| S-4/YH-24 | |
|---|---|
 YH-24 in flight | |
| General information | |
| Type | light helicopter |
| Manufacturer | Seibel Helicopter |
| Designer | Charles Seibel |
| Primary user | United States Army |
| Number built | 2 |
| History | |
| First flight | January 1949 |
| Developed into | Cessna CH-1 |
The Seibel S-4 was a two-bladed, single-engine helicopter built by Seibel Helicopter. Designed by Charles Seibel, the S-4 was evaluated by the United States Army under the designation YH-24 Sky Hawk, but would be rejected for service. The S-4B would serve as the basis for the design of the Cessna CH-1 Skyhook, the only helicopter Cessna ever produced.