Questions tagged [aerodynamics]

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0answers
43 views

Which of these propeller configurations is most efficient?

All propellers shown in the figure above are identical and are operated at identical speeds with four separate (numbered 1 through 4 vertically) configurations illustrated. The physical distance ...
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1answer
28 views

Why don't we use feather like structures for hang gliding?

I'm not entirely sure if this is the right site for this question, but I recently went on a Greek Myth Binge and came across Daedalus again, and his famous first hanglider, made from feathers. Now, ...
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2answers
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Is it known how streamlined the Shinkansen 800 bullet train is when on rails?

This question is different from What is the optimal streamlined shape?. That question is probably about an ideal situation of flowing through space with no gravity in a fluid with zero viscosity and ...
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15 views

Wind behavior and pattern

From the 5 options, which one shows the worse wind effect? Is it (b) because wind speeds accelerate through a gap? But how about in comparison to (c)? Or (d) due to the height and sharp corners? If it'...
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0answers
23 views

Convergence problem in RANS simulation of unsteady flow

I am simulating an air flow through a two dimensional rectangular channel. The channel splits into two channels, one of them is followed by a 90 degree bend downwards and leads into a cylindrical ...
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0answers
33 views

Why does the tapered part of a Wing have such high coefficient of Lift?

If we take a Trapezoid wing shape as an example and see that it has low $c_l$ near the root of the wing and very high $c_l$ at the tip. The Lift generated, however, is reversed to the that of the $c_l$...
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2answers
30 views

Is air density calculated using Total Pressure (Dynamic and Ambient) or just Ambient?

I have some wind tunnel data and static and dynamic pressure are logged (temperature too). I need to calculate lift and drag but I’ve been confused whether to use only ambient pressure to calculate ...
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2answers
44 views

Why does flow separation cause stall when it creates a low pressure zone?

In an airfoil, a low-pressure region forms in the turbulent wake created when the flow separates. Wouldn't this cause an increase in the net vertical force acting on the airfoil since the pressure at ...
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1answer
40 views

How to do Blade Element Momentum Theory Analysis for NACA airfoils?

I wanna perform BEMT analysis on blades of different geometry and not just symmetric thin airfoil. How to do this?
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1answer
47 views

Extracting Uncertainty from Numerical Solution

I am performing numerical and uncertainty analysis for an oblique shockwave angle function: $$ \tan(\delta)=\frac{2}{\tan(\theta)}\frac{M^2\sin^2(\theta)-1}{M^2(\gamma+\cos(2\theta))+2} $$ where $\...
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2answers
77 views

why do centrifugal compressors have curved blades?

Why are centrifugal air compressors built with backward curving blades?
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1answer
31 views

What is the most efficient way to heat air?

I'm currently playing with a school project. My goal here is to heat a stream of air to a significant temperature so I can demonstrate air expansion. I have a cylinder, with a few turbines, turning in ...
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0answers
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How does NASA's QueSST X-59 jet work?

The QueSST (Quiet Supersonic Transport) is a project to create a more diffuse sonic boom in order to use supersonic flight commercially without the usual abrupt 1~2 psf pressure spike damaging the ...
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1answer
115 views

Would this air amplifier attachment increase a leaf blower's effectiveness?

With the start of the leaf raking/blowing season just a month away, I have been thinking of a way in which I could make my old leaf blower more effective so I can spend less time doing leaf blowing. I ...
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1answer
49 views

What is pitch stability in cars?

Can reduction in pitching moment of a car be referred to as improved pitch stability? Or is this term strictly only with regards to aircrafts?
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1answer
905 views

How does a helicopter hover

I am wondering how a helicopter manages to stay balanced and stay in one spot while it is in the air. I understand that there is a second rotor that is used to counteract the angular momentum and also ...
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1answer
35 views

How far downwind of a Covid-19 emitter has a 1000-fold reduction in PPM?

How far downwind of a Covid-19 emitter has a 1000-fold reduction in PPM? Assuming that Covid-19 (0.12μm diameter) particles have the aerodynamic properties of a gas: Particles < 20 μm behave same ...
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1answer
31 views

Does a V shape of quadcopter rotors give stability?

If I build a quad copter but angle each rotor slightly inwards, should it be self stabilizing like an aeroplane with V wings, or does a variation of the rocket pendulum fallacy apply here? I feel like ...
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1answer
35 views

Stagnation,static and dynamic pressures

Please can someone help out with the actual concept of stagnation,static and dynamic pressures . I have learnt all that stagnation pressure is when velocity of flow is 0 when isentropically stopped ...
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0answers
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Superimposing a Vector Field onto a Toroid in Matlab

I am a systems and control PhD student in Aerospace Engineering. Currently, I am trying to create a wind shear model of a toroidal thermal "bubble" in Matlab similar to the one in this paper (shown ...
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2answers
48 views

How to make a oblique wing without areodynamics skill?

Is it possible to make a oblique wing just by skewing a profile of a standard wing? Take a wing profile from web Divide it in sagittal slices Move slices along a new axis (still lying on horizontal ...
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1answer
54 views

Does the shape of a car really matter for how much gasoline it drinks?

Let's say that we have a mid-1950s "gas guzzler". Now, we take away the exterior "shell"/chassis and replace it with a modern car's. That is, it will visually look just like a modern car from the ...
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42 views

Mathematical transformation of a heading angle to a roll angle

I'm trying to understand a function in a SIMULINK example of a path following UAV simulation. The gist is that, the UAV Waypoint Follower block provides a required heading from a list of waypoints and ...
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1answer
29 views

Efficiency of propeller with Wind perpendicular to rotation axis

What happens to air flow and propeller efficiency if it is moving with Wind perpendicular to rotation axis. The air is blowing in a direction lying on the Planet of the tips.
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1answer
31 views

Why is it when taking the moment coefficient relative to c.o.p., the weight is ignored?

I have been working on a question, and my lecturer has hinted me with this equation that doesn't include forces due to weight? $C_{M_x}=C_{M_{ac}}+C_L(x/c−x_{ac}/c)$ What he told us was that due to ...
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1answer
23 views

What determines if a shockwave is normal or oblique

So I am studying Gas dynamics and I know the math regarding Normal and Oblique shockwaves, but I am not sure why would one occur and not the other. Is there a rule when normal shocks will occur or ...
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1answer
34 views

Normal Shockwaves occurrence at cone tip with Angle Theta

I have a question regarding shockwaves. So as far as my knowledge, a flow moving at Ma= 1 will create a normal shockwave ($arcsin(1/Ma)$) , and a flow moving faster will cause an oblique shockwave. So ...
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1answer
34 views

Achieving dynamic similitude by sacrificing geometric similitude?

The goal is to scale up a general aviation aircraft by 15%. Dynamic similitude is the primary goal. I have reviewed research on scaling aircraft models but it seems most of it is focused on creating ...
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0answers
13 views

Skelet Theorie, can anyone help?

I am studying Gas dynamics and came across the lift angle approximation as based on Skelett Theorie (in german). I have done google searches on finding this theory but no luck on any information. Can ...
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1answer
63 views

What shape does a rod bend into when you push the ends together?

If I have a uniform rod -- And then I push on each end toward the center >--< So it bends ...
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1answer
44 views

Aerodynamics - How can you solve for mass when velocity & chord are not given?

My prof is the type who makes up his own questions (rather than pulling them from textbooks). This is his latest work... Anyone got any ideas on how to solve this? He assures me that you don't need ...
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2answers
62 views

How do those “dipole-shaped” weights attached to sections of electrical power lines work?

I see these frequently on tall power lines like the one in the image below, sometimes a single one at each end, sometimes pairs as are shown here. Sometimes on one side of the tower but not the other. ...
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1answer
25 views

How do I calculate the forces on a glider's foundation?

I want to calculate the forces applied on a bar holding the wings, and there is a load connected to the middle of the bar. My question is, how are the forces act on the bar, supposed the wings are ...
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3answers
58 views

Rocket vs aeroplane? Difference in take off?

Although both aeroplane and rocket burn fule and eject smoke but Why aeroplane moves and runs horizontally before take off ?why does not it takes off at its original/initial place just like rocket?
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1answer
31 views

Using RC scale-down model to pre-test aircraft design

I'm a bit involved into building an actual airplane. And while the guys go conventional ways, I'm trying to look around to see other solutions. One of that is to try and use and RC scale-down model (...
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2answers
105 views

Turn rate of a jet vs. biplane

A friend and I were debating whether a biplane/propeller plane has a faster turning rate than jet aircraft. I argued that the propeller planes often do have better turning rates than jets, but I could ...
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1answer
44 views

Torque induced regular precession/ nutation calculation and visualization out of attitude Data

I have a rocket body with given Euler Angles, Quaternions and Angular-Velocities for given time steps. And I'd like to calculate the regular precession and nutation for every time step, so that I can ...
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3answers
784 views

How to Find Drag Force from Skin Friction

Just wondering if someone can please can give me some idea, as to how I can solve this question that is not related to current study. I haven't been able to work out where to start with it just yet. ...
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1answer
155 views

Calculating mass flow rate of a scramjet engine?

First post here. I'm an undergraduate ME interested in fluid mechanics. I came across scramjets and I was interested about the engine. I want to calculate the mass flow rate of the engine and I made ...
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1answer
60 views

Pressure Coefficient with a Minima of 0 on Compressor Airfoils in Cascade

I am a relatively recent BSME graduate working on reproducing the results of a technical paper to strengthen my ANSYS CFX skills. The paper is "Effect of Section Thickness and Trailing Edge Radius on ...
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1answer
57 views

Laminar flow hood/air straightener

I was looking at laminar flow filters to aid in my mycology work I'm doing. Most filters use an aluminum extrusion with fins. I figured the options out there are pretty expensive for what you get and ...
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1answer
136 views

Closed loop guidance and control: how to tune a system with multiple feedback controllers?

I'm trying to design a closed-loop guidance system for rockets - something that can be implemented in Kerbal Space Program, for example. To do this, I'm following the design process described in ...
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0answers
25 views

How to evaluate the fuel consumption rate of an air conditioner in a vehicle?

Using two cases studies: I. When the windows are wound up and air conditioner is turned on. II. When the windows are wound down and air conditioner is turned off. Case studies are evaluated for ...
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1answer
139 views

I have a problem with my representation of roll in Simulink

I am currently an engineering student and a member of the aerospace club of my engineering school (ESILV) which is called LéoFly. We’re a team of 12 students and are building a Fusex (...
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1answer
79 views

In horizontal axis wind turbines, why does axial component of absolute velocity stay constant (wake rotation theory)

I am having hard time understanding how does the axial component stay constant through the rotor. Every resource i look just says it is due to mass conservation but never gives the actual conservation ...
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4answers
455 views

Should Engineers Understand Equations without Relying on Derivations?

As I've progress through my undergraduate engineering program, I've noticed a shift away from physical intuition - understanding why certain phenomena or equations make sense because of basic patterns ...
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2answers
57 views

Would a plane lift from ground if in a free treadmill?

I was wondering if the force generated from the engines of a jet plane would lift it up from the ground if in a free treadmill. Would it take off?
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3answers
443 views

How do drag and downforce in a rear spoiler of a car vary with angle of attack?

I ran an two aerodynamic simulations, one for a spoiler angle of 0 deg and the other for the same spoiler declined at 30 deg. The results showed a considerable increase in downforce, but only a slight ...
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0answers
51 views

Determining thrust equations for a custom UAV

I have been tasked to mathematically model and simulate a 2 propeller, 2 motor UAV. But I am struggling with determining the thrust equations, of the propeller, for my design. I know that: Ft = Ct * ...
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3answers
75 views

Max Lift to drag ratio

I have a question that I can't solve. Coefficient of drag= x, Coefficient of Lift= y, it is given that x= 0.015 + 0.05*(y^2), FInd Max Lift to drag ratio and I know that Lift to drag ratio is L/D= ...