i havn't made one but i would maybe do the body out of cake and do the wings and tail out of cardboard covered with either fondant or buttercream or whatever you are doing and they could be held up by cake or rice krispie (i think it is called) engines under the wings.
Maybe to help with the body you could use a loaf pan to cook the cake or the pipe loaf pans or could just use a square pan and cut in half and stack half onto of other then carve to shape, i dunno lol.
Well atleast this is a bump until someone who has actually done one can chime in lol 
Ohhhhh, the nightmare LOL! I just tried to model a small gumpaste P-40 Flying Tiger for an 85th birthday for a WWII Army pilot! It was to go on a flag cake. At any rate, it was a miserable failure for me - the humidity and my lack of modeling skills were a deadly combo. Check a hobby shop - I was able to find a scale plastic model kit to use as reference. If you are planning to use cake for the fuselage, there are larger models than can help you visualize or maybe even use the lower parts of the kit as your cake board. I was surprised at the number of model kits available from that era. Good luck!
Well I did my very first one, and it came out "ok", I say not great...but the guy I made it for...was very happy...he flys for southwest airlines.
I just did the shape and airbrushed it in color, didnt put any details...I think I might have the pictures as to how I did it....I can check if you need it....or if it would help.
It the picture doesnt post in here...its in my album....
I have made one, afraid it was not my best work. I bought the replica toy from dollar shop and tried to scale it up to prepare the gumpaste pieces that need to dry.
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=821893
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