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Questions tagged [aircraft-physics]

Physics as they apply to aircraft. Including aerodynamics, flight dynamics, stability and control, aircraft hydraulic and electric systems, engine thermodynamics.

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26 votes
3 answers
8k views

Can someone explain the damage distribution on this aircraft that flew through a hailstorm?

An A320 flew into a hailstorm 20mins from landing. I’m intrigued by the damage distribution. Seems like everywhere else wasn't touched at all. Why?
4 votes
2 answers
127 views

How does ground effect work with a banked wing?

How would an explanation of ground effect such as this one from Peter Kämpf be modified to account for a highly banked wing? A paraglider and HP canopy pilot told me that when he banks a wing to touch ...
-2 votes
1 answer
77 views

What is the speed and temperature profile of the boundary layer at the stagnation point?

At the statgnation point where the air velocity is zero, what is the shape of the velocity and temperature profile of the boundary layer? Is the velocity profile of the boundary layer in the form of a ...
-3 votes
1 answer
132 views

What's gonna be the physics behind building 'futuristic' airplanes? Use physics formulas or even theories to answer this question [closed]

After thinking about these 'futuristic' airplanes, I wonder if there's any special physics theory or law behind them. I wonder how faster they can be, persevere more and fulfill the aviation's lover ...
2 votes
1 answer
1k views

How does airfoil affect the coefficient of lift vs. AOA slope?

I'm trying to understand whether the airfoil shape can affect the slope of Cl vs. AOA (coefficient of lift vs. angle of attack) in the "linear" portion, e.g., from a few degrees negative to ...
-4 votes
2 answers
104 views

In a straight and level flight if thrust is equal to drag how is aircraft moving forward?

If two forces are equal and acting in opposite direction should not the object remain stationary. Is there an excess thrust which actually pushes the aircraft forward ?
4 votes
4 answers
279 views

In a hot air balloon what proportion of the lift comes from the heated air compared to that from the combustion products?

A hot air balloon is heated with propane or similar hydrocarbon. One of the products of combustion is H2O with molar mass 18 so it is substantially less dense than air (78% nitrogen, molar mass 28 and ...
0 votes
0 answers
41 views

induced drag at supersonic speed [duplicate]

for a delta wing with supersonic leading edge at small angle of attack there is no stagnation point on leading edge so There is no connection between the top and bottom of the wing. Therefore, the air ...
6 votes
3 answers
1k views

How does an aircraft's weight affect the V-n diagram?

I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the ...
0 votes
0 answers
34 views

Does partial flow separation due to toggle input affect the physics of paraglider/ canopy controls?

A skydiving canopy designer said the following: Airflow is separated even before stall on a big portion of the canopy.... It's specific to [the] way toggle[s] distort the trailing edge. Is this true,...
1 vote
0 answers
47 views

Does ground effect affect a paraglider/ canopy?

I've heard that ground effect is only significant if the wing is closer to the ground than its span, and I've never seen a canopy/ paraglider that would qualify for that. Is that true or would there ...
1 vote
1 answer
217 views

How does elevator control effectiveness change with altitude/ air density?

Suppose an unpowered, rigid, mechanical, lightweight aircraft (e.g. sport glider) is descending at a steady glide in a constant trim (hands off) configuration in a standard atmosphere. The pilot ...
3 votes
0 answers
72 views

Is the thrust/lift trade-off for powered lift linear?

On the wikipedia page Powered lift there is this graph of thrust vs lift: (public domain) This graph shows a roughly constant (not exactly constant but that's not the point) sum of thrust and lift. ...
25 votes
9 answers
28k views

Does lift equal weight in a climb?

This subject keeps coming up in the discussions and questions such as this one, which asks if lift equals weight in level flight. Good answers there, pointing out that upwards force has many sources. ...
1 vote
1 answer
265 views

Does the routine flown by the Thunderbirds in the F-16 feature true sustained knife-edge flight?

Does any aerobatic routine flown by the USAF Thunderbirds in the F-16 feature true sustained knife-edge flight? By "true sustained knife edge flight" we mean that the aircraft is maintaining ...
0 votes
2 answers
127 views

How to maximize L/D ratio by design in a high altitude glider? [closed]

EDIT: Some initial confusion with TAS and IAS confused me, I now understand this better, thanks for everyone who helped. I'm designing a high-altitude glider, and I'm wondering how the angle of attack ...
2 votes
0 answers
86 views

Doubt in the Coriolis component of the net force acting on the aircraft

I dig a little and got to know that the force equation in 6DOF are nothing but a mathematical depiction of the fact that for a translating & Rotating body in 3D,The net force is the Translational ...
1 vote
0 answers
28 views

Intersecting Boundary Layers in XFLR5

I am analyzing an airfoil called RevE-HC. While doing a type-1 analysis, I encountered that the BL is intersecting towards the trailing edge. The panels are refined and the geometry is also smooth. ...
23 votes
1 answer
3k views

Does a carbon fiber fuselage suffer wear from pressurization/depressurization?

I've heard many times that one of the factors that causes wear and tear to the fuselage of airliners is the pressurization and depressurization from each flight. From what I recall these were ...
3 votes
4 answers
631 views

What are the correct Cd0 and Cdi values for a NACA 2412 airfoil?

According to an answer to this question, at best L/D the the drag coefficient is evenly split between Cd0 and Cdi. I'm going to limit the question to the Cessna 172 and its NACA 2412 wing with an ...
4 votes
1 answer
955 views

Does a deflecting 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. ...
2 votes
4 answers
417 views

Would it be practical to have missiles that can aim forward and backwards?

I have been researching recent air-to-air combat kills in some recent wars and in every case it seemed that the pilot who was in the back won. So I was wondering why they don't just design a missile ...
0 votes
2 answers
237 views

why does the rotor could head (Nr) "overspeed" if the collective is lowered suddenly, what is the Physics behind it

I know that in helicopters the N2 and Nr are coupled. I would appreciate a physical explanation leading to the cause of how the rotor blades could overspeed if collective (power) is lowered suddenly I ...
2 votes
1 answer
150 views

What's the efficiency between the duct and the fan blade?

I've heard many times that the smaller the gap between the fan blade and the duct, the better the efficiency/thrust is. Is there a formula or graph available to see how much efficiency is lost as you ...
12 votes
2 answers
5k views

If a Cessna 172 is dropped from the sky, what minimum altitude is needed to safely land?

If an aircraft like a Cessna 172 is dropped from a helicopter, what absolute minimum altitude above the ground will be required to safely land the aircraft? CONDITIONS: Weather: Perfect conditions, ...
1 vote
1 answer
190 views

Could an passenger jet perform a complete power down & up IN FLIGHT? [duplicate]

I've read various references that it is not uncommon that modern passenger jets' computer systems need an occasional reboot to fix some erratic state. Of course, that is done on the ground and ...
8 votes
3 answers
2k views

Is it possible to hear a sonic boom when the aircraft is exactly at Mach one?

Will an observer on the ground hear a sonic boom if a plane passes overhead at exactly the speed of sound? That is, the plane does not cross the sound barrier. The plane just hits Mach one - and ...
0 votes
0 answers
66 views

Gyroscopic Precession in Coaxial Helicopters

I'm trying to understand gyroscopic Precession in the case of coaxial helicopters. Obviously the effect still exists. But if gyroscopic Precession is a result of counter torque. Shouldn't the effect ...
6 votes
5 answers
6k views

How can L/D Max be both Best Glide speed and Max Range speed?

According to the book "Aerodynamics for Naval Aviators", best glide speed AND max range speed for propeller aircraft both occur at L/D max. This is a little confusing because in an A36 ...
2 votes
2 answers
515 views

What causes magnetic compass acceleration errors?

I was trying to find out what exactly causes magnetic compass acceleration errors, and I found two completely different and contrasting explanations online (both are supported by an equal amount of ...
1 vote
1 answer
731 views

What causes magnetic compass turning errors?

What exactly causes magnetic compass turning errors? I found two completely different and contrasting explanations online and I'm confused as to which one is correct. Explanation 1: Reference: ...
0 votes
0 answers
115 views

How do you calculate the theoretical vertical speed of an aircraft? [duplicate]

I'm doing this for a High School research paper, so it would be preferable if little calculus is used for any calculations (up to Calculus I is probably okay). This should be based off of the flight ...
0 votes
1 answer
166 views

Does the “Torque-Induced Precession” of the two rotor blades cause the V-22 Osprey to tear itself apart

Concerning Bell Boeing V-22 Osprey Aircraft: Does the “Torque-Induced Precession” of the two rotor -- 3-blade, propellers cause the V-22 Osprey to become unstable. In the case of a helicopter the ...
9 votes
2 answers
2k views

How AeroVironment's Switchblades steer their flight?

I'm very intrigued with how AeroVironment Switchblades: SW-300, and SW-600, steer their flight. There are plenty of images and animations and to my observation, none of the Switchblades have ailerons, ...
1 vote
1 answer
162 views

Exhaust temperature of CFM56 engines range (Nozzle downstream temp)?

EGT is available but not the temp of the exhaust nozzle in the CFM56 series.
12 votes
5 answers
4k views

Why isn't the rudder below the tail?

Most airplanes have a rudder on top of the tail. When it is turned to the left, it causes the plane to yaw to the left. But it also puts a roll force to the right, because it is usually above the ...
0 votes
1 answer
135 views

Yawing during turns

This is a question about aeronautics. Does an airplane yaw while it is turning?
0 votes
0 answers
168 views

Why does the F/A-18 use external aileron and flap hinges?

As seen in the picture, the legacy Hornet uses ailerons and flaps with external hinges, and I was wondering what were the advantages of external hinges compared to flush hinges in the land-based ...
0 votes
0 answers
102 views

Deriving Accurate Exit air velocity of rotor

My goal is to derive the equation for exit air velocity as a function of: Pitch angle RPM Rotor Radius Constants like ρ Assumptions: Vc is relative velocity of air upstream, and is = 0 Inflow is ...
9 votes
5 answers
3k views

Why do newer engines have such wide fan blades?

Every treatise I read about propellers/fan blades/wings states that long, thin wings are more efficient than wide stubby ones. So why is it that the blades in high-bypass turbofan engines fitted to ...
0 votes
0 answers
31 views

Is the Lift required for a steady-state climb and descent equal for the same absolute value of the kinematic climb angle? [duplicate]

Here is my confusion : I found in my lecture script the following equation for the steady-state climb and descent (wings level) ...
1 vote
1 answer
226 views

Is the Reference Speed (Vref) the same as the speed at which the aircraft cross the runway threshold in landing phase?

Just a little confuse when I learned about the aircraft classification based on approach speed. Can anyone help me to have an accuracy look about this question?
0 votes
1 answer
210 views

Does pilot need to increase thrust when gust hit him at landing and where is axis of rotation?

Let's say a plane is flying above a runway in straight line, and gust of wind hits the plane from side. Do pilot need increase thrust to stay above runway and where is axis of rotation ? It often said ...
11 votes
5 answers
4k views

Do airliners respond to mild turbulence in real time?

I've always been fascinated with the impact of ailerons on an aircraft's trajectory; from what I have seen sitting by a wing is that the slightest movement can bank the aircraft quite significantly. ...
3 votes
3 answers
8k 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 to ...
1 vote
1 answer
1k views

What happens to the pressure differential of airflow under and over the wing as the critical angle of attack is reached?

I've been doing a research project for mathematics which involves calculating the relationship between lift and angle of attack. While this may seem pretty easy, it's not for a 12th-grade student like ...
8 votes
3 answers
5k views

Flying upside down without feeling it

A friend of mine told me that several years ago she flew on a two-seats general aviation aircraft. She does not remember the exact model, but she remembers well that the pilot flew upside down for a ...
6 votes
2 answers
953 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?
5 votes
2 answers
1k views

Do fuel tanks need to be pressurized?

Do fuel tanks need to be pressurized? It's my understanding that the pressure difference between the outside air and the inside fuel would force the kerosene out of the fuel tank. What stops this from ...
1 vote
2 answers
145 views

Why will all air slow down by the same amount in an adverse pressure gradient?

Boundary layer separation is caused by air slowing down to zero and reversing before reaching the end of the body. This is due to friction (viscous effects) + adverse pressure gradient. The formation ...

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