While there are many famous aviation innovators, such as Kelly Johnson (Lockheed), James McDonnell (Martin and McDonnell) or Kurt Tank (Focke Wulf), I'll mention a lesser known but very important character. Irv Ashkenas.
While the P-51 Mustang was one of the most beloved piston engine fighters, it was Irv who ironed out some problems and made it great.
Irv was just 21 years old when North American Aviation hired him, fresh from Cal Tech with a master's degree in aeronautics, the first with such a degree to work for NAA, for $160 per month. His forte wasn't to design whole airplanes, but to fine tune and improve what was already there, particularly wings and control surfaces. Even before being hired by North American, he had already done work for Kelly Johnson at Lockheed, running the wind tunnel test station at Cal Tech where he studied and tuned the booms and side scoops on the Lockheed P-38.
One of his first new projects was to work on the Mustang. The Mustang wasn't designed or built for the US Army Air Force, it was built as a request originally from 1938 from the British government, looking to see if NAA could build P-40s for them as Curtiss-Wright was already running at capacity and that plane was in short supply. North American thought they could build a better plane, but to satisfy the British, they bought the plans and data from Curtiss for £56,000. Then they designed a better airplane. One of the British requirements was that the plane be designed and built, ready for production in 120 days from the May 29, 1940 contract date. They beat it by two weeks.
Here's Irv looking out of the cockpit as he runs some tests:
This early model still had the chin guns.
Irv was a proponent of super clean laminar flow wing surfaces and convinced NAA to use flush rivets for at least the front third of the wing. They agreed, and ended up doing the whole wing and body this way.
They also had many problems with the belly radiator scoop; Curtiss had tried the same location on the original P-40 designs and couldn't overcome wind turbulence that cause the air to burble all over the place instead of cleanly going through the scoop, until they gave up after three different designs and put the scoop up front in the familiar place that we know of for the Warhawks. But Irv remembered some German technical documents from school, which suggested that moving the scoop away from the aircraft body and out of the boundary layer would give a clean air flow. So he designed the scoop like this and it worked very well. The underslung scoop had to let air in, slow it down, direct it around the radiator and exit without causing too much drag, in that respect he succeeded. In fact, as the air came in and was heated up, it pushed out of the rear flap and created enough thrust to offset 90% of the drag, one of the reasons the plane flew so well.
As well, Irv was working on the next up coming project which would turn into the B-25 twin engined bomber, fixing a roll problem by removing the wing's dihedral outside of the engines. The plane was so successful that nearly 10,000 were built.
But once the assembly lines were going full tilt and NAA had their hands full, Irv figured the company would be doing more manufacturing and less innovating and so he moved on. His next stop was to work at Northrop just a mile down the road when they offered him a big raise to join.
Northrop's biggest contribution to the war was the P-61 night fighter, a twin engine, twin boom fighter that was having wing design problems until Irv showed up. He totally revised the control surfaces, combining flaperons, elevons, curved, retractable spoilers made of sheet magnesium with slotted flaps. Small ailerons went on each wing tip and surface gaps were sealed. He made the plane fly well.
He also worked on the pusher prop XP-56 Black Bullet, Northrop's first tailless aircraft with a pusher prop which flew at 465 mph. but came along as jets were taking over the fighter fleets so it didn't enter production.
Remember the flying wing, the XB-35 bomber, and the later XB-49 jet powered version? Irv Ashkenas designed the control surfaces, with combinations of elevons, small electrically operated rim flaps and split flaps to control yaw. They also worked as dive brakes.
Working to produce the first jet interceptor for the US, one of his major works was the F-89 Scorpion all weather fighter. Using some of the wing design that went into the flying wing, the Scorpion was a success with over 1,000 built and remained in service for twenty years.
He also worked on the SM-62 Snark cruise missile.
After Northrop, he was a co-founder of Systems Technology, Inc, specializing in systems analysis of air, sea and ground vehicle dynamics. He's held multiple patents for aircraft control systems, and even after retirement was still involved in consulting with projects such as the B-2 Spirit flying wing stealth bomber.
Irv passed away in 2011, at 94 years old.