Sound Barrier

AVRO Arrow

From the Wikipedia article about the AVRO Arrow, a Canadian jet aircraft that was developed in the 1950's:

Avro engineering had been considering supersonic issues for some time at this point. Supersonic flight works in a very different fashion and presents a number of new problems. One of the most critical, and surprising, was the sudden onset of a new form of drag, known in the West as wave drag. Wave drag was so powerful that engines of the era could not provide enough power to overcome it, leading to the concept of a "sound barrier".

German research during the Second World War had shown the onset of wave drag was greatly reduced by using airfoils that varied in curvature as slowly as possible. This suggested the use of thinner airfoils with much longer chord than designers would have used on subsonic aircraft. These designs were impractical because they left little internal room in the wing for armament or fuel. However, they also discovered it was possible to "trick" the airflow into the same behaviour if a conventional thicker airfoil was used, swept rearward at a sharp angle, creating a swept-wing. This provided many of the advantages of a thinner airfoil while also retaining the internal space needed for strength and fuel storage. Another advantage was that the wings were clear of the supersonic shock wave generated by the nose of the aircraft.

First time I ever heard of "wave drag" or the reason for swept wings. And once again we've got Nazis in the mix. Will we never get shut of these warthogs?

Update May 2020 replaced missing picture.