Swept wing design with engine cutout in the center

Finally I got time to check the difference between flying wings (swept wing design) that have a cut out in the center part of the wing  for the prop. I was surprised to find out that it was not reduced lift but additional induced drag that made the wing with a reduced depth of the wing in the center (because of forward mounted engine to meet the CG) less efficient.

Here is a comparison of two similar wing designs, one with a cutout for the engine in the center, one without:




Click on the animations for a higher resolution video.

It is interesting to observe how the drag increases significantly in the center, if there is a cutout for the engine.

The yellow surface visualizes the induced drag, the colored arrows lift.