I just have a thought (not much use to you, I am afraid!!) that you might not get a sensible answer to this question, even on such a knowledgeable site as this is! Would love to help but, after approx. 5,000 hours on the 'Van, all I can say is that, despite its rather ungainly appearance, it did exactly what it was meant to do - and very well! I doubt that the fuselage shape contributed to any great extent to the superb performance of the aircraft!!!! However, it was an excellent STOL machine with not unpleasant flying characteristics. I can find nothing in my (limited) notes/publications about fuselage generated lift - does not mean that it does not exist!!
