Questions tagged [drag]

Aerodynamic drag is the fluid drag force that acts on any moving solid body in the direction of the fluid freestream flow. Part of the drag is the direct consequence of the wing generating lift.

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How does area ruling cancel drag from bodies that are neither upstream nor downstream of each other?

This might sound like a silly question, but it's one I've had for quite some time. (source) How is having that.....waist okay? I mean, the more complicated your body is, the more drag it creates, ...
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How do coefficient of lift/drag variation with speed differs between swept and unswept wings?

Trying to understand the coefficient of lift/drag of swept and unswept wings as speed increases. Some example questions and statements- A swept wing will have a lower max Cl at subsonic and ...
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What is the difference between interference drag and form drag? [duplicate]

What are the differences between interference drag and form drag? And which factors affect them?
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For subsonic aircraft, would adopting a higher wing loading decrease drag?

First, let's assume that problems with approach/TO speeds can be fixed by high-lift devices. Here we read that the wings create more drag than the fuselage. So, an improvement seems obvious; shrink ...
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Database for NACA airfoil polars [closed]

Is there anywhere where I can find a database of experimental or CFD-obtained NACA series four or series 6 airfoil data? I'd like to have access to a relatively large set of high-fidelity drag polars/$...
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Is co-flow jet wing technology workable?

Coflow Jet claims that their idea of sucking air from the trailing edge and blowing it out the leading edge improves efficiency. But this looks like glorified (and overcomplicated) flow control to me. ...
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Could drag in a turn be twice the drag in straight and level flight?

Just wanted to see if my understanding of drag is correct as I am unsure. I understand that during straight and level flight, the drag can be calculated as: With the first term being the parasitic ...
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Determining the total drag of a propeller driven aircraft while turning with a load factor of n = 2?

I understand that the total drag includes the parasitic and induced component, with the parasitic component being the same as with straight and level flight. How do I calculate the induced component? ...
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What was the lift-to-drag ratio for WWI biplanes?

I will be interested to know what was the lift-to-drag ration for a few more known WWI biplanes at take-off, cruise and landing speed; with the propeller running, stopped or non existent (tests in ...
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Is lift/drag the same as coefficient of lift/coefficient of drag?

I see it being used interchangeably (for example by Airfoil Tools Fusion360 AddIn), so can I just pick an airfoil from the airfoiltools database with a certain CL/CD for my aircraft and assume L/D is ...
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I calculated that Flyer I and II (1903-04) of the Wright brothers were underpowered. Are there better (drag, lift) coefficients than those of Culick?

Based on what the Wright brothers said in a few letters and two article (all relevant excerpts have been attached to this post), and also using the experimental data in the study "AERODYNAMICS, ...
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Is it possible for a plane to accelerate easily from 30 to 45 mph in flight while it struggles to reach 30 mph (the engine runs at constant power)?

In two letters sent to Dr. G. A. Spratt (an aviation enthusiast), Wilbur Wright reported the progress he and his brother had made, up to September 10, 1904, regarding Flyer II, a plane powered by a 16-...
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Why does a mid-wing aircraft have lower drag?

Why does an airplane having a mid-wing have lower drag than high- or low-wing configuration even if they have wing of same shape and size? This article (PDF) claims it's true.
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Wing vs wall to wall wing,total drag comparation at same AoA?

Compare total drag of wall to wall wing vs wing(open tips) in wind tunnel,AT SAME AoA. My first intuition is that wall to wall wing has higher pressure drag at outward parts of wing,because side-walls ...
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How to distinguish the induced drag of a lift-producing wing from its pressure drag?

Quote John Anderson Fundamentals of Aerodynamics: "The three-dimensional flow simply alters the pressure distribution on the finite wingin such a fashion that a net pressure imbalance exists in the ...
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Does ducted fan require more engine torque than unducted-fan,at same RPM?

Two identical fans, one is unducted and other is ducted,both operate at same RPM. •Does ducted fan require more engine torque than unducted-fan ,measured both at same fan RPM? power=torque x RPM so ...
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How does altitude affect drag? [duplicate]

Consider two aircraft. Aircraft A flying at sea level with weight (W) and Angle of attack (α). Aircraft B flying at altitude h in level flight at the same weight (W) and same angle of attack (α) (same ...
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How much thrust is produced on an A320 at takeoff and during cruise?

Where can you get the drag polar of the A320 at cruise and TakeOff?
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Why does drag coefficient decrease with Mach number in the supersonic regime?

I'm trying to understand why the drag coefficient decreases in the supersonic regime with Mach number. While it is easy show this using supersonic, potential flow theory, I'm looking for a more ...
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Is there any specific location on airframe for gaining higher drag?

I have a model rocket and I want my rocket to reach specific height above the ground level. As soon as desired height is reached, an air brake (umbrella type) is allowed to deploy. In order to have ...
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When using the Source Panel method and dealing only with sources and sinks, why do lift and drag equal zero?

I am trying to deal with the airfoil with the "Source Panel method", and when I try to calculate the lift and drag, they always equal to zero. And I have found an explanation in some ...
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How calculated the drag coefficient lift coefficient with pressure coefficient?

I have got the Cp Plot on a wing, now I am trying to calculate Cl and Cd. And the angle of attack is 0 degrees, the wing has been split into N Panels, and the normal vector ni for every Panel is ...
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Why is hybrid laminar flow control preferred for swept wings over other options?

As I understand it, a (the?) major form of laminar-to-turbulent transition on the swept wings of large jets is the crossflow caused by the sweep. One way to control this is laminar flow control by ...
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How is NASA going to get high fuel economy on the X-57? [duplicate]

This X-plane is meant to fly soon. It's a modified Tecnam. The propeller direct wash over the wings, increasing lift. This allows the use of a smaller, high-aspect ratio, low drag wing. But this isn'...
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How do viscous drag and form drag individually change as a function of angle of attack?

Typically, when dealing with airfoils, the drag coefficient $C_d$ is given as a function of angle of attack. If we limit the discussion to 2D subsonic incompressible flows, then the drag is the sum of ...
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Is it true that blowing cannot be used for laminar flow control? Why?

Aerospace Engineering Desk Reference, page 505 Tangential blowing can only be applied to the prevention of separation...The flow caused by blowing tends to be very vulnerable to laminarturbulent ...
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Can the wing stagnation point be bled off and used for laminar flow control?

The stagnation point at the leading edge contains slow-moving, slightly compressed air. This sounds ideal for laminar flow control. This slow air will create little losses in ducts, and it's pressure ...
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Why does the A320 still have this old fashioned nose?

Another answer stated that Airbus was less focused on just brand image, and more on aerodynamics, explaining the more rounded nose of it's 320 vs the 737's. But it still has flat cockpit panes which ...
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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 signi®cant reductions in both vortex and wave DDL via an extreme arrow con®guration and could be favourable to LFC via ...
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How much might soft skin reduce aircraft skin friction?

According to Peter Kampf's answer here, soft skin can damp a (vibrational?) mode that cause laminar flow to become turbulent. Thus, it could help delay boundary layer transition. My question is, for a ...
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What are the variables of the induced drag formula and where does this force apply?

I want to understand a little bit more the induced drag force, therefore in analyzing the formula: $$ F_D = C_DA\frac{⍴V^2}{2} $$ what do the following variables actually mean? $ F_D $ Is the 3D ...
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How high does the “bug layer” extend?

As far as I know, a big obstacle to attaining laminar flow in aircraft today is the so-called "bug layer", presumably a lower layer of the atmosphere where bugs are encountered. So, my question is ...
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Would supersonic bi/tri/multiplane wings have less lift interference drag than a subsonic version?

Biplane wings interfere with each other, reducing the total lift often to about only 20% more than a mono wing of the same chord and span. But at supersonic speeds - say, Mach 2, where Mach angle is ...
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Does increased fineness ratio decrease skin friction drag?

From the Wikipedia article on parasitic drag: a designer can consider the fineness ratio, which is the length of the aircraft divided by its diameter at the widest point (L/D). It is mostly kept 6:1 ...
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What are some first-order drag approximations for airframe/propwash interactions?

What are some first-order drag approximations for airframe/propwash interactions, both for dynamic flight and for static thrust, in a traditional tractor configuration?
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What are typical values of the lift-to-drag ratio for normal small aircraft?

Hi I am trying to do a rough estimation of forces acting on an aircraft wing and would like to know what kind of lift to drag ratio is normal. The exact profile hasn't been chosen yet, but the ...
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Why are heavy flaps better than just a bigger wing?

Flaps increase lift during landing and T/O. But when retracted, they do nothing. The space needed to stow the common fowler flaps can't be used for anything else - fuel or structure. Extended flaps ...
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Is drag the only aerodynamic force that acts upon an asymmetric body (a glider in particular) travelling through the air?

It is known that for a symmetric body, like a sphere falling through the air, the only aerodynamic force that acts upon it is the drag that points always in the opposite direction relative to its ...
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Blunt noses subsonic drag - why a complete ellipse?

At subsonic speeds, blunt noses - both fuselage and airfoil - are good for two reasons: the need to maintain attached flow at varying angles of attack. it has less surface area for the volume, ...
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Is there any go to formula in the designing of a winglet? [duplicate]

we have to design a commercial airplane as a part of a college assignment and i was wondering if there are any rule of thumb /formulas involved in the designing of winglets? Or does one have to assume ...
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Why is it harder to maintain laminar flow on larger aircraft?

I am told that on larger aircraft, suction will be needed to maintain laminar flow because of the larger leading edge radius. Why so? Is it because the air has to travel over a longer distance on the ...
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Will wingtip drag always be more for a smaller aircraft, keeping constant aspect ratio? [duplicate]

Sometime ago, I came across an article (I couldn't find it) which stated that wingtip drag was only related to absolute wingspan. That is, for the same wingspan and lift force, varying the chord will ...
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What is boundary layer tripping?

I came across the term "Boundary layer tripping" but I can't really underastand it. After searching on internet I cannot find any video or an image explaining that concept. Could you please explain ...
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Why do flaps retract?

Why do flaps retract? I know, it might seem obvious at first, because of drag, but instead of retracting the flaps, can't they just make the flaps flexible enough to get into a reduced drag position, ...
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Do horizontal stabilizers on airliners have varying angle of incidence in the span-wise direction (washout or negative twist)?

Reading this question and answers, I was wondering if modern airliners with cruciform tail have some noticalbe washout or negative twist along the horizontal stabilizer's span. During cruise, if wing'...
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Is it possible to create Interference Drag without physical surfaces conjoining?

Interference Drag is when boundary layers mix/combine, usually it's caused by pieces of metal conjoining (wing struts/gear retracting). Is it possible for interference drag to be created without ...
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Why are crop dusting spray booms not integrated into the wing?

All crop dusting aircraft seem to have an externally mounted spray boom for distributing their pesticides, I imagine this significantly increases drag & therefor performance. What gives? why not ...
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How do you calculate Profile Drag?

second year aeronautical engineering student here. I'm doing some aerodynamics coursework but have run into a problem. I've read through the answers to the question "what is profile drag?" but ...
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Vertical autorotation with passive rotor

Let's say we have a simple hollow cube(chosen for simplicity) with outside side length=10cm, thickness=5mm (or another arbitrary shape with arbitrary dimensions). Clarification: I am NOT talking ...

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