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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168 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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In the US, would a DPE typically fail a student who suggested that the “stall speed” was a meaningful concept? [closed]

In the US, would a DPE typically fail a student who suggested that the "stall speed" was a meaningful concept? Even if the student demonstrated an understanding that when we speak of the "stall ...
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2answers
127 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
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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
129 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
400 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
651 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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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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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
181 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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120 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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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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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
60 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
317 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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0answers
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What does the “nose-high” product of inertia represent?

I am reading this slide: Source: http://www.stengel.mycpanel.princeton.edu/MAE331Lecture10.pdf And my question is: What does the “nose-high” (or high/low) product of inertia represent?
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174 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
165 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 ...
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1answer
81 views

does a semi sphere have more drag in comparison to a flat plane with equal surface area?

What the title says, some things to know is that these aren't solid shapes, think of a bowl and a sheet of wood.
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Why did Air France flight 447 fail to recover from the stall? [duplicate]

I have read the wikipedia entry about the accident but I don't understand why did the stall happen and why the plane couldn't recover from the stall. Correct me if I am wrong but I would think a ...
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1answer
133 views

How energy efficient is an aircraft take off?

How much work is generally done by an aircraft (e.g. B737NG) in order to reach V_rotate, and how does this compare to the energy content of the fuel that is used?
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1answer
266 views

How fast do four Tire-Propellers have to rotate to lift 2000 lbs? [closed]

I just saw this come out, Goodyear's Tire-Propeller Concept – a combination tire that can also act as propeller (well, more like a ducted fan I guess). There's a neat video that goes with it, ...
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Why does elevator still raise and lower the nose when the aircraft is steeply banked?

In a steep turn, the aircraft is basically sideways. However, when executing a steep turn, one still raises and lowers the nose of the aircraft by using the elevator. Intuitively, it seems to be ...
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How does a single engine tail wheel landing gear airplane turn when it is on the ground?

Say Cessna 140 as in this video, look like no additional device to make it turnable when it on the ground. It is a single engine and a tail wheel landing gear. Then, how does it turn?
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Which one is more effective produce power of this two turbine's location?

Consider we have the exactly same turbine which is possible to be mounted to the tail (left picture) and to the wing (right picture) as picture below. Which one will produce more power to the airplane?...
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How does pulling back provide better steering during rollout for light GA planes?

I had requested clarification on an answer to the question, How do I keep a C172 straight on the centerline during landing/rollout? I did not comprehend how pulling back after touch down provides ...
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How does the F-35B not flip over during transition?

As the engine nozzle rotates, the lift-fan cannot. Wouldn't this imbalance of moments around the center of gravity result in the F-35 pitching up onto its back? As can be seen at 5:14 in this video: ...
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1answer
165 views

Which one needs longer runway of an airplane between take off and landing for a constant weight?

Consider we have an airplane that the weight will be constant when take off and landing (in fact will be no such common airplane right now as the fuel will be less due to engine consumption. But in an ...
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1answer
207 views

Why are all-moving horizontal stabilizers common but all-moving rudders rare on fighters?

According to Wikipedia Stabilators were developed to achieve adequate pitch control in supersonic flight, and are almost universal on modern military combat aircraft. All non-delta-winged ...
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1answer
153 views

What is the most effective of propeller's rotation in a two-propeller engine airplane?

Consider two-propeller airplane as picture below (picture 1 (the above) and picture 2 (the below)). Which one is the most effective configuration to produce thrust power, stability, structural design, ...
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2answers
437 views

If a twin-engine airplane's propellers both rotate in the same direction, do they still produce a left-turning tendency?

If an airplane with two propellers has both propellers with the same rotation direction (say, both the propellers rotate counter-clockwise as seen from nose to the tail), will be the four left-...
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4answers
405 views

What is the maximum angle between an airplane and runway centerline when touching down at a crab angle in a crosswind landing?

What is the maximum angle between the airplane's heading to the runway when an airplane is being landing sideway due to crosswind?
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People in a rollercoaster or falling elevator feel the rapid descent, so why don't pilots in the cockpit?

Judging from the CVR transcript, the AF447 pilots didn't realize for most of the plunge that they were stalled and rapidly losing altitude. Why don't pilots in the cockpit get the same sensation of ...
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212 views

How does the power requirement change when weight and speed change?

Suppose I have an airplane with a certain weight M, which uses a certain amount of power P, to fly at a certain speed V. If I use the same airplane, but quadruple the weight (4xM) and double the ...
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563 views

What is the derivation of 15 and 11.3 used for computing pivotal altitude?

Pivotal Altitude Explained: Teaching eights on pylons the easy way at AOPA repeats a common formula for pivotal altitude. To estimate pivotal altitude, square the groundspeed and then divide by 15 ...
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555 views

Why are the leading edges of wings not always made as 'sharp' as possible?

Why is an airplane's wing (the leading edge) not made as sharp as possible to break the air, in the same way that a ship's hull is made sharp to easily break the water? This is unlike Concorde's nose ...
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2answers
142 views

Why is the force that moves an airplane forward called THRUST and not PULL?

As we know, there are four forces acting upon an airplane. Thrust ($T$), Drag ($D$), Lift ($L$), and weight ($W$). Since most propeller-driven airplanes over history have had the propeller mounted ...
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1answer
105 views

How do we derive Lift Coefficient of an airplane's wing?

In many references I read that lift coefficient ($C_l$) is a product of wind tunnel test. But many times I read the formula to calculate the coefficient of lift. From the lift equation, $$L=\frac{1}{2}...
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1answer
259 views

What was the lift equation used by the Wright brothers?

NOTICE: The modern lift equation and the lift equation used by the Wright brothers in 1900 are slightly different. The lift coefficient of the modern equation is referenced to the dynamic pressure ...
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1answer
191 views

What is the wing span in aspect ratio's calculation?

We all know that the aspect ratio of an airplane is calculate as: $$AR=\frac{b^2}{S}$$ Where: $AR=$ Aspect ratio $B=$ Wingspan $S=$ Wing's area In an airplane, wing span is the distance from tip ...
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143 views

Is it possible to make an analogy between a lever and an airplane wing in terms of force applied over distance?

On most aircraft the engine force (thrust) is lower than the weight. Since wings therefore are always capable of generating greater force (lift) than the engine, there is an analogy between an ...
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1answer
425 views

If all passengers moved to the back, front or one side, would they crash the plane? [duplicate]

all-time classic: Would the load shift of all passengers herding at the back, front or one side make the plane hard or even impossible to keep in the air ? Are there any passenger aircraft where ...
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6answers
678 views

How does Bernoulli's principle contribute in lifting airplane?

I have searched if any explanation that bind Bernoulli's principle in lifting airplane. There is one here which receive many appreciations, but still did not answer the question. So far, it was taught,...
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4answers
205 views

How does scaling of UAV size impact range?

Lets say you have two autonomous small aircraft, one with a wingspan of 200 cm and one with 400 cm. Both have the same general design. They are both optimized for travel distance on one full tank (gas ...
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1answer
274 views

What is the exact purpose of the string attached between front fuselage & the tail section of the transport aircraft's? [duplicate]

]2 228]3]3 Usually I got to notice a string attached between front fuselage to rear tail section of the transport aircraft's, what exactly might be the purpose or function of it? But comparatively, I ...
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3answers
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Is the purpose of variable pitch propellers to maintain an optimal angle of attack?

I recently had a discussion with an aviation expert, who works as a Flight Instructor, about constant speed propellers - variable pitch propellers - on light piston aircraft. I have always known that ...
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3answers
94 views

What factors affect the minimum time to go from point A to point B?

I've created this trajectory for a small RC aircraft to go from 15m to 61m as quickly as possible (e.g. quickest time to get from point A to point B). I'm trying to perform a sanity check for why the ...
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5answers
307 views

Which one is required more power between helicopter and airplane?

For the given same mass (say it 400kgs), which one requires more power (in HP) between helicopter and airplane? Say that both are designed maximum (the required material are considered during design) ...
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1answer
184 views

Does a rotating control surface change the wing area?

It might seem like a silly question, but bear with me. I am using the standard formula to calculate the lift force of a wing. L = (1/2) d v2 s CL My question related to the s part of the formula. ...
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2answers
284 views

Confusion about Aerodynamic center

suppose, i assume Aerodynamic Center lies at Center of gravity. Then apparently moment by lift will be zero about CoG. But in reality Centre of Pressure may be behind aerodynamic center and still be ...