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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.

4
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4answers
224 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 ...
2
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3answers
154 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 ...
0
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1answer
357 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 ...
2
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4answers
204 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 ...
2
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2answers
129 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 ...
0
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1answer
47 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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0answers
146 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 ...
1
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1answer
51 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 ...
1
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3answers
117 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 ...
1
vote
1answer
219 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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4answers
164 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
161 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 ...
0
votes
1answer
133 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 ...
2
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3answers
148 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 ...
0
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3answers
86 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 ...
0
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5answers
261 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) ...
2
votes
1answer
140 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. ...
1
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2answers
99 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 ...
0
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2answers
91 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 ...
0
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1answer
96 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, ...
2
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7answers
381 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
103 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 ...
2
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5answers
265 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
42 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
14
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3answers
978 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. ...
0
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1answer
81 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 ...
2
votes
5answers
92 views

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 ...
5
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2answers
281 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 ...
1
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5answers
229 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 ...
1
vote
0answers
51 views

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 ...
4
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1answer
125 views

How do you know the maximum load a control surface can withstand?

source This is a separate strength testing (load testing) of the elevator of an airplane, how was the load determined? How did the engineers determine the maximum elevator load?
2
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4answers
345 views

Does the required torque to spin a propeller increase with RPM?

I‘ve currently been experimenting with different propellers: 12x12 prop, 16x12 prop (both two blades) and a 22x14 (6 blades) prop. They were propelled by a 2.4 kW electric motor with 260 kV on a 6S/...
2
votes
4answers
297 views

Why is best angle/rate of climb indicated in airspeed?

I understand the difference between best angle of climb $V_{x}$ and best rate of climb $V_{y}$. When I take off I would aim to maintain one speed or another depending on what I want. But I don't ...
1
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5answers
281 views

Do swept back wings affect the moment of inertia of an aircraft enough to be relevant for the roll response?

I have studied that swept back wings help in delaying the shock waves formed on the wing, but also to my understanding I feel swept back wings reduce the moment of inertia (like for example a ...
0
votes
1answer
62 views

How do the vortices affect the flow of the horizontal stabilizer upon leaving the wing?

Other than the downwash effect, what other factors that affect the flow to the horizontal stabilizer? such as Dynamic Pressure? Air Flow Disturbance?
1
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2answers
92 views

Where can I find the best site to learn aircraft design on a small scale? [closed]

I am undergraduate student still trying to figure out a lot about Aerodynamics and aircraft design. I am learning how to design rc planes. So the thing I know the weight of my plane which is between ...
0
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1answer
119 views

How to determine the maximum servo torque required for a nose gear?

It's pretty much it. I know how to calculate the friction force on the nose gear for a three-point landing condition using the method set forth in ...
1
vote
2answers
225 views

What is the average aerodynamic load on a control surface of a commuter-sized airplane?

I'm doing a study about aircraft hydraulic pump sizing. In order to do that, I need to know the size of a flight control actuator, then determine the maximum flow and pressure that the actuator needs. ...
1
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0answers
241 views

How to calculate the shear force, and the bending and torsion moments on a wing?

I want to calculate the loads (shear force, bending and torsion moments). Assuming I have the force distribution along all the surfaces of the aircraft, my starting point is to consider the wing (and ...
3
votes
5answers
293 views

How do thrust reversers in high-bypass turbofan engines counteract initial thrust?

I've been searching the internet for awhile and haven't really come across a good answer for this question. So: I have a basic understanding of the principles of flight (thrust, lift, drag, etc). But ...
3
votes
2answers
718 views

What forces act on an airplane's door from the outside in cruise?

The inside cabin pressure from what I understand is pressurized to the values found at 6000-8000 feet high (11.34 psi at 7000 feet), at which point we can find the amount of force can be found acting ...
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votes
4answers
416 views

In which direction will an aircraft drift after taking off in a crosswind?

Assuming the pilot applies the appropriate crosswind flight controls (see below) during takeoff and rotation, and releases those flight controls after the aircraft leaves the ground, in what direction ...
1
vote
0answers
45 views

Single Engine operation on Twin Engine aircraft [duplicate]

I recently came across ETOPS and I wanted to know: How does a twin-engined aircraft balance out the lack of thrust on one side in the event that one of the engines is non operational? Any ...
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votes
2answers
415 views

What is the difference between centripetal and centrifugal force?

In a homework problem I was asked: In a balanced banked turn an increase in angle of attack will :? Answers are : 1/ reduce indused drag. 2/ increase centripetal force . 3/ increase centrifugal ...
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0answers
48 views

Could a airship be built using vacuum as the lighter-than-air “material”? [duplicate]

Could an airship be built that uses instead of a very light gas a vacuum to keep it floating? Or would the materials needed to keep its volume even without the pressure from the inside always be ...
1
vote
2answers
187 views

Is it possible to build a honeycombed vacuum balloon? [closed]

Is it possible to build a vacuum balloon with a near perfect void that can lift heavy objects and doesn't collapse and buckle under the atmosphere? I expect perhaps a honeycombed or lorimerlite ...
1
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2answers
211 views

Does angle of rotation during takeoff affect the g-force?

(Original) When an airplane banks 60° during row, 2 g of force is induced. When an airplane pitches 60° during takeoff, is 2 g induced on the airplane? Is the angle of rotation during takeoff ...
6
votes
2answers
626 views

How does the fuselage handle the different loads?

I have been trying to find out how the loads experienced by a fuselage are transferred between structural members (bulkheads, formers, frame assemblies, skin, longerons, stringers). I understand that ...
0
votes
1answer
211 views

What is the lift-to-weight ratio during takeoff for an ultralight?

Lift to weight ratio at cruise is 1:1, what is the average lift to weight ratio during takeoff (rotation) of an ultralight with 2m/s as rate of climb?