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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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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Why do modern turbofans have swept blades?
(Picture sources: CF6 and GE90)
Aircraft have swept wings for two reasons:
It reduces the thickness-to-chord ratio of the effective chord, which is ideal for flight at higher Mach numbers.
At ...
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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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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 ...
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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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In a plane with airbrakes, such as a glider, how do slips and airbrakes interact?
While adding a slip to enhance my descent rate, I got to thinking that the airbrakes might be losing effectiveness as the slip twists them out of the relative wind. This thought arose because I did ...
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PZL-104 Wilga and Wilga 2000 slats question
Looking at some details about this aircraft's wing, I wondered why the latest version slat's design
has been modified so that it is no longer a continuous slat that runs the whole wingspan, rather ...
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Maneuvering Speed Discrepancy
In this page from the limitations section of the Extra Flugzeugbau 330SC, it states
I’m curious as to the discrepancy between maneuvering speeds Va between operation in the Normal Category and the ...
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How does the pressure distribution at the blades of a radial turbocharger look like?
Consider a piston engine equipped with a turbocharger.
In the turbine section of the turbocharger, the pressurized exhaust airflow comes from the center (radially) to the blades, then changes ...
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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 ...
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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 ...
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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 ...
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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). ...
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UH1 fin under chin bubble
What is the purpose of the fin under the nose. It’s close to the co pilot side and starts at the bottom of the battery compartment and ends Near the bottom of the chin bubble.
Wikipedia Photo
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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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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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Oswalds efficiency factor for trapezoidal wing
For a part of my university project we have to approximate 2d to 3d data ideally using oswalds efficiency factor, the equations given to us are for either rectangular or swept wings however the wing I ...
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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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Is there a difference from alignment with the fuselage between J79 and Spey engine versions used in the F4?
Is there a difference between the J79 and Spey engine versions used in the F4 Phantom in terms of alignment with the fuselage? It looks to me like the Spey nozzles are pointing downward.
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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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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 ...
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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 ...
user53913
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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 ...
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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 ...
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What aircraft has the highest critical Mach number?
What aircraft has the highest critical Mach number? The highest I heard of was BAC/English Electric Lightning at Mach 0.95. Are there planes with higher Mcrit. and is it plausible to go higher than ...
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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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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 (...
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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, ...
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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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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 ...
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Why is it harder to maintain laminar flow on larger aircraft?
I am told that on larger aircraft, suction will be needed to maintain laminar flow because of the larger leading edge radius. Why so? Is it because the air has to travel over a longer distance on the ...
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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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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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Is this method to calculate a biplane's center of gravity using 57% of the biplane's gap and 23% of each wing's MAC correct?
Once you have the MAC for both wings and the CG balance point as a percentage of the MAC. connect the two CG positions with a line. Measure up between the wing Gap distance and place your center of ...
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Does the reduced aerodynamic damping at higher altitudes affect the Vno (maneuvering speed) of an airplane?
Since reduced aerodynamic damping at higher altitudes reduces the needed control input for maneuvers, is this just about the required force to move the controls or also about the speed of the ...
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Are Foward Swept Wings for a Rear Propeller Airplane Feasible?
Would going with a forward swept wing design, with the same cord and length of the "A Wing", bring more air the the propeller and tail to increase range, power, or stability?
Consider the ...
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Would the dle 55ra engine be enough to power my paramotor(ducted fan)?
I plan on using the dle 55ra engine to produce 5hp at 8,500 rpm. I am using it in a paramotor, and to save space I am considering using a ducted propeller similar to the Fulcrum power pod. The duct ...
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What is the glide ratio of the Ozone Mojo Power 2?
The ozone mojo power 2 is a paramotor wing aimed towards beginners. I am interested in purchasing it, however I have not found any data on the lift to glide ratio. Does anybody know this info?
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Evaluating maximum TAS for a given available power
This is the original problem:
A turboprop aircraft with a weight of 162 kN is equipped with a power plant with a power derating model described by $\frac{P_A}{P_{A,0}} = 0.9\sigma^{0.75}$, where $P_{...
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How have aerodynamicists improved transonic wing performance over time?
The following two graphs depict improvements in transonic wing technology that have occurred over the past 20-25 years. Both are sourced from Boeing Commercial Aircraft.
In essence, both note that ...
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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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Circulation around an airfoil at negative α
I was recently reading this very helpful string What is the physical meaning of circulation found in Kutta condition? and it explained very nicely potential flow around an airfoil. My question then is ...
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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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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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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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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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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) ...
user53913
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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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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 ...
user52248
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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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