The motor-jet

The CC engine arrangement was a particular one being much different from contemporary and later (turbo)jet planes. It can be called a motor-jet to underline similarities and differences with a usual turbo-jet.
While a usual turbojet has roughly the following arrangement: air intake, compressor, burning chamber, turbine, exhaust
the CC engine system can be subdivided in this way: air intake, compressor, piston engine, burners, exhaust

Differently from what happened in a contemporary turbo-jet these sections were phisycally divided, this being a key factor of the modular concept. The CC engine switched the turbine section to a more traditional piston-engine to act the compressor; anyway it must be noted that from the very beginning (1931) the project was fully a modular one, with provision to use a turbine, a piston engine, different kinds of compressor or something else alternatively.
The reason that brought Eng. Campini to choose the piston-engine variant may only be speculated; most likely the industry encountered some probs in developing appropriate high speed turbines. Campini himself designed many different turbines for his naval and/or aeronautical projects.

This arrangement had its own advantages and drawbacks.
On the odd side it was a bit too complex and heavy, with a poor thrust to weight ratio.
Among the plus must be noted the modularity and the ability to run it as a kind of ducted-fan for economical cruise; in fact the burners were not strictly needed, say as happened in a Jumo 004, and the plane could fly turning them off.

Data

The Campini-Caproni compared