So your 40% over 11 hours appear on the high side for that aircraft!
The way you wrote, it looks as if you *tankered* an extra 27,270 Kg of fuel, of which you burned 7,770 kg. Right ?
Remember, the formula I gave is about
landed weights. from that point of view, in order to land 27,270 - 7,770 =
19,500 kg, you used 7,770 / 19500 = .398 or 39.8 % of the landed fuel.
Secondly, K will increase 1/- with higher weights, 2/- with longer flights and 3/- with your cruise schedule (the higher the CI, the higher the trip fuel and the TO / LW ratio ).
Thirdly, that extra fuel takes our computation probably away from the realm of quick computation as we're coming - my estimation - some 22 to 25 % of the LW and with that extra load, the flight profile will be very different (Step climbs...) and the fuel consumption will reflect that.
But my example, for obvious reasons, did not portra an actual flight. Let's just say that betwen CDG and HKG with a 30kt tail wind, the real example came out with an 11 hr 6 mins and a K= 1.347. The airplane was some 36 T below MTOW.
Please, re-do the calc using actual weights.
Regards