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 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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Can engines with a fixed nozzle in the angle of attack have the same effect as the thrust vectoring?
If the figure above represents a missile at the angle of attack and we vector resolution the thrust output from the nozzle, we can see that the thrust is divided into sine and cosine parts. Does the ...
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Why arrow wings are more efficient than delta wings?
From page 29 of this slide (https://archive.aoe.vt.edu/mason/Mason_f/SupersonicPres.pdf), an arrow wing has higher lift slope and lower induced drag slope than a delta wing with a straight trailing ...
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Why phase lag on helicopter blade is sometimes 90°, and sometimes less?
On semi rigid rotor head, phase lag is 90°, and also the advance angle between pitch link and coresponding blade. But of fully articulated rotor the phase lag is less then 90°, and also the advance ...
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Is an airfoil's critical angle of attack measured using "geometric angle of attack" or "effective angle of attack?"
One of the first things we learn about stalls is that they occur when a wing exceeds a certain critical angle of attack, which depends on the specific design of the wing. But if a given wing has a ...
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How to calculate lift force of a revolved NACA 0009 airfoil?
How would I calculate the lift force as a function of angle of attack for a revolved NACA 0009 3D body (incompressible flow)? I have data for CL vs. AoA for the 2D airfoil, but how would I use this to ...
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What are the flight formulas for aircraft
I am making a 2D flight "simulator" (trying to be as realistic as you can for 2d) and I need flight formulas for lift, speed and pitch. I have tried a few sites but I do not understand what ...
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Helicopter blades flapping with the cyclic – can you help with the explanation?
I am now reading books about helicopter aerodynamics. And I have one question about blades flapping.
If you push forward on the cyclic, the swashplate will tilt forward and will set the maximum pitch ...
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What would the effect be of flap deployment on a UAV such as the Reaper or Predator?
I've read answers that said that the climb performance is usually worse with flaps extended, and the pilots would, if they could, just retract them and get into a clean config as soon as possible. ...
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Why would a lower trailing edge angle allow for more rear-loading?
In reading a paper on transonic aerodynamics by Jeff Jupp (Chief Wing Designer for the A310), he states, "the trailing edge angle in modern airfoils is reducing significantly, almost to zero in ...
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How to export cp vector plot obtained in xfoil?
How can I export an image of the plot showing the distribution of pressure coefficient vectors on the surface of an airfoil generated in Xfoil?
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What is a wing theory?
I have an assignment to summarize the topic "wing theory", with the preferred reference used is the book Fundamentals of Aerodynamics by John D. Anderson. But there's no dedicated chapter ...
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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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Does the obstruction in a propeller duct increase exhaust pressure or decrease pressure/increase speed?
I came up with this question when looking through the answer for this question, which states that a convergent duct(obstruction) compresses the exhaust so that its pressure matches the ambient ...
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Forward Slip - Which speed to maintain?
Which is the proper speed to be maintained during a Forward Slip? Near Vfe or Vref? Which one will let you lower with the shorter ground distance and why?
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effect of wing chord length on lift coefficient
In the bertin's Aerodynamics book
It is written that reducing the wing chord increases the lift coefficient( decreases stall angle) and as a result, the wingtip stalls earlier than the wing root
how ?
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Why does thrust differ in different reference frames?
If a jet engine flies with 4 m/s in the air and we want to calculate thrust for two different reference frames, can we prove that the calculated thrust for both reference frames are equal to each ...
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What causes the "dead band" phenomenon during takeoff on the Boeing 737?
During takeoff, the Boeing 737 encounters a distinctive "dead band" phenomenon after the initial pitch reaches approximately 10 degrees. Essentially, a slight increase in back pressure is ...
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what is the effect of cone back pressure on shock wave angle?
this is a part of anderson's book :
"Note that, for a given cone angle θc and given
M∞, there are two possible oblique shock waves—the strong- and weak-shock
solutions. This is directly analogous ...
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Is it possible to determine a maximum L/D possible
Over the last couple of decades L/D ratio has increased significantly. Is it possible to determine an "upper limit" on how much more potential there is for common tube-wing aircraft to ...
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Turbofan engine fan blade leading edge fairing?
A lot of aircrafts feature a leading edge fairing for the wing, at the connection with fuselage, in order to reduce the airflow interference.
Aerodynamically speaking, those fan blades in the turbofan ...
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Can the use of flaps reduce the steady-state turn radius at a given airspeed and angle of bank?
Note that for the purposes of this question, I am only interested in the scenario described below. By 'steady-state' I mean to exclude from consideration the short-term effects of changing the flap ...
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How can the effect of wind gradient in a glide be calculated?
If an airplane glides in a mass of air where the headwind changes with altitude, it seems logical to think that the length of the glide –as measured by a ground-based observer– will be longer in the ...
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why induced drag decreases in supersonic speed?
In John Bertin's book Aerodynamics, it is written that the induced drag at subsonic speed decreases with the increase in wing aspect ratio but the opposite happens at supersonic speed so that in ...
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If an aerofoil is placed in a narrow wind tunnel, how will that affect the lift it produces?
This is NACA 0000 aerofoil:
This is just a straight line - roughly what a paper plane's aerofoil section looks like (I chose this aerofoil for its simplicity). If we put this aerofoil in a wind ...
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How is the geometry of slotted flaps and slats designed?
I am currently doing a school research project attempting to find the effect of single-slotted flaps and slats on an airfoil's (NACA 2412 or similar) lift coefficient. I will be using a small homemade ...
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Conversion of downward velocity to forwards velocity?
When a plane dives down and then pulls up (assuming that the plane is not in a stall), how exactly does the plane keep its speed when leveling out?
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Size of speed brakes for glider
I have a concept glider and I am trying to calculate the required speed brake area. The clean glide ratio is currently 30, and with speedbrakes, I am aiming at reducing it to something around 7.
I ...
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How can flow in the compressor of a jet engine go back to the inlet?
In aerodynamic lessons and books about jet engines, it is always said that there is a risk that air flow in the combustion chamber or compressor can go back to reverse direction, towards the inlet if ...
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How to convert body frame-relative aerodynamic coefficients to wind frame-relative aerodynamic coefficients
I have a rocket flight simulator that takes in aerodynamic coefficients defined relative to the vehicle body frame axes (Cx, Cy, Cz). These are in a lookup table based on mach.
I have some aerodynamic ...
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Calculating Lift-To-Drag ratio of a rotating propeller with zero forward velocity
I'm simplifying some blade element theory problems by assuming that the propellers are perpendicular to the ground and their motion is constrained to being purely vertical (without forward velocity).
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4 Basic Forces of flight [closed]
I am looking for shortened but precise and understandable definitions for the 4 forces of flight for an essay I have to do (Lift, Weight, Thrust and Drag) or key parts I need to emphasise.
Any help or ...
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Can a bullet/finless rocket shape be a stable lifting body?
Consider a reentry vehicle that looks like this
If this re-entered the atmosphere from orbit, presupposing a sufficiently forward CG, could it stabilizer into a nose-first lifting attitude?
I'm ...
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is it necessary for the velocity distribution profile over a flat plate to have that kind of parabolic shape?
A wind tunnel boundary layer experiment was done for a flat plate with 5 stagnation probes distributed horizontally (each probe has 5 vertical sensors) and a variable flap, for 2 different free stream ...
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wingtip vortex in negative angle of attack
If a wing is at a positive angle of attack, then the vortices produced at the wingtip will generate downwash and induced drag
but on the contrary, if the wing is at a negative angle of attack, then ...
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Why is the lift coefficient not 0 at the initial time t* = 0?
In an experiment on pitching airfoil. Experimental results are given by the following graph, the curves are the evolutions of the lift coefficient.
Why is the lift coefficient not zero at the initial ...
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How to calculate boundary layer thickness?
So I have a flat plate with a surface of 7sqm and an aspect ratio of 12 with air blowing straight at it (like a wing) at a speed of 50km/h. I would like to manually calculate the thickness of the ...
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How does distance between wings of a biplane affect its horizontal stabilizer design?
When for instance pitching down, a biplane's upper wing has higher airspeed than lower wing, therefore higher drag that should dampen the pitching down rate.
How significant is this, if it is, ...
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what is Limit load factor structural and aerodynamic envelope at structural design gross weight and maximum gross weight?
As an aerospace engineer, as soon as I saw the words "structural and aerodynamic envelope" the first thing that popped into my mind that is it V-n diagram? But when I searched about it in ...
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Why do dihedral wings increase induced drag?
I read somewhere before that the effect of the dihedral wing is similar to the swept wing so dihedral wing increase wingtip loading and increase induced drag
Can anyone tell me how physically this is ...
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Does sudden downdraft increase or reduce drag?
Let say wing section in wind tunnel operate at 10° AoA, somehow we force downdraft that reduce wing effective AoA to 6°.
Of course lift sensor will show reduction in lift.
Will drag sensor show ...
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Why do vapour cones appear for such short periods of time?
Is it just because the air they are going through is more humid than the surrounding air so when they leave that patch the cone disappears?
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To what extent were/are area rule considered when designing the flap-track fairing of transport aircraft?
As you'd know, certain older transport aircraft in the 20th century, such as Convair 990 or Tu-134 featured very distinctive, large anti-shock bodies situated on the trailing edge of the main wing so ...
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Inudced drag distribution at eliptic and rectangular wing?
I am intersted in induced drag distribution at recnatugular and eliptic wing? It would be even better if graph show downwash distribution, lift distribution and stall behaviour for more wing shapes..
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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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Is Biot–Savart law physical in aerodynamics?
Biot–Savart law comes from electromagnetics theory.
Vorticity behind the wing(in the wake) induce downward vertical velocity upstream of the wing, so effective AoA of the wing is reduced.
Is this ...
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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 do expansion fans cause oblique shock waves to curve?
When there is an expansion fan aft of an oblique shock such that its bounding mach waves intersect with the oblique shock, the oblique shock is curved in that region. What is the physical phenomenon ...
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Airplane speed retention question? [closed]
Imagine the scenario when a plane is flying, then it turns off its engine and nose dives. After gaining a lot of speed, if the pilot pulls the stick back and the plane now points upwards again, will ...
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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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