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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Does the reduced aerodynamic damping at higher altitudes affect the Vno (maneuvering speed) of an airplane?
Since reduced aerodynamic damping at higher altitudes reduces the needed control input for maneuvers, is this just about the required force to move the controls or also about the speed of the ...
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Why and when to use flaps?
On a commercial airliner, what is the purpose of the flaps? I understand that depending on which direction they move in, they can be used to decrease airspeed, but I don't know when flaps are used. ...
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Why aren't thin, delta-shaped wings used for fighter aircraft?
In the past, we used thin, delta-shaped wings (ogival wings) such as those on the Concorde.
These wings can be used up to mach 2.2. Due to high fuel consumption, these wings are no longer used ...
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Lateral Aerodynamic Derivatives from Digital DATCOM
As far as I know the Digital DATCOM can be used to estimate longitudinal aerodynamics by varying the angle of attack. Does it have the capability to vary sideslip angle for lateral analysis? and How? ...
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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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Do helicopters use more fuel when hovering?
This answer says
A helicopter uses a LOT more fuel hovering than it does in forward flight.
Is this correct? Why?
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What is the most efficient way to reduce interference drag when surface imperfections are unavoidable?
Interference drag can start to appear when there’s imperfections or excrescences on an aircraft outer surface. For example the following image shows some of these typical imperfections:
Source of ...
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If a hot air source was added to the wingtips, would it help control the formation of wingtip vortexes?
Let's say that somehow, an engineer made an exhaust pipe that constantly sprayed hot air at the wingtips in order to help control the formation of less turbulent wingtip vortexes.
Would that have any ...
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Are Foward Swept Wings for a Rear Propeller Airplane Feasible?
Would going with a forward swept wing design, with the same cord and length of the "A Wing", bring more air the the propeller and tail to increase range, power, or stability?
Consider the ...
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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 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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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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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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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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Aerodynamics moment of a wing
An old flight book that I am reading discusses the aerodynamic moment about a wing and talks about an upper and lower lifts. I can see how the pressure distribution on the top surface produces an ...
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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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Change of absolute ceiling with weight
Let's say an aircraft has an abs ceiling of some value at the start of its cruise and then it consumes some percentage of its fuel during cruise. How will this change the new abs ceiling at the end of ...
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What is the working principle of a Gurney Flap?
Recently I came across a airfoil improvement called a 'Gurney flap', see image.
I don't really understand the working principle of a Gurney.
Wikipedia states:
The Gurney flap increases lift by ...
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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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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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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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How do I calculate the center of lift?
See my other question here for the background context.
Consider this simple plane. I have applied the 4 basic forces: lift, drag, weight, and thrust. My question is, where, precisely, do I apply the ...
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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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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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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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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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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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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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Streamline Curvature Theorem applied to Airfoils?
I am new to studying aerodynamics and taking up aeromodelling and am currently learning how lift is obtained in-depth. When studying the two common explanations as to how lift is generated by an ...
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Why does transonic drag happen?
I have heard of transonic speed and it is between supersonic and not supersonic. What is it and why does it happen to aircraft and how does it produce a lot of drag. How do you prevent it from ...
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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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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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Can lift be created without air downwash?
I was looking at the great site code7700.com, but I don't really understand their explanation of lift and drag:
The so-called infinite wing
displaces air for a while, but the air particles return ...
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Does altitude affect glide ratio?
Lower altitude means higher air density, which means more liff, which means a glider can maintain a given glide slope at lower airspeed.
As a rule, aircraft tend to have higher peak L/Ds at low ...
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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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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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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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Is a winglet better than an equal span extension?
Is there indisputable evidence that a winglet improves performance over an equal span extension? Please note: I am only interested in L/D improvements.
Winglets do improve roll performance, that is ...
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What is the force to change the pitch of a variable pitch propeller?
At the moment I am struggling with the problem that I do have an idea how to calculate this force by using the blade element theory and going over a whole propeller blade in order to calculate the ...
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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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Definition of a Deep Stall
I've been doing some research for a uni assignment and I noticed that the RQ-11B uses a "deep stall landing" to get back onto the ground. What I don't understand though is how this aircraft gets into ...
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Are there cases where a double horizontal stabilizer is useful?
I was watching Agents of Shield recently, and in it the team fly a plane that's claimed to be a modified C-17 Globemaster. It has two extra engines, rotary turrets, and, according to the wiki, a pair ...
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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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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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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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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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Ground effect and Lift coefficient
Is there a correlation between the lift coefficient and the proximity between the wing and the ground? I know that the lift coefficient is dependent on angle of attack; However, based on experiments ...
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