[quote="RicoS"]You must see it as a long term investment. You can count on it that there will be an instensive calculation done to compare the savings on fuel cost in the long term and the accuiring cost of the winglets.
And with the excessive oilprices these days the turningpoint to buy and instal winglets are getting smaller and smaller. Thats why nowadays almost every 737 is delivered from the factory with winglets (altough this is a little guess, i don't have exact figures on this statement!)
Rico, you can find that also on this site:
http://www.b737.org.uk/winglets.htm" onclick="window.open(this.href);return false;
They made a short calculation it looks like this concerning the distance:
Series Range (nm) Normal Range (nm) With Winglets
-700 3250 3634
-800 2930 3060
-900 2670 2725
Now you can calculate what you will save, but they say about that:
Winglets lower drag and improve aerodynamic efficiency, thus reducing fuel burn. Depending on the missions you fly, blended winglets can improve cruise fuel mileage up to 6 percent, especially important during a time of rising fuel prices.
So now you can calculate how long it takes before you make profit after modification.