I've been working on two new features for the pre-Farnborough issue of Flight, one on 777 and the other on the 747-8. While researching yesterday, I came across a very interesting fact. With the help of the Way Back Machine, the historical archive of the entire internet, I found that the range of the 777-300ER has increased almost 11% (7,175 nm to 7,930 nm) since 2001! The maximum takeoff weight increased 25,000 lbs in that same time as well without a change in fuel capacity. To boot, the 777-200LR had a 6% increase in range too.
See for yourself.
See for yourself.
November 21, 2001 ----------------- June 18, 2008
Is this marketing spin or does this reflect real-world use? Everything's improved, but nothing on the aircraft has changed. And could they be holding back on actual 787 performance?
Underpromise but overdeliver perhaps...
Remember that the 777-300ER didn't even fly until 2003 (and the -200LR in 2005), so the numbers from 2001 were conservative estimates, but during the flight test program the actual performance of the aircraft was determined to be better than the estimates by quite a bit.
Well not only where the perfomrnace estimates in 2001 conservative but in the years since the 777-300ERs entry into service Boeing and GE have been consistently adding improvements to the airplane to lighten the aircraft and to improve fuel efficency and range.
As for the 787, I think we'll know by late 2009 or early 2010 how it does in real world use vs estimates.
Massive scoop on the USAF tanker contract.
You da man!
With the 787, are they as conservative as when they built the 777?
To me this looks like an estimate on one hand and data based on actual measurements on the other. I would expect that most know that until we have something real, estimates are swags (but, we can get better at it).
Before getting into this a little, is there more information? Such as: When each of these first flew? How many observations went into the measurements? How the estimates were obtained?
Now, how this relates to 787 is that we have too much of a belief in methods based upon mathematics and modeling. Oh yes, the attitude seem to be, it's okay since we got it from a computer. This view is rampant everywhere, and a company like Boeing ought to be on the forefront of making a scientifically-based view more prevalent than just play with numbers via marketing schemes. I don't know yet that 787 problems taught them a lesson in this manner. Perhaps, it did.
As an aside, you know the later numbers are probably a means of some sort. So, what are the distributions? There are just oodles of questions that could be raised. As one would think, all sorts of operational factors would influence these types of performance numbers.
This little comparative bit of data could be used, Jon, for some tutorial reasons, except that you might feel that this is outside of your bailiwick.
Gosh, what if Boeing used means for the estimate but then did some maximum for the performance. That is, take the best numbers that they can provide in order to make some marketing point about performance.
On another note, will the 'new media' be any better at getting the 'picture' right? Based upon some efforts, one has to doubt that. Were most 'old media' under some type of vow to do it right? Who will watchdog the 'new media' efforts?
@ OldGuy: I don't have a frickin' clue what you just said.
Without repeating what others have already pointed out here, Boeing bases its performance estimates on established criteria, such as minimum fuel reserves, prevailing winds, etc. The apparent increase in performance is simply a consequence of Boeing's habit of (unlike other major commercial airframe manufacturers) underpromising and overdelivering.