From
Armstrong Whitworth Whitley - Wikipedia
As Lloyd *** was unfamiliar with the use of flaps on a large heavy monoplane, they were initially omitted from the design. To compensate, the mid-set wings were set at a high angle of incidence (8.5°) to confer good take-off and landing performance. Although flaps were included late in the design stage, the wing remained unaltered ; as a result, the Whitley flew with a pronounced nose-down attitude when flown with the wings in the cruising position, resulting in considerable drag.
*** John Lloyd, the Chief Designer of Armstrong Whitworth Aircraft