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 happens if no fuel is stored in the wings? [closed]

I wonder what happens if no fuel is stored in the wings. How to estimate the structural impact and what is possible due to this in wing design? Has this topic already been researched?
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Can gliders and single-engine planes have vortices?

I read, A third physical explanation of the source of induced drag is that the wing tip vortices contain a certain amount of rotational kinetic energy. This energy has to come from somewhere; indeed, ...
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In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?

Assume I am flying straight and level with power setting 21 inches of MAP and 2300 RPM with TAS=100 kts, now I change my Prop lever only (MAP = no change & TAS = no change) from 2300 to 2500, ...
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When TAS=0 and when throttle is increased to MAX PWR, will the blade angle be at its finest pitch? [closed]

Just before Take-off, the throttle is set to maintain idle RPM (1000-1200), and propeller lever will be at its Finest pitch (max RPM), and since the power output from the engine is minimum and ...
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is there any information on the B-8 side stick? when was it made? [closed]

is there any info on the B-8 side stick? its history? in which airplanes was it used? I've been looking around the internet for information and can't seem to find any unfortunately
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How does the F-16 stabilizer counter the yaw in eventuality of spin?

In a specific state of aerodynamic stall the vertical tail and rudder airflow is blanked by wings, so now it is hard to counter the yaw. However the stabilators will help. How?
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What is the correct definition of “spanwise” and “chordwise” with a swept wing?

What is the correct definition of "spanwise" and "chordwise" with a swept wing? For example, in the context of "spanwise airflow" and "chordwise airflow"? a) ...
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In this MD-11 stall test video, are we seeing the tail stalling first?

Watching this short stall test video for the MD-11, one can notice obvious buffeting (starting at about 0:04) of the tail section, while at the same time – at least apparently – there doesn't seem to ...
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Drag coefficient of a hemisphere [migrated]

I am looking for the aerodynamic drag coefficient of a hemisphere that is set up to flow as follows: In the literature, I only found coefficients for the hemisphere placed in a different setting. ...
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Does lift-to-drag ratio asymptote to 4 (or 6) at high Mach numbers?

The Kuchemann equations for L/D at high mach numbers, approximately verified by wind tunnel tests, were: $$\left(\frac{L}{D}\right)_{max} = \frac{4\cdot(M+3)}{M}$$ and, for wave riders $$\left(\frac{L}...
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What is causing these “corners” on this F-104 V-n diagram?

In this V-n diagram for an F-104 (source: this Wikipedia link), on the left-hand edge of the flight envelope, what is causing the "corners" that we see at the following points? (Numbers are ...
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How does the turbulent boundary layer thickness affect separation?

I read that for a turbulent boundary layer, a thicker boundary layer separates earlier than a thinner boundary layer? Why is that? Or is it the other way around?
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Why do X-wing configurations missile/guide bombs use symmetric airfoils?

From all the missiles/guide bombs I have come across, I've always observed that a symmetric airfoil is used for both the wing and tail. Why not have a cambered airfoil for the wing and a symmetric ...
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1answer
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How are foam cores shaped for tapered and swept back wings?

How are foam cores shaped for tapered and swept back wings? I understand that many constant chord, constant thickness rectangular wings use the same sized airfoil shape from root to tip. Let's assume ...
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1answer
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Why does Vx have a relationship with thrust but Vy has a relationship with power?

https://www.boldmethod.com/learn-to-fly/performance/vx-vy-altitude-and-where-they-meet/ After I watch this article, now I understand the relationship between altitude and the rate of climbs. But I ...
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How does airfoil affect the coefficient of lift vs. AOA slope?

I'm trying to understand whether the airfoil shape can affect the slope of Cl vs. AOA (coefficient of lift vs. angle of attack) in the "linear" portion, e.g., from a few degrees negative to ...
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Does altitude affect glide ratio?

Lower altitude means higher air density, which means more liff, which means a glider can maintain a given glide slope at lower airspeed. As a rule, aircraft tend to have higher peak L/Ds at low ...
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Do manufactures list the maximum speed of an aircraft based on its theoretical maximum speed or dive speed?

I know that the absolute maximum velocity of an aircraft is based on the thrust available. However the aircraft is usually limited beforehand by other speed limits such as dive speed and Mach Never ...
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1answer
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What is the Mach Never Exceed number for a C-130J Hercules under ISA conditions (approximations are welcomed!)

I am looking for the Mach Never Exceed number for a C-130J Hercules so that I can create an approximate 1g envelope. Does anyone have any idea what this can be? I am trying to find the value for ...
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1answer
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What is the CLmax of the CF-100 Canuck?

I've been struggling to find specifications for the CF-100 Canuck. What is the CLmax of the CF-100 Canuck and how can I find it?
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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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What is the approximate thrust at sea level for a C-130J Hercules?

I am looking for the approximate thrust of a C-130J Hercules under ISA sea level conditions. Also the efficiency of its propeller would be of help. An answer to this question would really help my ...
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Swept back wing theory

I'm a beginner in airfoil design. I just came across swept-back wings. There is a point that I couldn't understand that theory. Why is the only perpendicular component of the airflow to the wing(...
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113 views

Why don't we simulate similarity parameters simultaneously in the same wind tunnel?

As 'Fundamentals of Aerodynamics' by JD Anderson suggest Today, for the most part, we do not attempt to simulate all the parameters simultaneously; rather, Mach number simulation is achieved in one ...
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What exactly causes pitch moment in the Phugoid mode?

I am trying to figure out exactly what causes the pitching moment for the Phugoid mode? We know that alpha remains mostly constant, so what is causing the pitching moment? I thought maybe it is the ...
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322 views

Is the Bede BD5 actually a tandem wing airplane, and not a mono wing?

Is the Bede BD5 a tandem wing airplane, and not a mono wing? The following picture (Source: Wikipedia.org) shows a Bede BD5 with a high angle of incidence on the horizontal tail, estimated at about 5 ...
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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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1answer
62 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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Could leading-edge dynamic stall occur for a tripped airfoil?

As far as I know leading-edge dynamic stall is characterized by the formation of a Leading edge vortex. This leading edge vortex forms due to the 'bursting' of the LSB (Laminar separation bubble). ...
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Would it be beneficial to have rotors AND propellers instead of a tiltrotor?

Would it be beneficial for tiltrotor aircraft if they had BOTH rotors and propellers, instead of the hybrid proprotors that are neither good propellers nor good rotors? Like imagine the V-22 Osprey ...
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Why do the ailerons of this flying wing work oppositely compared to those of an airplane?

I made this simple wing glider and put some ailerons on it. I thought that the ailerons in this glider would work the same way it works on airplanes, wherein the roll will be in the direction of the ...
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Are 0g pushovers in a C172 safe/legal?

I see YouTube pilots do it all the time, but I’m wondering how safe this maneuver really is given the fuel is a gravity fed system. Also, is it legal?
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Can boundary layer blowing increase transonic efficiency?

One of the problems faced by transonic aircraft is flow separation by recompression shock. Can the pressure drag that arises due to this flow separation be reduced by re-emerging the boundary layer ...
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Relation between weight of the aircraft and mach number [closed]

Is there any formula that relates weight of the aircraft with mach number?
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Why aren't isentropic noses and tails used in supersonic aircraft?

An inside out paraboloid would theoretically produce isentropic compression for an inlet cone. But this question is about nose and tail cones on fuselages, and leading and trailing edges of wings. An ...
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What are the pros and cons of putting a propeller immediately before a slipstream pylon vs. immediately after

In the following situation with a slipstream pylon for a self-launching glider, what are the tradeoffs in sticking the propeller before vs. after the pylon? The wind turbine industry has the same ...
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For jetliners, how is a swept wing justified over a thin wing?

For a given speed, a swept wing is a fatter alternative to a straight, thin wing. But why? Does not the sweep lengthen the wing and make it heavier? Is the swept wing chosen for the extra fuel tank ...
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Induced drag reduction from tandem wing

Induced drag is proportional to the square of span loading. The normal method to decrease it would be to increase span. This, however, leads to an exponential weight increase. So, my question is, if ...
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How does gross weight affect helicopter autorotation?

The factors which affect helicopter autorotational aerodynamics include airspeed, gross weight, rotor RPM, and density altitude. The effects of these factors can be examined during a few phases of the ...
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Is possible to stick two '2-blade' propellers to get multi-blade propeller?

Does propeller blades' airflow interfere with each other blades and decrease overall thrust? Should I consider high pitch propeller for this purpose? My purpose: I'm looking for a 20-inch four-blade ...
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What are the advantages and disadvantages of the MiG-29's horizontal stabilizers (not what do they do)?

The MiG-29's tail axes are located fairly close to the leading edge, and rotate along an axis oblique to the chord. What are the possible consequences to this arrangement (e.g. actuator torque, ...
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Is there any formula that directly relate density to altitude for a wide range of altitude?

I am working on a code to simulate a vehicle trajectory based on forces act on it in different altitudes, I need a formula that gives density in an altitude range between 0 and 40 km to obtain lift ...
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Explained intuitively, why does aspect ratio affect induced drag?

Over the last few hours, I've been trying to intuitively understand induced drag, and how aspect ratio affects it. I already know the equations, but while they explain the relationship, they do not ...
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So fast, it melts the ice off?

Approximately, how fast would an aircraft have to travel through freezing air to melt the ice off the wing, propellers, or rotor blades?
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When does root bending moment start to become important?

I guess for small aircrafts ,hangliders etc root bending moment is not important at all,because it is relativly easy to achieve sufficient strength ,so their ideal solution will be eliptic..? Does ...
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The relation between Euler-angle rate and body-axis rates?

A paper about quadcopter dynamics and control shows the relation between Euler-angle rate and body-axis rates as: Q1: why are there $R_{v2}^{b}(\dot{\phi})$, $R_{v1}^{v2}(\dot{\theta})$, and $R_{v}^{...
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What are benefits of unloaded wingtips?

What are aerodynamics benefits of using unloaded wingtips (zero lift)? does unloaded wingtip make inner parts of wing more efficient? (I know that unloaded wingtip reduces bending moment,so structural ...
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How do wing tip vortices that interact with the wing surface affect drag?

Often people say vortices are behind the wing so they cannot produce drag, I am not interested in those vortices behind the wing.... I am interested how wing tip vortices which interact with the ...
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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) ...
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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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