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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93 views

Why are some dynamic derivatives not included in DATCOM file? [closed]

I am trying to understand Flight dynamics, particularly I am using Missile Datcom to get aerodynamic parameters of a missile, then use MATLAB, simulink to simulate its trajectory. It seems there are a ...
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368 views

What is the difference between static and dynamic stall?

What are the static and dynamic stalls on the aircrafts wing? When would we encounter static and when dynamic one? What is the difference between them?
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Is the physical MAX8 design bad because software is required for the aircraft to stay airborne? [closed]

I'm not an aviator by any means, but one thing that has come up in recent conversations with friends is that the MAX8 is inherently unsafe because alone, unpowered, the craft is not 'aerodynamically ...
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Is there a conventional notation or name for the slip angle?

Angle of attack is usually designed by alpha (as in alpha_prot). Is there such a conventional notation or name for other axes? I'm particularly interested in the slip angle.
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How do ground effect vehicles perform turns?

Considering that Wing-In-Ground-Effect (WIGE) vehicles fly with a rather low ground clearance, there is not much room for banking. How do WIGE vehicles turn? Do they turn just very slow with a low ...
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What's the theoretical background of the critical angle of attack?

The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it ...
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Are the holes inside the engine nacelle used for uniform intake of air? [duplicate]

I read the post here: What is the function of the holes in splitter plates? My question is, what are those hole looking things inside the engine nacelle? It seems reasonable to me that as air enters ...
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How does having a bigger engine placed slightly more forward and higher impact the plane in pitch?

I'm asking about general aerodynamics for under-wing twin-jets – I'm not after information/speculation on the Max 8 crashes/systems, but I mention the crash below because of what I see as an unclear (...
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What is scrub drag?

I've come across the term "scrub drag" in several papers recently, but can't find a detailed definition of this phenomenon. This is specifically in reference to aircraft and seems to apply to engine ...
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Compute Thrust from RPM and Induced Velocity

I'm attempting to calculate the difference in thrust in a secondary propeller operating in the wake behind a primary propeller, in the context of a trailing quad-copter following a leading quad-copter ...
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Are flaps a good idea for airfoils with a lot of camber?

I have a wing with an airfoil s1223 which is an airfoil with a lot of camber. the take off distance is limited so I want to implement flaps for this issue but I have the doubt if this is a good idea.
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What are the effective span and lifting properties of a circular wing?

Today I read an article on FlightGlobal about the Bell air taxi demonstrator. It includes some paraphrased quotes from the Bell VP of innovation, Scott Drennan, among which the following stood out: ...
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Why does transonic drag happen?

I have heard of transonic speed and it is between supersonic and not supersonic. What is it and why does it happen to aircraft and how does it produce a lot of drag. How do you prevent it from ...
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Does altitude influence the flight range of an engine driven aircraft?

I'm reading a chapter about flight performance during the cruise phase and the influence of altitude. My book (Aerodynamica, prestatieleer en vliegtuigtechniek by Bas Vrijhof on page 155, written in ...
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4answers
276 views

Could flaps replace spoilers by deflecting more than 90°?

Could flaps replace spoilers by deflecting more than 90° after touchdown?
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What is the relationship between the Center of Pressure and flap deployment?

I have been reading regarding the Center of Pressure of an airfoil (Cp) and the relationship with angle of attack. What is a good way to explain in layman's terms why the pressure changes in such a ...
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Why does the A320’s maximum allowable aileron deflection decrease, rather than increase, when the flaps are extended?

According to this answer to why the A320 uses mainly spoilerons for roll control during landing, rather than conventional ailerons, the ailerons can’t extend as far when the flaps are extended, for ...
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Was the adoption of conventional tailplanes as 'everyday aircraft' inevitable, or are there other designs that can be just as good?

I originally asked a variant of this on Worldbuilding.SE, but they didn't seem to like it. So I apologize if it's out of place even here. I ask, because I've been forming in my head an alternate ...
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1answer
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Could Falcon 9 fairing become glidable / flyable?

Reading and thinking about this and this questions on space exploration stackexchange, I was wondering if the fairing could shape itself, so that it becomes one stable and steerable gliding element ...
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Are there any airplanes with the Centre of Gravity behind the Centre of Pressure? [duplicate]

We are used to seeing a forward CG in all airplanes, from a small Cessna to a large Boeing. I wonder whether any airplane with CG behind wing CP exists in production? Is it even possible? If so, what ...
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What is the effect of airflow speed on separation?

We know that in real viscous flow, boundary layer exists around the airfoil and there will be a separation point which flow starts to separate from the back of the airfoil( velocity gradient equal ...
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How to calculate the power required during transition from VTOL to fixed wing?

In a VTOL, I have calculated the power required for take off and cruise which was not difficult at all. Between take off and cruise, there is a phase where the VTOL has to transition by tilting the ...
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What is subcritical and supercritical boundary layer?

What is subcritical and supercritical boundary layer? What is the difference between them?
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1answer
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Can the ball on a turn coordinator be to the full right/left while the wings are level?

Can it ever happen in a wings level flight that the Turn and Slip indicator ball is to the full right/left? If so then when and what will be the flight path of such an aircraft? Thanks in advance.
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Would a propeller extracting air from a cylinder with holes in it be an ideal lift apparatus for a VTOL aircraft?

I am wondering if enough lift can be created for a VTOL aircraft using a propeller that is extracting air from a cylinder which is closed at one end and has holes in the top half of the cylinder. ...
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Was the Space Shuttle aerodynamically neutral while piggybacking, or did the combination act like a giant biplane?

Trying to investigate this question, I see that 'Ask the Captain' says: The weight of the shuttle is calculated like any payload. The 747 produces enough lift to fly and to carry the weight of ...
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How can I calculate the velocity of air drawn by a pusher configured propeller?

I am attempting to construct a model plane using Custer channel wings. In order to calculate (or at least approximate) the lift generated I need to find the speed of the air through the channel due to ...
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How are these parameters derived from readings of sensors in an aircraft: angle of attack, slip angle, and airspeed?

From what I've learned, the reading comes from an angle of attack sensor and a slip angle sensor. Let's call the readings $\hat\alpha$ and $\hat\beta$ respectively. These are of either the ...
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405 views

Why does an aircraft's nose tend to pitch downward at higher bank angles?

In the usual aircraft configuration, the center of lift is located behind the CG producing negative pitch moment (the horizontal stabilizer counteracts it by producing downforce - positive pitching ...
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Force Balance in Wind Tunnel

I am considering a model wing inside a wind tunnel supported from underneath from its center of mass. Two load cells can be used, when properly oriented, to measure the lift force and the drag force. ...
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Wing Shape: Long/Wide Span Wings vs Deep Wings [duplicate]

Planes use wings to generate lift. The wider the span of the wing (looking at the plane from the front) the more lift it generates, however, this is at the expense of more drag. Some planes like the ...
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What is a rudder or fin stall?

What is a rudder or fin stall, how will the aircraft behave in that situation, and how should the pilot recognise it? What is the recovery procedure? And what is rudder reversal?
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Why is the 737’s aileron/spoiler authority reduced at low flap settings?

According to the NTSB report on the crash of United Airlines Flight 585, the ability of the 737’s lateral controls (ailerons and flight spoilers) to counteract the rolling forces produced by (say) a ...
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Why does the rotor thrust decrease at smaller tip clearance for shrouded rotor?

Consider this system, rotor with shroud: From this research, we see that: at the same rpm, the rotor thrust decreases,the shroud thrust increases as tip clearance decreases. But why does the rotor ...
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What is the glide ratio on the CE-S550 Citation S-II?

I couldn't find it in the AFM. Is it different then the square winged citation II?
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Does rolling or yawing affect the angle of attack?

If I'm on final in windy conditions and I need excessive rolling and yawing movements to stay on centerline and say, my pitch stays constant - does rolling or yawing change my AOA such that I could ...
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Why does elevator input move the turn coordinator ball in steep turns?

When practicing steep turns, I'm running into an unusual phenomenon. If the airplane is losing altitude in coordinated flight and I apply aft stick pressure to pitch up and correct, I notice that the ...
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Where am I wrong at aerodynamic center calculation?

I'm currently taking aerodynmics course.In the classical thin airfoil theory. we saw that both for symmetric and non-symmetric airfoils the term $dc_l/d\alpha= 2\pi$. But in the preceding chapter, ...
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How do split winglets reduce bending moment in the wings?

I am doing a study on split winglets and how they are more advantageous than blended winglets . While browsing through the net, I was reading an article about the Boeing 787 Dreamliner and they had ...
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Did the airfoil choice on the P51D affect its maneuverability? [closed]

Did the wing design on the P51D, which used a laminar airfoil, affect its maneuverability? If so, how? To what extent?
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Where can I find complete aircraft blueprints for the purpose of study?

Where can I find aircraft blueprints for the purpose of study? I find that I learn a lot more when I am able to get the big picture of a machine that is used in real life (for example, to understand ...
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What causes the adverse pressure gradient that leads to flow separation?

When reading about flow separation I generally see a diagram like this: imp source: Wikimedia commons This shows that the boundary layer slows as it passes over the wing, eventually creating an ...
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Is it reasonable for flight economy to correct banking tendencies with stick and rudder?

An aircraft with side-by-side seating but only one person aboard should fly banked. Banking decreases lift and more elevator is needed than in leveled flight which increases drag. Correcting the ...
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424 views

What is the most efficient symmetrical airfoil shape?

What is the most efficient symmetrical airfoil shape to make for a covering for a round upright bar that measures 40mm outside diameter? The speed of travel will be 25Kph and I also need a shape to ...
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Is there any evidence that the downwash vortices impact the performance of a wing?

Or is it merely flow separation on the upper surface towards the end of the wing? The assumption seems to be that the air "leaks" from under the wing to low pressure above with sufficient rapidity to ...
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Wing pitching moment decomposition into two terms

Summary: Assuming constant angle of attack $\alpha$, speed $V$, and lift $L$ applied at the center of pressure CP (whose position is $x_{CP}$), the distance $(x_{CP} - x_O)$ between the moment ...
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Where can you find wind tunnel visualization data online?

I was wondering if there was a repository of flow visualization results somewhere online, preferably of wing sections categorised in some manner.
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How does the power requirement change when weight and speed change?

Suppose I have an airplane with a certain weight M, which uses a certain amount of power P, to fly at a certain speed V. If I use the same airplane, but quadruple the weight (4xM) and double the ...
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Where should the support points be for testing a model wing in a wind tunnel?

When testing a certain wing profile inside a wind tunnel where should the model, small scale wing be supported? Should the support be under the center of mass of the wing or under the aerodynamic ...
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Pressure Distribution Pattern around Wing

it is clear that the overall integrated pressure on the top of the wing is less than the overall pressure at the bottom of a wing in order to produce a net nonzero lift force. Based on the attached ...