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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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520 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
48 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
304 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
38 views

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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3answers
159 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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0answers
48 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
72 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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3answers
343 views

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
125 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
232 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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4answers
207 views

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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3answers
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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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2answers
90 views

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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2answers
176 views

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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3answers
6k views

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
156 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
197 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
143 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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1answer
294 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
334 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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5answers
6k views

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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3answers
183 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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1answer
443 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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4answers
444 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
141 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
73 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
250 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
133 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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3answers
135 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
338 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
619 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
192 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
234 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
345 views

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
90 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
284 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
166 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
227 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 ...
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2answers
298 views

if center of pressure moves forward with angle of attack, then does it move forward of center of gravity also at a particular angle?

Consider an aircraft where- Center of gravity lies forward of Center of Pressure in CRUISE. Now as angle of attack increases, CP moves forward, then for particular angle, it must move forward of ...
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1answer
237 views

Why is A320's CG optimum position at 25% MAC?

I have read a320's optimum CG position is 25% MAC. But, the aerodynamic center is also at 25% of chord. So since CG and aerodynamic center at the same position, there would be no moment arm of lift, ...
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7answers
881 views

How does maximum speed vary with altitude?

Question: How does a commercial jetliner's highest possible groundspeed vary with altitude (assuming wind=0) ? My understanding is that drag decreases with altitude, therefore maxspeed increases with ...
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2answers
116 views

Is drag higher when flying in a crosswind?

Is this true that during a flight with a crosswind the drag increases due to the fact that the relative wind blows at a certain angle to the aircraft's nose but not precisely in the opposite direction ...
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5answers
747 views

Are we changing the angle of attack by changing the pitch of an aircraft?

For example: if I pitch the airplane up, but also increase power and am able to maintain the same speed, then no, the AoA hasn’t changed, although it may have varied in the transition between one ...
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0answers
48 views

How to compute actuator torque requirement for Variable pitch mechanism??

Suggest me any reference to compute the torque requirement for actuator/motor to control the pitch angle of propeller (Variable Pitch Propeller). Thanks in advance Arun Ravindran
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3answers
1k views

Does the pressure at the static ports drop as the aircraft's speed increases?

This answer by Tyler Durden explains what static ports are and how they work: The "static ports" allow air into the instrument to provide the input for the air pressure on the side of the aircraft. ...
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1answer
201 views

How to calculate the induced drag coefficient?

In an exercice of Flight mechanic, I have to compute the drag coefficient at zero lift: $C_{D0}$.We saw in class two ways to find it : $$ C_{D0} = \frac{\pi AR e}{4E_{max}^2} $$ With $AR$ the aspect ...
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5answers
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Is there any effect that contributes to roll stability even in the absence of sideslip?

Is there any physical dynamic-- involving high wing placement, "pendulum" effect of CG far below wing, or anything else-- that contributes to roll stability in a way that is NOT dependent upon the ...
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2answers
341 views

Flight physics for a roll [closed]

I am working on a pet project to write a game with flight physics. It will not be a simulator but instead much simpler. What I have done so far I have created winged components that generate lift ...
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5answers
348 views

Which way (if at all) do the ailerons need to be deflected in a full-rudder sideslip in a Cessna 152 or 172?

Do you typically have to maintain an aileron deflection in a constant-heading full-rudder sideslip in a Cessna 152 or 172? If so, in which direction? And why -- what is the source of the roll torque ...
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0answers
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Induced drag - inverse proportion between induced drag and parasitic drag [duplicate]

I recently learned that the slower an aircraft is traveling, the higher the induced drag and the lower the parasitic drag. The parasitic drag is lower because the particles have less force against the ...