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 ...
tedioustortoise's user avatar
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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}$...
Hamzalihi's user avatar
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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 ...
M Kartik Reddy's user avatar
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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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How do Antishock Bodies / Cuchemann Carrots delay shock-induced flow separation?

There are several online resources that describe these aerodynamic devices as either "Antishock Bodies" or "Kuchemann Carrots" and that they are used to produce some combination of ...
EquipmentOperator's user avatar
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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 ...
Miracle Airfoil's user avatar
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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
Anthony Martinez's user avatar
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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 ...
xxavier's user avatar
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Why does the density decrease equal the speed gain at Mach 1?

In this answer, it says : "At small Mach numbers, changes in speed cause negligible changes in density, but as Mach approaches unity, both are of similar magnitude. With Ma>>1 , changes in ...
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For a fixed density altitude, how does climb performance depend on pressure altitude?

Below is the climb performance from the 1978 Cessna 152 POH, which I've plotted as climb rate versus density altitude. It shows that higher pressure altitude gives decreased performance even when the ...
Chris's user avatar
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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 ...
Vincent Cerowski's user avatar
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1 answer
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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 ...
DanjSmith98's user avatar
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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 ...
Luan Arita's user avatar
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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 ...
Karol Chojecki's user avatar
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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 ...
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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 ...
Abdullah is not an Amalekite's user avatar
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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 ...
Fred's user avatar
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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 ...
Francis L.'s user avatar
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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 ...
george's user avatar
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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 (...
Élio Pereira's user avatar
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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 ...
SF.'s user avatar
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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 ...
Abdullah is not an Amalekite's user avatar
1 vote
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How much of the Virgin GlobalFlyer's L/D is due to laminar flow?

Despite travelling much faster than the Voyager, it has a significantly higher L/D. The latter seems to have two features that disrupt laminate flow, that are absent in the former. Namely the canards ...
Abdullah is not an Amalekite's user avatar
1 vote
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How to retrieve the thrust distribution over a blade using XROTOR?

What is the procedure for retrieving the thrust distribution over a propeller blade using XROTOR? I need the sectional (i.e., for each station) thrust coefficient values. I was only able to retrieve ...
floyd123's user avatar
1 vote
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Critical angle of attack at high altitude

I remember hearing somewhere that at very high altitudes, the critical angle of attack for a given airfoil can decrease a bit. Is there any credence to this idea? Thank you
Terry's user avatar
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Does the bending air on a wing create one or multiple vortices?

As explained in the first paragraph of this answer, air will bend inwards on the top of the wing, and outwards on the bottom of the wing. This creates an inward flow component on the top of the wing ...
Wyatt's user avatar
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Why does the twin otter have wing fences?

Why does the twin otter have wing fences? Planes like the Cessna 172 don't have them, so why does the twin otter have them? (I know that it is used for STOL purposes, but how would wing fences help in ...
Wyatt's user avatar
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1 vote
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Can I reduce drag with channeling freestream air at the backward facing surface?

Idea is to increase static pressure at backward facing surface to reduce drag. Can I reduce drag with channeling freestream air at the backward facing surface, like picture suggest?
user707264's user avatar
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Why is spanwise flow more prevalent in the boundary layer?

Spanwise flow is stronger in the boundary layer, but to me it's kind of counterintuitive because the BL flow is slowed down by friction, experiencing less of a pressure gradient over the wing, ...
Wyatt's user avatar
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1 vote
1 answer
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What are the effects of wing washout and anhedral on induced drag?

I am studying for my ATPL and was curious if and how induced drag varies based on wing anhedral and geometric washout. I have a basic understanding that spanwise flow affects induced drag since there'...
Nick M's user avatar
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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). ...
Jacob's user avatar
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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, ...
user721108's user avatar
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1 vote
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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 ...
Wally's user avatar
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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 ...
Erik Stens's user avatar
1 vote
0 answers
111 views

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 ...
Justintimeforfun's user avatar
1 vote
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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 ...
Lelotz's user avatar
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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?
Lelotz's user avatar
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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_{...
kene02's user avatar
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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 ...
interested22's user avatar