After World War I, the category of specialized ground attack aircraft was virtually ignored until, the Spanish Civil War showed, again, it was one of the most important of all and in 1938 the RLM issued a specification for such an aircraft.
First flown in early 1941, the Henschel Hs 129A, powered by two 495hp Argus As 410A-1 air-cooled inverted-vee 12s, was found to be grossly underpowered, and in late 1942 the Hs 129B came into service with the French 690hp Gnome-Rhône 14M 04/05 14-cylinder two-row radials.
The Hs 129B was used with considerable affect on the Eastern Front but with less success in North Africa due to finding an effective sand filter for the Gnome-Rhône engine. The most novel armament, used against Russian armour with devastating effect, was a battery of six smooth-bore 75mm tubes firing recoilles shells down and to the rear with automatic triggering as the aircraft flew over metal objects.
The modern Fairchild (Republic) A-10 Thunderbolt II is a perfect example of this category of aircraft.
Source:
Info: Fighting Aircraft of World War II
Published by Salamander Books.
Profiles: German Warplanes of World War II
Published by Temple Press/Aerospace.
