Shortround6
Lieutenant General
Some of this is questionable.The production version of the He100 had several fuselage changes, enlarged canopy, a conventional cooling system, armed comparable to the Bf109 at the time, was faster and had a better combat radius.
Fuselage changes happened.
Enlarged canopy happened (most racers would need that) but the claims of "....canopy were slightly redesigned, with the pilot sitting high in a large canopy with excellent vision in all directions." maybe somewhat wishful thinking. No common photo shows a canopy offering anything any better than a Spitfire with a Malcom hood, if that.
The "conventional cooling system" is something of a myth. The cooling system was modified and retracting or semi-retracting ventral radiator was added. This was because the surface cooling system was not up to the task of service use. Both in climb and for ground running. There were other planes that had problems with ground running.
Cooling at high speeds is not that hard although it sounds contrary. What is really hard is cooling while climbing for several minutes or more. Same power as high speed but under 50% of the air flow through the radiator or over the cooling surfaces. On the He 100 they used the rear turtle deck, part of the vertical fin and the horizontal stabilizer as part of the oil cooler system. There was a tank filled with alcohol that had the oil cooler suspended in it and the the alcohol was pumped from the tank to the cooling surfaces and back instead of using a normal oil cooler.
The armament comparable to a Bf109 is questionable. They claimed a single 20mm in the nose and a pair of 7.9mm machine guns but a most (all?) of the export aircraft were delivered with only the 7.9mm guns. While the Germans managed to get a 20mm MG FF cannon into the nose of the early 109Fs that was over a year after the He 100 was in contention. The 109Es never got the 20mm gun in the engine or it was taken back out. It was still jamming too much for service use in 1939 and most of 1940. Heinkel was thinking about trying to put 2 7.9mm guns in each wing root.
No question that the He 100 was faster. With it's low drag it could stretch the fuel more than a 109E.