Comparing the Whitley IV and V with its contemporaries.
We begin in Europe and start with Germany and the He 111, specifically the 'E, which was the most numerous variant of the type in Luftwaffe service in 1939 and the 'P, which entered service in 1939 and from which came the standard production H model. The Whitley is slower than all versions of the He 111. It has a greater range and better ceiling than the He 111s represented here. The Whitley carries a heavier bomb load than the He 111s here and has better defensive armament. The Heinkel looks snazzier
Compared to the Do 17Z, the Whitley is slower and has a lower ceiling, it has a greater range and a heavier bomb load and has better defensive armament. The Do 17Z is one of those that breaches the upper end of the speed range I posted earlier.
Compared to the Ju 88A-1 (the A-4 model entered service in 1940), the Whitley is slower and has a lower ceiling. The Whitley has a bigger bomb load and longer nominal range, and better defensive armament. The Ju 88 is the fastest bomber here, but it's worth noting that the type was in service in very small numbers in 1939, around 30 or so by the end of the year. I'm not including the Ju 86 since by September 1939 the type had been relegated to a training role and the high altitude Ju 86P did not enter service until 1940.
Italy now, with the understanding that Italian bombers were not available in the same numbers as other countries' bombers, production and service numbers were not high compared to Britain and Germany. We start with the Fiat BR.20, which was faster, had a longer nominal range, but a lower maximum range and ceiling than the Whitley, it also had a smaller bomb load, less than half that of the Whitley and poorer defensive armament.
Onto the Italian racehorse the SM.79, which was faster and is one of the fastest here, along with the Ju 88. It had a lower ceiling, less than half the bomb load and shorter range than the Whitley, as well as poorer defensive armament.
Now the CANT Z.1007, which was faster and had a greater range than the Whitley, but had a lower ceiling, a smaller bomb load and poorer defensive armament, and by the end of 1939 not many had entered service.
France next, and I will turn to this site for accurate information on its aircraft compared to the likes of wiki. The sources for the information presented here are listed at the foot of each page.
Site dedicated to the French Air Force in 1939-1940. In these pages, you will discover the Airplanes, the Squadrons, the forces in presence, but also the Pilots and Crews who fought in extreme conditions: the record of the casualtys and victories is there to attest.
www.passionair1940.fr
Firstly, France's big bomber and one of only a few four-engined machines in service in the 1930s, the F.220 series. The Whitley was faster and had a bigger bomb load, more than twice its size, but had a lower ceiling and shorter range, but with better defensive armament, the Farman was equipped with a pitiful 3 machine guns. In 1939 only a handful were in service.
The old Amiot 143 was still in French service by 1939 and compares rather poorly to the Whitley, possessing a greater ceiling as its only redeeming feature, in fact, at around 31,000 feet it had a spectacular ceiling for this group, but don't expect operational usefulness at this height.
The Bloch MB.200 and MB.210 next, the former is sub-par to the Whitley in every respect, and the latter fares a little better, with lower speeds, bomb load, defensive armament and range, but it has an impressive ceiling of over 9,000 metres, or 32,000 feet.
Finally the Potez 540, which the page in question is missing, so over to wiki and our French ugly duckling is poor all-round compared to the Whitley with the exception of ceiling, which beats even the Bloch MB.210, at 33,000 feet.
To Poland and the neat PZL.37, which compares favourably to the Whitley with greater speeds, better nominal range but lower maximum range, lower ceiling, smaller bomb load and fewer defensive guns. The Zubr is not really worthy of comparison since it was largely relegated to training by the time Poland went to war in 1939 and there was only a small number built.
Now the Fokker T.V from the Netherlands, which has a faster maximum speed but lower cruise speed and better ceiling, but lower range, bomb load and defensive armament.
Finally, for context in Europe we turn to Britain and the Handley Page Hampden, which was faster than the Whitley, but had a lower ceiling, maximum range, bomb load and defensive armament. The Handley Page Harrow was still in service in 1939 but was no longer operational, being progressively replaced by the Wellington.
The Vickers Wellington I was faster than the Whitley, but had a lower ceiling and a lighter bomb load, but a longer maximum range. In the Wellington I, the defensive armament was the Vickers powered gun installation in the nose and tail and flexible mounts amidships, but it did not have turrets at this stage, these were introduced with the Wellington IC, which brought the type's defensive armament on a par with the Whitley.
Out of interest's sake since the Bristol Blenheim was used as a strategic bomber in the opening years of the war, the Whitley was slower and had a lower ceiling, the Blenheim being one of the fastest in this group, but the former had a longer range and a bigger bomb load and better defensive armament, although the Blenheim was the only other bomber in 1939 that was fitted with a power turret until the Wellington IC makes an appearance.
Next, we go further afield to Japan, the Soviet Union and the United States.