TVeditor writes –

A soothingly quiet trike driven by a 7-ft., pedal-powered propeller. I spend a month a year working on a commercial fishing boat with a loud diesel engine, and the greatest sound in the world is to hear it turn off. Recumbent trike built from aircraft-supply cro-moly tubing and salvaged bike parts. Prop hot-wire-cut pink foam, coated it with fiberglass — and then added LED lights so the blades display colored patterns as they turn.

Propeller Driven Bicycle (Recumbent Trike) – Human Powered – Link.