Questions tagged [aircraft]

Aircraft are man-made vehicles intended to operate while flying through Earth's atmosphere.

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31 views

Is climate change going to render the atmosphere unsafe for air travel? [closed]

It seems that climate change on the whole induces instability in the atmosphere, more intense and unpredictable storms, etc. Obviously we don't fly into major known storm systems, but I imagine that ...
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1answer
24 views

Which direction will a truncated cone be pushed by airflow?

Consider the shape below, with the bottom and top faces being holes. Imagine we hold the shape in place and blow a wind into the big hole. The air will exit the small end at a higher velocity due to ...
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Does general relativity predict different forces on aircraft than Newtonian mechanics?

When taught how airplanes fly, we are probably always given the Newtonian mechanism: that four forces act on an airplane; lift and weight on the vertical axis, and thrust and drag on the horizontal ...
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Relative efficiency of airplanes and helicopters, why is this argument wrong?

I'm trying to better understand why helicopters are less fuel efficient per unit distance than airplanes. One argument I keep seeing in other questions on the topic is that helicopters actively ...
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40 views

How are shockwaves created if no particle goes around the wings at supersonic speed?

so,the title could be a bit misleading, let me elaborate: whenever studying aerodynamics, the explanation starts with considering the wing of a plane still, and the flow of air arriving from either ...
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Is the downforce of rain on airplanes negligible?

Is the downward pressure exerted by raindrops in even a strong storm on a lightweight aircraft negligible? Someone better informed may likely improve the following reasoning, cobbled together from ...
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Finding windspeed gave me negative time value

This is a homework question, I will make it as concise as possible: A 1-way plane trip is 2800km and the plane's airspeed is 790km/h. The plane flies with the wind on the way there, and against it on ...
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Newtonian mechanics vs. Pressure in Flight [duplicate]

Which one is better to describe lift of a plane wing: Newton's third law of motion: (The wing applies a force on air and the air applies an equal and opposite force on wing - which causes lift.) OR ...
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Why is an airfoil shaped like a teardrop?

I understand the reason airfoils are cambered on the top: to create lift. But one would assume this would result in aircraft wings having a semicircle-shaped design. Why is the cross-section of an ...
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1answer
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The lift of an airplane is similar to that of a balloon. It uses the density difference of air, right?

The lift of an airplane is similar to that of a balloon. It uses the density difference of air, right? The air density on the top surface of the balloon is low and the air pressure is small. The air ...
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Impact of the location of the aircraft propeller on yawing moment

we know that the effect of P-factor on puller propellers is the yawing moment in the opposite direcrion. i mean if we had a load(thrust or lift) on the right side of propeller , then airplane will yaw ...
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How can we calculate $g$ force in this maneuver?

How can we calculate $g$ force in this maneuver? We are not dealing with conventional maneuvers like level turn or loop so what equation used to calculate g force in this maneuver? What about other ...
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Would helium-3 be a better lifting gas than normal helium?

Buoyant force is proportional to the mass of the fluid displaced minus the mass of the volume doing the displacing. Thus the best choices of lifting gas are nothing(vacuum), hydrogen, and then helium ...
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Subsonic flight in saturated steam vs. air

I am wondering whether differences in density, temperature, viscosity, drag coefficient, or lift coefficient between steam and air might affect subsonic flight through these media. Let's assume ...
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1answer
37 views

How much energy does a bird use gliding, vs how much energy is there to capture in the moving air?

So I have this image in my head of a robotic pigeon with a wind turbine strapped to it. For the purpose of this mental image, imagine the robotic pigeon is in every relevant way just like an actual ...
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4answers
139 views

Why does a fluid follow the wing?

When air is moving above and under a wing that is curved, why does the air at the top of the wing follow the wings shape and go downwards when it could just go in a straight line? It doesn't make ...
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What direction is aerodynamic lift in?

So I was researching about aerodynamic lift, in all the research I read it says lift is perpendicular to the flow direction. But in 3d space there isn't only one perpendicular vector to a given vector....
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Converting heat to mechanical energy

Could an object convert heat in the air around it to mechanical energy in order to accelerate itself? In other words, the craft would take in surrounding air composed of random-velocity molecules and ...
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1answer
44 views

The effect of velocity on the $g$-force applied to the pilot [closed]

In a level flight (not maneuvering), if an aircraft increases its velocity from Mach 0 to Mach 10, how much $g$-force is applied to the pilot? Is that any equation for it?
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Is there a formula to calculate how much thrust flapping flight generates? [duplicate]

Suppose you have a bird or an ornithopter flapping wings - is there a formula and what parameters would would you need to figure out how much thrust the flapping of wings generates?
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Is Joukowsky Transformation still for airfoils?

The only example I can find for airfoil using Joukowsky Transformation is the 1912 Gottingen aircraft. I assume it's not used anymore ? What is the most recent math model / formula used nowadays ? ...
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20 views

How can air turbulence be less powerful than the wind shear that produced it?

The vortices from a plane's wingtips can rotate at a speed of 220 mph or ~300 feet per second. But I read that the air turbulence intensity resulting from these vortices can reach up to 85 feet per ...
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Using gyroscopes to turn airplanes

Could multiple gyroscopes be used to change direction in a flying vehicle? Im a physics noob and don't really know what else to add... If having one gyroscope allows you to change your direction in 90°...
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Can ellipsoid aircraft reach high speeds [closed]

Imagining an ellipsoid aircraft/spacecraft something like Could something like this reach high speeds? Assuming those nacelles hold some high tech ramjets or something equally powerful. I noticed ...
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1answer
49 views

What is the difference between a kite and a glider?

A kite and a glider, both fly without an engine. If both are unpowered, then what is the difference between a kite and a glider? Are all gliders kites? Or are all kites gliders? How do they differ? ...
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32 views

Propeller Spiral Slipstream

I know the common accepted answer is that in an airplane, the propeller pushes air back but imparts rotational flow to the air, and the rotating air around the body of the aircraft hits the back ...
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How would the air flow rate be affected in a fan if it was subjected to moving air?

Now I know the flowrate in a given fan when it is kept stationary, but if the air around the fan is moving at some speed or if the fan itself is moving relative to the air, how would the effective ...
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56 views

"Constant thrust" engine vs "constant power" engine

I read that a piston engine, under maximum fuel intake, provides constant power, while the thrust depends on velocity, while a jet engine is the opposite - provides constant thrust, with the power ...
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90 views

Why don't CPU fans have the buzzsaw effect (as in planes), even when their blades spin faster than 5k RPM? [closed]

I saw my CPU fan using HWinfo spinning faster than 5k RPM, in which the buzzsaw effect starts in an A3xx plane. Why doesn't my CPU fan do the buzzsaw effect, even though it's spinning faster than 5k ...
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20 views

Finding aerodynamic coefficients of an airfoil using numerical data measured in wind tunnel

I am trying to find all the aerodynamic coefficients of an airfoil at different angles of attack. I have .DAT files for data which have 4 columns of data all in order {angle of attack[deg], Lift[N], ...
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44 views

Measuring Bernoulli in airplanes

One common explanation for airplane lift is that air pressure over the wing both moves faster and has lower pressure, a la Bernoulli. A very different explanation is that air is deflected downward by ...
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Compression limits of hypersonic air

I'm finding my way around a bit in the realm of super/hypersonic flight particularly around sc/ramjets. The question is thus: What is the theoretical upper limit for air compression on a sc/ramjet and ...
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95 views

Why does Wind Velocity over a wing to increases and what is its cause?

Why does wind velocity increase over a wing? Also I have a bit of a paradox, people explain lift by saying there is a lower pressure region on the top of the airfoil and a higher pressure region on ...
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244 views

What is the bare minimum of air density you need to fly a helicopter?

How high will a helicopter be able to fly before the propellers have not enough air particles to achieve lift? What is the minimum air density needed to achieve flight with a helicopter? Could you ...
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Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled?

Why doesn't the static pressure in a jet engine change if the outside of the engine is cooled? Usually pressure goes down with temperature.
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Why is the propulsive force related Coriolis term ignored in flight dynamics (rocket equation)?

Consider a variable mass vehicle body $B$ with it's center of mass $B$ stationary with respect to the body fixed referenced frame $B$. We obtain the translational dynamics of the variable mass body as ...
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1answer
35 views

Swords and wing flutter

In order to retain structural integrity it is understandable that a sword has to be flexible enough to be able to absorb impact without shattering and rigid enough to not be bent due to it. Is this ...
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Yet another airplane question

The point of discussion here is the pressure distribution across an airfoil. In order to simplify the question, I'd like to consider an airfoil which looks like a triangle wedge with the blunt face of ...
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Pressure drop on diver and airplane against acceleration

I'm curious about the relationship between the pressure drop an object is experiencing and the acceleration it is experiencing. From book Frank 8ed Fluid Mechanics, this equation show that sum of per-...
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1answer
46 views

How to derive the bank angle of an aircraft from its roll angle and pitch angle?

From Young (2017) (https://onlinelibrary.wiley.com/doi/book/10.1002/9781118534786) it is stated that we can define the bank angle ($\Phi$) of an aircraft as the angle between its Y body axis and the ...
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How does a ram-air parachute move forward?

I'm trying to understand the "physics" behind the flight of a ram air parachute, Do you know / how could I know, whether the main parameter that makes a ram-air parachute move forward is: ...
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120 views

Plausibility of underwater planes [closed]

Wood floats on water because its density is lower than water. A ship made of steel floats on water because the ship is hollow, the overall density of the ship is lower than water. Now if you seal the ...
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Why is it that we ignore height difference when applying Bernoulli in an airfoil

I learn physics myself and sorry if this is a very simple question Why is it that we can apply Bernoulli on above and below the plane even if the are not in the same streamline? Why do we ignore ...
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Lift on Airplane wing

Why commercial airplanes use long, slender wings? Isn't it to maximize lift, we make the plane's wings as wide as possible?
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Can we make a drone fly on the Moon by using cylinders with compressed air (or cold helium)? [closed]

Suppose we want to make a drone fly on the Moon (the gravity on the Moon is 1/6 of that on Earth), only by making use of its rotors and air. The drone is as light as possible ($m_{min}(kg)$, has ...
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1answer
48 views

Wind tunnel experiment that measures lift (not the lift coefficient)?

Does anyone know of a wind tunnel experiment on a wing or airplane that measures the absolute amount of lift (not the lift coefficient); and demonstrates conclusively that the lift generate by a wing ...
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68 views

Can an airship tack? [closed]

A sail ship leverages the keel’s resistance to turning moments to allow a wind crossing a sail at an angle to tack, achieving a speed greater than the driving wind. But is it possible at all for an ...
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What causes the Coandă effect? [duplicate]

What causes the Coandă effect? Here's my understanding of it: When a fluid flows around a curved surface it has high velocity and so low pressure its pressure will be lower than the atmospheric ...
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1answer
209 views

Effects of altitude on paper airplanes

If one were to fly a paper airplane at the Dead Sea (400 meters below sea level) and another identical paper airplane at the peak of Mount Everest (8800 meters above sea level) would there be any ...
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Why do airplane wings have fins?

I was watching this video and it shows that adding fins on the wing helps the air get turbulent on the upper part of the wing, which forces the air to stay longer, and ultimately this helps with lift. ...

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