Memphis Belle

Im building an 81.5" Span Optica designed by John Wright, its an old Plan pack I bought off someone with a lot of the balsa etc missing but I do have some foam outer wings for it, the centre section however is still built up, what Im after is some advice on how to join & secure the outer foam wings to the inner built up structure so they are removable, if anyone out there has built one with detachable wings please get in touch with any information you could give me, thank You