The Penguin was a 3/4 scale version of the Gossamer Albatross II, and had a 71 ft.(21.64 meter) wingspan and a weight, without pilot, of 68 lb (31 kg). The powerplant was an AstroFlight Astro-40 electric motor, driven by a 541 watt solar panel consisting of 3920 solar cells.
Initial test flights were performed using a 28 cell NiCad battery pack instead of a panel. The test pilot for these flights was MacCready's 13-year-old son Marshall, who weighed 80 lb (36 kg).
The official pilot for the project was Janice Brown, a charter pilot with commercial, instrument, and glider ratings who weighed slightly less than 100 lb (45 kg). She flew the Penguin approximately 40 times before a 1.95 mi (3.14 km) public demonstration at NASA's Dryden Flight Research Center on August 7, 1980.