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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Why does the Tu-134UBL have a sharp/pointed nose cone?
Russian/Soviet aircraft design has always intrigued me, and even more so when coming across this photo of the Tupolev Tu-134UBL with its pointy nosecone.
Having looked up the performance ...
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Do box-wings suffer from induced drag the same way as normal wings?
Most wings suffer from induced drag due to a pressure difference above and below the wing causing air to sneak around the tip, forming a vortex. There are various methods to minimize these effects, ...
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Calculating best glide speed
I recently started flying a SGS 2-33 glider. The POH lists the stall speed as 31 mph for solo flight. Min sink speed is 38 mph and optimal glide speed is 45 mph.
Being an old glider with imperfections,...
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What should be the ideal distance between wings in a multi-winged air plane?
What is multi-wing or multi-plane:
For those who may not know, multi-wing air planes or multi-planes are aircraft that exceed the three sets of wings.
The idea is while increasing the number of wings,...
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Maximum Rotary Lift Altitude
Given that all factors are optimal, What is the physical maximum absolute ceiling altitude of a rotary wing aircraft?
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Rate and radius of turn formula
From this question and answer here there is a formula for both rate of turn and radius of turn. The formulas input are knots and degrees.
I have no doubt the constants in the formula (11.26 and 1,091)...
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Helicopter total power required: zero wind speed while climbing --vs-- down wind speed while hovering
I've been stumped on this for a while. Let's say you have a helicopter in climb mode (i.e., 100 ft/min) with zero wind speed present. Would the total power requirement be the same as if the helicopter ...
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The F104 tail pipe is not parallel to the runaway when the aircraft taxi.What is the reason?
The tail section is upward for clearance or to vector up the engine exhaust that will help to rise the nose when the aircraft take-off?
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Why do airplanes lift up their nose to climb?
Is it right that basically an airplane just needs to accelerate to climb?
Greater velocity of an airplane leads to greater lift - and since its weight remains constant (or even decreases) - a greater ...
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Streamwise Pressure Gradient on Curved Walls
Could someone help me to understand how can a wall generate differents streamwise pressure gradients just by its curvature? I can understand how it works in cross-flow (perpendicular to the streamline)...
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What does the pressure distribution over a glider's wing look like?
Can someone explain the design of glider wing airfoils and the subsequent pressure distribution over them?
I hypothesize that:
The pressure distribution should form a resultant force in the forward, ...
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Thrust = Drag. What about Power?
Understanding all this has been a work in progress, but now from start to finish we have:
Fuel/second ---> shaft Horsepower---> RPM ---> Thrust ---> Drag
Drag Force = $\rho$ × Area × ...
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Can an aircraft use ram air to generate power while flying?
I am a student carrying out a project focused on efficiency on aircraft. I have arrived at an idea I believe to be feasible. I am looking for suggestions, specification of what I would need, and any ...
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Lift direction at non-zero angle of attack for a swept wing, or for a straight wing in sideslip
When the direction of forces is popularly explained, they say "the lifting force is directed perpendicularly, and the drag force is parallel to the oncoming flow".
But what if it's a swept ...
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Could the Wright Flyer II takeoff without wind?
The Wright Flyer II could reach about 20 mph of airspeed on the track alone. The aircraft needed an airspeed of about 30 mph to make a proper takeoff (without hanging in ground effect). Before the ...
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Why is the tail group of virtually every airplane swept instead of straight?
Even low performance airplanes like ultralights have their tail group (vertical and horizontal stabilizer with rudder and elevator) swept backwards knowing fully well that a straight tail group will ...
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The F/A-18 Hornet , F15 and MiG-29 ailerons from the external parts of the wings go up some degrees in flight ,meaning adding " crow" .Why?
In some parts of the flying envelope of the F/A-18 Hornet and MiG-29 the ailerons from the external parts of the wings go up in sync. They're made to go one up one down in order to get rolls, not up/...
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Other than looking cool, what is the reason behind the TSR-2's anhedral wingtips?
Pretty much what the title says. What is the purpose of the TSR-2's anhedral wingtips? I've heard someone say that they use it to counter yawing I think but is this the true reason or is it something ...
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Why are the trailing edges of wings not always made as 'sharp' as possible?
I noticed that wing trailing edges of new airliners like A220 (CSeries) are not completely sharp. Instead, they are blunt. I always thought that the sharper the better in subsonic flow. What is the ...
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Subsonic Bump Inlet?
Contemporary high-performance supersonic aircraft such as the F-35 use bump inlet (alternatively known as DSI). These have a sophisticated 3-D bump that causes a 3-D weak shockwave in supersonic ...
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Why use indicated airspeed instead of dynamic pressure [closed]
It uses the difference between total pressure and static pressure, provided by the system, to either mechanically or electronically measure dynamic pressure. The dynamic pressure includes terms for ...
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Will two counter rotating vortices cancel each other?
Suppose that an aircraft flies with its wing through a tip vortex of another aircraft which flew in the opposite direction. Suppose that the shed wing tip vortex of both aircraft are exactly the same ...
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Making sailplane go faster
Sailplanes have much higher L/D than jetliners. But they are three times slower.
Is it practical to make a vanilla sailplane glide at 600mph by lifting it to a ridiculous altitude? If so, what would ...
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A Confusion about Digital DATCOM Calculations of a Tail Pitching Moment Coefficient
I'm using D DATCOM to estimate cm-alpha curve for a small tail planform with NACA-0012 airfoil using the namelist ($HTPLNF).
When taking the Tail planform aerodynamic center, ac (about 25% of MAC), as ...
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Why do the wings in these pictures go from swept back to parallel with the airflow? [duplicate]
To better understand my question, look at this A320 below
As you can see, the wing becomes parallel with the airflow at the wing root. Same thing on this 737
But this is not found on bigger planes ...
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Lifting-Line Theory - Numerical solution for a wing with dihedral angle
I'm trying to calculate lift for a wing with a dihedral angle using the Lifting-Line Theory. While using the thesis "Non-Planar Lifting-Line Theory for Fixed and Deformable Geometries" as a ...
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What happens to aerofoil downwash with Flaps extended vs retracted and how does it affect the Tail down force?
In my logic: Flaps extended will cause a greater Angle of Attack, to maintain Straight and Level Flight, AoA will be reduced, due to the increased "Surface", this allows to fly at lower ...
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Why does an aircraft fly a looping when pulling the stick?
let's assume an aircraft flies in straight level flight in the direction of an x-axis with an angle of attack of 3°. When the pilot pulls the flight stick, an additional lift is produced which acts ...
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Is it possible to get into a spin situation while coordinated?
Is there any possibility of spinning while coordinated? Of course, any CFI would tell you no, but I wonder if the the following situation could result in a spin while coordinated:
Slow level flight ...
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What differentiates the entry procedures for spins and snap rolls?
Both a spin and a snap roll are aerobatic manoeuvres involving stalling one of an airplane's wings earlier and more deeply than the other. Both are entered by pitching up sharply to stall the ...
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Why is ground effect greater over smooth hard surfaces?
Helicopter Flying Handbook: Ground effect is the increased efficiency of the rotor system caused
by interference of the airflow when near the ground. The air pressure
or density is increased, ...
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Fighter jet with two rudders, the deflection angle it is not identical. One have more angle of deflection. Why?
If an aircraft have two vertical tails then pilot push in the rudder pedal the rudders will not be deployed at the same angle.It is used throughout the all envelope of flight or is it possible only ...
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Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward?
Could an aerofoil be designed to give reasonably good lift for both flow directions?
I was motivated by this related question on Aviation SE: Can a plane fly backward if its propeller is in reverse?
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How does the line of thrust affect longitudinal stability?
I’ve been studying Pilots Handbook of Aeronautical Knowledge FAA-H-8083-25B and on p 5-17 they talk about thrust line and stability. Can someone explain why the moment changes when thrust is applied?
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Why does the stagnation point on airfoil move with the angle of attack?
What is the physical explanation for the reason the stagnation point is where it is? And, why does it move further down the lower side of the airfoil with an increase in angle of attack?
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How does inlet spillage drag produce a lip suction effect?
From this page:
Spillage drag, as the name implies, occurs when an inlet "spills" air around the outside instead of conducting the air to the compressor face. The amount of air that goes through ...
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Why cut off the tips of a delta wing to form a cropped delta?
According to wikipedia, the reason to cut off the tips of a standard delta wing is
maintain lift outboard and reduce wingtip flow separation (stalling)
at high angles of attack
This type of delta ...
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P Factor vs Spiral Slipstream
Does anyone know of any real aeroplane or wind-tunnel tests that quantifies the effects of asymmetric propeller blade loading (P factor) versus the Spiralling Slipstream effect in creating yaw.
Which ...
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What is the relation between airspeed and generated heat at constant drag?
I understand higher speed, and higher drag mean higher adiabatic compression leading to heating up the air, and the plane as result. X-15 needed ablative coating to prevent overheating. On reentry of ...
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Does a left spin differ from a right spin for a single-engine propeller aircraft, in terms of spin characteristics & ease of recovery?
Given a single-engine propeller aircraft with its nose-mounted propeller rotating on the right-hand side when viewed from the cockpit, and given the typical effects like P-factor, prop-wash and ...
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What are the aerodynamic characteristics of the flying saucer?
It seems that Canadian VZ-9 Avrocar was aerodynamically unstable. Particularly at high altitudes, and so the project was cancelled. IIRC there was considerable interest in flying saucers in the 1950s ...
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How do the Tiger Moth's anti-spin strakes work?
As originally designed, the DH.82 Tiger Moth had unpredictable spin characteristics. Many aircraft were lost because spin recovery took too long (i.e. too much loss of height). Many examples of the ...
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What is the Beggs/Mueller emergency spin recovery technique?
I've always used PARE for spin recovery:
Power to idle
Ailerons neutral
Rudder opposite the spin until rotation stops
Elevator forward to break the stall
What is Beggs/Mueller emergency ...
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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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What are the merits of an inlet cone/spike/centerbody vs. a 2D inlet?
And which is better for a scramjet?
Is a 2D inlet basically a "2D cone"? Similar to how an aerospike engine is made "2D" in the linear aerospike?
What's inside the cone/spike? Or is it just hollow?
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Between hover and moving straight forward, which one is this Sikorsky uses more power?
Source:
Consider this Sikorsky–Boeing SB-1 Defiant is being flying forward level and straight and being hover, which state is consumes more power? For both states, we assume that air is very still and ...
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Would it be more effective to increase the length or chord of a rotor blade for better performance?
Would it be more effective to increase the length or chord of a helicopter rotor blade for better performance? (Say, 10%?)
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How can wall to wall airfoil in wind tunnel produce downwash?
I see that some members(Peter,JZYl..)claim that wall to wall airfoil in wind tunnel produce downwash.
Can you explain how this is possible?
If air goes down behind wall to wall airfoil than above must ...
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Which source(s) provides the most authorative and correct flight dynamics theory? [closed]
Just like many curious people, the question: " How airplanes actually work?" occupied my mind for a long time.
Different sources gave different answers where most claimed the Bernoulli ...
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How the placement of the pitot and static ports decided?
Forgive the this topic placement as it might be similar to other older ones (Although I a bit sure that the main contents might be different than other older ones).
In the upcoming days I will have a ...
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