A bit of help on the "RIBBING" for the Tiggie's fuel tank...
The PIPE Here again - and thanks to the detail photo (that I've attached) of a typical Tiggie's fuel tank that I JUST grabbed off the 'Net, that you'll see at the bottom of this posting...
...there are exactly FORTY-SEVEN "ribs" making up the corrugations on the Tiger Moth's upper wing centre fuel tank, as I just got finished counting them THREE times to be absolutely certain.
With such an "odd number" of ribs on that fuel tank, ONE of the "peaks" of them IS directly on the fuel tank's centreline, just for your information.
Hope you can figure out how wide to space them, and what material SIZE to use for the "ribs", so that you know that there are
47 of them there !!
Got to get my dinner now...hope the photo helps!