to airplanes - we can make more!

In either scenario you need ground based fighters flying defense.

Answer 9

Crimson Skies is a PC game that covers this very topic. The world is shattered and transport infrastructure is degraded to the point that air transport is the only viable option for the most part.

The game revolves around the airship Pandora and is set in the 1930's. Aircraft are launched by dropping from underneath the airship and are recovered by a hook connected to a crane. The crane lifts the aircraft back into the hanger. Besides its integral squadron of aircraft, each airship tends to be armed with AAA turrets and aerial torpedoes.

Here is a trailer.

Answer 10

No. You'd be much better off focusing your efforts on perfecting mid-air refueling.

You have the tankers drag the fighter aircraft to the edge of the combat zone. Dragging means the tankers escort the aircraft they are supporting the whole way, topping them up enroute as needed.

Before they reach the point where enemy fighters could threaten the tankers, every fighter tops off tanks, and the tankers hang back and loiter. The fighters spend all their ammo, and return to the tankers, who drag them back to a friendly landing site.

It's also possible the "escorting-to" tankers could drag the fighters in, turn around and go home, and a fresh squadron of tankers appear to drag the fighters back home.

This would be more effective, and much more practical, than a dirigible. The number of fighters it could support would be limited only by available aircraft and pilots.