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When Did Aerodynamic Technology Allow...  
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Posted (7 years 2 months 3 weeks 23 hours ago) and read 2004 times:

When did technology first allow in the civilian sector for a wing as efficient as a 757 in terms of fuel-burn (over a given distance), and L/D ratings while allowing Mach 0.85?

Andrea Kent

14 replies: All unread, jump to last
 
User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 1, posted (7 years 2 months 2 weeks 6 days 16 hours ago) and read 1849 times:

Really efficient wings were first used on a large three engine wide body turbofan powered transport jet airliner manufactured at Palmdale California starting in the early 1970's.
It's design also featured the finest automatic approach/land autopilot installation, and the airplane could cruise comfortably and efficiently at M.86.

It's name was...Lockheed TriStar, aka L-1011.


User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 2, posted (7 years 2 months 2 weeks 6 days 16 hours ago) and read 1838 times:

Actually I think she was more properly referred to as the Queen of the Skies...just a minor correction  Wink

DeltaGuy


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 2 months 2 weeks 6 days 15 hours ago) and read 1822 times:

Quoting Blackbird (Thread starter):
When did technology first allow in the civilian sector for a wing as efficient as a 757 in terms of fuel-burn (over a given distance), and L/D ratings while allowing Mach 0.85?

The 757 wing isn't that efficient at M.85. If I remember correctly, and it's been 15 years, but Econ Cruise was around .79/.80 and LRC was just about .80. If you bumped it up to .85 the fuel flow went way up.


User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 4, posted (7 years 2 months 2 weeks 6 days 15 hours ago) and read 1821 times:

Phil...

I mean, when did technology allow wings to be as efficient at Mach 0.85 as a 757 is at 0.80?

Andrea Kent


User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 5, posted (7 years 2 months 2 weeks 6 days 14 hours ago) and read 1817 times:

Quoting Blackbird (Reply 4):
I mean, when did technology allow wings to be as efficient at Mach 0.85 as a 757 is at 0.80?

Did that ever happen? If the 757's most efficient/long range cruise speed is M.8, what aircraft do you have in mind that cruises at M.85 (besides the 747) in a similar econ/LRC mode? Seems to me like many planes CAN cruise at M.85, but consume the least ammount of fuel over a given distance at a lower Mach number. Thus, my understanding is that truly efficient M.85 plane is an exception.



Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 6, posted (7 years 2 months 2 weeks 6 days 14 hours ago) and read 1810 times:

Queen of the Skies would be quite correct, DeltaGuy.

Now lets look at the L1011 design.

Designed as a fast cruiser from the outset, it delivers as advertised, without compromise.

Extreme UNhappiness is being stuck behind an Airbus at the same level.


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 7, posted (7 years 2 months 2 weeks 6 days 13 hours ago) and read 1797 times:
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Quoting 411A (Reply 6):
Extreme UNhappiness is being stuck behind an Airbus at the same level.

Having to slow your Lockheed down is a decidedly good problem to have, all things considered.  Wink


2H4





Intentionally Left Blank
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 2 months 2 weeks 6 days 10 hours ago) and read 1750 times:

Quoting Blackbird (Reply 4):
Phil...

I mean, when did technology allow wings to be as efficient at Mach 0.85 as a 757 is at 0.80?

Andrea Kent

The 744 was probably the first aircraft to use modern aerodynamic applications to allow a more efficient cruise. The 777 with it's raked wingtips is probably the most modern airfoil in commercial use today.


User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 2 months 2 weeks 5 days 23 hours ago) and read 1638 times:

Thank you Phil for your response...

Are these wings (744) as efficient, more efficient, or less efficient, aerodynamics-wise at it's desired cruise speed (0.85) as the B-757-200 is at Mach 0.80?

Andrea Kent


User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 10, posted (7 years 2 months 2 weeks 5 days 20 hours ago) and read 1600 times:

Quoting Blackbird (Thread starter):
When did technology first allow in the civilian sector for a wing as efficient as a 757 in terms of fuel-burn (over a given distance), and L/D ratings while allowing Mach 0.85?

I'd cast the vote in for super critical wings, I know they existed prior but the requirement for higher sustained speeds for long duration might have increased research to make the increase from circa 0.80M to 0.85M.



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlinePihero From France, joined Jan 2005, 4392 posts, RR: 76
Reply 11, posted (7 years 2 months 2 weeks 5 days 20 hours ago) and read 1593 times:
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Quoting 411A (Reply 6):
Extreme UNhappiness is being stuck behind an Airbus at the same level

I used to captain Tristars too. What I hated most was a London-originated 767 or 757 stuck at FL350 and M.80 going the same route I was...forcing me into a lower level ...The 'Buses didn't gave that muchj of an initial ceiling to be a nuisance.



Contrail designer
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 12, posted (7 years 2 months 2 weeks 5 days 17 hours ago) and read 1549 times:

Lephron,

When did supercritical foils first exist that could achieve the same efficiency levels (aerodynamically) at 0.85 Mach than the 757 / 767 does at Mach 0.80?

Andrea Kent

[Edited 2007-05-16 02:37:01]

User currently offlinePihero From France, joined Jan 2005, 4392 posts, RR: 76
Reply 13, posted (7 years 2 months 2 weeks 5 days 8 hours ago) and read 1500 times:
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Before you did anything, you have to define "efficient" : mission type (distance / payload)...
Otherwise, it's just a sentimental assumption.
I know that there is a number of 757 fans on this site, generally in love with the plane's climb performance.
The 757 wing -and in a lesser mode the 767's- were made bigger than required 1/ for better climb performance on hot'n'high airports (DEN was part of the design) and 2/ to allow for growth. That wing was very heavy.
The corollaries of that design were the possibility of extra range and gynormous stretch (the 764 was probably the excessive maximum).
At the same time, Airbus designed its aircraft too closely to original specs . I remember the A-300 / 600 being with better performance / economics on a Gulf to London stage than the 767...that performance peaked very soon while the 76's would keep improving.

Now, to answer your question, Lehpron rightly pointed at the supercritical airfoil. As the requirement for a .85M cruise are rather new, all the liners designed after 1972 flying at .85M are more efficient than a 757 That would include the 744 ,the 777, the787, the 350 and the 380...

Regards



Contrail designer
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 14, posted (7 years 2 months 2 weeks 4 days 19 hours ago) and read 1435 times:

Okay, so the 744, 777, 787, A-350, A-380's wings can get the same L/D ratios during climb, and at M 0.85 as the 757-200 can get during climb and at M 0.80?

Andrea Kent


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