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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Is there an aerodynamic reason for airship fins to be at the tail?
I've read this interesting Stack Exchange question about why airships have fins:
Why do blimps have fins?
Which has me wondering why the fins are almost always located in the tail section.
After some ...
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How does drag change efficient cruise conditions?
If I have an aircraft, and I reduce the induced drag produced by it, does this mean I should operate it at a higher altitude and faster speed to take advantage of the drop in total drag, or slower at ...
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Does AOA become 0 after the aircraft flies in a particular attitude for sometime as the relative airflow has changed and how does it affect Stall AOA?
As AOA is the angle between relative airflow and Chord Line. Then after you increase the angle of attack and fly at that angle of attack for some amount of time and the relative airflow changes ...
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why lift coefficient decreases at supersonic flow?
In Anderson's performance book, he wrote that the higher the speed, the greater the pressure difference between two points, and as a result, the lift coefficient is greater.
But when we reach the ...
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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 ...
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Where does the main CoP move when deflecting the elevator up & down and trimming?
I recently asked a question and in the comments I got this response
"The CP changes with angle of attack, so it is not a useful point in terms of stability. The NP does not change with angle of ...
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Is turbulence a random process?
Is turbulence in air/fluid a random or a deterministic process, and why is it so hard to solve?
For sure if it is random it can't be solved...
Or maybe it just appears to be random because of our lack ...
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Why does a lower chord length reduce the pitching moment?
I've heard that higher aspect ratio wings (also lower chord length wings) are more stable and less maneuverable. Why is that?
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Why doesn't more resistance lower on a plane (or higher), for example an airbrake sticking way down, make the plane have a pitch down moment?
What initially sparked my question is when I saw the Redbull plane swap stunt, where there was an airbrake deployed on the bottom of the plane. Why wouldn't this cause there to be more drag lower down ...
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What velocity is used to calculate maximum range and maximum endurance?
These are my data;
$C_{L_0} = 0.4$
$C_{L_{\alpha}} = 5.7$
$C_{L_{minD}} = 0.14$
$C_{D_{min}} = 0.022$
$k = 0.035$
$\alpha_{stall} = 15$
$S_{ref} = 20m^2$
Mass Data
$W_{total} = 2500 \text{ kg}$
$W_{...
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How does the Boeing TTBW reduce fuel consumption?
Compared to a traditional airliner wing, the Boeing TTBW showcases a much longer wingspan and an associated higher aspect ratio. Intuitively, this seems to reduce fuel consumption by lowering induced ...
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Can vortex ring state (VRS) be solved by shaping the blades so that the vortexes they produce are weak enough not to form a vortex ring?
Vortex Ring State is one of the hazardous states a helicopter can find itself into. VRS happens when a helicopter has low airspeed (and usually hovering OGE) and is descending. If the helicpoter is ...
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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 ...
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Would a winglet be able to work in supersonic airflow? [duplicate]
Of course, there is a reason why existing supersonic airplane designs do not use winglets in the same way that an airliner wing uses winglets. I imagine the parasite/wave drag penalty from a winglet ...
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Are there fixed wing planes that have a Vne above their terminal velocity with the nose pointed straight down?
Are there any fixed wing aircraft that will not exceed Vne if they are taken to their ceiling, engine is pulled to idle or shut down, and then the nose is pointed straight down? Lets assume they are ...
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Can the use of wide-chord supercritical airfoil blades in a helicopter with coaxial counter-rotating rotors solve retreating blade stall?
The problem with retreating blade stall is that it limits the VNE and the overall top speed of helicopters. Retreating blade stall is basically the tip of the retreating blade having too much AoA at a ...
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Delta wing RC aircraft unstable
I've been building and testing an tailed delta wing'd RC aircraft, but it has seemed that the plane is extremely pitch happy and tends to somersault when at high speed, is there some type of easy fix? ...
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Wing incidence angle of tandem wing aircraft
I'm trying to design a tandem wing model aircraft with both wings with the same wingspan. The front wing will have 2 and the rear will have 1 deg of incidence angle, also the front wing will have ...
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If you could put multiple smaller ejector pumps in the same space, would it work better than one larger ejector pump?
I saw somewhere how, for Dyson bladeless fan systems to work for hovering, you'd need an entire grate of ejectors rather than a single ring. However, if you had five ejectors in the same space, each a ...
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Is it feasible for an individual with limited current knowledge to undertake the development of an aircraft from scratch? [closed]
The world of aircraft engineering is truly remarkable, and even the smallest components involve a wealth of knowledge. I'm eager to explore this field and embark on the journey of building an aircraft....
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What open-loop control inputs can guarantee non-divergent descents in fixed-wing aircraft?
(Inspired by What's the best way to get through clouds when not instrument rated? which has at its heart a good question, but isn't getting good answers because everyone is jumping on the "...
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How to slow down while maintaining altitude
Is reducing throttle/power already enough? Or do I have to adjust the pitch as well? If so, I suppose pitching up as well? If pitching up is needed as well, is it because as speed decrease, there is ...
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How to calculate lift and drag coefficients of an airfoil with slotted flaps?
I am doing a project attempting to determine the increase in lift and drag coefficients of an airfoil as the angle of its flap increases. In my research, I have found the thin airfoil with flap ...
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General Thin Airfoil Theory
I can't understand where the equation in the blue circle comes from or is derived from, I know it says the sum of the perpendecular components should be zero, but can you explain visually? and what ...
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Why does a flat plate create less lift than an airfoil at the same AoA?
This picture of the lift curve slopes for four-digit NACA airfoils and a flat plate is from another question on this topic. It shows that at the same positive AoA, a flat plate generates less lift ...
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Confusion about center-of-lift vs center-of-gravity [duplicate]
As usually depicted, in a small aircraft (maybe larger commercial ones too), the lift due to the main wing (excluding the elevator) is depicted as on average aft of the center of gravity, with the ...
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Ram Rise and Total Air Temperature explantation [duplicate]
Since ram rise is the same as total air temperature, why does Total Air Temperature minus Static Air Temperature give ram rise? What is really the meaning of ram rise: is it the kinetic components ...
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How do swept back wings delay shock wave
Swept back wings can delay the formation of shock wave and increase the aircraft critical mach number of the aircraft, right? But how
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Why does a rectangular wing stall at the root first?
Study of countless aerodynamic questions and answers on this site has reshaped my understanding of both lift and and induced drag.
Questions like this: How does an aircraft form wake turbulence? have ...
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Spanwise location of mean aerodynamic chord for Swept Wing
How would I calculate the spanwise location of the mean aerodynamic chord for a swept wing?
I see a general formula for an elliptical planform wing, but having trouble finding anything on swept wings.
...
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Do you pitch the nose up or down when flying at best glide speed during a glide
So in a glide, flying at the best glide speed, will you be pitching the nose up (nose points above the horizon) or pitching the nose down (nose points below the horizon) or does it depend?
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Is more rudder pressure needed in gliding turns than normal turns
The FAA Airplane Flying Handbook says
the rudder compensates for yawing tendencies when rolling in or out of a gliding turn; however, the required rudder pedal pressures are reduced as a result of ...
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Should I advance my propeller lever forward during a glide?
I am reading the FAA Airplane Flying Handbook, chapter 3. It says:
To enter a glide, the pilot should close the throttle and, if equipped, advance the propeller lever forward. (...)
Why do we ...
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How is Vx speed and Vy affected when climbing?
If my speed for best angle of climb is 60 and rate is 79, if I kept a 500 fpm climb to my cruise altitude of let’s say 4500, would those speed change?
The flights are being done on separate occasions.
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Why the heavier the aircraft is, the higher the airspeed must be to obtain the same glide ratio?
I know weight does not affect glide ratio. But why does higher weight need higher gliding speed?
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FAA's Airplane Flying Handbook says more lift is necessary during a climb. Isn't it the opposite? [duplicate]
"If a climb is started from cruise flight, the airspeed gradually decreases is the airplane enters a stabilized climb attitude. The thrust required to maintain straight-and-leve flight at a given ...
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Is more lift needed for a stabilized climb [duplicate]
First, the photo depicts a vector diagram during a climb. L means Lift. Lv means the vertical component of lift. Lh means the horizontal component of lift. T means Thrust. D means drag. W means weight....
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Can I climb with no excess thrust [duplicate]
I've been searching on the internet about this question and all say you are not able to climb with no excess thrust. But I am wondering that if I have no excess thrust, can I still climb in exchange ...
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Cause of Drag From Windmilling
I know that when a propeller is windmilling it creates drag, I assume this is from the propeller being flat against the air causes drag, but propellers are designed to essentially pull an airplane ...
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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 ...
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What are some of the advantages of inverse-tapered wings?
Inverse tapered wings are rarely used in aviation. The only legitimate plane I know about with inverse-tapered wings is the XF-91 Thunderceptor. So why aren't they used. What are the disadvantages of ...
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Does the X-59 comply with the "area rule"?
The Lockheed Martin X-59 was rolled out yesterday :-)
Brett Tingley, Watch NASA's sci-fi-looking X-59 'quiet' supersonic jet roll out of the hangar, August 2023.
I am no expert here (and no English ...
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Did the dog-tooth notches in the wing of the F-8 Crusader really have anything to do with "yaw stability"?
What was the real function of the "dog-tooth" notches in the leading edge of the wing of the Vought F8U crusader?
Wikipedia says:1
Vought's design team... produced... a relatively ...
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How to Define Aerodynamic Center for Real-World Airforil?
When using thin airfoil theory, there exist a point that the moment about this point does not vary with Cl, which is the aerodynamic center.
However for most of the real-world airfoils, Cm does vary ...
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How do I plot Cd vs Re graphs for an airfoil?
I am looking for a platform where I can plot the value of the drag coefficient of an airfoil for a range of Reynolds numbers (Cd vs Re plots). I wish to analyze the trend of Cd with changing Re and ...
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What is the formula used to display energy markers on HUD?
I would like to know what is the formula used to display energy markers on the head-up display (HUD) of fighter aircraft. Does it consist of Mach number or TAS or CAS?
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Helicopter induced velocity
I found this on one book I am now reading, and I dont uderstand how induced velocity is decreasing whyle climbing? And what is the difference between induced velocity and inflow velocity ?
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How to calculate and understand glide distance?
How would I calculate my glide distance?
If I am at 8000 feet would I multiply 1.5 by 8 because the ratio is 1.5 NM per thousand ft?
Which would be 12 NM
Also where did a ratio of 9:5 come from?
I may ...
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Textured Spray Paint for Promoting Turbulent Flow
I'm looking for textured spray paint to apply on my RC model to ensure turbulent flow on a few of the smaller aero surfaces.
Does anyone have any experience doing this and have any recommendations on ...
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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 ...
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