# Questions tagged [wing-sweep]

Angle of a line from root to tip, 25% of the way back from the leading edge, measured from the perpendicular to the longitudinal axis of the aircraft.

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### Comparisons between the A340 and 747-200 wing: sweep angle and span

Here is a picture of the wings of the A340 (launched in the late 1980s) and the Boeing 747-200/400 (launched in the early 1970s / 80s) superimposed upon each other (source: https://www.amazon.com/...
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### Taper sweep angle

Is the Taper sweep angle the same as the sweep angle? So I know that the sweep angle is the angle from the vertical line from the leading edge to leading edge wing line.
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### How does forward sweep of a wing affect the formation of shock waves?

I understand that sweeping a wing back reduces the component of velocity perpendicular to the wing and can allow it to travel at subsonic conditions, and reduce the formation of shock waves, even if ...
1 vote
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### Does the quarter-chord-angle rule still hold for wings with very long chords or large differences between leading- and trailing-edge sweep angles?

For most fixed-wing aircraft, the effective wing-sweep angle (i.e., the angle that the aircraft aerodynamically behaves like its wings are swept at) is equal to the angle of the quarter-chord line (...
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### Why is sweep angle measured at the 25% chord?

If you look at wing planforms of e.g. the Spitfire, you can see that the sweep measured at the 25% chord line is 0°. However, the leading edge is rounded/slightly swept and therefore induces spanwise ...
1 vote
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### If sweep delays compressibility, why does 747 cruise slower than A380?

B747 has a sweep angle of 37 deg and A380 has a sweep angle of 33 deg. If the main reason for sweep is to delay compressibility effects and increase operating Mach number, why does B747 cruise at a ...
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### What is the purpose of the fin sweep on small piston airplanes? [duplicate]

Why some small piston airplanes, like Cessna 152/172, Tecnam P2008 and many more, have the vertical stabilizer with a sweepback? I don't think that those airplanes may encounter compressibility ...
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### Swept back wing theory

I'm a beginner in airfoil design. I just came across swept-back wings. There is a point that I couldn't understand that theory. Why is the only perpendicular component of the airflow to the wing(...
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### What characteristic my canard needs to have when the canard also carries a pair of engine?

I am in 3rd year Aerospace Engineering and trying to do a preliminary design of an airplane. My design has a front wing that also has an engine at its root on both side of the fuselage. There is ...
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### How does one calculate the Mean Geometric Chord in extended Trapezoid Wing?

The general formula to calulate MGC of a wing is given for a trapezoid in many books but there isn't an example showing how to calculate it for a wing shaped like the one below. I tried to solve ...
1 vote
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### Difference in lift generation for a swept wing and straight wing in subsonic condition

Would there be any differences in lift for a straight wing and swept wing (front or back) with the same airfoil cross section, same chord length, same wing span, and same area when flying in subsonic ...
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### How does a variable-sweep-wing aircraft keep wing-mounted payloads straight?

So, a variable-sweep wing is an interesting design, but I am wondering: if the aircraft wing moves back or forward, then the payload's angle will also change. Is there a another rotating mechanism in ...
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### Can wing sweep decrease total drag force at low-subsonic speeds?

From experience everybody knows if you put your arm out of car window at high speed(150km/h), it's a lot easier to hold arm angled backward then hold arm straight out(prependicular to airlfow).So ...
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### Why do semitailless swept-winged aircraft, but not delta-winged aircraft, suffer from (primarily) pitch oscillations at high mach?

Semitailless1 swept-wing aircraft without active stability enhancement2 generally3 have extremely poor handling characteristics, most notably a tendency towards violent pitch oscillations at high ...
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### How ribs angle change wing overall shape? [closed]

How ribs angle change wing overall shape?
1 vote
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### Why doesn't a wing in supersonic flow produce a shock that results in flow parallel to the leading edge?

When we look at a wedge in supersonic flow, a shock emanates from the leading edge such that the flow after the shock is turned and is parallel to the airfoil surface. The shock angle is based on the ...
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### Does an increase in lift always cause an increase in lift-induced drag?

An increase in lift causes an increase in drag. Is it always true? I am confused with two points. Lift increases with an increase in airspeed but induced drag reduces with an increase in airspeed. ...
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### Could an arrow planform be better for a supersonic aircraft than a delta? Why?

From this review paper Page 11: Strut-bracing for the SST allows very significant reductions in both vortex and wave DDL via an extreme arrow configuration and could be favourable to LFC via reduced ...
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### For aircraft with variable-sweep wings, how unstable is it to have each wing in a different position?

Wikipedia presents this photograph of an F-14 Tomcat, with one variable-sweep wing swept forward and the other back: I was surprised to see that this configuration was possible; much less feasible or ...
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1 vote
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### Tapered Wing Providing low Coefficient of Lift

Hi I am currently analyzing different wing designs using ANSYS Fluent. One of my designs has a straight leading edge but a swept trailing edge thus it is tapered with wing root chord at 50mm and wing ...
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### Why do swept wings decrease the drag increase that occurs in transonic flows?

Swept wings are used in aircraft that fly in the transonic regime because they 1) delay the critical Mach number 2) reduce the drag increase that occurs (smaller drag divergence). I am trying to ...
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### Is airflow deflected inwards or outwards by wing sweep?

We are often told that wing sweep causes the airflow to be deflected outwards. I can understand this for the underside, but for the upper surface it seems inconsistent with other effects. For example ...
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1 vote
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### Why don't commercial airliners use variable sweep wings? [duplicate]

I know they're not used in military aircraft because it decreases the stealth factor, but why don't commercial plane manufacturers make variable sweep planes?
1 vote
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### How do I choose the correct params?

I am very new to airplane design. I am working on this project to design a flying wing glider (no propeller) that would glide in a circular pattern with a fixed radius of 250 m after being released at ...
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### How do I factor sweep and dihedral in the lift equation?

I'm guessing that you add cos(angle of dihedral) to calculate lift loss by dihedral, but I'm not sure how to factor in the lift loss by the wing swept. Could someone help me include lift loss due to ...
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### Why don't commercial aircraft have variable sweep wings? [duplicate]

I was wondering why commercial aircraft don't have variable sweep wings just like the Bell X-5 did? By sweeping the wing further at high altitude it helps the aircraft move faster and also it helps ...
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### How does gust affect a swept wing

I have a basic question that I cannot seem to find a solid answer for: How does a gust affect a swept wing?
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### What were the typical rotation and landing speeds of the X-29?

Looking online through all the available literature, I could not find the typical rotation ($V_r$), landing or even stall speed of the experimental forward swept wing X-29 aircraft. I'm curious to ...
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### Jettisonable wingspan for early long-range airplanes

Reading this question, I was wondering if, at some point early in aviation history there may have been designs or concepts anticipating variable swept wing by "expendable wingspan wing"? For ...
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### Why does the effective alpha/CL increase at wingtip of swept wing?

If anybody could explain this in an intuitive way I'd really appreciate it. I haven't been able to find a clear answer on this. I understand that the increase in effective AoA/CL and the spanwise flow ...
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### Why are Vertical tails generally tapered?

I'm just intrigued to know why the vertical tail of a majority of aircraft is tapered? Is it due to aerodynamics, structural design or due to some instrumentation or multiple other reasons?
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1 vote
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### Would throttle steering of a forward-swept-winged aircraft be possible?

Fortunately (or perhaps unfortunately, given the number of crashes that had to occur for us to figure it out), the use of throttle manipulation to control an airliner with disabled primary flight ...
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### Why does wing bending cause wingtip twisting?

(semanticscholar.org) When aft swept wings bend/flex, the outer wing is twisted leading edge (LE) down (this reduces wave drag), the reverse (LE up) is true for forward swept wings. I've searched ...
1 vote
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### Is some sweep beneficial with taper?

I'm developing a canard glider which requires some taper for the canard to stall first. I understand that sweep is typically only for aircraft in a compressible airflow (M >= 0.3), but is there any ...
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### How is the change of moment handled in a Weight and Balance calculation with a swept wing aircraft?

I'm writing a weight and balance calculator for a charter operation. Every aircraft I've ever flight planned for has all the tanks on the same moment arm, so I don't know how you calculate the W&...
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### How can the F-15 and Su-27 achieve a high top speed without variable wing geometry?

I watched a documentary once that explained, I believe, how the Su-27 and similar aircraft such as the F-15, can achieve a high top speed without variable wing geometry. How does this work? How do ...
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### Straight Wings VS Delta Wings, Variable wing with Forward swept capability [duplicate]

What are the Pros and Cons (Advantages and Disadvantages) of a Delta wing and a Straight wing against each other, and if a Variable wing with a capability to become a Forward Swept wing is even ...
1 vote
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### Where is the wing sweep angle measured from?

If you look at a 747 planform wing you see something like this: In several aerodynamics and aircraft design text books they use the wing sweep angle as an important parameter to measure the wing ...
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### Why do some airplanes have simultaneously a straight wing and a swept horizontal stabilizer?

I'm sure there are many other examples like this one: Embraer EMB 120 with an almost straight wing and an obviously swept horizontal stabilizer. Why is there a difference in sweep angle between the ...
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### Can the divergence Mach be greater than 1?

I know that by decreasing t/c and increasing the sweep angle it is possible to increase the divergence Mach, but what is the limit? I am calculating the Mach for a wing with a quarter chord sweep ...
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### Is wing sweep needed on supersonic aircraft?

Area rule states that bodies with the same crossectional area distribution have the same drag. Does that mean I could use a straight wing on mach 1.2 aircraft with performance as high as sweep winged ...
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### Spanwise flow and wingtip vortices in forward-swept wings

One of the benefits of forward-swept wing is that spanwise flow direction is from tip to root. However, in this answer an X-29 has quite significant sweep angle, at which drawbacks such as ...
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### Why manufacturers does not producing variable sweep wing in our current scenario? [duplicate]

I read about many types of aircraft wing configurations like rectangular, swept forward, swept backword, and Delta wing. These configurations have their own advantages and disadvantages. But why we ...
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### Why would lift coefficent change with weight on swept-wing aircraft?

Today I encountered a problem. There is a book saying, "Why does the lift coefficient of a swept-wing airplane decrease with the increase in the weight of the airplane?" I cannot think of the reason. ...
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### How I determine numerically the roll rate of an aircraft?

I'm a Spanish student of aerospace engineering and I'm doing my final bachelor work that consists in designing an unlimited aerobatic plane, and I wonder if it is possible to calculate an ...
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### Does wing sweep affect the direction of lift?

Given both a straight and swept wing (identical otherwise), exposed to the same airflow, would the direction of lift be the same? Please see below a crudely drawn example of my thinking. Additionally,...
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### What aerodynamic characteristics arise from trailing edge sweep angle?

I drew 3 wing planforms, each with the same leading edge sweep. But they have different trailing edge sweep. Let's just assume for the moment that all those wings have the same surface area, so that ...
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### Why did the DC-3 have wing sweep?

When looking at the silhouette of a DC-3, one can clearly see that the wings are swept. This design is from 1935, before the high-speed research work on wing sweep was ever implemented, and the DC-3 ...
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### Why does the U-2 Dragon Lady not have swept wings?

Swept wings increase the critical mach number for aircraft with otherwise identical wings (Source 1). The U-2 Dragon Lady is limited in altitude by its critical mach number, as it needs more speed in ...
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