RE: Gap for Biplanes?
Measuring the gap on the SE-5 in a Wylam drawing, the gap is 1.125", the chord is 1.21".or the gap is .93:1.
Most bipes have gaps above .7 or so.
The relatively slim fuselage of the SE-5 makes the gap look larger.. I'd have guessed over 1:1 before I measured it.