The development of the 25 ft tall Hermes A-1 (CTV-G-5/RV-A-5) rocket was begun by General Electric in 1946. Constructed mostly of steel, it was an American version of the German Wasserfall anti-aircraft missile; the Wasserfall was about 1/2 the size of the German V-2 (A-4). Hermes A-1 had one major difference from the Wasserfall. The Peenemünde nitric acid/visol (vinyl isobutyl ether)-fueled P IX engine was replaced by a General Electric pressure fed 13,500 lb. thrust liquid oxygen/alcohol-fueled engine. Beginning in 1947, the engine of the A-1 was tested at GE's Malta Test Station in New York. The G.E. engine had a novel fuel injector which had great influence on future engine development in the USA. Combustion instability problems delayed engine development.