737-800 aileron position
 

I just noticed that unlike most planes, the 737 has the ailerons well inboard of the wingtip. I wonder why boeing did that. It's notorious for relatively high approach speeds. Wouldn't it help to move the ailerons further outboard (which would enable them to be smaller), and add a bit more flaps to lower the approach speed?

Does anyone have any insight as to why Boeing designed the wing that way?

Perhaps to reduce the twisting load on the wing structure? AFAIK, the only bigger Boeing that has only one set of ailerons (i.e. not high speed/low speed pairs) is the 757. Even the 727 was fitted with high speed ailerons, though its span is sevral feet less than that of the 737NG.

The 738 has a roughly six meter longer wing span than the 737 classic. As far as i kow the position of the aileron relative to the fuselage was not changed, they just added a bit more wing outboard of the previous wing span. Same for wing anti ice, the last outboard slat, which covers that added span, is not heated on the 738, they simply didn't increase the length of the bleed duct.

All probably for the reasons mentioned above.

Thanks for the insight. I'd have preferred a beefed up structure to allow for lower landing speeds, but I guess money talks.

Against that I'd suggest a few extra knots on the approach speed is probably an acceptable trade-off - n'est pas?

Especially when airlines always try and land at less than max flap settings to save fuel.

Good point, Rat.
To that I'd add noise, traffic flow management (16024 etc!) and airframe wear.
The field performance of the classic must have been a selling point to many.

They kept design changes to a minimum from the classic as they had a maximum percentage that they were able to change and had they surpassed it then it would have required recertification.