Why have an aircraft with three engines?
The de Havilland DH66 Hercules was a three engine twobay biplane with room for seven passengers.
The Trident was a three engine jet airliner with seats for between 101 180 passengers. This video is a brief chat about these interesting aircraft.

With thanks to BAE Sytems Heritage for use of some of the images in this video
https://www.baesystems.com/en/heritag...