georgiaame
Topic Author
Posts: 988
Joined: Sat Aug 13, 2005 7:55 am

Why Haven't Winglets Been Retrofitted Onto the 772 Series?

Sun Jul 16, 2017 8:26 pm

On the rare occasion you see a 727, they've added them. 737s are on their 2nd generation. 757s and 767s even with the start of supercritical wings still acquired them early, the 764, 773, 787s got the raked tips, but shouldn't there be enough 772s out there to benefit from a wing improvement too? (Wiki shows there are about 400 772s flying.) In advance, this non aeronautical engineer says thanks for the input.
"Trust, but verify!" An old Russian proverb, quoted often by a modern American hero
 
StereoTechque
Posts: 139
Joined: Sat Nov 28, 2015 7:24 am

Re: Why Haven't Winglets Been Retrofitted Onto the 772 Series?

Sun Jul 16, 2017 11:33 pm

B777's were designed primarily for long haul missions. Due which they spend quite less time in lower speed ranges. And lower speeds cause induced drag (as both are inversely proportional to each other).
So the designers must have decided to not install anything at all reducing weight and not causing any form drag. Later they must have realized that something is required to make the wing more efficient and installed the raked wing tip on the 777L/W/764 giving advantages in both form drag as well as induced drag.
Looking California.. Feeling Minnesota.... R. I.P. Chris Cornell...
 
User avatar
Starlionblue
Posts: 17986
Joined: Fri Feb 27, 2004 9:54 pm

Re: Why Haven't Winglets Been Retrofitted Onto the 772 Series?

Mon Jul 17, 2017 12:37 am

The number of older 777s flying, and their projected remaining service life, might not justify the cost of developing and retrofitting such devices.

StereoTechque wrote:
B777's were designed primarily for long haul missions. Due which they spend quite less time in lower speed ranges. And lower speeds cause induced drag (as both are inversely proportional to each other).
So the designers must have decided to not install anything at all reducing weight and not causing any form drag. Later they must have realized that something is required to make the wing more efficient and installed the raked wing tip on the 777L/W/764 giving advantages in both form drag as well as induced drag.


While you get less induced drag at higher speeds, any lift will cause some induced drag. The induced drag curve is also, ahem, a curve, thus even at high speeds you'll get a significant proportion of the induced drag at, say, minimum drag speed. Airliners flying in the same speed range as the 777 have wingtip devices, i.e. 747-400, 787, 350.

The reason the original 777 didn't have wingtip devices was the extra cost and weight was not justified. However when the more capable versions were developed, more efficiency was needed, both from a performance and from a fuel burn standpoint..

If the original 777 had been developed today, it would most assuredly have had wingtip devices.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
georgiaame
Topic Author
Posts: 988
Joined: Sat Aug 13, 2005 7:55 am

Re: Why Haven't Winglets Been Retrofitted Onto the 772 Series?

Mon Jul 17, 2017 2:11 am

Starlionblue wrote:
The number of older 777s flying, and their projected remaining service life, might not justify the cost of developing and retrofitting such devices.

StereoTechque wrote:
B777's were designed primarily for long haul missions. Due which they spend quite less time in lower speed ranges. And lower speeds cause induced drag (as both are inversely proportional to each other).
So the designers must have decided to not install anything at all reducing weight and not causing any form drag. Later they must have realized that something is required to make the wing more efficient and installed the raked wing tip on the 777L/W/764 giving advantages in both form drag as well as induced drag.


While you get less induced drag at higher speeds, any lift will cause some induced drag. The induced drag curve is also, ahem, a curve, thus even at high speeds you'll get a significant proportion of the induced drag at, say, minimum drag speed. Airliners flying in the same speed range as the 777 have wingtip devices, i.e. 747-400, 787, 350.

The reason the original 777 didn't have wingtip devices was the extra cost and weight was not justified. However when the more capable versions were developed, more efficiency was needed, both from a performance and from a fuel burn standpoint..

If the original 777 had been developed today, it would most assuredly have had wingtip devices.
"Trust, but verify!" An old Russian proverb, quoted often by a modern American hero

Who is online

Users browsing this forum: No registered users and 15 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos