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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Do tufts show boundary layer flow or outer flow?
Outer flow and boundary flow are often different.
Do tufts at the wing surface show boundary layer flow or outer flow?
Picture source.
Paint shows boundary layer flow.
Picture source
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Landing gear drag and weight calculations
I have read numerous books and researches, but I couldn’t find any formulae that actually work for how to calculate the following (for commercial aircrafts):
1- Drag coefficient for a retractable ...
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Why do helicopter performance charts for hover out of ground effect (HOGE) have a "knee"?
Have a look at the following performance charts from Section 5 of Robinson R-22 Pilots Operating Handbook for hover out of ground effect (HOGE). If the temperature and gross weight are known, the ...
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What is this phenomenon and why does it happen? [duplicate]
I captured this phenomenon occurring on a recent flight trip during the landing. I'm not sure why it happens or what it's called, but I thought it could be some form of condensation. I came across the ...
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Why do modern turbofans have swept blades?
(Picture sources: CF6 and GE90)
Aircraft have swept wings for two reasons:
It reduces the thickness-to-chord ratio of the effective chord, which is ideal for flight at higher Mach numbers.
At ...
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Why do helicopters experience a brief dip in altitude during IGE marginal power takeoffs?
The scenario is this: A helicopter is hovering IGE, and executes a marginal power takeoff. What causes the dip in altitude that occurs around 10 knots during the takeoff?
Most pilots seem to describe ...
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The Aim 9 missile mounted on the left side spin in the same direction as right side mounted after launching?
When the AIM 9 sidewinder missile is fired the spin is in the same direction?
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How to calculate wing upwash angle?
How can I calculate upwash angle(alpha u) at the wing? I notice at every position upwash angle is different, which angle is chosen as the reference upwash angle?
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What limits maximum Cl of wing with active jet blowing ("Blowing BLC")?
Maximum lift coefficient of wing (single-element or multiple-element) without suction or jet blowing are limited by boundary-layer separation(flow separation).
Wings that use jet blowing for boundary-...
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Does climbing or descending affect the rate of turn?
In the past, I used to have this idea that if all other factors remain constant, then climbing increases the rate of turn while descending decreases it. This idea was most likely planted into my mind ...
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How is blended winglet better?
*Make sure to read the following as I cannot explain my question in one sentence
Winglets are a kind of wingtip device that is installed on an aircraft to reduce drag and improve fuel efficiency. ...
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Under what conditions do airplanes stall? [duplicate]
I've seen somewhat conflicting information on when planes stall. I've seen references to "stall speed," apparently a speed below which the airplane will stall, but stalling also seems to be ...
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Can wingtip vortices formed around an unswept wing produce vortex lift?
Vortex lift is a kind of aerodynamic lift force due to vortices formed along the leading edge of highly-swept (usually 60 degrees of swept angle or higher) wings at high angles of attack. The "...
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Would the dle 55ra engine be enough to power my paramotor(ducted fan)?
I plan on using the dle 55ra engine to produce 5hp at 8,500 rpm. I am using it in a paramotor, and to save space I am considering using a ducted propeller similar to the Fulcrum power pod. The duct ...
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What is the glide ratio of the Ozone Mojo Power 2?
The ozone mojo power 2 is a paramotor wing aimed towards beginners. I am interested in purchasing it, however I have not found any data on the lift to glide ratio. Does anybody know this info?
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What was the Vbg and glide ratio of the Rutan VariEze and the Beechcraft Starship?
These pusher designs were marketed featuring high cruise efficiency.
No doubt the pusher configurations offered advantages in propulsion efficiency and cabin comfort, but how did this compare to ...
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If induced drag is caused by the downward deflection of the air streaming around the wing,why airfoil(that also deflect air down) has induced drag=0? [duplicate]
In this site induced drag is often explain as downward deflection of the air streaming around the wing.
Airfoil (2D) also deflect air downward(otherwise it would not produce lift), why then airfoil ...
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Is induced drag zero for finite wing with constant lift distribution (dΓ/dy=0)?
Part 1
Observing how induced drag is derived, induced drag is loss of kinetic energy due to total vorticity that is produced by wing.
I want to find induced drag of finite wing with L=const over span.
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In a CFD simulation the wingtip vortexes gets reduced/cancelled by means of Wingtip End Plates- if this is true is it then useful?
I am just working on a special kind of wing and I do named it a Transformer Wing.
The transformation is about the wing camber.
The main requirement of the project is that the wing is to be not ...
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Does the rotation direction of intermeshing rotors have any noticeable effect?
Consider the Kaman K-Max, which has intermeshing (side-by-side) rotors that rotate as indicated below (when viewed from above, the rotor on the right (green) rotates clockwise, the left one (red) ...
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Why does the helicopter Robinson R22's rotor blade have flat part as in the picture? What is it for?
Picture source:
Picture source:
This is Robinson Helicopter R22's rotor's blade. What is this flat part for as indicated by the red line? What is the aerodynamic benefit of putting it? There are many ...
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Why do airplanes usually pitch nose-down in a stall?
Why do airplanes usually pitch nose-down in a fully-developed stall?
I've seen this seemingly-simple question discussed on other aviation forums, but there doesn't seem to be a single agreed-upon ...
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location of aerodynamic center at hypersonic speed?
as we know , at low subsonic speed the aerodynamic center is located at 25% of chord line and for supersonic flow it lies at 50% of chord line. what about hypersonic speed? is it moves further aft?
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Does Navier-Stokes "recognize" existence of induced drag, can we get induced drag from them?
"Early aerodynamic mathematical methods rely on potential flow concepts that formally isolate aerodynamic drag into a profile and an induced drag component. The more recent evolution of Navier–...
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Does wing really "feels" effective airflow or it is just theory to fits numbers with experimental results?
Theory predict downwash that will cause reduction in airflow angle,this we call effective airflow.
Does wing of aircraft during flight really "feels" this effective airflow or this is just ...
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Why does a paraglider not need a vertical stabilizer
I am looking at a question I found in the internet: why can a paraglider fly without a tail rudder and elevator assembly whereas a normal fixed wing aircraft can't?
One part of the answer is , the ...
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Is effective AoA increased at wing in ground effect?
Some ground effect theory explain increase in lift with reduction in downwash,which cause increase in effective AoA.
One theory mention only increase in static pressure under the wing "cushion ...
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What are the type of airfoils being used in Russian fighter?
I've tried to search for airfoils that are being used for Russian fighters such as Su 27/ 30/ 35 and MiG 29 on the internet, but it seems that this type of information is classified. What type of ...
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Dynamic pressure limit of Concorde
What is the maximum dynamic pressure The Concorde could achieve without disintegrating? How does Mach number affect it?
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How does pressure distribution change when a wing enters ground effect?
How does ground effect change the pressure coefficient distribution over the top and bottom sides of a wing?
I want to compare the diagram of pressure coefficients vs percent chord length for wing in ...
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How does an aileron actuator work considering the following?
My question is how does an aileron work considering it rotates around a fixed point and the actuator arm moves in a straight line. If what is shown in the first picture I have provided is true, then ...
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Difference between the lift coefficient of the wing-profile and the wing
Let $ c_l $ the wing-profile lift coefficient and $ c_L $ the wing lift coefficient. For small values for the angle of attack $ \alpha $ both coefficients are linearly approximated:
$$ c_l(\alpha)=C_{...
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Explaing lift tilt back in induce drag pictures?
This is usual induced drag diagram.
What is black vector in diagram below?
If it is lift you cant decompose lift in lift(L in diagram) and induced drag (Di), this you can do only if this is resultant ...
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Does induced drag of wing change with speed for fixed AoA?
In wind tunnel we put 3D wing at fixed AoA, then tested at two different subsonic airspeed.
At higher speed, wing will produce more lift and more overall drag.
Will induced drag also rise at higher ...
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Can weight reduce a plane's glide ratio?
The FAA says glide ratio doesn't change, regardless of weight, here on page 5-7.
Glide ratio is not affected by weight because,
while a heavier glider sinks faster, it does so at a greater
airspeed. ...
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Do trailing edge vortices exist in reality? [duplicate]
Please don't talk about wing tip vortices and leading edge vortices(vortex lift)
Is it possible to see trailing edge vortices in real life, do they exist in reality?
How looks air in wake between ...
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Why I cant see this downward movement infront wing which reduce effective AoA, (I see only upwash)?
Circulation theory predict downward airflow that reduce effective AoA,which cause induce drag.
To change effective AoA this downward airflow must be infront of wing, to "hit" wing with ...
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Is increase in lift allways follwed by increase in drag and vice versa?
We look at lift,drag and L/D at multi element wing with slots and same wing shape just without slots.
wing without slots:
Completly top side is stalled, so here is all low pressure(blue at picture),...
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How deliberately stall fixed wing reduce drag if stall decrease static pressue? [closed]
In this VIDEO at 5:40 we can see how stall decrease pressure at upper wing surface.
If stall/flow separation reduce static pressure how in this VIDEO they reduce drag when stalling the wing?
Here is ...
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How is lift produced when the aircraft is going down steeply?
If a positive angle of attack (AoA) is needed to produce lift, then how is it created when a plane is in a 30 degree nose low dive?
How does it not stall? At this attitude the AoA has to be negative, ...
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Does Cd number change at different speeds during wind tunnel testing?
When meassure Cd or Cl of airplane/car in wind tunnel, does number change at different speeds, for example at 100km/h compare to 250km/h?
If yes,how much?
I know from theory that coefficents change ...
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Is the steep spiral maneuver criteria in the FAA Commercial ACS Flawed?
The Commercial ACS steep spiral maneuver calls requires a pilot to fly a descending spiral with power set to idle and maintain a constant radius around a point. The maneuver is supposed to be flown ...
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How does camber location (xf/c) affect Cl max and stall angle of an airfoil [duplicate]
I'm trying to compare 4-digit airfoil and 5-digit airfoil about the effect of camber location towards Cl max and stall angle.
Is it correct if i assume the higher the camber location value the Cl max ...
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is aircraft weightless during vertical climb?
in vertical climb , if velocity is constant (no acceleration) the pilot feels 1g gravitational acceleration that is equals for crusing flight. but in vertical climb lift must be zero so load factor is ...
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load factor in high altitudes
if load factor equation is lift devided by weight , so in very high altitude for example 1000 km above the earth atmosphere, there is no air to produce lift so load factor is zero but in newton ...
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Why does my paper airplane with the ailerons configured to make it spin fly straighter than with them configured for straight flight?
I made a paper airplane with a standard design, except I cut out the back ~2 cm of the body, leaving ailerons on the wings. If I throw it with the ailerons straight, it doesn't fly very far and turns ...
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Area under curve lift vs angle? Any significance?
I'm looking at AOA vs Cl graphs and comparing low AR vs high AR curves. What does the area under the curve mean? Thank you
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How are canards designed to stall before the main wing?
I understand that aircraft with canards are designed so that they pitch down when at a high angle of attack. The canard is designed to stall before the main wing, thus the canard produces no lift ...
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What airfoil parameter should I focus on to achieve the maximum service ceiling?
I am working on a design competition project where I have to design a low subsonic aircraft for high altitude performance.
From what I have studied service ceiling will depend on excess power ...
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Estimating Moment Coefficient about Aerodynamic Center for wing-body combination
Are there any references or analytical methods to estimate the moment coefficient about the aerodynamic center, C_M,ac for a given wing-body combination? Even something rough would be useful such as &...
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