Some word of explanation is needed here!
Now I fully understand why Poles had to flight combat missions with unarmed or WWI-style planes. That is obvious taken into account their air forces and air defense system were destroyed by Luftwaffe in a first week of fighting. After 7th September Poles were able to shoot down only about 1,5 German combat plane daily on average!
So I do not understand what is this book about??? There were practically no Polish air units capable to fight Soviet air forces in 17th September because deplorable remnants of Polish military aviation escaped to Romania that day!