Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [aircraft-physics]

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

0
votes
3answers
302 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 ...
1
vote
1answer
118 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?
2
votes
1answer
218 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, ...
5
votes
5answers
184 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 ...
9
votes
3answers
3k views

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?
1
vote
2answers
88 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?...
1
vote
2answers
158 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 ...
17
votes
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: ...
3
votes
1answer
151 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 ...
5
votes
1answer
182 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 ...
1
vote
1answer
136 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, ...
4
votes
1answer
220 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-...
4
votes
4answers
271 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?
15
votes
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
votes
3answers
165 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
votes
1answer
401 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
votes
4answers
316 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
votes
2answers
135 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
votes
1answer
57 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}...
4
votes
1answer
241 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
vote
1answer
74 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
vote
3answers
127 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
286 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 ...
1
vote
6answers
385 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,...
0
votes
4answers
176 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
182 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
votes
3answers
265 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
votes
3answers
88 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
votes
5answers
266 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
151 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
vote
2answers
169 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
votes
2answers
203 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
votes
1answer
158 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
votes
7answers
582 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 ...
0
votes
2answers
110 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 ...
3
votes
5answers
519 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 ...
0
votes
0answers
44 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
votes
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. ...
0
votes
1answer
138 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
96 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
votes
2answers
300 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
vote
5answers
314 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
53 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
votes
1answer
145 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
votes
4answers
467 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
423 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 ...
2
votes
5answers
342 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
70 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
vote
2answers
102 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
votes
1answer
165 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 ...