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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2answers
152 views

How to fly a quick return to origin after takeoff

If I want the shortest traffic pattern to play touch and go or I got a emergency right after liftoff but the engine is still working, I just want to get back to ground as soon as possible, what is the ...
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5answers
206 views

Relationship between hover power and climbing power

I've been told that, generally speaking, rotor efficiency increase with rotor diameter. This is because the thrust generated by a helicopter rotor equals the mass of air moved times the delta V of the ...
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2answers
418 views

How much does the fuselage of an airplane contribute to yaw stabilization?

Obviously considering that (almost) every plane has a vertical stabilizer, probably not, but for a relatively long aircraft does the fuselage measurably contribute to the yaw stabilization relative to ...
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4answers
337 views

What is maximum acceleration that can be achieved by afterburner in level flight?

I am wondering how a fighter jet (let's take F-22 for example) would compare to other vehicles in terms of acceleration while in flight. For cars and motorcycles, achieving 0-100 KPH in 2 seconds is ...
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4answers
183 views

Which way to turn to return to runway for downwind landing— into crosswind or with crosswind?

The scenario-- you are taking off with a significant headwind component but also a significant crosswind component. You experience a power loss (or perhaps a tow rope break in a glider). You judge ...
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1answer
113 views

Is total upwards vertical force higher than weight in a steady climb? [closed]

And again related to questions on forces in a climb: if any aircraft is climbing with a constant velocity, is total upwards force higher than weight?
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0answers
46 views

Does a fighter aircraft slow down when firing machine guns? [duplicate]

I imagine the recoil of a powerful machine gun or cannon would decelerate a plane significantly. Is this an issue?
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2answers
159 views

Center of Gravity and Center of Lift stability

I have recently been reading about the center of gravity and center of lift. On the German Wikipedia there are many different graphics about the relation between the center of gravity and the center ...
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3answers
226 views

Is lift less in a steeper descent than in a shallower descent, and if so, by how much?

Is lift less in a steeper descent than in a shallower descent, and if so, by how much? For example, if we change our ratio of horizontal distance travelled to vertical distance travelled (through the ...
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1answer
126 views

Would mid-air refueling for an air-to-space vehicle that flies like a plane be a viable advantage if the tech was available? [closed]

Let's take the style of an F-22 Raptor (awesome!), build the fuselage, wings, etc to handle runway takeoff horizontally and then vertically (if needed) up to orbital space flight to reach the ISS in ...
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1answer
107 views

How can one change the wingtip geometry to enhance the wingtip vortices?

I'm doing some research on enhancing wingtip vortices as part of my Honours project. After spending a fair bit of time in the literature and on this forum I have some models which should kick-start my ...
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6answers
2k views

Is a trimmed flight not always an unstable system?

As soon as I am flying in trimmed flight condition, my pitching moment around the center of gravity becomes zero. So my center of pressure has to be located in the center of gravity, so that there is ...
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4answers
506 views

Engine out over a mountain road. Do you land upwind or up hill?

You're flying solo in a late-model, fixed-gear Cessna 172 with half-full fuel tanks. You are at 1000 feet AGL, 100 knots indicated, directly above the middle of a 2000 foot long straight section of ...
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2answers
178 views

In this F-104 V-n diagram, why does the stall speed (in terms of IAS) decrease with altitude in some parts of the flight envelope?

(This question has been edited to reflect a change in perspective: based on answers to the related question What is causing these "corners" on this F-104 V-n diagram?, I now believe that the ...
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1answer
440 views

What is causing these “corners” on this F-104 V-n diagram?

In this V-n diagram for an F-104 (source: this Wikipedia link), on the left-hand edge of the flight envelope, what is causing the "corners" that we see at the following points? (Numbers are ...
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5answers
297 views

What causes the ball to not be centered in a slip/skid?

I've reviewed quite a few questions on this forum including Forces in a slipping turn is-this-vector-diagram-of-the-forces-at-play-in-turning-flight-correct what-does-the-balance-ball-actually-...
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1answer
59 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 ...
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0answers
53 views

Boundary layer thickness calculation

I have tried to calculate all the losses associated with the serpentine intake to calculate the total pressure recovery. I have considered the frictional losses, pressure loss due to bend, approach ...
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2answers
138 views

Why is this equation for TAS only valid for subsonic flow?

I came across the equation for calculating True airspeed (TAS) on Wikipedia: $$ \text{TAS} = a_0 \sqrt{\frac{5 T}{T_0} \left[ \left( \frac{q_c}{P} + 1 \right)^{2 / 7} - 1 \right]} $$ But this equation ...
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1answer
174 views

Why did TWA800 not stall?

I believe the NTSB account, but based on this graph, http://twa800.com/lahr/zoom-climb.htm, why did the flight not stall after the nose separated?
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2answers
197 views

Can a plane with a thrust-to-weight ratio less than one fly vertically and perform loops?

In the game Battlefield 1 you can fly a Sopwith Camel vertically and perform different kinds of aerobatic maneuvers like loops. According to its specifications, its thrust-to-weight ratio should be ...
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1answer
89 views

Relationship between Load-Factor AND Gliding Ratio

I am wondering about the g-load and its relation to the so called gliding ratio. I read this really good contribution here on this forum: Does lift equal weight in a climb? So the g load factor is ...
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2answers
973 views

What is the effect of thrust vectoring effect on the rate of turn?

I just got a question after reading my old Principles of Flight book. The equation for the rate of turn is $\textrm{ROT} = 1,091 \cdot \frac{\tan(\phi)}{V}$, with $\phi$ denoting bank angle and $V$ ...
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0answers
118 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 ...
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1answer
95 views

What counts as the wingspan of a tandem-wing aircraft?

When calculating the wing-span of a tandem-wing aircraft, like the QAC Quickie Q2, which set of wings do we use for that value? There are two sets of wings, and they both provide lift. In the class, ...
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4answers
318 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 ...
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1answer
111 views

Question about the difficulty of a couple of airplane maneuvers [closed]

I have a hypothetical scenario and I was wondering if any experts might be able to speak to it. I will lay out the scenario, with a couple of specific questions, and maybe some honest answers will ...
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1answer
61 views

How does the airflow above an airfoil account for the downward turning-action of the airflow below the airfoil?

Wikipedia provides an explanation of the lift force in terms of flow deflection and Newton's laws, emphasis mine: An airfoil generates lift by exerting a downward force on the air as it flows past. ...
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1answer
183 views

Why does a force on a propeller act 90° “ahead” due to gyroscopic precession?

This is a common explanation: A tailwheel airplane is on the takeoff roll and the tail comes up, the propeller disc rotates forward. That's akin to someone pushing on the top of the disc. The force ...
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4answers
141 views

What is the influence of yaw on P-factor?

From William Kershner's “The Advanced Pilot’s Flight Manual”- page 2-17, P-Factor: If the airplane is yawed, the P-factor effect is encountered. A left yaw would mean a slight nose down tendency and ...
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3answers
155 views

Can plane climb without increase pitch angle?

As I know plane climb "with nose up", but can plane climb without change pitch angle? Can I force plane to climb like this: If I fly in straight level flight at 100km/h and now increase ...
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2answers
189 views

How should I attach an aircraft model in a wind tunnel when testing wind gust/yaw stability?

Where should I attach the rod to the aircraft model when simulating wind gust /weather vane effect in wind tunnel testing? At the center of gravity, behind the CG, in front of the CG...?
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3answers
185 views

Does aircraft allways rotate about center of gravity like weather vane about pivot point?

When gust of wind hit plane form side,does plane allways rotate about center of gravity like weather vane about pivot point or CG as pivot point is just "math areegment" for easier solve ...
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2answers
135 views

How does an aircraft designer increase dynamic stability?

This question explains that an aircraft can be statically stable (it will seek to return to equilibrium) but dynamically unstable (the amplitude of the oscillations increase) if there isn't enough ...
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4answers
4k views

What does it mean when an aircraft is statically stable but dynamically unstable?

I am reading this book: "Flight Stability and Automatic Control", second edition, Dr. Robert C. Nelson. In the chapter 2, page 42, the author wrote: Note that the vehicle can be statically ...
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7answers
272 views

Is the elevator really an 'angle of attack control' as described in Stick and Rudder?

I've been reading Wolfgang Langewiesche's book Stick and Rudder and am a little confused about the definition of the elevator as the "Angle of Attack Control" or rather, the idea that each ...
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4answers
227 views

Is the turning motion of a banked airplane caused by true centripetal force?

Virtually every explanation I have read of the aerodynamics of a turning airplane ascribe the turning motion simply to centripetal force, without further comment. I'm hoping someone can check my ...
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3answers
296 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 flying the Ka-50, when 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 flapping up on the left, ...
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2answers
120 views

How to properly compute the stable vertical path load factor

I've been told by someone else that in a stable flight when the vertical path of the aircraft is maintained, the Nz value is equal to cos(pitch)/cos(bank), but I can't seem to figure out how that is ...
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0answers
36 views

Is axial dynamics important for the helicopter equations of motion?

While analyzing helicopter performance, why do we always ignore the axial dynamics from the equations of motion?
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1answer
152 views

Why does pressure remain constant in the boundary layer?

From Fundamentals of Aerodynamics by JD Anderson. It can be shown experimentally and theoretically that the pressure through the boundary layer in a direction perpendicular to the surface is constant....
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2answers
132 views

What is the physical difference between an airplane having let's say 150 horsepower to an airplane having 250 horsepower?

I was wondering what defines horsepower in an airplane piston engine and how can it be changed?, is horsepower changing during flight?
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2answers
151 views

Bernoulli Principle — Reversed [closed]

The Bernoulli Principle states that as the velocity of a fluid increases, the pressure of that fluid decreases. However what if it were to be reversed: As the velocity of the fluid decreases, the ...
2
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6answers
519 views

Why can't you have sail-powered airplanes?

So, sailing boats take the kinetic energy of a crosswind and turn it into thrust by using their sails as lifting surfaces, and the discussion I had in the comment section of this question made me ...
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1answer
124 views

After decades of solid research, mostly led by Robert J Englar, why is Circulation Control, the Circulation Control Wing not in use at all?

Any research on the CCW by Robert J Englar at Georgia Tech from the 60's into the 2000's. Many papers have confirmed Englar's work and in many cases, advanced it. This research has proven extreme lift ...
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4answers
376 views

What's the relationship between AOA and airspeed?

We know that any aircraft will stall at its stall speed (for a specific weight, CG position, etc.) but also, that the same airplane will always stall at the same angle of attack. I´ve read that IAS is ...
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2answers
202 views

What is the purpose of downthrust?

Many light general aviation aircraft-- and perhaps many other aircraft as well-- are designed with some of amount of downthrust in the engine mounting, relative to the centerline of the fuselage. ...
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2answers
173 views

How does the aircraft keeps propelling forward when airflow and thrust are not aligned?

Assume an aircraft is flying at an angle of attack of 10 degrees, and that the incidence angle between the aircraft fuselage and the wing as well as the angle between the wing and the engine mount is ...
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3answers
173 views

Is “excess thrust” possible in a steady state vector diagram?

Being recently very much sold on the lift-weight-thrust closed triangle (with weight forming the hypotenuse) model for climbing flight, I proceeded to put the logic through its paces (validation) and ...
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4answers
687 views

Effect of touchdown on angle of attack, tailwheel vs tricycle

I have a theory but I can't find any documented confirmation. Please let me know if my theory seems right: My theory: During a regular touchdown, a tricycle gear equipped airplane, since the main ...

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