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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3 votes
4 answers
439 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
903 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
361 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
135 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
143 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
178 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
54 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
5k 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
145 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
200 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
160 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 ...
0 votes
0 answers
38 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 ...
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
124 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.
13 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
128 views

Yawing during turns

This is a question about aeronautics. Does an airplane yaw while it is turning?
0 votes
0 answers
147 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
72 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
28 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
141 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
209 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
7k 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
4k 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
925 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
990 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
1 answer
146 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 ...
1 vote
2 answers
128 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 ...
5 votes
3 answers
847 views

How does momentum thrust mechanically act on combustion chambers and nozzles in a jet propulsion?

I'm asking this question since I can't intuitively understand how the acceleration of mass flow and therefore the increase of its momentum can actually mechanically act on the combustion chamber ...
2 votes
2 answers
481 views

Are the gyroscopic precession and P-factor of a pusher propeller in opposite directions?

according to this picture the P factor cuases airplane to yaw to the right but if pilot wants to pitch up , then p factor and gyroscopic precession acts on airplane at the same time but in opposite ...
6 votes
4 answers
1k views

On the Ka-50 coaxial helicopter, why does the bottom rotor flap up on the right side instead of in front during forward flight?

In the game DCS World, when flying the Kamov Ka-50 Black Shark flying forward at high speeds, the bottom rotor will flap up on the right side of the helicopter (also note that the top rotor is ...
1 vote
1 answer
174 views

Why does bank angle have no effect on pivotal altitude?

Pivotal altitude is the height for a given ground speed at which the line of sight from the cockpit directly parallel to the lateral axis of the aircraft will remain stationary on an object on the ...
0 votes
1 answer
235 views

Does the cross-sectional shape of a fuselage affect drag?

Comparing two bodies with the same streamlined longitudinal shape, and the same cross-sectional area, one with a circular cross-sectional shape, the other with a quadratic cross-sectional shape, ...
1 vote
1 answer
167 views

What are the flight formulas for aircraft

I am making a 2D flight "simulator" (trying to be as realistic as you can for 2d) and I need flight formulas for lift, speed and pitch. I have tried a few sites but I do not understand what ...
3 votes
1 answer
133 views

Energy Maneuverability Theory Applied to WW1 Fighters

I am trying to test the Fokker D.VII, Spad S.XIII, Sopwith Camel, Nieuport 28, and the Se5a using the model in this paper: https://apps.dtic.mil/sti/pdfs/ADA066034.pdf It's called Combat Performance ...
2 votes
0 answers
65 views

Anyone knows where i could find the McMaster, H. C., “FAR 23 LOADS”, Aeroscience Software, 2.02 Edition?

I am currently conducting research on wing lift distributions and came across the existence of a software tool called "FAR 23 LOADS," developed by McMaster, H. C. (Aeroscience Software, 2.02 ...
2 votes
0 answers
175 views

Why aren't Biplanes designs used when size and wing span restrictions are involved? [duplicate]

This research paper shows that for a given aspect ratio and wing area, compared to a monoplane a biplane produced a better L/D. So, wouldn't it make more sense to manufacture biplanes for subsonic ...
2 votes
1 answer
74 views

How can the effect of wind gradient in a glide be calculated?

If an airplane glides in a mass of air where the headwind changes with altitude, it seems logical to think that the length of the glide –as measured by a ground-based observer– will be longer in the ...
11 votes
7 answers
3k views

Explained intuitively, why does aspect ratio affect induced drag?

Over the last few hours, I've been trying to intuitively understand induced drag, and how aspect ratio affects it. I already know the equations, but while they explain the relationship, they do not ...
4 votes
1 answer
216 views

aerodynamic forces on an engine cowling

In Mendenhall's book about the Gee Bee racers, he describes that on the Models Z, R-1, and R-2, there was a strong tendency for the engine cowl to get pulled forward and into the prop during races, ...
0 votes
2 answers
485 views

How does a zero g aircraft work?

In upward motion, drag and gravity is in the same direction (both in downward direction). So in this situation G is negative or less than 1 or something else? In downward motion with thrust greater ...
13 votes
3 answers
3k views

Why did the F-104 Starfighter have a T-tail?

The F-104 Starfighter was launched in 1954, nine years after WWII. It had short stubby wings and a T-tail. According to wiki, the short stubby wings caused inertia coupling and the T-tail reduced this....
0 votes
4 answers
2k views

Center of Gravity, Aerodynamic Center and Center of Pressure, how do they connect?

I read an article that described static margin by taking the aerodynamic center and the center of gravity. It explained why the center of gravity has to be in front of the aerodynamic center for a ...
2 votes
3 answers
388 views

What is airflow direction in turn?

Let imagine that we put wind indicator on rotating merry-go-around. Will wind indicator stay prepedicular to the radius of circle,showing tangetinal airflow velocity? (Wind indicator has equal mass ...
0 votes
1 answer
240 views

Lateral location of the center of pressure

I am working on a simple flight simulator. For this, I need to calculate aerodynamic forces and apply them to the aircraft. As I understand it, lift and drag act through the wings center of pressure. ...

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