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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Are there studies to find surface treatments to reduce the drag of an airfoil?
I know that by designing an airplane or a car close to a teardrop, we can reduce the drag. My question has to do with the surface friction treatment. Some torpedoes glide in water more efficiently ...
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What are the effects of wing washout and anhedral on induced drag?
I am studying for my ATPL and was curious if and how induced drag varies based on wing anhedral and geometric washout.
I have a basic understanding that spanwise flow affects induced drag since there'...
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How does drag change efficient cruise conditions?
If I have an aircraft, and I reduce the induced drag produced by it, does this mean I should operate it at a higher altitude and faster speed to take advantage of the drop in total drag, or slower at ...
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How to calculate lift and drag coefficients of an airfoil with slotted flaps?
I am doing a project attempting to determine the increase in lift and drag coefficients of an airfoil as the angle of its flap increases. In my research, I have found the thin airfoil with flap ...
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Cause of Drag From Windmilling
I know that when a propeller is windmilling it creates drag, I assume this is from the propeller being flat against the air causes drag, but propellers are designed to essentially pull an airplane ...
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Forces acting on ram air parachute (for pulling ships)
I recently stumpled across this question about the ram-air parachutes for use in pulling ships.
In this answer it is stated that the parachute needs to travel perpendicularly to the ship's motion in ...
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Does the cross-sectional shape of a fuselage affect drag?
Comparing two bodies with the same streamlined longitudinal shape, and the same cross-sectional area, one with a circular cross-sectional shape, the other with a quadratic cross-sectional shape, ...
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Does CG change airspeed in a descent or glide?
If the CG of an airplane moves forward, would it fly a faster or slower airspeed in a descent?
Usually during a descent or landing, you'd use pitch to change airspeed and power to control descent rate....
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Reference Area of Airfoils
Airfoiltools.com shows a higher Lift/Drag coefficient for thick symmetrical foils than for thin symmetrical airfoils.
Is this because the higher drag coefficient of those airfoils is hidden in the ...
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Determining optimum area of parafoil, and then drag
I am designing a parafoil recovery system for a small payload of 300x100x500mm (2.4kg).
I have chosen an Aspect Ratio of 3, and from a NASA wind tunnel test report, the coefficient of lift and drag is ...
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What is viscous induced drag?
In this video he talk at 17:04 about viscous inudced drag, induced drag comes exclusively from inviscid theory,by the definition this drag exist only in inviscid world, so what is viscous induced ...
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Has resultant pressure vector backward component at 2D airfoil in viscid flow?
When we integrate static pressure around 2D airfoil that produce lift(viscid flow), has resultant pressure vector backward component?
I think pressure vector will point slighlty back, so it has some ...
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Why total drag formula include drag at zero lift?
Total drag = Do + DL
Why total drag include drag at zero lift if we are interested at drag when wing produce lift?
We cant assume that friciton and particularly pressure drag at zero lift AoA dont ...
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Does induced drag drop when wing is stalled?
From formula, induced drag is function of lift. When wing stalls, lift is reduced so induced drag must also be reduced?
Stall decrease static pressure at suction side of wing, so I know pressure drag ...
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What technical features account for the P-51B/D's low drag relative to other fighters of the day (e.g, Spitfire Mk IX)?
I am really sorry to dredge a popular topic up again. Unfortunately, after reading through some papers on the P-51 as well as all the past forum threads I could find on this topic, I have found myself ...
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How to approximate the drag for rectangular vertical flat panel placed along the wind and inclined?
So on the top is the view from the top, below it is the side view.
If the angle is zero it is similar to simple flat airfoil.
So I calculated the Cl and Cd in xfoil and
got the Cl = 0 and Cd = 0.02398 ...
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Induced drag vs parasite drag understanding
I am having the following graphic from one of the question for the EASA PPL(A) exam.
While I know that:
(1) represents "induced drag", as its decreasing with higher speed
(2) represents &...
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Does the 787 vertical stabilizer have a connection fairing?
In general, a vertical stabilizer connected with the fuselage will form junctions. The junctions trigger a mix of airstreams, and causes interference drag. A fairing is used the ease the sharp ...
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Why is icing more critical on smaller airplanes?
My professor mentioned that the contour of smaller airplanes changes more drastically than that of larger airplanes. In this context, he mentions the surface-to-volume ratio. But how does that relate ...
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What is the most efficient way to reduce interference drag when surface imperfections are unavoidable?
Interference drag can start to appear when there’s imperfections or excrescences on an aircraft outer surface. For example the following image shows some of these typical imperfections:
Source of ...
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Landing gear drag and weight calculations
I have read numerous books and researches, but I couldn’t find any formulae that actually work for how to calculate the following (for commercial aircrafts):
1- Drag coefficient for a retractable ...
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Is there a formula for calculating drag coefficient based on the 4 digit NACA airfoil?
Are there any existing formulas that can be used, or maybe some methods to derive an equation that can calculate the drag coefficient based on the NACA airfoil?
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How is blended winglet better?
*Make sure to read the following as I cannot explain my question in one sentence
Winglets are a kind of wingtip device that is installed on an aircraft to reduce drag and improve fuel efficiency. ...
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Explaing lift tilt back in induce drag pictures?
This is usual induced drag diagram.
What is black vector in diagram below?
If it is lift you cant decompose lift in lift(L in diagram) and induced drag (Di), this you can do only if this is resultant ...
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Does induced drag of wing change with speed for fixed AoA?
In wind tunnel we put 3D wing at fixed AoA, then tested at two different subsonic airspeed.
At higher speed, wing will produce more lift and more overall drag.
Will induced drag also rise at higher ...
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Why I cant see this downward movement infront wing which reduce effective AoA, (I see only upwash)?
Circulation theory predict downward airflow that reduce effective AoA,which cause induce drag.
To change effective AoA this downward airflow must be infront of wing, to "hit" wing with ...
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Is increase in lift allways follwed by increase in drag and vice versa?
We look at lift,drag and L/D at multi element wing with slots and same wing shape just without slots.
wing without slots:
Completly top side is stalled, so here is all low pressure(blue at picture),...
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How deliberately stall fixed wing reduce drag if stall decrease static pressue? [closed]
In this VIDEO at 5:40 we can see how stall decrease pressure at upper wing surface.
If stall/flow separation reduce static pressure how in this VIDEO they reduce drag when stalling the wing?
Here is ...
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Does Cd number change at different speeds during wind tunnel testing?
When meassure Cd or Cl of airplane/car in wind tunnel, does number change at different speeds, for example at 100km/h compare to 250km/h?
If yes,how much?
I know from theory that coefficents change ...
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How can I calculate the TOTAL drag of the ENTIRE airplane?
I have an aircraft similar to a Cessna 172 and am using a virtual wind tunnel software (flowdesign) to get a drag estimate. I import the airplanes 3D model and I get around 2240 lbs of drag with a ...
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Can I calculate fuel consumption for given reduction of drag coefficient?
If plane or car has Cd of 0.35 and 5L/100km, how much will be fuel consumption if Cd is reduced to 0.20 and everything else stay the same(weigth, frontal area,power etc)?
Is it possible to calculate ...
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How does an extended slat generate drag?
I am wondering how does an extended slat generate drag because I often read that slots agument lift by increasing critical angle of attack, but they do generate some extra drag. I am curious what is ...
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Induced drag - where does it actually arise from?
Several explanations about induced drag exist. Even if these explanations are simple and appealing (and not necessarily correct) they lack any connection to how actually the concept of induced drag ...
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Do symmetrical airfoils generate induced drag?
Cambered airfoils generate induced drag because they have a pressure differential between the upper and lower surface. However symmetrical airfoils don't. So does this mean that symmetrical airfoils ...
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How high could modern transonic commercial transport designers reasonably push L/D ratios?
One facet of the evolution of commercial transonic transport design since 1970 years is that L/D ratios (alternatively, the M * L/D) have increased only mildly over time. For example, see the ...
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How to calculate lift and drag of commerical aircraft in different phases of flight?
What is the best way to mathematically calculate values of lift and drag forces, in different phases of flight: takeoff, climb, cruise, descent, and approach?
Edit: I have the idea of calculating the ...
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Why XFOIL predicts a lower drag coefficient at higher Re?
A well known idea is that for aerodynamic/streamlined bodies the friction drag is larger than pressure drag. Hence, a laminar boundary layer is preferable (only looking at minimal drag, no other ...
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Has there ever been a VTOL aircraft thruster that generated lift through the use of a drag force?
I have been recently thinking about a conceptual VTOL aircraft thruster that should generate lift through the use of a drag force and I am very curious to know if such a thruster has ever been built ...
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Extrapolating Oswald Efficiency Factor from CL^2 vs CD Graph
I have plotted this CL^2 vs CD graph for a glide test performed in a flight simulator. I want to find the Oswald Efficiency Factor, e from it and I assume I can do that from its gradient. With a wing ...
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Can induced drag be negative?
For an aircraft in straight and level flight, lift-induced drag is the horizontal component of the force perpendicular to the wing chord. Positively cambered aerofoils generate lift starting at small ...
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What's the relationship between mach number and drag force on an airplane?
From what i've read drag coefficient at mach 1 is several times (up to 10x) the drag coefficient below drag divergence mach number. It drops as the mach number increases.
It's easy to find plots ...
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Why does lift decrease and drag increase when approaching the stall condition?
This is an ECQB-PPL question specifically asking what happens before the stall. I do understand that after the critical angle has been reached, the airfoil is no longer generating lift (so obviously ...
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Is it possible for the lift force unit vector to be equal to the weight force unit vector?
I know that the drag force is parallel to the direction of flow, thus equal to the unit vector of velocity. But if you consider a vehicle, when its angle of attack is below the velocity vector from a ...
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Help with calculate forces from pressure distribution
V=50m/s
deltaPg= -981 Pa
deltaPd=490,5 Pa
c=1m
r.com/PCshZ.png
Above is calculate Fz with integrals and with average pressure.
Why F3 is calculate from 0 to C/2 if pressure distribution is drawn at ...
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How can PreciseFlight speedbrakes double the drag while being so small?
Look at this photo of some PreciseFlight© speed brakes:
On the website it is claimed that these little red plates can double drag and descent rates. I cannot believe that. Can this be true, and if ...
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How to calculate drag of a flat rectangular surface at given area, air density, airspeed and angle of attack?
I'm a complete noob in aerodynamics, and I'm trying to calculate the drag of a rectangular flat area, given the air pressure / density, area, angle of attack and airspeed. I've read this question, but ...
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How much drag is actually caused by open cowl flaps?
I am modelling the Cessna 210 for FlightGear, which has cowl flaps. I want the model to be as realistic as possible, and so, I want to know: how much drag do cowl flaps produce ? I could not find any ...
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Round or sharp separation edges for lower drag?
Two same object,only difference is in separation edges,one has round ,other has sharp edges.
Round edges decrease wake but edges itslef produce low pressure because of curvature.
Sharp edges increase ...
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Why is the CG assumed to be between the CP and the tail?
While discussing stability (Longitudinal, Lateral, Directional), invariably, all texts assume CG to be between CP and tail.
Ex: Look at the specific image in wikipedia https://en.wikipedia.org/wiki/...
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Does $C_d$ change with speed? [closed]
In aircraft drag calculations, drag D is computed as $ D = C_D \cdot \frac{1}{2} \rho V^2 \cdot S$, with $C_D$ a dimensionless factor determined by the "streamline shape" of the measured ...
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