B-29 Wing Design

[Jim Oxley]

Anyone know why the slightly swept wing design was chosen for the B-29? As opposed to the more standard tapered wing design of earlier bombers eg B-17, B-24, Lancaster, B-26 etc?

[Graham Boak]

I do not remember seeing any discussion of this, but then early configuration changes are rarely discussed for any type. The usual reason for small overall sweep angles is because the cg has come out in the wrong place, after the overall configuration has been chosen. In the case of the B-29 I'd suggest that the positioning of the main spar/centresection between the two bombbays fixed the wing position, and a small adjustment of the aerodynamic centre was required once the fuselage had been planned out.

[Lippert]

The B-29 wing is still tapered, it just sports a more tapered leading adge than trailing edge. A swept wing would have a swept leading and trailing edge.

In my opinion, I think it has a lot to do with the size of the wing itself. Its spars at the time were the largest aluminum extrusions made. To give the aircraft great range, it was a design requirement that it have a very high aspect ratio wing, and the only way to do this with the materials avalable was to create a wing that was long and tapered - as you have mentioned with the other bombers. The lessons learned from those bombers, however led to better understanding of the need for very high aspect ratio wings, which the B-29 has a much higher one than its predeccesors.

[Graham Boak]

Semantics. It has a swept 1/4 chord line, which is where the aerodynamic forces are assumed to act. There is no good reason for that, unless you are moving the cg.

You need more then 25 degrees on the 1/4chord line to get any transonic benefits, so it is a straight wing in that sense. So was the Me 262. Excuse me if you knew that.