Rt1583
"The company compares the force on a fan blade at takeoff to a freight train weighing almost 1,000 lb hanging off of each of the 68 turbine blades." This comparison makes absolutely no sense. Understandably, any percentage gain in efficiency is great but is a 16% gain over 20 years par for the industry?
MarylandUSA
So how efficient is it, thermodynamically—55 percent? 60 percent? And how more more efficient is it than the runner-up?
Nelson Hyde Chick
If you make something 25% more efficient over a twenty year period, but usage goes up to 300% what is gained? It is projected that airline travel will triple by mid century.
Volodya Kotsev
GREAT! I would also like to see what is the specific fuel consumption? How much fuel/per time/per unit thrust? At what rpm? What is the bypass ratio?
pmshah
Would not gallons / 1000 passenger miles give a better perspective of overall efficiency of the plane ?
Rt1583
@ Nelson Hyde Chick - At the risk of feeding the troll, what is gained is less fuel used overall. Say you have a vehicle that gets 20 miles per gallon with a 5 gallon tank. Simple math says that you can go 100 miles on that tank. Now, make an improvement on that vehicle so that it is 25% more efficient than it was, you are now able to get 25 miles per gallon. You can now go 125 miles on one tank of gas. Now to triple that to 300 miles, at 20 miles per gallon you will need 15 gallons of fuel and at 25 miles per gallon you will need 12 gallons of fuel. To put it another way, for the same 15 gallons of fuel you can go 75 miles further at 25 miles per gallon than at 20 miles per gallon which brings us back to the 25% increase in efficiency. Quite simply, your argument of 25% gain in efficiency against an increased usage of 300% with nothing gained is a strawman which can't stand on its own. Granted, efficiency does have an effect on how many people travel (due to the possibility of lower fares) but efficiency is not the only factor involved and the number of people traveling will go up regardless so is it better to have no gains in efficiency against a 300% usage increase or your mentioned 25% gain in efficiency against the same 300% usage increase?
Dr.Veritas
rt1583! I am glad I am not the only one. "The company compares the force on a fan blade at takeoff to a freight train weighing almost 1,000 lb hanging off of each of the 68 turbine blades." What freight train weighs only "almost 1000 lbs."? That is a tiny freight train unless it is a model freight train in which case it is HUGE. Are we talking axial load or centrifugal load? I would assume axial but then again? I am more interested in how the turbine deals with 2000ºC temperature.
zylstra
A freight train weighs 1000 lbs?
Tom Weymes
The 1,000-lb freight train, and the ludicrous confusion of units of force (kN) with units of torque (ft-lb), together indicate a really sloppily-put together article. These clangers can't have come from the engineers of Rolls-Royce.
Andrew Zuckerman
1000lb freight trains are so efficient! Why use a jet then?...