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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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34 votes
1 answer
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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 ...
Koyovis's user avatar
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17 votes
4 answers
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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 ...
Nelson's user avatar
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17 votes
4 answers
6k views

Why did the Avro Vulcan use a delta wing?

Why did the Avro Vulcan use a delta wing? The B52, from the same era, used a swept wing, and had a higher maximum speed. In the answer to What are the advantages and disadvantages of a delta wing ...
Crosbie's user avatar
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17 votes
2 answers
6k views

Why is the coefficient of drag for straight wings at supersonic speeds lower than for swept wings?

Why is the coefficient of drag of a straight wing lower than the coefficient of drag of a swept back wing at higher supersonic speeds (above, say, Mach 2)?
Adder's user avatar
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16 votes
2 answers
18k views

What is the reason for the poor low-speed characteristics of sweptback wings?

I know there are advantages of swept-back wings delaying shock-wave allowing a aircraft to fly faster. However, what are the disadvantages. I know one of them is that they have very poor low speed ...
Harry Wang's user avatar
15 votes
2 answers
3k views

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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14 votes
3 answers
11k views

What are the advantages and disadvantages of an oblique wing over a swing wing?

This question asks about the benefits of an oblique wing over a delta wing, but I am more interested in the benefits of an oblique wing compared to a swing wing. Wikipedia states: This is a ...
ROIMaison's user avatar
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14 votes
1 answer
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Did the contemporaries of the F-14 also have automatic swing wings?

The F-14's Central Air Data Computer was a innovative design, using microprocessors for its implementation. This computer was used to control the swing wings of the F-14. How did the contemporary ...
Eric Urban's user avatar
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12 votes
3 answers
2k views

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 ...
Tom W's user avatar
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12 votes
2 answers
4k views

What is the aerodynamic benefit of trailing edge sweep?

Sweep will allow flight at higher speed because the perpendicular air flow speed (over wing) is less. But why is there trailing edge sweep? We can have a swept leading edge and unswept trailing edge ...
Selva's user avatar
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10 votes
2 answers
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Why should isobars be aligned with the leading edge of the main wing for a transonic cruiser?

When designing an airplane meant to cruise at transonic speeds (or supersonic speeds), I heard that one should look at the isobars on the main wing in order to assess if the shape, sweep angle and ...
Ludovic C.'s user avatar
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9 votes
1 answer
394 views

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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9 votes
2 answers
638 views

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 ...
JGG's user avatar
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7 votes
4 answers
21k views

Where is the spanwise flow? How does the span wise flow point the air towards the wingtip?

If you search Google for span wise flow, the first result under the pictures tab is a image of a wing with the span wise flow at the trailing edge: (Source) If you look at some other photos you ...
Crafterguy's user avatar
6 votes
2 answers
3k views

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. ...
Rajakr's user avatar
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6 votes
3 answers
2k views

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?
CuthillMckee's user avatar
6 votes
2 answers
2k views

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 ...
DrZ214's user avatar
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6 votes
3 answers
2k views

What are the benefits of a pivot wing?

The answer to another question mentions the rather unusual pivot wing. From an aerodynamical standpoint, what are the benefits of an oblique wing compared to a delta, a trapezoid or a forward swept ...
usernumber's user avatar
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5 votes
2 answers
935 views

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 ...
Guy Inchbald's user avatar
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4 votes
3 answers
701 views

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/...
interested22's user avatar
4 votes
2 answers
844 views

Swept outer section of the wing on turboprops

It's quite common to see turboprops having a wing with the outer part of the wing with a small sweep (around 3 deg at 1/4 of the chord). What's the reason? It's usually stated that wing taper is used ...
user72410's user avatar
4 votes
1 answer
168 views

Impact to lift curve slope for a tapered wing with only trailing edge sweep?

I'd like to use a tapered wing with 0 deg leading edge sweep and 12 deg trailing edge sweep as shown below for my RC model. I understand that lift curve slope, a, is reduced for wings with leading-...
Seth's user avatar
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4 votes
1 answer
2k views

How is a variable sweep wing constructed?

How is a variable sweep wing able to change its sweep?
user15878's user avatar
4 votes
1 answer
6k views

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 ...
user30728's user avatar
  • 143
4 votes
2 answers
424 views

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,...
TheFlyingFisherman's user avatar
3 votes
3 answers
560 views

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&...
Paul Tomblin's user avatar
3 votes
5 answers
2k views

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 ...
Francis L.'s user avatar
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3 votes
4 answers
695 views

How do swept back wings delay shock wave

Swept back wings can delay the formation of shock wave and increase the aircraft critical mach number of the aircraft, right? But how
Hitomhi's user avatar
  • 349
3 votes
1 answer
299 views

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. ...
SJ2050's user avatar
  • 85
3 votes
2 answers
1k views

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 ...
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3 votes
1 answer
219 views

What are the effects of a corrugated surface on spanwise flow deviation, for a swept back flying wing?

Considering a Ju-52 wing in some hypothetical swept back flying wing configuration using the same strucural design as the Ju-52. What would be the effects of that corrugated skin, regarding spanwise ...
user avatar
3 votes
2 answers
811 views

How do the orientation of spars and ribs affect the aerodynamic efficiency of wing?

There are various ways the ribs and spars can be oriented in the swept wing. Do the placement of ribs and spars affect the aerodynamics? And, what are the structural advantages of both orientations ...
Auberron's user avatar
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3 votes
1 answer
1k views

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 ...
S. Durand's user avatar
3 votes
2 answers
2k views

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 ...
Nick Hill's user avatar
  • 616
3 votes
0 answers
53 views

Literature request for effect of Aspect Ratio and Wing Sweep on critical angle of attack?

So I'm trying to find academic literature detailing how both aspect ratio and taper ratio affect the critical angle attack of an aerofoil - namely for a v. low AR wing (AR<1), and high sweep (~75 ...
Harry Karmel's user avatar
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3 votes
0 answers
135 views

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 ...
Paranoidone's user avatar
2 votes
3 answers
3k views

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 ...
Bilal Mirza's user avatar
2 votes
2 answers
926 views

Could a variable sweep aircraft also use negative angle?

Variable sweep on fighter aircraft is a bit out of fashion, but seems to a worthwhile option to adjust the wing to the current speed and needed lift. All this is bought with complexity and weight of ...
sargas's user avatar
  • 175
2 votes
3 answers
663 views

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 ...
AlphaCentauri's user avatar
2 votes
3 answers
2k views

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.
Mags's user avatar
  • 21
2 votes
1 answer
1k views

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 ...
Speedalive's user avatar
2 votes
2 answers
629 views

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(...
Sankara Narayan's user avatar
2 votes
1 answer
2k views

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 ...
itisyeetimetoday's user avatar
2 votes
2 answers
200 views

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 ...
Vikki's user avatar
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1 vote
3 answers
793 views

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?
Carsen Wastell's user avatar
1 vote
1 answer
240 views

Why did the F-14 sweep wing control have a cover?

I learned from Top Gun maverick that the F-14 had what seemed to be a metal cover in front of the wing sweep adjustment cursor. Maverick modifies the sweep angle twice, and twice needs to first lift ...
Stefano Borini's user avatar
1 vote
1 answer
390 views

Why do most canards have swept wings?

So most canards have swept back wings. Now I have been told that it is that way to ensure yaw stability (for example in a crosswind) - not sure though. But then I look at the new Lilium jet, which is ...
Vincent Cerowski's user avatar
1 vote
1 answer
821 views

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 ...
user39178's user avatar
  • 313
1 vote
1 answer
427 views

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 (...
Vikki's user avatar
  • 28.4k
1 vote
2 answers
315 views

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 ...
Nick Hill's user avatar
  • 616