The idea of a delta wing as I understand it is to reduce stress on the wing and drag on the leading edge. Now using two delta wings on separate planes, on one planeframe would presumably allow for a reduced wing size, and therefore less drag. I imagine it could also lead to a nice compromise with better control in slow flight than delta wing designs?
However, clearly there are some major issues with this design, as a quick search uncovers no results for this design shape. therefore I pose the question: Why is it that designers have rejected this possibility; what are its major (dis)advantages?
