 In the course of the trials, more equipment was added which increased the weight, and as a result, in an attempt to reduce weight, the dorsal turret was removed.The aircraft was also modified with small auxiliary fins fitted beneath the tailplane.Despite the changes incorporated from the fifth aircraft, the type was deemed not suitable for training and the original order for 250 aircraft was reduced to only 50 aircraft, 20 of which were delivered as engineless airframes for ground training.