Robert Goddard's Rocket Plane by Ron Miller

From The Space Library

In 1931, Robert Goddard filed a patent (#1,809,271) for an aircraft that would be powered by rocket turbines. Although Goddard never had anything more in mind than a new way of propelling aircraft, Popular Science took the idea and ran with it, turning the invention into a moon rocket, among other things...something I have no doubt had Goddard pulling out what little hair he had left.

The notion was that the exhaust gases from a pair of rocket engines would power a pair of turbines. These would in turn drive a pair of ordinary propellers. As the plane climbed to higher altitudes, a rack-and-pinion device operated by the pilot would remove the turbines from the exhaust jets. The plane would then be powered by the rockets alone, where it would then be capable of (according to Popular Science) "high speed voyages in the thin upper air or even of voyages outside earth's air to the moon and beyond." Goddard tried to interest the military in his invention, but received the cold shoulder he had grown to expect.

As jury-rigged and unlikely looking as the design appears, it is still a forerunner of the many hybrid air and spacecraft being developed today.

Reference: http://www.google.com/patents/US1809271