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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1answer
63 views

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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3answers
223 views

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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2answers
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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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1answer
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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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1answer
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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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2answers
170 views

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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2answers
210 views

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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1answer
76 views

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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3answers
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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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1answer
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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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1answer
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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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4answers
155 views

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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1answer
157 views

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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2answers
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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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1answer
57 views

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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2answers
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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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2answers
107 views

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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0answers
99 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
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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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1answer
86 views

Pitching Moments CG vs CP vs AC

Probably the question will be a little bit confusing but I'll try my best to make it clear. Due the position of the CP with respect of the AC, symmetrical airfoils don't produce pitching moments, but ...
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2answers
175 views

Has anyone tested or flown permeable wings to increase efficiency?

See this article: Aerodynamic Performance Improvements Due to Porosity in Wings at Moderate Re Was wing porosity ever tested/used for real aircraft? source: The aerodynamic efficiency parameter ...
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1answer
99 views

Do raked wingtips reduce drag of a hang glider?

https://rakedwingtip.wordpress.com/ Do they realy reduce drag or improve performance? If so, how?
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2answers
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Why are the Antonov An-124 horizontal stabilisers directly behind the wings?

With the wings being on the same plane as the horizontal stabilisers, turbulent air from the wings would interfere with the airflow over the elevators making them flutter. Surely putting the ...
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1answer
163 views

Why does the Tu-134UBL have a sharp/pointed nose cone?

Russian/Soviet aircraft design has always intrigued me, and even more so when coming across this photo of the Tupolev Tu-134UBL with its pointy nosecone. Having looked up the performance ...
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1answer
136 views

Is there an ideal lift distribution for human-powered aircraft?

Is there an obvious, ideal lift distribution for human-powered aircraft? Eliptic or Bell(unloaded tips) distribution? For this who will tell Bell distribution,I have counter question ready,why dont ...
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2answers
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What are differences between vortex, swirl, eddies and wake?

These terms seem to have the same meanings. Can anyone differentiate them?
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4answers
174 views

Wing dihedral in a biplane

Would a biplane be able to fly if the upper and lower wings were in opposite dihedral? Imagine a wing configuration similar to the fictional "X-wing" design from StarWars. What would be the ...
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3answers
76 views

What determine hang point and bar position of hang glider?

1.What is relation between C.P., A.C., hang point,bar conection to made glider to fly well,when I lift hands from bar ,he will not pitch. 2.Does hang glider change stabilty from stable to neutral to ...
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3answers
170 views

Downwind Myth Question

I was reading a discussion about the "Downwind Myth" and a doubt arose: If we are taking off with a 50knots headwind, that wind component will be part of our dynamic pressure, and so in that ...
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3answers
152 views

Is this glider stable?

In level flight all forces must be in balance,that mean center of overall pressure(lift) is in line with C.G. Disturbance comes in such way that shift C.P. back. Is this glider stable? If I use ...
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0answers
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What is typical sink rate of sinking air, and the typical rate of climb for a glider with a sustainer engine?

What is the typical rate of climb for a glider with a sustainer engine with only lift provided by the engine (no thermal lift, ridge lift, etc.) I understand a self launching glider is almost like a ...
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1answer
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Why do few small planes have reflexed flaps?

Reflex flaps capability is very common in flapped gliders, but outside of gliders I am only aware of the Maule which has this feature. https://aviation.stackexchange.com/a/37753/20394 shows the ...
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1answer
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Is it fairly common for student glider pilots to have wing tip strikes, especially in gusty cross wind conditions?

Is it fairly common for student glider pilots to have wing tip strikes, especially in gusty cross wind conditions? I understand gliders are landed level, slow down and then the wing drops onto a wing ...
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2answers
170 views

How can a large passenger airline in midair hover motionless for 10 minutes above my house? This happened in 12/2020 [closed]

A few weeks ago, sometime in December 2020, I walked outside to get my mail around 1300 and saw a large passenger plane hovering roughly 5000ft above my house. I watched it for 5 minutes when a UPS ...
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4answers
97 views

What is the influence of yaw on P-factor?

From William Kershner's “The Advanced Pilot’s Flight Manual”- page 2-17, P-Factor: If the airplane is yawed, the P-factor effect is encountered. A left yaw would mean a slight nose down tendency and ...
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4answers
122 views

Why does power help us maintain altitude in slow flight?

I was asked this question and didn’t know how to phrase a nice and easy explanation. What I said is- well because drag is now increasing Un- proportionally to lift, we need something to generate more ...
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1answer
128 views

Why it doesn't matter if tail produce lift or downforce for neutral point position?

I am really strugle what neutral point represent and what it depends on.. In this link we can see how neutral point is calculated.Thay use wing and tail areas and distance between aerodynamic center (...
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4answers
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Are canards actually more efficient?

Another post here triggers this question; Since I was a kid I have read endless articles about how canards are more efficient because both wing-like surfaces are lifting, whereas a tail surface is ...
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3answers
152 views

Can plane climb without increase pitch angle?

As I know plane climb "with nose up", but can plane climb without change pitch angle? Can I force plane to climb like this: If I fly in straight level flight at 100km/h and now increase ...
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6answers
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Do black wings have better aerodynamics?

This news article links to a 2019 academic study: Thermal impacts of wing coloration on surface temperature during bird flight. Most of birds have dark upper wing feathers. Dark colors keep a sunlit ...
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2answers
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Does a constant speed prop maintain the optimal angle of attack at all time?

From an answer on this site: The governor just knows: Speed too fast, flyweights move out, routes pressure to move the blades more coarse; speed too slow, flyweights move in, routes pressure to move ...
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2answers
176 views

How should I attach an aircraft model in a wind tunnel when testing wind gust/yaw stability?

Where should I attach the rod to the aircraft model when simulating wind gust /weather vane effect in wind tunnel testing? At the center of gravity, behind the CG, in front of the CG...?
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3answers
171 views

Does aircraft allways rotate about center of gravity like weather vane about pivot point?

When gust of wind hit plane form side,does plane allways rotate about center of gravity like weather vane about pivot point or CG as pivot point is just "math areegment" for easier solve ...
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1answer
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Can Bell-lift distribution increase glider efficiency(L/D)?

Can a Bell-lift distribution without a rudder has higher overall efficiency (L/D) then current gliders, if the wingspan is not limited? (Is it really possible that most of aerospace engineers don't ...
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1answer
41 views

Does a constant speed prop deliver max speed at max manifold pressure and max RPM?

I was reading a discussion in flight simulator forum and I found this statement: Ignoring the issue of engine overheating, max MAP and max RPM is the best thing for max speed Do you agree with that? ...
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0answers
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Why do tapered wings not stall at the root first?

Why do moderate tapered wings stall first at mid-wing section and high tapered wings stall at tip first? The effective AoA should be always higher close to the root? (considering no geometric or ...
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1answer
72 views

How do you calculate the optimal cruising speed of an airfoil?

I am working on a school project (aircraft design). I would like to know how to calculate the cruising speed of a given airfoil. For example, if I have a NACA 5613-35 airfoil (that is the NACA 4 digit ...

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