Complex sentence: Although Krueger flaps have been tried before as insect-mitigation screens, previous designs caused additional drag; the newer design being tested is variable-camber and designed to retract as seamlessly as possible into the lower wing surface.
Split into simpler sentences: Although Krueger flaps have been tried before as insect-mitigation screens, previous designs caused additional drag. The newer design being tested is variable-camber and designed to retract as seamlessly as possible into the lower wing surface.