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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What differences would a helicopter designed to withstand many negative Gs have compared with a normal one?
There are a few helicopters that are able to take negative G's, and to this day only one can actually perform aerobatics (ie. Chuck Aaron's BO-105). The BO 105 is a rigid rotor helicopter that has ...
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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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What are the effects of a corrugated surface on spanwise flow deviation, for a swept back flying wing?
Considering a Ju-52 wing in some hypothetical swept back flying wing configuration using the same strucural design as the Ju-52.
What would be the effects of that corrugated skin, regarding spanwise ...
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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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Pitching moment due to control surface deflection
How can you predict the change in lift and pitching moment produced by control surface at a certain deflection angle?
I am aware that the effectiveness of the control surface is affected by ...
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How many versions of the P-51 dorsal fin fillet are documented?
How many different versions of the P-51 Mustang DFF are there?
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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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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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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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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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How do coefficient of lift/drag variation with speed differs between swept and unswept wings?
Trying to understand the coefficient of lift/drag of swept and unswept wings as speed increases. Some example questions and statements-
A swept wing will have a lower max Cl at subsonic and ...
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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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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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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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What happens to the pressure differential of airflow under and over the wing as the critical angle of attack is reached?
I've been doing a research project for mathematics which involves calculating the relationship between lift and angle of attack. While this may seem pretty easy, it's not for a 12th-grade student like ...
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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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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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Why does Vx have a relationship with thrust but Vy has a relationship with power?
https://www.boldmethod.com/learn-to-fly/performance/vx-vy-altitude-and-where-they-meet/
After I watch this article, now I understand the relationship between altitude and the rate of climbs.
But I ...
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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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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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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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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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Why is more angle of bank (AOB) at the best gliding speed giving less altitude loss?
Reading the manual for the T6b (turboprop aircraft single engine), it says different altitude losses during a 360 degree turn, holding 125 kts (the best glide for range speed), power is either dead, ...
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Can the use of flaps reduce the steady-state turn radius at a given airspeed and angle of bank?
Note that for the purposes of this question, I am only interested in the scenario described below. By 'steady-state' I mean to exclude from consideration the short-term effects of changing the flap ...
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By aircraft design, excluding engine power, how do you make planes that have a tight turn radius while maintaining speed?
What are all factors in design, excluding engine power and acceleration, thrust vectoring and flight computers, that makes a plane that have a real tight turning radius while maintaining speed? Like ...
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How to calculate angular velocity and radius of a turn?
How can I calculate with known tangents of different angles and by rules of thumb?
Which formulae should I use for fps and NM?
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Oswalds efficiency factor for trapezoidal wing
For a part of my university project we have to approximate 2d to 3d data ideally using oswalds efficiency factor, the equations given to us are for either rectangular or swept wings however the wing I ...
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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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How do uncoordinated turns (skid, slip) affect a helicopter's turn radius?
Is a helicopter's flight path (track made good) an arc of constant radius regardless if it's a coordinated or uncoordinated turn? (Assume nil wind conditions and that the pilot maintains the angle of ...
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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 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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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 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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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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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 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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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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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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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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Do airliners stall first at the wing tip?
One of the disadvantages of the sweepback aircraft is the tendency of a stall to occur at the wingtip first. Various high lift devices are added by design to the wings of the sweepback aircraft like ...
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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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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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Does CG change airspeed in a descent or glide?
If the CG of an airplane moves forward, would it fly a faster or slower airspeed in a descent?
Usually during a descent or landing, you'd use pitch to change airspeed and power to control descent rate....
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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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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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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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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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