K Class Aerodreadnought

By the early 1930s, the D and F Classes were beginning to become obsolete, so a programme was initiated to design replacements for these: namely an aerodreadnought and an aerobattlecruiser. The K Class was designed for major fleet operations, with emphasis on the air-to-ground role. It proved to be very much more successful than the D Class it replaced, having a vastly higher speed and reliability. It was also far more manoeuvrable, having large control surfaces. As a result of this, the weapons payload was reduced, though more powerful weaponry meant that this did not hinder the K Class’ performance.

Type: Aerodreadnought
Commissioning: K1 – 1936, K 11 – 1942
Length: 412 m
Diameter: 43 m
Height: 47 m
Propulsion: 24 x 400 kW diesel engines
Lifting Gas: Helium
Lifting Gas Volume: 577 492 m3
Empty Weight: 512 Tonnes
Normal Weight: 322 Tonnes
Maximum Take-Off Weight: 740 Tonnes
Fuel Weight: 30 Tonnes
Normal Payload: 190 Tonnes
Maximum Payload: 228 Tonnes
Ferry Range: 7 000 km
Operational Ceiling/Altitude: 1 100 m
Maximum Altitude: 2 000 m
Cruising Speed: 82 km/h
Maximum Speed: 106 km/h
Turning Circle (radius): 2.5 km
Crew: 6 Officers, 3 Pilots, 24 Gunners, 15 Crew
Cost: 400 Mnai (400 000 Prevaks, or about US$ 800 000) (or 15 000 000 Prevaks or US$ 30 000 000 in 2010)

Armament

The main armament of the K Class was two Mk. I Ordnance QF 25 pounders mounted fore and aft of the middle gondola. Each was directed by a mechanical computer mounted next to the gun which calculated the traverse and elevation needed to hit a target, factoring in height and, to a limited extent, wind. 60 shells was the normal load for the two guns. The guns were limited by the gasbag and the other gondolas. As such, they were not permitted to fire above 50 degrees or within 20 degrees of the forwards or 35 degrees of the rear. This was supplemented by a large bomb bay which could hold up to 35 tonnes of a mixture of bombs, glide bombs, depth charges and other munitions.

Anti-aeroplane defence was primarily in the form of the Bofors 40 mm Mk. I (twin mount), of which 2 were mounted: one on either side of the middle gondola. They each had a mechanical predictor connected a decimetric radar array to provide targetting. Each gun had 4 gunners: 2 loaders, one radar and predictor operator and one gunner.

Furthermore, three Oerlikon AL guns were mounted at the prow, stern and on top to protect against aerial attacks from these directions. They each had one gunner and one loader.

Armour

The K Class was lightly armoured with sheets of 0.5 cm thick aluminium around the fuel tanks, engines and gun positions. 1 cm aluminium armour was mounted around important areas of the gondolas (bridge, bomb bay, etc), and bullet-resistant glass was mounted on the bridge.

The floor of the fore gondola was specially designed. At the bottom was a 0.7 cm layer of aluminium. 10 cm above this was another layer of aluminium, 0.4 cm thick. In between this was the secondary fresh water storage tank, which acted to improve the resistance of the fore gondola from ground fire.

Engines

For the K Class, speed, whilst important, was not a priority. Thus, 24 of the highly efficient and reliable 400 kW diesel engines were mounted in six gondolas of four engines; three on either side of the airship. The mountings were designed such that each gondola was able to rotate by 20 degrees in either direction to improve manoeuvrability.

30 one tonne fuel tanks were mounted on the keel below the centre of mass, so as not to unduly disturb the trim when emptied. The fuel was fed to the engines using pumps powered from a small wind turbine mounted on the skin. When stationary, the pumps were able to use electricity from the airships auxiliary power unit, a small 50 kW diesel generator that provided power to the entire airship.

Ballast

Ballast was in the form of water, which was stored in two main tanks mounted on the keel above the fore and aft gondolas. Trim tanks were spread throughout the structure to maintain balance.

‘Dew catchers’ were mounted above the engines on the skin to recover water vapour from the engines to help maintain trim. They were also able to recover limited quantities of water whilst the airship was flying through cloud.

Variants

KA Class

The original build of the K Class, consisting of K1 to K11. They were operational between 1936 and 1954

KB Class

In the 1950s, with the advent of SAMs, jet aircraft and other advanced weaponry, the KA was becoming obsolete. As a result, an upgrade programme was initiated to save the money required to build new airships. The KB Class was the result.

Type: Aerodreadnought
Re-Commissioning: K1 – 1955, K11 – 1958
Length: 412 m
Diameter: 43 m
Height: 47 m
Propulsion: 12 x 900 kW diesel engines
Lifting Gas: Helium
Lifting Gas Volume: 577 492 m3
Empty Weight: 512 Tonnes
Normal Weight: 322 Tonnes
Maximum Take-Off Weight: 740 Tonnes
Fuel Weight: 30 Tonnes
Normal Payload: 190 Tonnes
Maximum Payload: 228 Tonnes
Ferry Range: 9 000 km
Operational Ceiling/Altitude: 1 100 m
Maximum Altitude: 2 000 m
Cruising Speed: 86 km/h
Maximum Speed: 111 km/h
Turning Circle (radius): 2.4 km
Crew: 6 Officers, 3 Pilots, 15 Gunners, 15 Crew
Cost: 1 Talent (1 000 000 Prevaks, or about US$ 2 000 000) (or 20 000 000 Prevaks or US$ 40 000 000 in 2010)

Armament

The main armament of the K Class was one Mk. IV Ordnance QF 25 pounder mounted fore of the middle gondola. Each was directed by a mechanical computer mounted next to the gun which calculated the traverse and elevation needed to hit a target, factoring in height and, to a limited extent, wind. 25 shells was the normal load for the gun. It was limited by the gasbag and the other gondolas. As such, it was not permitted to fire above 50 degrees or within 20 degrees of the forwards or 35 degrees of the rear.

This was supplemented by a large bomb bay which could hold up to 30 tonnes of a mixture of bombs, missiles, glide bombs, depth charges and other munitions.

In addition to the gun, the AGM-12 Bullpup missile was carried. This air to ground missile was used for destroying small targets for which the gun was unsuitable. It was fired from a rotary launcher in the bomb bay.

The KB Class could also be modified to carry the GAM-87 Skybolt air launched ballistic missile with a NBC warhead. This necessitated the removal of the gun, which allowed 4 to be carried.

Anti-aeroplane defence was primarily in the form of missiles: the medium range AIM-7 Sparrow and the short range AIM-9 Sidewinder. They were launched from a dual launcher at the rear of the middle gondola. This contained 3 Sidewinders and 2 Sparrows. Reloading was manual, with the aid of a hoist.

A gun locker on board also contained small arms for the crew.

Armour

The K Class was lightly armoured with sheets of 0.5 cm thick aluminium around the fuel tanks, engines and gun positions. 1 cm aluminium armour was mounted around important areas of the gondolas (bridge, bomb bay, etc), and bullet-resistant glass was mounted on the bridge.

The floor of the fore gondola was specially designed. At the bottom was a 0.7 cm layer of aluminium. 10 cm above this was another layer of aluminium, 0.4 cm thick. In between this was the secondary fresh water storage tank, which acted to improve the resistance of the fore gondola from ground fire.

Engines

The KB upgrade also included an engine upgrade. This was in the form of replacing the 24 400 kW diesel engines with 12 900 kW engines. These were designed so as to be able to fit two into the existing gondolas, so the engine gondolas needed only small modifications to fit the new engines. The 900 kW engines represented a great improvement over their predecessors, being more fuel efficient and faster at changing speed.

30 one tonne fuel tanks were mounted on the keel below the centre of mass, so as not to unduly disturb the trim when emptied. The fuel was fed to the engines using pumps powered from a small wind turbine mounted on the skin. When stationary, the pumps were able to use electricity from the airships auxiliary power unit, a small 50 kW diesel generator that provided power to the entire airship.

Ballast

Ballast was in the form of water, which was stored in two main tanks mounted on the keel above the fore and aft gondolas. Trim tanks were spread throughout the structure to maintain balance.

‘Dew catchers’ were mounted above the engines on the skin to recover water vapour from the engines to help maintain trim. They were also able to recover limited quantities of water whilst the airship was flying through cloud.