Here are some patents that follow helicopter recovery:

2,400,175 May 14, 1946 Sofranio M. Suyat - Helicopter toy - essentially a nose cone with folding helicopter blades.

3,098,445 July 23, 1963 Calvin D. Jackson - Aerodynamically Supported Rocket - external folding helicopter blades.

3,903,801 September 9, 1975 Walter E. Senoski - Model Rocket helicopter recovery - internal folding helicopter blades (Kopter)

Dwayne Surdu-Miller
SAROS #001