Jun 242015
Found on ebay a while back was a translation of a WWII-era German report on the Dornier P 232/3 design. This was a proposed derivative of the Dornier Do 335 fighter… while the Do 335 had a piston engine in the nose and another in the tail, the P 232/3 replaced the tail engine with a turbojet. This would have chewed through the fuel in a hell of a hurry, but it also would have increased top speed. Mixed propulsion fighters like this enjoyed a brief burst of popularity for a short span of years immediately following WWII, but apart from some prototypes nothing really came of them.
The ebay sale helpfully provided some good scans of some diagrams.