41

Winglets are less effective at producing added lift than an equal-length wingspan extension. They are used on airliners when simply enlarging the wing would put the plane into a larger size class, or outside the 80 m "box". A longer wingspan, which the An-225 has (10% over the limit), is better at producing lift. The An-225 is a special purpose cargo ...


30

These are called Split Scimitar Winglets and they are offered as an upgrade for some existing Boeing 737 NG series aircraft: Split Scimitar Winglets are offered by APB for the 737-800 and 737-900ER and came into service in early 2014. They are available as a retrofit to existing winglet aircraft. A set of SSWs weigh 133kg (294Lb) per aircraft but ...


27

First off, awesome question and great investigation! This kind of let's-see-what-happens inquiry will take you far should you decide to pursue aerodynamics at an advanced level (and, of course, in other pursuits). Not so long ago, I had to write a similar report: lacking the resources and knowledge of the aerospace giants, I, too, wondered why I could ...


27

The first possibility is that that the CFD in your cad isn't as sophisticated as the software used by boeing's engineers. Which means that your design may have flaws that don't show up in your software but do in Boeing's (or not even in there but do in a windtunnel). Second is that I only saw one flight configuration being tested. Airplanes do more than ...


9

First of all great analysis! I am not expert in aerodynamics but from the little I know, aircraft are a compromise. When you design a plane you have to make shapes that are possible to manufacture, don't cost too much and are strong (and compliant to the regulations). Last but not the least, you have to test the drag over multiple phases of the flight and in ...


4

While all other points raised are valid, it is also important to go back to basics and first understand what winglets are actually supposed to do, and what drives the performance of an aircraft: Winglets do not reduce 'profile drag', or the drag force that exists when there is no lift being produced. They more than likely will increase profile drag slightly....


4

I would say the biggest thing is that the computer model has to be validated with wind tunnel results. As anyone truly familiar with the climate debate knows, computer models trying to simulate extremely complex phenomena often at some point start to diverge from reality and you still need to test in the real world to validate or falsify the model to really ...


3

A winglet makes lift like a wing. That's why it's called a wing...let. It's basically a sail (originally they were called "tip sails") designed to exploit the otherwise wasted circulation of air from bottom to top around the tip, placed so that the local flow curling around the tip strikes it at a positive angle of attack. It makes lift/thrust and, being a ...


2

The best way to understand why elliptical winglets may be better than blended winglets is to read the text of the patent obtained by the inventor of the elliptical type, Dr. Fort Felker, a former NASA wind-tunnel researcher and expert in the field of computational fluid dynamics, and co-founder of Winglet Technology LLC. The short answer is that the ...


2

The projected European spaceplane Hermes did indeed have winglets. Those were needed for drag reduction in the landing phase. So they did not help at supersonic but at subsonic speed. Without the winglets the energy would had bled off too quickly during rotation so the descent could not be stopped in simulations. The spaceplane without winglets was in ...


2

Aston Martin do something similar with their 'Aeroblade', which replaces the rear spoiler, so the concept of using air to guide surrounding air is viable. Whether it's more efficient than using a physical object, remains to be seen.


2

The basic idea is to try to extract as much of the available energy in the tip circulation as possible, and it's thought that soaring birds like eagles have this bit figured out. What it is in essence is an array of winglets. You have a spiral flow field circulating around the tip, with the most intense part of it near the center - the tip vortice - but ...


2

Splayed wing tips are like .... Fowler flaps. Totally useless for cruising flight unless .... you want to try the "coffin corner" at perhaps 60-70,000 feet. The best wing for cruising remains the high aspect albatross style. However, they may wish to fold them back in cruising flight. The writer had imagined this for the Etrich Taube. Unfolding them on ...


1

The "Bird of Prey" is nothing more than an artist's conception at this point so there is nothing to review from a mechanical design standpoint. Somebody thought it would be neat to make a plane that looked like a bird, but the methods by which birds achieve flight is far different than in modern aircraft. I don't believe there are any practical ...


1

The short answer is they exploit the flow circulating around the tip by generating lift that is oriented toward the fuselage, with a slight forward component because the local flow is slightly inboard as it curls around the tip, and lift is 90 degress to the flow. They are basically sails, and were originally called "tip sails". The result is a small ...


1

Firstly congrats on your ‘out of the box’ thinking and an interesting concept! The previous answers have hit a lot of the major points so apologies if I repeat any of them, but here are my initial comments: All wing tip devices (or extensions) reduce lift-induced drag. The operating condition heavily affects the amount of induced drag present. There is a ...


1

If using Prandtl's lifting line theory, then mathematically/analytically, ignoring issues of wing weight that lead to bell shaped lift distributions and other sorts of intrusions of reality (e.g., stall behavior) the elliptical wing with the elliptical lift distribution is optimal for minimizing induced drag given a fixed wing area. You can get an ...


1

One aspect of efficiency that downward pointing wingtips improve is increased bottom lift from increased compression of air underneath. "End caps", wing tip fuel tanks, anhedralled wings, Lippisch ears, downward folding wing tips (as seen on the XB-70), and downward pointing winglets achieve the same effect. These be benefits must be weighed against the ...


1

Another example of an aircraft with wingtip tanks is the T2-C Buckeye. They hold approximately 102 gallons each, and so add to the total fuel capacity of the aircraft. There are a number of reasons that the wingtip tanks might be part of the design of an aircraft. Decreasing flutter is one reason that you might add wing tips, and this hasn't been ...


1

One possible explanation is that large amounts of sweep and higher indicated airspeed are less common in "smaller" GA aircraft. Larger and faster aircraft with large amounts of sweep literally plow the air aside, resulting in a significant spanwise airflow at the wingtips. Winglets are touted for reducing the strength of wing tip vortices, and are said to ...


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