RE: Royal Zero Kit Build into Rufe
Done a little more math.
A 1/7th zero should have a span of 1575mm or 36.1' (1592 is generous over scale)
Now, using the 9%, it comes out to 1716.75mm for the 60 size Zero to become a Rufe's wingspan.
In order to make the 40 size Rufe a 60 size the 1490 span still needs 15% to become 1713.5mm