Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [aerodynamics]

156 questions
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How can a piece of paper be shaped to guarantee it falls slower than a plain sheet of paper?

My son and I are playing "MAKE" (think "HORSE") and we challenged ourselves to build the slowest falling object using only a sheet of paper. We cannot build anything that falls slower than a plain sheet of paper. Any ideas?
Corey Alix
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How to design the most hydro/aerodynamic shape for a 'vehicle' that goes back and forth (using ANSYS)?

I am interested in making a very small scraper blade that moves back and forth along a submerged surface, however I need to make it as hydrodynamic as possible so I disturb the liquid as little as possible. I understand I can model different things…
user88720
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Why do some high speed trains have long noses, while others do not?

Why do some high speed trains like the Shinkansen E5 and E6, have really long noses while other trains, like the Eurostar and Javelin, have shorter noses? How does the shape of the nose affect the train?
user3831089
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Why use non-dimensional coefficients?

Aerospace engineering textbooks make frequent use of non-dimensional coefficients like $C_L$, $C_D$ and a whole host of others. Usually, for equations of motion, it is preferred to replace variables with non-dimensional coefficients. However,…
Joshua Koelewijn
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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 (Experimental Rocket) for the launch campaign of the CNES in…
Axel JOLY
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Do all airfoils have a lift curve slope of $2\pi$?

I know that according to the thin airfoil theory all airfoils (symmetric or not) have lift curve slope of $2\pi$. I also know that finite wings should have less inclined lift curve because of the downwash. Then I saw this formula used for finite…
emcyaman
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Questions about the level flight lift equation

In level unaccelerated flight we have relation $$ W=L=\frac{1}{2}\rho\cdot V_{stall}^2\cdot S\cdot C_{l,max} $$ taken from book Daniel P Raymer "Aircraft Design: A Conceptual Approach" equation (5.5) at page 85. The question is: why does this…
d.pensopositivo
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What is "Bernoulli-Lift", and why does it only account for 20% of an airplane's lift?

Whenever the question "Why do airplanes fly?" is asked (e.g. »What really allows airplanes to fly?«, »How an airfoil works?«) at a certain point the following is cited: Bernoulli's principle accounts for 20% of an airplane's lift… In a very…
rul30
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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 we are already familiar with - to mathematical…
user109474
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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 hand, older profiles, like Clark YM, work quite…
user1493362
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Can air suction be increased by consecutive pc fans in small air tunnel?

I want to make a small air filter using standard axial pc fans in order to suck smoke like that have been produced in soldering process. But I assume filtering will make it difficult. Am i wrong? The air have to be forced through the granulated…
Alnus
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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 the use of swashplate to direct the helicopter…
ychnh
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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 hose. Due to the strong vacuum's pull on the ball,…
user18610
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What is the area when calculating the drag coefficient for a race car wing?

The drag coefficient is given by the following expression $$C_d = \frac{2F_d}{\rho v^2 A}$$ For a race car wing (which is simply an airplane wing upside down to generate downforce), what should we consider as the area? The cross-sectional area…
user1790813
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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 environment. I understand that traditionally jets…
KryptofTen
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