Why ?

[ringmaster]

Why are large scale paper aircraft 1/33 when plastic planes are 1/32 except some helicopters that are 1/35

[codex34]

Because paper shrinks back to 1/32 scale when it gets damp..... (joke)

[Papercaptain]

This topic has already been discussed some time ago, but as far as I can see, it has to do with History of Modelbuilding and different measuring systems:
During the 1930ies, the Germans had a Nazi organization for preparing the youth to flying: NSFK (Nationalsozialistisches Fliegerkorps). They edited a series of paper models to teach them IFF (identification of friend or foe), that was published by the Berlin firm Dr. M. Mathiesen & Co. in the decimal scale of 1/33.3 i.e. 1/3rd of 100. This scale system is valid today in Austria and Poland as well. Plastic modeling was mainly an American domain - so their base of scaling was the duodecimal inch/feet system. Helicopters in 1/35 are fitting to the soldier figures in that scale...
Kind regards, -
Papercaptain

[Yale]

Right, Captain. And in US measurements, 1/72nd scale means that each inch of the model corresponds to 6 feet of the actual aircraft, so it was sort of natural for us here. The same thing might have happened with one inch corresponding to one yard (three feet) -- an additional scale of 1/36 -- which would have complicated the other scales you mentioned.

[ringmaster]

Thank you Captain.