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Questions tagged [aerodynamics]

Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design.

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0answers
24 views

Are there any lift or lift coefficient equations which factor in the flap deflection angle?

I'm asking this because I tested a NACA 2412 wing with an adjustable flap in a subsonic wind tunnel and I'm getting the lowest Cl values for the highest flap deflection angle.. which to my knowledge ...
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1answer
97 views

Calculating lift with lifting-line theory in MATLAB

I am attempting to calculate the lift generated by a model wing (~0.8$m^2$ wing area) using Prandtl's lifting-line theory in MATLAB. I am starting with the equation below from Anderson's 2005 book ...
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1answer
44 views

Can accelerations be used to calculate load factors?

Can I use the z accelerations to calculate the load factor in that axis? Please explain how or why not.
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3answers
145 views

How do flaps help an aircraft take off at a lower speed, yet cause drag at the same time?

Wouldn’t the drag caused by the flaps just decrease the acceleration, so, although they can lift off at a lower speed, wouldn’t it be faster to just use no flaps and rotate at the higher speed that is ...
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5answers
11k views

If Space Shuttle flies “like a brick”, why does it need the wings?

I have seen the Shuttle named a "flying brick" multiple times. However a brick, as understood in the building industry, is a simple rectangular shape without wings and without any adaptation of the ...
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4answers
179 views

What makes airplanes pitch up during landing?

So what exactly pitches the plane upward with the rear end down? Do flaps help lower the nose when deployed 80%-100% down with such low speeds?
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1answer
108 views

Solutions to improve the aerodynamic behavior of a UAV

So I'm working at a project of a UAV with the follow characteristics: Rectangular planform Conventional tail The fuselage is just a metal/aluminum rod So we need to improve its aerodynamic behavior/...
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5answers
203 views

How much of an airplane's forward energy is lost to lift?

An airplane needs to move forward to generate lift, and because energy isn't created from nothing, all the kinetic energy of lift comes in the form of drag, where air (air resistance) turns forward ...
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1answer
94 views

Why did this delta wing generate a lower Cl at a higher wind tunnel velocity?

I'm an aerospace engineering student,and just did an aerodynamics lab in which we measured the lift & drag of a delta airfoil inside a wind tunnel between 0 and 40 degrees, in 5 degree increments, ...
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1answer
53 views

If pitching moment creates drag, how can high and low moment airfoils have almost identical drag polars?

If pitching moment creates drag, how can high and low moment airfoils have similar drag polars? Let's call a symmetrical airfoil like NACA0015 a low moment airfoil having no moment at an AOA of 0. ...
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2answers
87 views

How to compute drag coefficient for falling book?

The book measures 20 x 20.3 x 1.4cm and I'm assuming it's sealed shut so the pages don't flap open. Mass is 450g. I want to understand how quickly it would fall if dropped straight down from 10km ...
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1answer
236 views

What Is a “Fully Stalled” takeoff?

Reading this article (on the Boeing 737 MAX saga; irrelevant), I found the following excerpt: Boeing ultimately accepted Davies recommendation and, we understand, halted production of the 707 for ...
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1answer
80 views

Application of Bernoulli Energy Conservation [closed]

In what cases does the static pressure decrease when the velocity increases in a flow. And in what cases does the static pressure remain constant whilst the velocity and stagnation pressure increases?...
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1answer
147 views

Do the F-18's leading edge flaps deflect symmetrically in rolls?

When the F-18 Hornet does rolls, do the Leading Edge Flaps (LEFs) deflect symmetrically or is the deflection different on the left and right LEFs?
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42 views

What is the effect of adding a slat and a slotted flap when using distributed propulsion?

What is the effect of adding a slat and a slotted slap when using distributed propulsion? I understand that distributed propulsion changes the local AOA to single digits. I understand that slats ...
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1answer
54 views

Why does lift curve slope increase when Fowler Flaps are deployed?

Below is an image for a Fowler Flap: Notice that as the flap is deployed, both the camber and the area increase. This change in wing shape modifies the lift curve as follows: (source: Development of ...
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1answer
131 views

Does distributed propulsion create unwanted lift at cruise speeds, requiring a negative angle of attack?

Does distributed propulsion create unwanted lift at cruise speeds? The great thing about slats and slotted flaps is that you can "turn them on" when you need high lift at takeoff, and "turn them off" ...
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2answers
64 views

Would converting a Lazair ultralight to 4 x 3 Hp engines and using the props as distributed propulsion produce a Clmax of 4.5?

Would converting a Lazair ultralight to 4 x 3 Hp engines ( 12 Hp total ) and using the props along the entire wingspan as distributed propulsion produce a Clmax of 4.5? I understand the original ...
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1answer
65 views

Individually controlled feather like winglets work?

I want to know how the individually controlled feather like winglets work on controlling and rolling by reducing drag.(concept of airbus bird's of prey) I just need a detailed review of the ...
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2answers
97 views

Effect of gravity vs airmass on a falling object

Let's say you were drifting along in a hot air balloon at a ground speed of 50 knots at an altitude of roughly 10,000' MSL/AGL. The airmass is uniform, moving at the same speed at all altitudes. In ...
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2answers
76 views

Why does the Biot-Savart law give the induced velocity of a infinitesimal segment of a vortex filament at point P?

My question is about the proof of how the Biot-Savart law can be used for vortex filaments. This is what I have in my textbook: However, I'm not certain how it was derived - I understand that the ...
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2answers
275 views

What is an airliner pilot's first go-to if he or she doesn’t have a positive climb rate immediately after take off?

Take for example a 737. Would the pilot just lower the nose to pick up airspeed, then raise it back up once they’re satisfied? Or maybe retract the flaps a bit? Assuming the throttle is at 94% N1, ...
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1answer
111 views

How can a runaway trim become so difficult to fight when all a pilot has to do, is “grasp and hold?” [closed]

and how can you even tell the pilots did “grasp and hold” during an investigation? Is it determined based off what they say?
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2answers
174 views

How to take into account wind in aerodynamic forces balance?

I'm trying to make a basic simulation for horizontal drift of a falling object due to wind. I need the force balance so that I can find out the acceleration of the object from the wind. The object is ...
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1answer
113 views

Does the aerodynamic center always have to lie on the chord line?

A lot of resources online state that the aerodynamic center is the "point on the body of an airfoil with respect to which the moment coefficient does not change with angle of attack." However, does ...
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1answer
78 views

Is there a relationship between transonic buffet magnitude and altitude?

Transonic buffet happens at mach 0.95. The correlated true airspeed varies with altitude. Does the transonic buffet magnitude also vary with altitude, and if so, how?
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3answers
5k views

Why do non-aerobatic aircraft have a negative G limit?

Why do airplane wings have limit load of both positive and negative g's (e.g., the Weedhopper ultralight has a load factor of +5 and -2gs). Why not just have a positive limit load since most airplanes ...
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2answers
227 views

What would be the minimum number of engines required to climb in a 747?

There was a really good Air Crash Investigation by Nat Geo which showed the British Airways Speedbird 9 issue where volcanic ash swept over all four engines and through the air vents inside the cabin. ...
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2answers
122 views

What is Circulation in aerodynamics? [duplicate]

Can someone please explain the concept of circulation? I am able to understand the mathematical form i.e. it is the line integral of the velocity field. But I am not able to understand the physical ...
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1answer
320 views

Why do wings prefer laminar flow if cd is lower for turbulent flows?

Can anyone please explain to me why we prefer to maintain laminar flow over wings, despite the fact that the overall coefficient of drag appears to reduce as the Reynolds Number increases? I have read ...
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1answer
176 views

How would a hole in the side of a plane affect its flight?

Let's say an explosion blew a hole in a plane's fuselage without ripping the aircraft apart or damaging the engine and wings. How would the hole affect its flight?
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2answers
123 views

Why is the stagnation point on the upper surface before the start of circulation?

In many textbooks, such as Anderson (Fundamentals of Aerodynamics), Bertin (Aerodynamics for Engineers), and Houghton (Aerodynamics for Engineering Students), the authors present the idea that there ...
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82 views

What is effective airflow?

As I understood, when the relative airflow meets the wing it changes, and the resulting flow is called effective airflow?
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1answer
138 views

Is the airspeed for the minimum the same for the theoretical power required curve as for the shaft power required curve?

I am aware that the efficiency of the propeller implies a difference in the values of the theoretical power required curve and the corresponding shaft power required, but does that efficiency ...
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0answers
166 views

If an fighter jet that it have twin rudders, in use the angle of deployment it is not identical. Which is more deflected and why?

If an aircraft have two vertical tails then pilot push in the rudder pedal the rudders will not be deployed at the same angle.It is used throughout the all envelope of flight or is it possible only ...
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1answer
77 views

Why do oblique-wing aircraft suffer from significant aerodynamic cross-coupling?

Oblique-winged aircraft (which have one long wing that pivots around a central point, so that the wing is straight at low speeds but strongly-swept - one side forwards, the other side back - at high ...
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0answers
61 views

Do most aircraft require a nose-up attitude for level flight? [duplicate]

I recently saw a picture of a HUD on a commercial plane, and I noticed the nose was level to the horizon but the flight path indicator is almost always under the horizon line no matter the speed, does ...
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0answers
92 views

In flat spin is rudder deflection used for recovery of the F16?

If the horizontal tails is used due MPO switch in recovery of the flat spin, is the rudder used for stopping the yaw of the F16 ? I know that for inverted flat spin is surely used, but I believe ...
4
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1answer
214 views

Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other?

Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other? The proposed application would be for a ultralight with high mount folding wings, where ...
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1answer
87 views

What airfoils are used for the current generation of general aviation VTOL aircraft?

What airfoils are used for VTOL ultralights at 60-70 deg AOA without flaps or slats? An example of this would be the Blackfly with a takeoff distance of 3', about 25% of it's own length....!!!! I ...
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4answers
86 views

Can airflow reverse over the flight surfaces of a uav in high wind conditions

Can airflow reverse over the wing of a uav in high tail winds and low forward airspeed i.e 25knt fwd airspeed in a 35 knt tailwind? What would be the overall effect on the elevator and rudder? I ...
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5answers
2k views

Where is the 'zone of reversed commands…'?

There seems to be some confusion about where the 'zone of reversed commands' really is, i.e. where a decrease of airspeed results in an increase of drag. Some references place that zone to the left ...
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1answer
84 views

Downwash distribution on basis of Lift distribution

I am new here so I might make some elementary mistakes. Correct me if I am wrong. I just stumbled upon the downwash distribution for a given lift per unit span distribution along the wingspan. I have ...
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1answer
247 views

What are the relative contributions of the body and wings to missile lift?

Slender bodies like arrow shafts, airliner fuselages, and submarine hulls are all capable of generating lift, albeit much less efficiently than a high aspect ratio wing. They also generate little drag,...
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2answers
119 views

What are the speeds for absolute ceiling and coffin corner?

This picture is taken from Safety First (Airbus magazine). Could you please clarify some things: 1). Is "Absolute aerodynamic ceiling" = "Coffin corner"? 2). Have I correctly understood that there is ...
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1answer
75 views

How to calculate aerodynamic efficiency at minimum power conditions?

The drag polar of a propeller driven aircraft is $C_{D}=0.039+0.071 C_L^2$. The lift curve slope of the wing ($C_{L_\alpha}$) is 0.09/deg and zero lift angle ($\alpha_{L=0})= -1.5^o$. Stall angle of ...
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4answers
142 views

Does a left spin differ from a right spin for a single-engine propeller aircraft, in terms of spin characteristics & ease of recovery?

Given a single-engine propeller aircraft with its nose-mounted propeller rotating on the right-hand side when viewed from the cockpit, and given the typical effects like P-factor, prop-wash and ...
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1answer
109 views

In fighter jets, is the minimum speed calculated with the flaps in the down position or up? [closed]

I asked that question because F16 flying straight and level at minimum speed does not have flaps down. So how is the minimum speed calculated by aircraft designers?
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0answers
21 views

How to calculate the moment/torque at the center axis of a blade?

How do I calculate the moment/torque at the center axis (same plane with lift and drag force) of a blade with NACA airfoil standard when it is placed inside a wind tunnel or exposed to airflow?
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2answers
190 views

Why the Mig21 don't use the ailerons like control surfaces on delta wings at landings or take off?

Mig21 is a delta wing , so why do not use the ailerons like any other delta's ? For lowering the approach and touch down speed. It is not possible that?