One really nice feature of the Fiddlers Green web site is the Massive amounts of information they have on the different airplanes represented by their models. You can spend hours on their site just reading up on the different planes. Great resource for any model builder, and you don't have to buy anything to access the information, it isn't hidden behind any members only log in.
So take a look at Fiddlers Green: www.fiddlersgreen.net
And here is the link to the Boeing B-17 Flying Fortress Paper Model page: www.fiddlersgreen.net/models/aircraft/Boeing-B17.html