Saturday, 18 April 2020

Pocket Fury

British tank building developed differently from other nations. For instance, the British built tanks in one weight category that had vastly different characteristics. It is no less interesting that the while the core of the British tank fleet was made up of light tanks, production of light tanks as a class ended in 1940. Although, the British later returned to the topic of light tanks. One light vehicle was designed and even released in small series at the end of the war. This is the Alecto I: an SPG that was too late for the war, but managed to serve in the British army nevertheless.

Bigger gun, same chassis

The British light tank development program during WWII is inescapably linked with Leslie Little, the chief designer of tanks at Vickers-Armstrongs. Stubborn in the best way and always ready to experiment, Little was an author of a whole line of unusual vehicles, a number of which found a place not only in the British army, but in the armies of other nations as well. The Valentine was the pinnacle of Little's creations, and it appeared largely due to the stubbornness of its creator, who was able to prove its usefulness. Another, even more original vehicle, did not far as well. This was the A17, accepted into service as the Light Tank Mk.VII. This tank had an original running gear that the engineer had been working on since the early 1930s. The two front road wheels could turn and the tank could turn like an automobile. This resulted in better steering at high speeds.

The first order was made for 100 tanks of this type. They were built slowly, as the Valentine was a priority. Trials of the Light Tank Mk.VII in the Middle East led to disappointment. It turned out that Little's tank steered poorly in the desert. The overheating engine was another serious problem. It was clear that the tank, indexed Tetrarch I as of September 1941, could not be used in North Africa. Later it was adapted as an airborne tank. The Tetrarch I even took part in the Normandy landings in this role.

Harry Hopkins I, the unsuccessful descendant of the Tetrarch I. Its chassis was used to build another vehicle.

Continued work on the A17 led to an improved vehicle that received the index A25E1. Vickers-Armstrongs created a new tank using components from the A17, indexed Light Tank Mk.VIII and better known as the Harry Hopkins. It was classified as a light cruiser tank. In addition to a new hull and turret, the tank had its armour thickened to 38 mm. A pool of 1200 registration numbers was allocated by the War Department, as the vehicle was highly anticipated. However, the tank was plagued by issues, and by 1943 it was obsolete altogether. As a result, a large batch was never built, and Tetrarchs were sent to fight instead. 6 Harry Hopkins I tanks were built in 1943. Some sources claim that 100 were built, but there is no confirmation of such a large production series.

The first Alecto I prototype. The gun has a characteristic muzzle brake, which was later removed.

Despite such a bland finish, the A25 program continued, in several directions at that. One was the development of the A46 tank, another was the development of an SPG on the same chassis, initially indexed A25E2. The cause of this development was success of self propelled artillery, chiefly German. The creation of tank destroyers using the chassis of obsolete light tanks did not go unnoticed. An idea was born to use the light tank that had no hope of being put into production as a chassis for an SPG. The issue of installing a 95 mm howitzer that would not have fit into the small turret was solved.

The same vehicle after improvements were made as a result of trials.

Work on the vehicle that was at different times called Harry Hopkins I CS, Q.F. 95 mm Self-Propelled Mounting based on Harry Hopkins, SP3, and finally Alecto I, began in 1942. The overall concept reflected the general desire of the Royal Artillery branch. They asked for minimum height, maximum mobility, and maximum firepower. The criteria set by the British military required some difficult work. It would not be easy to install a 95 mm gun into the Harry Hopkins, and at least a minimal amount of ammunition would also be required. The chassis was radically redesigned.

Thanks to clever layout choices the Alecto fit 5 crewmen.

The resulting SPG was one of the most unusual light SPGs of WWII. Five men fit into the tiny hull: the commander, gunner, two loaders, and a driver. The driver was moved to the center of the fighting compartment into a semblance of a raised racing car cockpit. The engine compartment was directly behind him, so the driver could hardly complain about the cold.

Cutaway view of the Alecto I.

This unusual placement of the driver was due to the fact that the gun was installed in the front plate, similar to the Canadian Sexton SPG. The difference was that the gun had less traverse. It could also be raised up to 25 degrees, but this was just a nice bonus. The Alecto I was designed to fire directly. The small fighting compartment fit 48 rounds of ammunition: 24 per side. The ammunition was placed so that the gun could be loaded without standing up.

Transmission and engine components.

Vickers-Armstrongs engineers maximally used components from the Harry Hopkins in the Alecto I. The Meadows HOP 11 engine, transmission, and most running gear elements migrated without changes. At the same time, experience in using the Tetrarch showed that the suspension needs to be improved. Even though the mass of the vehicle was only 7.75 tons, additional hydraulic shock absorbers were introduced to improve reliability.

Armour diagram of the Alecto I prototype. The production vehicle had the same layout.

Any fighting vehicle is a result of a compromise, and there was a price to pay for the Alecto's mass. In order to retain high mobility and the possibility of air dropping the SPG, the armour had to be cut down significantly. The maximum thickness was only 10 mm, making it vulnerable to rifle fire from close range. However, considering the developments in anti-tank weapons at the time, the decrease did not make much of a difference.

Tardy armoured cockroach

The first prototype of the Q.F. 95 mm Self-Propelled Mounting based on Harry Hopkins was put through trials in 1944. They showed that it was very mobile. The top speed was 48 kph and the maximum grade it could climb was 35 degrees. However, it was still being gradually improved. A muzzle brake was added to the gun as an experiment, but it did not last long. Trials also showed that water and mud entered the fighting compartment through the front when fording or driving off roads. A dirt-catching "pocket" was introduced. Then, the vehicle was sent to army trials.

Alecto II on trials. By the time this vehicle was built, the 6-pounder was considered obsolete.

While the Alecto I was being developed, an idea was raised to develop several other vehicles with different armament. The Alecto Recce was one of them, a purpose built alternative to the Stuart Recce (the turret was removed from Stuart tanks and a heavy machine gun installed instead). The result was a speedy and well protected reconnaissance vehicle with mobility equal to that of armoured cars, but better characteristics during off-road driving. The armament consisted of a 6-pounder (57 mm) gun.

Dimensions of the mass production Alecto I.

According to available information, one prototype was built. Its design was nearly identical to the Alecto I. However, the 6-pounder was already obsolete by 1944. There were other arguments against this variant. The HE ammunition was significantly weaker that that of the 95 mm howitzer, and these types of shells were just beginning to be issued. The 95 mm howitzer also had a HEAT round by this point with satisfactory penetration characteristics. There were other alternatives. One was the Alecto III with a 25-pounder (88 mm) field gun, which was also inferior to the 95 mm in firepower. The Alecto IV had a 32-pounder (94 mm) howitzer. It was also never built, but for another reason: this gun was too powerful for such a small chassis.

Production Alecto I. There are noticeable differences between it and the prototype. The biggest one are the "ears" that house the radio and toolkit.

Unlike its alternatives, the Alecto I continued to develop. Trials showed that the idea with two loaders was too bold and the crew was cut down to 4 men. The commander's station was removed from the front and the commander moved to the second loader's former position. At least some degree of comfort was achieved. From the outside, the production version can be distinguished by characteristic "ears" that were added along the sides. The right "ear" had a No. 19 Wireless Set, the typical British tank radio of this period.

The production vehicle received a ton of new equipment, which drove up its mass.

Due to various conversions and additions the final mass reached 8 tons. The mobility did not suffer: the 158 hp HOP/2 8.86 L engine provided high mobility with a power to weight ratio of 20 hp/ton. According to the War Department, the top speed was 50 kph and the average speed was 25.6 kph. Enough fuel was carried to travel for 192 km on a highway or 162 km on dirt roads. The ammunition capacity was the same: 48 rounds. A mix of HE and smoke ammunition was usual, but an alternative layout called for 12 HEAT and 36 HE/smoke per SPG. The result was a very viable reconnaissance vehicle, especially due to its height: even with the "ears" it was only 1676 mm tall. 

Alecto I from the 11th Hussars in Berlin, summer of 1945. The SPG was only a few months late for the war.

The success of the Alecto program gave some hope that it would reach the front lines soon. According to correspondence dated December 1944, these vehicles would be sent to reconnaissance units, 4 apiece. However, the plans fell through. Production of the Alecto I kept being delayed. A registration number pool was not allocated until the last minute. The Alecto I was accepted into service and issued only in June of 1945. The 11th Hussars, at the time a part of the 7th Armoured Division, received two SPGs of this type in late June.

Alecto I in the Middle East.

The further fate of the Alecto is shrouded in mystery. It is not known how many vehicles were built or what units they served in. According to the research of Peter Chamberlain and Chris Ellis, the Alecto I was used for training until 1955. It is also interesting that they were not only used in Germany: there are post-war photos of them in Palestine. The fate of the Alecto is similar to that of another British SPG, the Avenger I. It was developed for a long time and was only issued after the war, but still served in Germany.

Alecto Dozer during trials. This is a conversion of the prototype.

In addition to armed variants, the Alecto chassis was used to develop other vehicles. One of them was the Alecto Dozer, an engineering vehicle with a hydraulic powered bulldozer blade. One of the prototypes was converted into this vehicle. The Centipede mine roller was also tested on this vehicle. However, the military was not interested.

The same vehicle seen from behind.

The end of WWII meant the end of many armoured vehicle development and production programs. The Alecto was no exception. The British army already had a large amount of armour available, and making more was pointless. The Alecto was potentially interesting to airborne units, but they already had American Locust tanks and there was no money for new ones. The last attempt to save the Alecto was an offer to foreign buyers as an artillery tractor. This attempt was unsuccessful. The Swiss army was interested, but went with the G-13 instead. The Czechoslovakian tank destroyer built using existing Jagdpanzer 38 components seemed more promising than the British SPG. The only successor the Alecto had was the Vickers VR180 Vigor tractor, based on Little's design.

An advertisement put out by Vickers-Armstrongs showing an Alecto artillery tractor.

Unlike the Tetrarch and Harry Hopkins, not a single Alecto survived to this day. Many mistakenly think that this was the end of British light tank development. Over a dozen various light tanks and SPGs were developed between the late 1940s and the 1960s, but they made it to the prototype stage at best. The Alecto was the last mass produced light armoured vehicle that was built by British industry. The next light tank, the FV101 Scorpion, was nearly three decades away.

1 comment:

  1. It reminds me a bit of the various post-war Soviet tank destroyer/SPG types for the VDV.