[autopilot]

Referring to the book "Junkers JU87" by Aero Publications
1966. The Stuka 'R' model was a 'B' model modified for long
range "R" Reichweite meaning Range.
However, Hans Rudel worked personally and passionately
to have the Stuka up-gunned. The need for more fire power
was a hounding desire for all those fighting with the
JU87. The JU87D-1 was the first factory production model
that was a product of war experience. The D-2 was the D-1
with a glider towing installation. The D-3 was the first
to be up gunned for strafing missions. The D-4 had a wing-
installed WB-81 weapons container under each wing replacing
the bomb racks. This was nicknamed "the watering can" and
housed six MG-81's, four firing forward and two firing back
during pullout and climb.
All models at this point were essentially factory modified
B's. Not to forget the field modifications that must have
been taking place.