Originally Posted by
SamYeager
As far as MCAS is concerned my gut feeling is that Boeing will stick with a software solution supplemented as necessary by training. However should they go down the route of aero changes I'm curious how much that might affect the claimed fuel savings for the MAX. Any ideas?
Micro VGs on the outboard slats would add a slight drag rise in the cruise, but that could also be offset if acting on the cross flow instabilities near the winglet-wing transition. A couple of biz jets have found benefit in that area.
Strake mods could go either way as well, Reducing or removal of the strakes would adversely affect TODR, but may actually improve cruise drag, if strut-nacelle-wing interference is worked on near the rear of the nacelle.
Tabs and wedges can improve cruise drag, however as the use of those would be to alter Cm at high AOA, the residual effect at low AOA would add to a cruise drag penalty from trim drag. That is able to be offset in part or fully by the flow improvements that occur from the transonic effects of the device itself.
Aft strakes have been used successfully on numerous aircraft, the Lear is the poster child for those. Cruise drag can be improved by their use dependent on design. They alter both directional and longitudinal stability. As a modern device, they are as recent as the DH-82 Tigermoth, would look right at home on a canary yellow B737 with roundels.
Bottom line is, make lemonade from lemons.