Questions tagged [aerodynamics]

Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design.

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Does a wing fly in its own downdraft?

I find in many books that a wing flies in its own downdraft. Does wing really fly in own downdraft and what does that mean? Video Source 18:15 - 19:30
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What is the speed and temperature profile of the boundary layer at the stagnation point?

At the statgnation point where the air velocity is zero, what is the shape of the velocity and temperature profile of the boundary layer? Is the velocity profile of the boundary layer in the form of a ...
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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 ...
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How to build a rocket? [closed]

I am trying to build a rocket (a small one for scientific purposes) for the very first time, I've never tried to do that before, and I can say I have almost little to no knowledge about this, so I am ...
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Why induced drag shows up as reduced pressure downstream of the wing?

Quote from book (Understanding Aerodynamics: Arguing from the Real Physics, Doug Mclean): "When we look at the force/momentum balance, the induced drag shows up in the flowfield primarily as ...
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Does lift decrease in hypersonic speed?

In John Bertin's Aerodynamics book, it is said that when the thickness of the boundary layer is low, the displacement thickness of the boundary layer is also low, and therefore the curvature of the ...
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Spiroid Winglets Cad models details requirement

Can anyone know where I can find spiroid winglets cad models? As iam conducting an experimentation on spiroid winglets.
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Do wake vortices interfere with the flow over/under the wing?

So as the title suggests, I was wondering if the wake vortices formed by a plane interfere with the flow over/under a wing. (My assumption is that they don't, but I'm not sure) Also, how would speed ...
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Does all of the air that 'leaks' from the bottom of the wingtip to the top create a vortex?

What I'm asking is does all of the air that spills from the high pressure bottom of the wingtip get pulled by the low pressure top of the wing? So some of the air curls around the wingtip to make a ...
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How do dog teeth and notches on wings create vortices?

According to this link (text right above F-18 picture) there are vortices made from leading edge notches and dog teeth, (2 vortices from notches and 1 from dog teeth). Why is that, and do other ...
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Does the flow over a wing decelerate upward, like air decelerates sideways with a swept wing?

In this answer, it states that the deceleration of air in the region of pressure rise over a wing acts in a direction perpendicular to the lines of relative chord, explaining how spanwise flow is ...
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How do I get rid of this chord line along the x-axis when importing an airfoil into XFLR5?

Whenever I try to import an airfoil into XFLR5, I always notice the chord centerline along the x-axis as you can see in the picture. Is there a way to somehow get rid of this line? I'd be thankful for ...
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Why is spanwise flow more prevalent in the boundary layer?

Spanwise flow is stronger in the boundary layer, but to me it's kind of counterintuitive because the BL flow is slowed down by friction, experiencing less of a pressure gradient over the wing, ...
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Are there any sources that contain information on the airfoils of the Boeing 737-500 and 737NG Aircraft?

I have found some information about this on airfoiltools.com (http://airfoiltools.com/airfoil/details?airfoil=b737a-il) but it doesn't specify the exact version of the aircraft, as the generations ...
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Why does the nose pitch up during power reduction in a T-tail with rear mounted engines?

For the CRJ700 for example, reducing thrust causes a pitch up. Why is that?
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Why does the F/A-18 use external aileron and flap hinges?

As seen in the picture, the legacy Hornet uses ailerons and flaps with external hinges, and I was wondering what were the advantages of external hinges compared to flush hinges in the land-based ...
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Is this "separation" caused by the boundary layer?

I was wondering if the void seen in this picture (on top of airfoil, not the wake from the airfoil) is from the boundary layer thickening, or from the fact that as you go further back on an airfoil, ...
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Does the pressure recovery on the rear side of an airfoil recover all of the pressure?

I was wondering if all of the low pressure created by the airfoil gets recovered on the rear side of the wing. (I know during a stall or flow separation, this doesn’t happen, I think) My main question ...
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Type of airfoil used by Briggs, Hull, and Dryden

What airfoil do Briggs, Hull, and Dryden use in NACA Report No. 207: https://ntrs.nasa.gov/api/citations/19930091273/downloads/19930091273.pdf They mention it a few times: "The airfoils tested ...
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How does more lift help during a stall (ex. flaps deployed) [duplicate]

How does more lift help in a stall? For flaps, I thought the effective increase in camber of the wing would make the wing have a higher AoA, therefore making a stall happen sooner. Thanks!
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Why does a helicopter that uses the Coandă effect need a direct jet thuster aswell

Why does a helicopter that uses the Coandă effect instead of a tail rotor need a direct jet thruster as well. Why couldn't they just vary the pitch of the ducted fan used for the Coandă effect?
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Chord Wise Load Distribution

I'm looking for some guidance on how to compute the chord-wise lift distribution of the wing using Xflr5 or OpenVsp or any analytical method. This is for designing the internal structure of the wing. ...
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Why does the turn tighten in a Spiral Dive as it progresses? Even without applying any elevator control?

Why does the turn keeps getting tighter as the spiral dive develops? Use of elevator control makes sense as it would increase the horizontal lift vector inside the turn. But even without any elevator ...
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How exactly does the startup vortex form, and why does it occur when circulation around the wing changes?

So I was wondering how exactly the startup vortex forms, why it dissipates, and where it's located in relation to the trailing edge of the wing. Also, why does a startup vortex form when circulation ...
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For a fixed density altitude, how does climb performance depend on pressure altitude?

Below is the climb performance from the 1978 Cessna 152 POH, which I've plotted as climb rate versus density altitude. It shows that higher pressure altitude gives decreased performance even when the ...
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Deriving Accurate Exit air velocity of rotor

My goal is to derive the equation for exit air velocity as a function of: Pitch angle RPM Rotor Radius Constants like ρ Assumptions: Vc is relative velocity of air upstream, and is = 0 Inflow is ...
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Why does Aerodynamic Center move to 50% chord when supersonic?

There are several sources available that state that when an airfoil is fully supersonic, the Aerodynamic Center will move to the 50% chord location. Some of these sources, the ANA shown above being ...
EquipmentOperator's user avatar
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Is blade flapping "fully automatic"?

I have a rather simple question just to "double check" if I understood blade flapping right. So, I understand that a helicopter, in forward flight faces an asymmetric lift. Blade flapping is ...
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How does speed and angle of attack affect pressure distribution at the wingtip?

So I was wondering how speed and AoA affect lift distribution at the tip of a wing. For example, if you are flying level and at a high speed, does that mean your wing has more even lift distribution ...
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Moving from 2D wing to 3D wing design

In terms of the design perspective of an Aircraft, once we decide on the airfoil that would be used for the wing, how would an Aerodynamics Engineer (or you) proceed to construct the wing? The ...
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Sources for Python Codes to do some aerodynamic Calculations [closed]

I am currently working to design a wing. I basically want the Python code which would take the coordinates of the airfoil (.dat file), freestream velocity, Span (b), planform of the wing as input, and ...
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Why don't modern military aircraft typically keep their guns covered?

Back in the 1940s, it was common to cover gun ports with tape. As well as improving streamlining, it would presumably help keep them clean. Spitfire Mk 1, with all eight .303 inch Browning machine ...
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Do winglets change the lift distribution of a wing?

In this answer, it claims that the reason for lift decreasing at the wingtips is due to airflow around the wingtips. If I'm thinking correctly, that is due to the air below the wing spilling on to the ...
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How does changes in Power vary the aerodynamic forces on an aircraft?

When we make changes to the Thrust by adding or removing power. In what way does it affect the other forces? As Power controls Rate of Climb or Descent of an aircraft, How is it acting on the other ...
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pressure wave propagation of shockwaves? [duplicate]

I can’t find a simple explanation of how the pressure waves propagate that leads to a shock over an aerofoil online. How does this happen with upstream flow that is high speed but subsonic?
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How does a shockwave form from a subsonic upstream?

How does a shockwave form over say an aerofoil from a subsonic upstream? Wouldn’t the flow have to be supersonic before it ‘shocks’? Also, does the flow in a shockwave jump from let’s say it is at M=1....
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Can an airplane propeller become supersonic?

Is it possible for an aircraft propeller to become supersonic? I am not referring as for the aircraft, only the rotating blade. I know it is extremely unlikely for a propeller plane to go supersonic, ...
Dody Him's user avatar
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How does aspect ratio affect stall speed and stall AoA?

I've read a few answers on here but they didn't really tell me what I wanted to know. So I get that high AR wings will stall before low AR wings but what makes that true? Higher AR wings have a higher ...
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what is the cross section of an elevator and trailing edge flap?

Is the cross section of both a Trailing edge flap and elevator an aerofoil please or, like i've shwon in in image below? I tried to find a side view of an elevator and TE deflected to see this for ...
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What is monotonous and non-monotonous flow?

I'm not an engineering graduate so I'm learning as I go along. I've just read a sentence that states: The transition shapes are identical, while the variety of growth rates of intermittency are non-...
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How do I know which outer grid shape is best for CFD?

I’m looking into running a CFD simulation on an aerofoil in transonic flow (M=0.8) but am unsure about what external grid shape to choose for my computational domain? I read into 3 main types: C-grid ...
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If I know both Re number and Mach, how do I incorporate both into my simulation?

I’m trying to simulate an aerofoil based on experimental data with flow in the following conditions: Mach=0.84 Reynolds number (Re) = 3*10^6 I wanted to keep my chord length at 1unit but then what ...
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Is the AOA on the horizontal stabilizer positive?

I am making a flight sim and would like some help. If I am correct, the angle of attack on the horizontal stabilizer should look something like this: aoa(Hstab) = aoa(Wing) - downwash + Hstab ...
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Why is it that when autopilot is maintaining cruise, we don’t feel the changes when lift increases?

When we’re inside an aeroplane, when we’re in cruise, why is it that we don’t feel the changes in altitude, lift and the adjustments for example from the elevator on the plane as the weight is burned ...
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How is an airliner trimmed nose-down or up? [duplicate]

so when a plane is in cruise, it loses weight and then the weight begins to exceed lift.when this happens, the plane begins to climb. My question is this please: The plane would be trimmed up or down ...
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If in a coordinated turn, the horizontal lift vector is equal to the Centrifugal force. Then how is the aircraft still turning?

Image source How does the Aircraft continue to turn when the both the Horizontal component of lift and the centrifugal force are equal?
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What is aeroplane trim and how does it control/adjust the elevator in cruise?

so in my last question, ‘trim’ popped up a lot and after reading up on it I got this: it’s used to adjust the forces on the control surfaces so that the aircraft maintains like a set input But what I ...
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How do Antishock Bodies / Cuchemann Carrots delay shock-induced flow separation?

There are several online resources that describe these aerodynamic devices as either "Antishock Bodies" or "Kuchemann Carrots" and that they are used to produce some combination of ...
EquipmentOperator's user avatar
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"Pure" Aerospace engineering vs mechanical engineering/pathway aerospace?

Does "pure" aerospace engineering give better aero-knowledge then mechanical engineering/pathway aerospace? What is point of specialization aerospace at mechanical engineering, isn't ...
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What are the effects of whiteout (snow) and brownout (sand/dust) on helos?

Is there any other effect besides low visibility? Both seem to show very similar conditions.
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