Just a quick one!

I absolutely love those JG53 kites Jan, so unique and un-German.... Someday I will do one of em.....

As for ur spirals, good luck... I know my hand aint steady enough to do it....

I have seen spiral decals advertised Jan, but can't remember which firm(s).
I hate doing spirals, even the broader ones, and normally use a combination of freehand and masking tape. In other words, mask as best as possible, then touch in afterwards. You could try cutting spirals from solid colour decalsheet, but it only slightly reduces the problem you'd have with masking tape.