Konrad
Very Strong User
Elsewhere it was asked by I think @thenated0g what is it about the wing tips.
Here I will try to give a very short, highly abridged and grossly simplified and inaccurate history of the winglet.
It started way back in the 20’s when some folks realized that the wing tip was a source of a lot of drag. When they saw the vortices coming off the wings as they flew through the clouds, somebody said; Hey we need to control is. This is when we started to see wings with very narrow tips. This is unlike the many WW1 wings where the tips often were wider than the wing roots. I think the epitome of this narrow tip design was the de Havilland Comet racer. I think the test pilot said nice plane please don’t build any more! Those narrow tips were/are vicious! To get them to work one needs to add a lot of drag inducing twist. This is counter productive!
Some smart folks said lets cut off those difficult to build round wing tips and just add a flat tip plate. This did help with the higher angles of attack often dealt with in a climb or turn. But for 99% of the flight they actually caused even stronger vortices. So until the late 40’s wing tips looked pretty much the same, some rounded, some square, and a few pointed ones. But basically just a fairing as a means to end the wing.
It wasn’t until folks like Dr. Sighard F. Hoerner actual described what was going on with the tip vortices that we got more than just glorified tip plates. We start to see this with tip tanks and later Cessna did a lot with their general aviation wings. By the 60’s we still didn’t see much excitement over the idea of radical wing tip shapes. Most aeronautical work was being done in the supersonic area.
But there was one area that was looking for any help they could get. That was the span limited glider competition. These guys were trying anything for an advantage. This caught the attention of NASA. And in the end they tried these on an A7 jet and showed that yes tiplets can work. In the 70’s Boeing looked into these (one of their VP was a glider pilot) and found that while the tiplets/winglets work they are only an advantage in very narrow coefficient of lift. For the rest of the flight envelope they are actually a source of more drag. Much like the simple tip plate we saw in the 20's. So, since drag is the #1 enemy of fuel burn and hence operating costs this put the winglets on the sideline of history, or so it looked.
Enter government regulation and the stage 3 noise requirements around airports. These had high fines for operators that violated the noise limits. This was a problem for business jets and FedEX. FedEx went the route of STC for hush kits on their aircraft. But Bombardier added winglets tuned at the max coefficient of lift to aid their business jets climb high above the airport microphones. Most major airlines bought the FedEX hush kits or just paid the fine.
In the late 90’s Boeing wanted to enter the business jet market with their 737. Selling a jet to none aviation enthusiasts can be a problem. Boeing’s marketing department was reporting back that many of the potential customers want their jet to look more modern with the winglets as seen on the Bombardier business jet. I was at a meeting where a Boeing VP of marketing said to a director of engineering find an engineering justification for the winglets. Lo and behold the Boeing 737BJ has winglets. You can see the first 737 winglet at the museum of flight in Everett. So Boeing added winglets to the 737 for marketing and sound abatement concerns not aerodynamic reasons directly.
One of the first Boeing airliners to have winglets was the Grace (of the Grace commission ) business jet a 727-100. It also had the FedEx hush kits.
Now one major operator is Southwest Airlines. As a short haul operator they operate their aircraft at higher lift coefficients for a much longer part of their flight, climbing to altitude (where fuel burn is a lot less). With so many take offs a day they have the largest benefit staying above the airport microphones! This is why you still see development of the winglet on the smaller jets and not on the long haul transports.
An antidote to show how worthless the winglets really are. I found it odd that they are not on the MEL (Minimum Equipment List) for the 747-400. I worked at an engineering department for a major aIrline. We had a 747-400 get hit by a service truck that tore off a winglet. Much to my surprise after inspecting the wing for secondary damage the aircraft was cleared to fairy back across the Pacific ocean with little more than adding some “600 mph speed tape” to heal the gash! The EVA (Engineering Variance Authority) basically added a few tons of extra fuel just in case there was an adverse drag component. This fairy flight was going to be hauling freight. I was interested in how the plane would perform with the missing winglet. So I asked an engineer from the engine condition monitoring group for the fuel burn on that flight. She said fuel burn was consistent with the weight of the aircraft. She showed me data going back 3 month with the same engines. And this flight’s fuel burn with the damaged winglet was “normal” for its take-off weight.
Boeing knows this and as such doesn’t use winglets on long haul aircraft that operate at low coefficient of lift for most of their flight. Even the 787 doesn’t have these even though it would be easy to mold whatever shape might be needed. It just isn’t needed or justifiable on aircraft that fly at low coefficients of lift.
Here I will try to give a very short, highly abridged and grossly simplified and inaccurate history of the winglet.
It started way back in the 20’s when some folks realized that the wing tip was a source of a lot of drag. When they saw the vortices coming off the wings as they flew through the clouds, somebody said; Hey we need to control is. This is when we started to see wings with very narrow tips. This is unlike the many WW1 wings where the tips often were wider than the wing roots. I think the epitome of this narrow tip design was the de Havilland Comet racer. I think the test pilot said nice plane please don’t build any more! Those narrow tips were/are vicious! To get them to work one needs to add a lot of drag inducing twist. This is counter productive!
Some smart folks said lets cut off those difficult to build round wing tips and just add a flat tip plate. This did help with the higher angles of attack often dealt with in a climb or turn. But for 99% of the flight they actually caused even stronger vortices. So until the late 40’s wing tips looked pretty much the same, some rounded, some square, and a few pointed ones. But basically just a fairing as a means to end the wing.
It wasn’t until folks like Dr. Sighard F. Hoerner actual described what was going on with the tip vortices that we got more than just glorified tip plates. We start to see this with tip tanks and later Cessna did a lot with their general aviation wings. By the 60’s we still didn’t see much excitement over the idea of radical wing tip shapes. Most aeronautical work was being done in the supersonic area.
But there was one area that was looking for any help they could get. That was the span limited glider competition. These guys were trying anything for an advantage. This caught the attention of NASA. And in the end they tried these on an A7 jet and showed that yes tiplets can work. In the 70’s Boeing looked into these (one of their VP was a glider pilot) and found that while the tiplets/winglets work they are only an advantage in very narrow coefficient of lift. For the rest of the flight envelope they are actually a source of more drag. Much like the simple tip plate we saw in the 20's. So, since drag is the #1 enemy of fuel burn and hence operating costs this put the winglets on the sideline of history, or so it looked.
Enter government regulation and the stage 3 noise requirements around airports. These had high fines for operators that violated the noise limits. This was a problem for business jets and FedEX. FedEx went the route of STC for hush kits on their aircraft. But Bombardier added winglets tuned at the max coefficient of lift to aid their business jets climb high above the airport microphones. Most major airlines bought the FedEX hush kits or just paid the fine.
In the late 90’s Boeing wanted to enter the business jet market with their 737. Selling a jet to none aviation enthusiasts can be a problem. Boeing’s marketing department was reporting back that many of the potential customers want their jet to look more modern with the winglets as seen on the Bombardier business jet. I was at a meeting where a Boeing VP of marketing said to a director of engineering find an engineering justification for the winglets. Lo and behold the Boeing 737BJ has winglets. You can see the first 737 winglet at the museum of flight in Everett. So Boeing added winglets to the 737 for marketing and sound abatement concerns not aerodynamic reasons directly.
One of the first Boeing airliners to have winglets was the Grace (of the Grace commission ) business jet a 727-100. It also had the FedEx hush kits.
Now one major operator is Southwest Airlines. As a short haul operator they operate their aircraft at higher lift coefficients for a much longer part of their flight, climbing to altitude (where fuel burn is a lot less). With so many take offs a day they have the largest benefit staying above the airport microphones! This is why you still see development of the winglet on the smaller jets and not on the long haul transports.
An antidote to show how worthless the winglets really are. I found it odd that they are not on the MEL (Minimum Equipment List) for the 747-400. I worked at an engineering department for a major aIrline. We had a 747-400 get hit by a service truck that tore off a winglet. Much to my surprise after inspecting the wing for secondary damage the aircraft was cleared to fairy back across the Pacific ocean with little more than adding some “600 mph speed tape” to heal the gash! The EVA (Engineering Variance Authority) basically added a few tons of extra fuel just in case there was an adverse drag component. This fairy flight was going to be hauling freight. I was interested in how the plane would perform with the missing winglet. So I asked an engineer from the engine condition monitoring group for the fuel burn on that flight. She said fuel burn was consistent with the weight of the aircraft. She showed me data going back 3 month with the same engines. And this flight’s fuel burn with the damaged winglet was “normal” for its take-off weight.
Boeing knows this and as such doesn’t use winglets on long haul aircraft that operate at low coefficient of lift for most of their flight. Even the 787 doesn’t have these even though it would be easy to mold whatever shape might be needed. It just isn’t needed or justifiable on aircraft that fly at low coefficients of lift.
Last edited:
