Originally Posted by
rkkwan
http://www.boeing.com/commercial/aer...icle_02_1.html
Drooped aileron is software only - 3 hours.
Vortex generators - overnight.
Ram air - several days, so should be done with heavy maintenance.
Can be ordered and done all separately, with 60% of the benefits achieved with just the first two. Amazing that UA hasn't even done those two already.
Hmm... that link has some interesting information. I find the drooped aileron to be a particularly odd way to increase efficiency, but then again, I know nothing about aeronautical engineering.