Seibel Helicopter Co.
Established early 1948. Seibel had worked with Bell Helicopters, but joined the Boeing company in 1946. With two collaborators built in 1947 S-3 light helicopter (lateral and longitudinal control effected by changing center of gravity). S-4A of 1948 had special blade-attachment system patented for S-3. Followed by S-4B with more powerful engine and side-by-side seats. In March 1952 company taken over by Cessna.