The best way to check this is to get the FPPM of an NG
with no winglet and one with... or the Performance Dispatch part of the FCOM for those. Unfortunately I don't have the correct data set (I got 900ER in kgs and 900 in lbs, so the rounding gets all screwed up!)...
But out of curiousity, I made some comparisons... 200nm, 400nm, 1000nm, and 2000nm trips at 60tons landing weight... for the NGs... (picked 60T because it was convenient on the table)
739 vs 739ER (prone to the rounding errors),
at 200nm and whatever the altitude the 900ER burns about 1.3% more.
at 400nm, the 900ER burns 2% less than the 900 at FL290, but diminishes as you go higher (zero or more at FL350)
at 1000nm, 900ER saves 1.5% at FL290 and diminishes to 0.5% at FL350.
at 2000nm, 900ER saves 1.75% at FL290 and FL350, goes down to 1.03% at FL330
Odd???? Well, perhaps the rounding is causing the problem...
But then, I decided to look at the holding fuel burn at 60tons at FL250 and FL350... and the savings for the winglets are about 3% at FL350, and 2.5% at FL250...
So, with the crappy and limited data I have, there's some truth to the scam... but the savings from the winglets are there... However, it's no brainer than for very short routes, the winglets will basically cost you more fuel burn... so I wonder what Mr. Arvai is fussing about???? 5% belongs to the 800nm and above regime, and because of the higher optimum altitude capability with the winglet... at the same altitudes, 3% is about right... but for long haul and talking optimum altitudes... 10% can be attained on the widebodies given the right circumstances of "the right wingtip aerodynamic gadget".
But we all know marketing is almost always too good to be true. Cut the marketing claims by 50% and we're probably at roughly the right number..
Now, if someone has the numbers that can really be used, it'll be appreciated!
|Quoting CM (Reply 1):|
The coup de grâce of Mr. Arvai's of his piece is this:
Unfortunately, it sounds ridiculous, but I've talked to some airline management who seriously wanted winglets on his jets because he totally believes the hype and also mentions "because it looks cool" as well! So while I may disagree with most of what he wrote on that article, I gotta agree in a way with his so-called coup de grâce!!!