It's time for something new, in theory this sub chapter would contain PZL P.23 Karaś but as Christmas is near I will give you something different. The most advance and famous Polish airplane before war, one that bear the noble place of probably the best of it class at the start of WWII.
PZL P.37 Łoś
PZL-37 Łoś ("Elk") remains to this day a pride of Polish aviation industry. It was designed to the same demands as PZL-30BI, but was a much more modern project.
First (flying, as opposed to the actually first used for ground trials) prototype took off for the first time on 13 December 1936 and despite certain teething problems trials were declared a success. Experiences with first prototype led to visible changes on the second one, flown around year later and characterized, among others, by twin vertical stabilizers, modified pilot's cockpit and new, twin-wheeled landing gear allowing effective operations from rough airfields. Third prototype was only slightly redesign from second one and most of it's modification was in mechanical elements.
Series production of PZL-37 begun in second half of 1937, with an order of 30 planes, including 10 modelled on first prototype (PZL-37A with single vertical stabilizer) and 20 modeled on second prototype (PZL-37Abis with twin stabilizers).
They were followed from late 1938 by upgraded PZL-37B version, 95 of which were made.
PZL-37 Łoś bombers begun entering service in the late 1938 in
211, 212 and 213 Eskadra Bombowa (that last one being provisional operational training and conversion unit). Replacement of gen. Ludomił Rayski by gen. Władysław Kalkus as head of air force in early 1939 led to revision of priorities for the service and to reduction of orders from 180 (planned for 21 squadrons of 6 planes each plus spares) to 108 planes. Also, attempts were made to sell PZL-37 abroad, with significant interest expressed in Belgium, Bulgaria, Denmark, Estonia, Greece, Iran, Romania and Turkey. To that end, prototypes of export versions - PZL-37C and PZL-37D - were built, though because of war they didn't entered production.
On the 31 august 1939 56 PZL-37's were used by 6 bomber squadrons (
211, 212, 216, 217, 221, 222 Eskadra Bombowa - last two being formed), 10 by training units, 5 in trials unit, 8 were stored and 9 more in repairs or awaiting delivery. During the war Polish PZL-37's flew 135 sorties (including 25 reconnaissance ones), dropping 119 tons of bombs (which didn't represent their full capabilities) and losing 26 aircraft, 9 crew members killed, 6 wounded and 42 missing.
23 PZL-37 Łoś aircraft were evacuated to Romania. There they were pressed into service with Royal Romanian Air Force with two squadrons:
Escadrila 76, 77 Bombardement. On 26 june 1941 they were used to bomb Košice (then held by Hungary, currently in Slovakia) in a (successful) attempt to led Hungarians into belief that they were attacked by Soviet Union. Therefore PZL-37's were used to support Romanian offensive against Soviet Union, until attrition forced their removal from the front line and disbandment of
Escadrila 77 Bombardement. Remaining squadron become operational training unit until 1944 when it was again used for combat operations (with just 8 planes left).
Two (of around 50 captured, including incomplete ones in factory) PZL-37's were restored to flying condition by Germans and tested in Rechlin.
Three were captured in flyable condition (and 5 more damaged) by Soviets and tested in Moscow.
Unfortunately none of these beautiful planes survived the war. In 2012 however PZL-Mielec built 1:1 non-flyable replica.