Why the Flycatcher's radial engine lacked a full cowling

Was the lack of an engine cowling a feature of the period or of the Flycatcher's engine?

It was common period practice for radial engines to operate without a full cowling.

An audience member notices that the Flycatcher's radial engine is not enclosed by a full cowling. Exposed cylinders were common on radial-powered aircraft of this period. Direct airflow simplified cooling before later cowling designs offered a better balance of drag reduction and temperature control. The detail helps distinguish period engine-installation practice from an accidental omission or incomplete prototype feature.