German Empire (1918)
Armored Ground Attack Aircraft [2 Built]
The AGO S.I was an armored, heavily armed ground attack aircraft designed to fill the requirement for the German Luftstreitkräfte their S type plane; a dedicated anti-tank ground attack aircraft. Before the end of the war, two of the type were produced, but the war would end before production could begin, nor did the prototypes see service. The aircraft featured a downward facing 20mm Becker cannon which it would use against the thinly armored roofs of tanks.
Tank Troubles and the Search for a Solution
The introduction of the tank in 1916 was a turning point for all modern warfare. The use of the machines to break through barbed wire and enemy trench lines proved itself effective, and as the war dragged on, the number of tanks increased year over year. Germany would use infantry based special weapons such as armor piercing K-bullets in rifles and machine guns, the heavy Tankgewehr m1918 rifle, or artillery bombardment to stop the metal monsters. The Germans would show hesitation in producing their own tanks due to resistance from the German High Command and a lack of industry to produce them in large numbers, but would eventually do so with the Sturmpanzerwagen A7V. The type however, would prove to be riddled with flaws that rendered it able to do little to counter the allied tank numbers. In addition, the A7V would only arrive in 1918, the last year of the war.
Aircraft were never used in a major role to destroy tanks during the war, but the two would encounter each other nonetheless, with German aircraft able to score several victories against them. There seemed to be little interest by the Idflieg in developing aircraft or aerial weapons to be deployed specifically against tanks for the majority of the war, until around the start of 1918. The Idflieg would designate a new type of aircraft, the S type, for a dedicated aircraft meant for ground attack and destroying tanks. The S type anti-tank aircraft was meant to be an armored aircraft with a requirement to mount the 20mm Becker automatic cannon. Armored aircraft themselves weren’t something new within the German Empire, as they were categorized under the J type. These were dedicated armored aircraft and were in use operationally by this point of the war. Some examples included the AEG J.I and Junkers J.I. The Becker Cannon was also in production and had been mounted on various aircraft by this time, mostly by twin engined G types but there were ongoing developments to put the weapon onto a single engine aircraft. The Albatros J.I was one such aircraft and a number would have the cannon mounted on a pintle on the side of the craft, but crews found the weapon placement and pintle mount made the weapon hard to operate and aim. Eventually it was found that this weapon could be most effectively mounted on a single engine aircraft by being placed at an angle inside the hull to fire downward towards the ground. The cannon would be placed this way on the new S types, where it could fire at the thin roofs of tanks. One would think that manufacturers familiar with designing armored aircraft would rise to the occasion, such as Junkers who were at the forefront of developing metal skinned aircraft, or AEG who were producing operational armored aircraft, but surprisingly, it was the the smaller company of AGO that proceeded with developing the only an S type aircraft, and complete it.
The AGO S.I
AGO Flugzeugwerke was a smaller aircraft manufacturing company in Germany that had found moderate success with its two-seater C type aircraft. The company was known for its C.I, which was the only mass produced single-engine pusher aircraft deployed by Germany in the war, and later, by the C.IV, its most successful aircraft. The C.IV was their most produced aircraft during the war, and the fastest C type at the time of its introduction thanks to its tapered wings, with over 70 being used operationally. Its moderate success however, was overshadowed by a hatred of it by its crews due to issues with its handling and problems arising with the constriction of the fuselage. This disdain for the aircraft would eventually lead to it being removed from service and its production being canceled around September of 1917. Despite this, the company had continued developing their C type aircraft line until 1916. While the S type was a two seater, AGO appears to have no experience with developing an armored aircraft, as all of their previous aircraft were of simple wooden and fabric construction. Development on their own S.I likely began around the time of the creation of the S nomenclature. A patent for the aircraft’s design was filed in July of 1918, showcasing how it’s seating and armor were laid out for the pilot and gunner. Details regarding its development are extremely lacking but it is known that two S.I aircraft were completed by October of 1918. The design was a rather large single-engine aircraft with a boxy fuselage, a consequence of its armor layout. The Becker cannon is known to have never been mounted on the aircraft but accommodations in the design were made, most apparent is the lack of an axle between the wheels. This was done to allow the hull mounted cannon to fire unobstructed. Despite this being done for the cannon, the removal of the axle was almost unseen in this era of aircraft and would become a standard design aspect in the postwar years as aircraft design streamlined. Due to its completion so close to the war’s end, it rarely flew and its performance went undocumented. All development of this aircraft was abruptly brought to a halt a month after the two aircraft were completed due to the war’s end on November 11th. With the signing of the Armistice, all combat aircraft were ordered to be destroyed or transferred, and this is without a doubt the former is the fate the two S.Is met. No further development of the type was allowed after this. The S.I was the last aircraft project AGO would work on before the end of the war.
Design
The AGO S.I was a conventional biplane designed to fill the role for the S type aircraft. While its specifications aren’t known, the size of the aircraft is evident in the photos that exist that the aircraft was quite large for a single engine aircraft. The fuselage was armored, evident via the angled shape of it. This was done to protect the aircraft in its low level attack runs on the enemy, and would offer protection against small arms fire. According to the patent, the armor was focused in the nose section, surrounding the engine, pilot and gunner positions. An armored plate separated the pilot and gunner’s positions at an angle to accommodate the 20mm cannon. The rear of the fuselage tapered into the tailplane. The two bay wings of the aircraft were large and rectangular in shape. Each bay had two wires going across. Control surfaces of the aircraft were standard, with a large rudder at the back, conventional elevators, and ailerons on the upper wing. At the front was a 260hp (194kW ) Basse und Selve BuS.IV 6-cylinder inline engine that drove a wooden two-blade propeller. This type of engine was often found on larger G type aircraft but the S.I likely had them to bring the heavily armored aircraft into the air. The aircraft would have a fixed landing gear located beneath around where the pilot sat. The aircraft had the unique distinction of having no axle, a feature virtually unseen in aircraft of the era. This was done to allow the hull mounted cannon to fire without having the axle obstructing it. For the extra support, three struts connected each landing gear to the aircraft. Each landing gear had one rubber wheel. At the tail end of the aircraft was a landing skid.
For its armament, the Ago S.I was to have two machine guns; one mounted in the rear for the gunner to use on a flexible mount to fire around the aircraft, and another was likely to be mounted forward for the pilot to use at the front. The centerpiece of the armament was a 20mm Becker Cannon. The cannon would be mounted in the center of the fuselage, directly underneath where the pilot would sit. To fire the gun, the gunner would sit down into the fuselage at a dedicated firing seat in the hull. From here he could operate the weapon and aim at tanks beneath the aircraft.
Conclusion
The AGO S.I was developed too late to see combat and with its performance being unknown its would-be impact on enemy tanks is likewise unknown. Despite this, it represents one of the very first instances of an aircraft built with the destruction of enemy armor in mind, a role that would continue to develop into the Second World War, with aircraft like the Henschel Hs 129, Ilyushin Il-2, and further even until today with the Fairchild A-10 Thunderbolt II.
Interestingly, a month before the two S.Is were completed, 20 of the aforementioned AEG J.II armored aircraft would be delivered with the Becker Cannon mounted in their hull similar to how it would be in the S.I for use against tanks. It is not known whether these aircraft saw combat or how they performed with the modifications.
Although the effectiveness of tank busting aircraft of WW2 has been debated in recent years, the AGO S.I would have several benefits going for it during the First World War. The tanks of this era were slow, and the Mark V tanks the S.I would no doubt encounter would have a top speed of 5mph, making the tanks a fairly easy target for S types. The Mark V also had considerably less armor then later tanks, with a meager 8mm of armor plate for the roofs, making these vehicles easier to damage if the aircraft’s gunner managed to hit it. However, being able to hit tanks was still quite a difficult task to accomplish, and with performance figures not currently being known for the S.I, it can only be debated as to how well it would perform its role.
AGO Flugzeugwerke would only survive for less then a year after the First World War, its founder attempting to instead shift their production into automobiles, but they would not find success and would close the production facilities down. Despite this, two decades later the Nazi government would reconstitute AGO for aircraft production once more in 1934, and would bring the company back to life. They would mostly produce aircraft from other companies in preparation for the encroaching war, but AGO would have their own design bureau and would work on a select number of their own designs, like the AGO Ao 192 twin engine transport plane.
Variants
- AGO S.I – Armored two-bay biplane design with an armored fuselage and a focus on attacking enemy armor. It was equipped with 2x machineguns and 1 20mm Becker Cannon. 2 built
Operators
- German Empire – The AGO S.I was meant to serve the Reichsluftkreite in a ground attack & tank destroying role but arrived too late to see service in the war.
Gallery
Sources
Herris, Jack. Otto, AGO, and BFW Aircraft of WWI: A. 2019.
Weird Wings of WWI: Adventures in Early Combat Aircraft Development. 2023.
Herris, Jack. Development of German Warplanes in WWI: A Centennial Perspective on Great War Airplanes and Seaplanes. 2012.
B. David, Sturmpanzerwagen A7V.https://tanks-encyclopedia.com/ww1/germany/sturmpanzerwagen_a7v.php
Stiltzkin. Effectiveness of Tactical Air Strikes in World War II – “Tank busting”. https://tanks-encyclopedia.com/articles/tactics/tank-busting-ww2.php