The Humu: Finland's home-built Brewster BuffaloFinland's aircraft depots did such a good job of rebuilding its Brewster fighter planes--even refitting them with Russian engines--that it was a natural next step to build the roly-poly fighters from scratch. The result was the "Humu"prototype built by Patria Aviation (State Aircraft Factory). It was powered by one of the Russian knock-offs of the Wright Cyclone engine and had plywood wings.
Evidently there were three Humus, and they differed slightly. (Possibly they were the same fuselage mated with different wings.) Here is the "Tikkakoski" Humu on display in the aviation museum of that name. It is said to be the third prototype, and it has no wing guns or fuel tanks. According to Jim Maas, the performance of the home-built aircraft was actually slightly better than the Buffaloes that came from the Brewster factory, but the hitting power and range were of course were reduced.
In the earlier models, the Humu had "sack" type fuel tanks mounted in the wings. An explanation of the change is that the sack tank mounted bneath the pilot shifted the center of gravity too far aft, and to solve this problem the builders moved the engine about four inches forward, moved the guns from the wing to the nose, and eliminated the wing tanks, thus correcting the CG. (They may also have decided that the Buffalo's remarkable combat radius wasn't required in the close-in combats typical in Europe.)
The first Humu actually had a Brewster Buffalo fuselage with locally built wings; this version was destroyed in a flying accident. It was followed by a built-from-scratch second version, and then apparently the third, which survived the war.
"This also explains why the fuselage had so pristine condition," emailed Marko Terävä, who photographed the Humu from all possible angles in order to model it more faithfully. "I was suprised to see the metal surfaces so shiny and without any wear marks - but didn't think about it much at the time. But naturally this Humu hasn't seen much life... it was only flown for about 20 hours. That's not enough to develope usual scratches and dings that you see in well used warplanes.
"There were infact 4-6 Humu fuselages built," Marko continued. "Only this one in Tikkakoski survives - rest were scrapped. The fuselages have right shapes - they are copies of the original [Brewster fighter]. But naturally there are differences. There were 450 men working on the project. There was going to be 90 Humus build. Hence the large amount of material waiting."
See the rest of Marko's photos at his website.