Questions tagged [aerodynamics]

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21 views

Confusing about the Induced Velocity of a Rotorcraft in Axial descent

I am trying to figure out how to handle the induced velocity of a rotor in axial unpowered descent. I know how to calculate it (for instance as explained here in 3.4.1 https://scholarcommons.usf.edu/...
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34 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
28 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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26 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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24 views

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
45 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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34 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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18 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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27 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
17 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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26 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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21 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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12 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
58 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
43 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
52 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
24 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
46 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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29 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
51 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
34 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
260 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
82 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
33 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
44 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
98 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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24 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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113 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
66 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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3answers
259 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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54 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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204 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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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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49 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= ...
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Fan starts making noise and air flow is reduced considerably

Yeah.. I dont know if this belongs here, I coulnd´t find a proper stack exhange site for this but it sort of involves physics I guess so... yeah. Basically, I have a ventilator, that after a few mins ...
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2answers
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Why do (some) high-speed trains have curved (convex) walls?

Comparing the cross-section of modern high-speed trains to old train waggons, which had straight walls and were limited to speeds around 200 km/h, I notice that most of them have curved outer walls. ...
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88 views

Will the airflow inside a vacuum hose keep a sphere centered inside of it?

Suppose you were to fasten a string to a ping pong ball, then fasten the string to a stationary object, and then use a vacuum cleaner with a strong vacuum to suck the ball partially into the vacuum ...
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29 views

What is the cycle of simulation editing?

So this is very general, but... How are simulations for vehicles done? I know that computational fluid dynamic simulations are used, but why are repeated tests of actual hardware done too? Obviously ...
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1answer
103 views

Why there are no jets (missile or aircraft) faster than Mach 3.3?

Fastest plane ever built: SR-71 ,Max Speed: 3.3 Mach , Development - 1950s Fastest drone ever built: Lockheed-D21 ,Max Speed: 3.3 Mach, Development -1960s Fastest cruise missile ever built: Brahmos ,...
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57 views

Is it possible to generate energy from indoor draft by opening windows on opposite sides of the building?

Wind flow always generates naturally when I opening windows on the opposite sides of the building. Is it possible to put turbine on the way and generate electricity from that? It could be optimising ...
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82 views

Why don't propeller designers use multiple profiles?

I'm designing a ducted fan, and I'm deciding on the airfoil profile. NACA 16-series profiles are well-suited to M > .5 or .6, but they're not particularly efficient at lower Mach numbers. On the other ...
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80 views

RC drone rotor air access

I am attempting to design a "flying saucer." The saucer is an ellipsoidal-ish body with a RC drone inside. I plan to allow for air access to the rotors as shown in the rudimentary diagram below: I am ...
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1answer
54 views

How can i calculate drag on an Angled area?

I want to calculate drag force at special angle on a sphere . There are some grooves on the sphere and these groove have a special angle on the sphere. In other words, I want to calculate drag force ...
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2answers
268 views

ENLIL road-side vertical turbine - creating drag?

A company called Devecitech has just created what it calls the 'ENLIL' vertical axis wind turbine, that sits at the side of a highway generating electricity from the wind-power created by passing cars ...
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Will a fan that is composed of several fans fixed inside rotating tube work?

I want to design a custom 3D printed fan that would be made of several axial fans that would be connected (fixed) to their cylindrical casing. I am planning to rotate the whole assembly (the cylinder ...
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Heating the air inside a turbojet instead of combusting it

Would an aircraft that uses propellers for movement but with a turbo jet like structure where the ignition chamber only heats the air a bit, similar to a hair dryer instead of releasing fuel and ...
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2answers
130 views

Compressing the air thrusted by an aircraft's propeller through a cone like tube

If I had an aircraft that used propellers for movement and took the air from the front running it through a tube that gets very small towards the end, would it have any impact on the speed? Would the ...
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336 views

Formula for “ram rise” that works all the way to orbit

True Airspeed (TAS) is the vehicle speed relative to the surrounding air. My assumption is that if I am in orbit say at 120 km altitude with an instantaneous velocity of 8 km/s my TAS would be fairly ...
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Is it possible to extract mechanical energy using Turbines behind PulseJet engine?

Pulsejet expels pulse of hot gas (unlike turbojet engine) which create some thrust(Not good enough for ). These gases are hot, fast and pulsed. Is it possible to convert kinetic energy of these gases ...