Questions tagged [aerodynamics]

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

120 questions with no upvoted or accepted answers
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6
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2answers
684 views

How does an aircraft's weight affect the V-n diagram?

I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the ...
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135 views

How do active blades work on helicopters?

Can someone throw some light on 'active blades' as used in helicopters? I'm mostly interested in the use of piezoelectric material and actuators. How are the actuators able to sense the change of ...
4
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0answers
195 views

Has there been any research on plasma-producing planes?

Many years ago I read in an expository scientific journal[1] an article about what the future of high speed aviation could be. It said that there were studies on airplanes capable of "plasma-izing" ...
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0answers
80 views

Can I just differentiate my Euler rates to get the angular rates?

There is this matrix: $${W_{\eta}}=\begin{bmatrix} -\sin(\theta) & 0 & 1 \\ \cos(\theta) \sin(\phi) & \cos(\phi) & 0 \\ \cos(\theta) \cos(\phi) & -\sin(\phi) & 0 \end{bmatrix}$...
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0answers
63 views

Do high wings aircraft create an additional vortex in the middle?

At the same time, the air on the upper surface has a tendency to flow in toward the fuselage and off the trailing edge. This air current forms a similar vortex at the inboard portion of the trailing ...
3
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94 views

Trailing Edge with Cavity

Question 5: I have noticed from PAPER "NASA Supercritical Airfoils - Technical Paper 2969" that they mentioned something called "Cavity" merged with the trailing edge. Although ...
3
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0answers
74 views

Matching the Drag Equation to Real Airplane Data

I am trying to compute airplane performance for a piston-driven airplane with constant speed prop using the standard equations for Lift, Thrust and Drag. I have found that there are a couple of useful ...
3
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0answers
73 views

Do contra-rotating props have worse tip vortices than single props?

As I understand it, blades from a propeller have their own tip vortices, because the blades produce lift via the same aerodynamic principles as wings. So they must have tip vortexes too. So with ...
3
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0answers
842 views

How to properly implement and understand Theodorsen's function?

I'm attempting to implement Theodorsen's lift deficiency function for an airfoil experiencing a harmonic variation in angle of attack due to an oscillating freestream (i.e., not pitch oscillations). ...
3
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1answer
544 views

What is the constant in this formula for additional lift?

Let’s consider the case of a plane flying s/l in a headwind with a positive gradient. A wing produces lift by inducing a bound vortex superimposed on the relative wind., and in the particular case of ...
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0answers
46 views

Streamline Curvature Theorem applied to Airfoils?

I am new to studying aerodynamics and taking up aeromodelling and am currently learning how lift is obtained in-depth. When studying the two common explanations as to how lift is generated by an ...
2
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2answers
137 views

How do thick and thin airfoils compare in lift generation?

I find myself confused when comparing the lift generation amongst Thick and Thin Airfoils. A paper to which I have added reference below claims that thin airfoils are better in generating lift because ...
2
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0answers
63 views

Modeling of the aerodynamic characteristics of the wing

As a part of the engineering thesis I work on the methods of modeling of aerodynamic characteristics of wing. In it, I rise an issue related to the impact of changes of aircraft attitude during ...
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0answers
95 views

How can I design a slotted flap?

I have not been able to find satisfactory methods on design of slotted flaps, or flaps in general. Most of the answers are about eyeballing or experience. Can you guide me on what could be good ...
2
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0answers
74 views

Is skin friction also pressure drag looking at microscopic level?

Roughness in boudary layer is taller than height of air which is not moving ,feel oncoming airflow in boudary layer, at front side must be high pressure at rear low pressure etc,so net force is to the ...
2
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0answers
31 views

Why is hybrid laminar flow control preferred for swept wings over other options?

As I understand it, a (the?) major form of laminar-to-turbulent transition on the swept wings of large jets is the crossflow caused by the sweep. One way to control this is laminar flow control by ...
2
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0answers
70 views

Can free flying twin drag rudders be mounted on a stabilator, aerodynamically speaking?

Can free flying twin drag rudders be mounted on a stabilator on an ultralight, aerodynamically speaking, or would it be disadvantageous? I understand free flying rudders need up to 40% less area than ...
2
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3answers
879 views

Aerodynamics moment of a wing

An old flight book that I am reading discusses the aerodynamic moment about a wing and talks about an upper and lower lifts. I can see how the pressure distribution on the top surface produces an ...
2
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0answers
218 views

Are there any airplane designs that are (relatively) insensitive to the effects of airframe icing?

Snow and ice buildup on airplanes (especially the wings) is a well-known and feared hazard of cold-weather operations; it roughens the surface of the wings and changes their profile, which combine to ...
2
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0answers
277 views

What Inertial effects should be considered to achieve blade stability on a Variable Pitch Propeller tailoredby aerodynamic loads?

I am developing a self adjusting variable pitch propeller tailored by its pitching moments due to aerodynamic loads setting the blade rotation axis in an offset from the aerodynamic center as shown ...
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0answers
336 views

Determination of a Joukowski airfoil chord (demonstration)

I'm currently studying Aerodynamics, and one thing that I noticed is that the maximum and minimum $x$ coordinate of the airfoils (which are necessary to compute the chord) on the transformed plane (...
2
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0answers
330 views

Where can I find information on dethermalizer aerodynamics?

A dethermalizer is a device that alters the aerodynamics of an airplane, glider etc, allowing it to descend quickly. Are there any sources - including equations and derivations - on dethermalizers, ...
2
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0answers
1k views

How does corrugated skin influence the effectiveness of ailerons?

Recently I found a paper about incorporating corrugated skins in aircraft called 'Corrugated composite structures for aircraft morphing skin applications' by C. Thill, J.A. Etches, I.P. Bond, K.D. ...
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0answers
599 views

What orders of Ram Rise Coefficient (Recovery Factor) are commonly encountered?

The answer to the question about OAT, RAT, TAT, and SAT has the following: Problem is, not all instruments will compress that air in the same way, and not all of them will pick up this Ram Rise ...
2
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2answers
136 views

How would flow angle change along the length of a propeller airfoil?

Let's assume I have: windspeed of 15 m/s blade length of 10 m rotational speed of one revolution per second Can someone please help me calculating how the flow angle would change along the length of ...
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0answers
34 views

Why does shear stress drop immediately aft of the leading edge?

From a CFD analysis on a wing, I obtained the following pressure and wall shear stress contours. Why does the wall shear stress show a dip aft of the leading edge and rise again? Re-700K pressure ...
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0answers
42 views

Variables of Dryden Wind Model

How to determine the turbulence intensities (σu, σv, σw), scale lengths (Lu, Lv, Lw) & Angular frequency (ω0) in the given Dryden wind model to generate wind speeds (u_w, v_w, w_w) of civil jet ...
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0answers
90 views

What do these terms related to airfoils mean?

I keep coming across some terms related to airfoils and I'm not able to find clear definitions for these terms. Bubble ramps pressure recovery suction side
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3answers
83 views

Projected Area & AoA - Projected area of the wing is variable (as projected on to a surface that is perpendicular to the relative wind)

Does Wing Area vary with angle ot attack? Edit: why we don't recognize that the projected area of the wing as variable (as projected on to a surface that is perpendicular to the relative wind) Per the ...
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0answers
26 views

Distance where transition from laminar to turbulent boundary takes place

How do we work out where the distance from the leading edge the laminar boundary layer would turn into a turbulent boundary layer? Assuming we have been given the length of the plate, speed, dynamic ...
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0answers
64 views

Model of aircraft banked turn

I'm trying to write a model of aircraft motion during a banked turn, so for say a 60Degree roll angle constant altitude turn will require 2g lift. However to achieve this lift the aircraft has to ...
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0answers
75 views

Why am I getting a low L/D of 4.3 for this supercritical airfoil in Autodesk CFD?

I am a high school student learning to analyze aircraft models in Autodesk CFD for the first time. My current project is analyzing a supercritical airfoil on Autodesk CFD (that was designed in ...
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1answer
83 views

Relation between lift force and torque produced in propeller used for vertical take-off and landing aircrafts

There are many answers for this question but none of them are specific. I need to find the exact relation between the lift force of a propeller of specific pitch, attack angle , dimensions and ...
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0answers
104 views

How much is thickness of air layer with zero velocity at wing surface?

How thick is the layer of air that is not moving(zero velocity) at the surface of wing, and can this be taller than the relative roughness height? Because everything that is inside this layer (V=0) ...
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0answers
54 views

Relationship of propeller RPM, blade pitch, and drag at very low blade pitch angles

I'm researching the 2016 crash of a PIA ATR-42 in Pakistan, the report on which was recently released. Link to the report: https://www.caapakistan.com.pk/Upload/SIBReports/AAIB-386.pdf During the ...
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1answer
222 views

What is the relation between sweep angle and lift-to-drag ratio?

What is the relation between sweep angle and lift-to-drag ratio? Ans does depend on wing planform? For subsonic speeds.
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0answers
92 views

Volume of air deflected down by a wing?

When trying to calculate, from first principles, the lift produced by the rotor of an autogyro, I have tried imagining the rotor as a circular flat wing set at an angle to the relative wind. The mass ...
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0answers
124 views

Is "V/n" geometric or effective pitch in advance ratio formula?

V is the freestream fluid velocity, typically the true airspeed of the aircraft or the water speed of the vessel n is the rotational speed of the propeller in revolutions per unit of time D is ...
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0answers
43 views

In a gyroplane, how can the angle of attack of the rotor disk be calculated?

In a gyroplane, how can the angle of attack of the rotor disk be calculated as a function of the relevant variables? Those 'relevant variables' are the rotor's angular velocity, the aircraft's ...
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0answers
43 views

Does momentum theory include deflected slipstream thrust lift at high alpha?

Does momentum theory include deflected slipstream thrust lift of a wing at high alpha? I understand that momentum theory calculates lift due to the angle at which the air is "turned" over ...
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0answers
342 views

Why does drag coefficient decrease with Mach number in the supersonic regime?

I'm trying to understand why the drag coefficient decreases in the supersonic regime with Mach number. While it is easy show this using supersonic, potential flow theory, I'm looking for a more ...
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0answers
63 views

Is it true that blowing cannot be used for laminar flow control? Why?

Aerospace Engineering Desk Reference, page 505 Tangential blowing can only be applied to the prevention of separation...The flow caused by blowing tends to be very vulnerable to laminarturbulent ...
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1answer
234 views

How pressure fields change around wing?

In the 3D case,downward turning is immediately above and below the wing is stronger than in 2D case,for the same lift.This is because more rapid dying off the pressure above and below the airfoil ...
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0answers
23 views

Are there polar plots and airfoil data points available for the RAF4?

Are there polar plots and airfoil data points available for the RAF4? I understand this is the airfoil used for the horizontal stabilizer of the Zenith 701, which should be similar to a NACA4412 ...
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0answers
84 views

What factors/equation(s) are used to relate aircraft weights and cruise speeds?

With the recent coronavirus issues, there have been lots of empty seats flying around, especially on long haul flights. I checked the seat map for a recent SFO-SYD flight (777-300) and there were 224 ...
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0answers
198 views

Carpet Plots for Aircraft Sizing

Generally, Carpet Plots are constructed to find out an optimal design which will satisfy all the performance needs and is least in weight & cost. I want to know how to construct a carpet plot? I ...
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0answers
70 views

Is there any bibliography for triplane aircraft design?

I've been tasked with designing an RC aircraft that has the greatest lift force for a specified wingspan, total length and takeoff velocity, and thus have been studying the different wing ...
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0answers
40 views

What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
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0answers
143 views

If props throw air outwards, why do some prop diagrams show a reduction in airstream diameter behind the prop disc?

If props throw air outwards, why do some prop diagrams show a reduction in airstream diameter behind the prop disc, or are these velocity vectors? Diagram showing airflow outwards as shown on nap.edu ...
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0answers
206 views

Are there any lift or lift coefficient equations which factor in the flap deflection angle?

I'm asking this because I tested a NACA 2412 wing with an adjustable flap in a subsonic wind tunnel and I'm getting the lowest Cl values for the highest flap deflection angle.. which to my knowledge ...