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Each of the twelve Helldivers would carry a 1,000 pound bomb in the internal bomb bay, a 260 pound fragmentation bomb under one wing and a droppable wing tank under the other wing. The drop tank weighed substantially more than the 260 pounder so it was anticipated that the Helldivers might be a bit unstable on takeoff.
From http://www.nzfpm.co.nz/aircraft/i16.htmThe aircraft soon proved to be rather difficult to fly - it was almost unstable under all three axes, and had to be flown with ceaseless attention.
http://www.flugzeugwerk.net/I-16.htmIn actual fact, the I-16 became quite unstable and required more attention from the pilot since it reacted to the slightest handling. Nevertheless, the I-16 boasted an excellent airspeed.
http://www.danford.net/nomon2.htmFirst some comments on planes involved in this conflict. The main Soviet fighters in Mongolia were Polikarpov I-152 biplane (I-15bis in Russian parlance) and Polikarpov I-16 Type 10 monoplane (better known as the Rata). According to "mutual support" doctrine the more agile biplanes had to engage enemy fighters so that monoplanes could simultaneously bust the bombers. You certainly wonder why it wasn't the other way round. The cause was in unstable flying characteristics of I-16--it simply could not hit anything smaller than a decent two-engined bomber. I'd like to quote the book Fighters of WW II edited by David Donald (Grange Books 1998, p 132): "Trying to bring guns to bear on another aircraft needed great skill and concentration... Any prolonged air combat, or tight turns, needed great skill and experience if the aircraft (I-16) was not to flick and spin." Such teamwork between mono- and biplanes had functioned in Spain and (not so well) in China, where biplane losses were already higher.