Questions tagged [aircraft-physics]

Physics as they apply to aircraft, including aircraft motion, forces affecting an aircraft, and stability and control.

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4
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3answers
116 views

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
1k views

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
52 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
273 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
212 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
84 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
116 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
144 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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6answers
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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
58 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
74 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
78 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
114 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
102 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
127 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
112 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
187 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
91 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
66 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
75 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 ...
5
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1answer
204 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
108 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
39 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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2answers
205 views

What is the “compression ratio” of air hitting the nose?

Sorry but I don't know how to accurately phrase this question. I want to know how much compression results from air hitting the nose of an aircraft. I'm interested in the traditional airliners (Mach ...
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3answers
179 views

What are accurate flight simulation models called? Is there a standard model?

I'm risking a question that might be "opinion based", but I hope it will not be seen as that. This question is touched upon in the following questions: What are the differences between PC and ...
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1answer
267 views

If the efficiency of a turbofan engine is 35%, where does the rest of the fuel energy go?

There have been a couple of questions on this site about the efficiency and propulsive power of turbine engines (here, here, here). In a high bypass turbofan engine, what are the losses in the ...
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1answer
79 views

At what angle-of-attack (sideslip angle) would a symmetrical vertical fin stop “helping” a deflected rudder produce sideforce? [duplicate]

For rudder deflection angles of 5, 10, 20, 30, and 45 degrees, at what (negative) angle-of-attack does a fin-rudder combination (including dorsal fin if present) create exactly the same amount of ...
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1answer
182 views

Would all these three things have the exact same effect on the flight duration of a glider?

Consider a glider trimmed to fly at some given angle-of-attack, gliding in smooth air (no thermal convection, ridge lift, wave lift, etc.). If air density is somehow kept exactly constant in all ...
3
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1answer
55 views

What does a higher pitching moment mean? (ie -0.095 vs -0.0022)

I've found that as the angle of attack increases, the moment becomes more negative. I wanted to know what does that negative value say about the characteristics of the airfoil, and what is its ...
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0answers
37 views

Two aircraft with same air speed, blank angle, but different mass, are the radius of turn the same? [duplicate]

Two aircraft with same airspeed, blank angle, but different mass, are the radius of turn the same?
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0answers
114 views

Why don't single propeller planes rotate around the horizontal axis? [duplicate]

According to Newton 3rd law, every action has reaction force in the opposite direction. That's how spaceship can move in space. That's why helicopter needs a second propeller in the back to prevent ...
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1answer
183 views

Could a rotor head wing be plausible?

Could a helicopter support a detachable wing with no controls on top of the rotor head in place of a radar dome? Could the rotor head be made to support more weight? Would it be more fuel efficient at ...
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2answers
4k views

How possible is a successful landing just with 1 wing?

Having in mind this famous F-15 incident : Would this be possible with any other fighter-jet? Or was there something really specific to F-15's design that allowed this ? Would this be possible at all ...
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3answers
333 views

Will the plane take off? [duplicate]

First, I was unsure where to ask, here on on Physics SE. Second, I have a strong feeling it might have been asked already somewhere but I didn't find it - so if it was, please link as a duplicate. ...
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2answers
138 views

With power off, is it possible to maintain constant altitude for some period of time, until the stall speed is reached?

With power off, is it possible to maintain constant altitude for some period of time, until the 1-G stall speed is reached, i.e. until the stall angle-of-attack is reached? Implicit in the question ...
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3answers
223 views

Is it better to have the engines center or apart on a plane?

Are there any advantages or disadvantages to having the engines closer or farther to the center of the plane? How is the ideal engine spacing determined length or span wise for performance? Related: ...
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1answer
164 views

How did Airbus A380 overcome corrosion issue in which aluminium wiring used? [duplicate]

The corrosion of aluminium is generally recognized to be a major problem. What new technologies or technics might be used in aluminium wiring to get away from the corrosion issue?.
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1answer
427 views

Using aluminium busbar/cables in an aircraft instead of copper [duplicate]

I have just found out Airbus uses aluminium wiring in the A380 to save weight. However, I didn't see anything about whether all the wiring is aluminium, or if copper wiring is also used. What is the ...
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2answers
665 views

At what altitude does a wing become useless? [duplicate]

At what speed or altitude does an aircraft become more efficient as a rocket then a plane using thrust vectoring instead of the wings to steer? At what altitude did the flight control surfaces of the ...
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4answers
3k views

How can lift be less than thrust that is less than weight? [duplicate]

Physics in schools teaches two contradictory and mutually exclusive things: That the upward lift force on an airplane in flight equal its weight (Lift = Weight = Mass x Gravity). This is based on ...
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2answers
124 views

May turn rate indicators (and turn coordinators) be calibrated to be accurate at all airspeeds, or only for one?

2 related questions: may a turn rate indicator be calibrated to be accurate at all airspeeds, or only for one? Likewise for a turn "coordinator". The meaning of "accurate" intended in this question ...
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4answers
278 views

What is the formula for the bank angle required for a turn in line-abreast formation?

Imagine we have a line-abreast formation of aircraft, with differing airspeeds, turning around a central pivot point, like points on the radius of a phonograph record, with an equal amount time per ...
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3answers
126 views

Does pumping fuel to each wingtip affect roll trim in a stabilized turn?

If an aircraft is stabilized in a constant-bank, constant rate turn with no sideslip, and then we pump 200 gallons of fuel from a fuselage tank to a tank on the tip of each wing, without changing the ...
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3answers
379 views

Why are Vertical tails generally tapered?

I'm just intrigued to know why the vertical tail of a majority of aircraft is tapered? Is it due to aerodynamics, structural design or due to some instrumentation or multiple other reasons?
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2answers
832 views

Would this be a dangerous impeller to use for a drone?

I am considering using a 3D printer to make unconventional impellers for a custom-made drone that I am planning to build. I am concerned that these plastic impellers may explode if their motors' RPMs ...
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1answer
67 views

Do aircraft performance figures include corrections for areas with especially strong or weak gravity?

The strength of gravity at the Earth's surface is not constant, but varies from place to place by as much as a few percent: (Image by NASA.) As a result, an identically-loaded aircraft weighs less ...
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5answers
405 views

How much energy is “wasted” in an aeroplane's descent?

In descent, an aircraft must lose both potential energy (in order to get down to the ground) and kinetic energy (in order to land at a safe speed). Weight and drag can take care of that. An unpowered ...
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3answers
262 views

What does the “nose-high” product of inertia represent?

I am reading this slide: Source: http://www.stengel.mycpanel.princeton.edu/MAE331Lecture10.pdf Is Izx always considered small and we can assume it is 0, as many texts assume? I need to make this ...
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3answers
233 views

What is the derivative of the angle of attack?

Suppose a flying missile's velocity vector has components $u, v, w$, as illustrated below. From my knowledge of flight dynamics, the angle of attack is $$\alpha = \arctan \left(\frac{w}{u}\right)$$ ...
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4answers
201 views

What is the effect of the Load Factor on wing Structures?

I am quite confused with the definition of Load factor and how it applies to the wing structures of an aircraft. For example, you have an Aircraft being subjected to a Load Factor of 2 and whose ...