This led to the requirement that the TSR-2 must be able to carry four WE.177As, two internally and two on external underwing stores pylons—the width of the TSR-2 bomb bay (originally designed to accommodate a single Red Beard weapon) necessitating the reduction in diameter of the WE.177A to 16 inches , the bomb's width and fin span being constrained by the need to fit two WE.177 bombs side-by-side in the aircraft's bomb bay.