Although I believe this is too broad a category considering the extraordinary accomplishments of so many, I would have to say Clarence Kelly Johnson, whose work pushed the aircraft performance edge and envelope to an almost unimaginable degree. This is most certainly demonstrated by the Lockheed P-38 Lightning, the U-2 and the mind bending SR-71 Blackbird. Very few have so fired the imaginations of so many both in and outside of the aerospace industry. Following would be Jack Northrop (P-61 Black Widow, XB-35, XB-49 and by extension, B-2) Kurt Tank(FW-190, TA-152), Dutch Kindelberger (P-51), Sydney Camm (Hurricane, Typhoon and Tempest) and Paul I. "Pappy" Gunn( Upgunning of A-20, B-25 and development of "Skip bombing" technique) Frank Whittle (a category of his own: Jet engine creation and development) and last but not least, Prof. Barnes Wallace (Geodectic aircraft structure for Vickers-Armstrong Wellington; Avro Lancaster "Dam Buster" variant with "Upkeep" cylindrical spinning bomb.
As I said, this is a very, very tough call as to who constitutes the "Greatest". Perhaps a composite representative entity? MDS, GHH, LLC www.emotionreports.com
Thank you for mentioning my Great Uncles name, Kurt Tank.
He would be proud to know some few still think of him if only in past Histories. His designs were to me very remarkable due to the circumstances he was placed in during the era. Many know of the constrictions of materials as well as man power, resources available and locations for fabrication. Setting aside all of that, he was a great designer. I am blessed by my name alone and can walk freely in most aerospace museums to run my hands down along the skin of an aircraft. to feel the ripples in its sheathing or a popped rivet. And if only by blood, to have a technician come and reset the rivet only as a request, its a blessing.
I hope in some small way, that those who by blood are in some way linked to these aircraft and their designers, their blood families. come to speak on their behalf.