Questions tagged [aircraft-physics]

Physics as they apply to aircraft. Including aerodynamics, flight dynamics, stability and control, aircraft hydraulic and electric systems, engine thermodynamics.

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4answers
79 views

Under what circumstances does the lift vector contribute a force component along a glider's path of travel as seen from the ground? Likewise for drag

Under what circumstances does the lift vector of a glider contribute a force component along the glider's path of travel (trajectory) as seen from the ground? Under what circumstances does the drag ...
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1answer
76 views

Does this web page really correctly depict the angle that is called “incidence” in the French language in the aviation context?

Does this web page really correctly depict the most common usage of the term "incidence" in the French language in the aviation context, in the context of speaking of an entire aircraft and not just ...
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4answers
162 views

How much torque can a Boeing 747 apply when pitching?

I know this is a weird way of thinking about / quantifying this, but I'm trying to figure out how much torque a 747 can apply to itself when it pitches upwards (turning about an axis from wing to wing,...
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1answer
113 views

A question about the exact meaning of one British usage of the term “Angle of Incidence”

This answer to a related question stated: Most anything can have an angle of attack. If you must be specific, you mention 'angle of attack of ...' ... When we talk about airplane as a whole, ...
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Is a “stalled” aircraft free-falling?

If I was in an elevator in a sky-scraper and the cable broke, I would free fall and feel weightless until hitting the ground. When I cause a stall on an airplane (power-ff) and the wings stop ...
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0answers
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is it possible for an airplane to fly without fluid or wings? [closed]

More clearly, is it possible to generate lift without presence of any fluid, I mean not dependent on fluid. Is there any other way to change pressure between top and bottom of object to generate lift? ...
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3answers
203 views

Is there a standard word or phrase in the English-speaking world to describe the angle between the fuselage and the flight path / relative wind?

Is there a standard word or phrase, or several alternative commonly-used words or phrases, in the English-speaking aviation world to describe the angle between the longitudinal axis of the fuselage, ...
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1answer
72 views

How common is it in current British usage for the angle between the chord line of a wing and the flight path to be called the “angle of incidence”?

In American usage, the angle between the chord line of a wing and the flight path is called the "angle of attack". The angle of attack is also represented by the greek letter "alpha". However, some ...
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1answer
620 views

Why do all fifth generation fighters (J20, F22, SU57) put their wing above the fuselage?

I heard that upper wing could increase stability, but why do fighters need it? Or are there some other reasons? Please specify.
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2answers
172 views

What is the average pitch of a plane?

I'm looking for the average pitch of big planes like an Airbus A300. For horizontal travel, is the plane horizontal or does it have a pitch like 1 or 2° (or more)? If the plane does not accelerate ...
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4answers
184 views

How do single engine airplanes handle changes in torque?

In multirotors, there is a regulation of torque from the rotors which keeps it stable. However, in single engine airplanes, there is only one engine with one propeller. How is the aircraft able to ...
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What exactly is a “coordinated” turn?

I am wondering what turn coordination really means and what makes a turn uncoordinated? I know that when the turn is coordinated, there is no slip and skid, an aircraft is flying a perfect circle ...
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1answer
152 views

Helicopter or Airplane, which is the most difficult to fly? [duplicate]

I know it varies from aircraft to aircraft, but I want to know in general, which would be the most difficult aircraft to fly even after years of experience. Helicopter or Airplane ? I tried to fly a ...
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2answers
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Why does an airliner have a shallow descent when heavier, opposite to gliders with ballast?

Gliders utilize water ballast to, among other things, descend faster: But sometimes you need to get down fast: This is when water ballast is added. In airliners however, the heavier the plane, the ...
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4answers
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Can a fixed-wing plane jump up by blowing air over its wings? [duplicate]

NASA's X-57 electric plane has 12 wing-mounted propellors which drive air past the wing. This video describes how the resulting increased air velocity causes an increase in the amount of lift the ...
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1answer
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Wing flex physics?

What physics is involved with wing flex when in air? A simplified answer will suffice. I can understand when on the ground that a heavier wing makes it bend more down. My feeble understanding: When ...
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2answers
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Why does each fan blade have a different mass and frequency?

From a documentary (at 16:39) on building a Rolls-Royce jet engine: ... no two finished blades are exactly alike, and with twenty in each fan, it will only spin smoothly if the blades are perfectly ...
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2answers
127 views

How do turbofan internals handle the load from the thrust?

To my understanding, turbofan engines get the majority of their thrust from the fan in front of the engine, up to around 70-80% while the core flow generates around 20-30%. Forward movement is ...
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2answers
130 views

XFY-1 Vertical take-off mechanics

Hi I saw this video the other day of an XFY-1 doing a vertical take-off and landing and moving left to right while hovering. See the video Here. After watching this I had a few questions on how ...
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3answers
105 views

How changes in Air masses, Air flow direction and intensity affect lift?

I have a question regarding the airflow an aircraft experiences during 3 distinct scenarios: An aircraft during landing, experiencing a sudden gust of 40 knots from the tail. What would be the ...
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8answers
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Can passenger airliners hover completely motionless in the air?

I've seen many stories of this occuring on r/glitch_in_the_matrix (a popular Reddit). People have been seeing big airliners just paused in the air, not moving. Some of them stopped their car and saw ...
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4answers
245 views

Why do gusts change the airspeed during landing, but turning (which changes where the wind is coming from) does not?

As we know it, aircraft are extremely sensitive to gust during its final landing stage. They can lose airspeed if the wind changes to tail, ad thus loose lift or need to adjust their thrust in order o ...
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4answers
223 views

Aerodynamics of Flight Control Surfaces

From what it appears to me, flight control surfaces seem to be taken for granted. In terms of how they actually work and what kind of physical outputs they give in terms of forces and such. Take for ...
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5answers
479 views

What factors influence the maximum speed of an airship?

I'm interested in learning about the physics of airships; in particular, how you determine an airships maximum speed. For example, the Hindenburg topped out at about 80 mph. The ship itself weighed ...
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3answers
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How can Lift = Weight; if airliners fly with Thrust-to-Weight ratios = 0.3? [duplicate]

Question: I'd appreciate it a lot if anyone could explain how the wings can generate lift that is 3.3x more than engine thrust? Is there any experimental proof that this? Or is the assumption that ...
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1answer
92 views

Since shock waves have non-negligible viscosity, why do the normal shock relations ignore friction/viscosity?

The normal shock relations (seen below) are derived by using steady, 1D, neglect potential, no shaft work, adiabatic and zero viscosity assumption. However, since shock waves are "thin regions of high ...
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2answers
158 views

Can planes go to space? [duplicate]

What are the reasons why planes can't go into space? https://thehumble.co.uk/aircraft-with-forward-swept-wings/
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3answers
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Why does the faster-moving air over the static port not result in a lower static pressure?

I understand the concept that the static port is measuring "static" pressure, meaning the pressure the air is exerting on its surroundings. However, there is also Bernoulli's principle, which, put ...
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5answers
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Does the power behind the engine make any difference to how strong the thrust is? [duplicate]

What difference does horsepower make? If the engine can spin the propeller fast enough, why does it need power behind it?
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1answer
61 views

Can accelerations be used to calculate load factors?

Can I use the z accelerations to calculate the load factor in that axis? Please explain how or why not.
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2answers
295 views

What is the aerodynamic reason that the An-225's vertical stabilizers are not simply vertical?

I am trying to understand the aerodynamic consideration that the two vertical stabilizers of this gigantic Antonov An-225 are not simply made vertical and are slightly pointing in. Then my questions ...
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4answers
233 views

How much of an airplane's forward energy is lost to lift?

An airplane needs to move forward to generate lift, and because energy isn't created from nothing, all the kinetic energy of lift comes in the form of drag, where air (air resistance) turns forward ...
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1answer
112 views

Which type of fan is better for wind tunnel testing?

I would like to build a small wind tunnel to test a miniaturized wing/airplane. I have two options, using axial blower (picture 1) or using centrifugal blower (picture 2). The first will be the wind ...
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1answer
138 views

Why are the Phugoid and Short period approximated instead of calculated exactly?

We can calculate the period and half-amplitude time for phugoid and short period using equations of motion. We will get an exact answer. Then why is there a need for doing approximations to ...
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3answers
155 views

What kind of motion will an airplane enter into when disturbed?

When an airplane is disturbed from a longitudinal equilibrium position, what sort of motion will the aircraft experience? Will it be a phugoid or a short period motion? Or will it be both?
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Do airplanes need brakes in the air?

A few days ago I flew on a Boeing 737-900ER. Luckily I was sitting just beside the left wing, seat 26B. I observed that the spoilers were activated (opened) just after the pilot spoke on the Passenger ...
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1answer
138 views

Why does lift curve slope increase when Fowler Flaps are deployed?

Below is an image for a Fowler Flap: Notice that as the flap is deployed, both the camber and the area increase. This change in wing shape modifies the lift curve as follows: (source: Development of ...
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1answer
88 views

How is the impact force on the landing gear distributed in fighters?

Upon landing, what percentage of weight is distributed on the main and the nose landing gears of fighters? Upon landing of a fighter aircraft, what would be the approximate time of transfer of the ...
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2answers
141 views

Why does the Biot-Savart law give the induced velocity of a infinitesimal segment of a vortex filament at point P?

My question is about the proof of how the Biot-Savart law can be used for vortex filaments. This is what I have in my textbook: However, I'm not certain how it was derived - I understand that the ...
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1answer
131 views

Does the aerodynamic center always have to lie on the chord line?

A lot of resources online state that the aerodynamic center is the "point on the body of an airfoil with respect to which the moment coefficient does not change with angle of attack." However, does ...
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3answers
114 views

Is there a method for calculating change in V-speeds with a change in weight for a Cessna 172?

For example, what would the rotation speed (Vr) and stall speed (Vs) be at maximum takeoff weight versus flying with a single occupant? (2297 lb vs 1807 lb)
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2answers
156 views

Why is the stagnation point on the upper surface before the start of circulation?

In many textbooks, such as Anderson (Fundamentals of Aerodynamics), Bertin (Aerodynamics for Engineers), and Houghton (Aerodynamics for Engineering Students), the authors present the idea that there ...
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1answer
133 views

Why does IAS decrease with lower air density if power is constant?

TAS increases with less dense air, which is intuitive. What I don't understand is why IAS decreases. This is assuming sub-transonic speeds where compressibility effects are negligible. To phrase ...
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2answers
224 views

What is the explanation of this airfoil phenomenon? Why the air from below the leading edge's tip deflected up?

I have difficulties to understand this air phenomenon, why the air from below the leading edge's tip (from below the horizontal line) is deflected up and not just follow the bottom wing's surface? ...
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0answers
115 views

Does the angular momentum of a jet engine affect aircraft performance?

I am interested, do jet engines have angular momentum? And how does such momentum affect airplane stability?
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0answers
273 views

How do I calculate the center of lift?

See my other question here for the background context. Consider this simple plane. I have applied the 4 basic forces: lift, drag, weight, and thrust. My question is, where, precisely, do I apply the ...
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1answer
118 views

How much force is produced by control surfaces?

Context: For some context, I'm a game developer and I'm building a flight sim game. My goal is to have realistic -- not arcade -- physics. The game is in Unity. Unity handles the actual application ...
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1answer
261 views

How do I obtain the max endurance altitude?

There are excellent explanations of the physics that determine maximum endurance speed here, here, and here. I was thinking of aircraft that have to be "on station" without an indicated altitude and ...
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1answer
143 views

What is an example of a quantitative analysis for the lift using Newtonian mechanics?

There are several different ways of explaining how an airplane generates lift. The simpler qualitative explanation uses Newtonian mechanics (the third law is invoked to explain how the wing pushes air ...
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1answer
55 views

How to calculate on ground aircraft yaw rate knowing the longitudinal speed and inferred yaw angle

Please consider the following scenario: a generic aircraft is on-ground taxing at 50 feet per second (~15.25 m/s, ~29.5 knots) The pilot inferred 20 degrees of yaw How can I calculate the yaw rate ...

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