Questions tagged [aerodynamics]

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

100 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
5
votes
3answers
462 views

How to calculate lift and drag coeffecients for VTOL aircraft in the takeoff stage?

How would I calculate CL and CD for a VTOL aircraft while it is in it's takeoff/landing stage? The particular aircraft is a fixed wing/quadcopter hybrid so I know that I can treat this as a thin ...
5
votes
2answers
448 views

How does an aircraft's weight affect the V-n diagram?

I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the ...
4
votes
0answers
133 views

How do active blades work on helicopters?

Can someone throw some light on 'active blades' as used in helicopters? I'm mostly interested in the use of piezoelectric material and actuators. How are the actuators able to sense the change of ...
4
votes
0answers
190 views

Has there been any research on plasma-producing planes?

Many years ago I read in an expository scientific journal[1] an article about what the future of high speed aviation could be. It said that there were studies on airplanes capable of "plasma-izing" ...
4
votes
3answers
143 views

How changes in Air masses, Air flow direction and intensity affect lift?

I have a question regarding the airflow an aircraft experiences during 3 distinct scenarios: An aircraft during landing, experiencing a sudden gust of 40 knots from the tail. What would be the ...
3
votes
0answers
70 views

Do contra-rotating props have worse tip vortices than single props?

As I understand it, blades from a propeller have their own tip vortices, because the blades produce lift via the same aerodynamic principles as wings. So they must have tip vortexes too. So with ...
3
votes
0answers
571 views

How to properly implement and understand Theodorsen's function?

I'm attempting to implement Theodorsen's lift deficiency function for an airfoil experiencing a harmonic variation in angle of attack due to an oscillating freestream (i.e., not pitch oscillations). ...
3
votes
1answer
501 views

What is the constant in this formula for additional lift?

Let’s consider the case of a plane flying s/l in a headwind with a positive gradient. A wing produces lift by inducing a bound vortex superimposed on the relative wind., and in the particular case of ...
2
votes
0answers
25 views

Why is hybrid laminar flow control preferred for swept wings over other options?

As I understand it, a (the?) major form of laminar-to-turbulent transition on the swept wings of large jets is the crossflow caused by the sweep. One way to control this is laminar flow control by ...
2
votes
1answer
94 views

Would plain and slotted flaps increase lift substantially in a distributed propulsion application?

Would plain and slotted flaps increase lift substantially in a distributed propulsion application for a slow moving aircraft (15mph)? I understand that: A classic NACA foil without flaps such as the ...
2
votes
0answers
70 views

Can free flying twin drag rudders be mounted on a stabilator, aerodynamically speaking?

Can free flying twin drag rudders be mounted on a stabilator on an ultralight, aerodynamically speaking, or would it be disadvantageous? I understand free flying rudders need up to 40% less area than ...
2
votes
1answer
109 views

What are the standard stability derivative formulas and typical GA values?

What are the standard stability derivative formulas and typical GA values? I suppose values for the C172 would be the best benchmark.
2
votes
3answers
647 views

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 ...
2
votes
0answers
216 views

Are there any airplane designs that are (relatively) insensitive to the effects of airframe icing?

Snow and ice buildup on airplanes (especially the wings) is a well-known and feared hazard of cold-weather operations; it roughens the surface of the wings and changes their profile, which combine to ...
2
votes
0answers
257 views

What Inertial effects should be considered to achieve blade stability on a Variable Pitch Propeller tailoredby aerodynamic loads?

I am developing a self adjusting variable pitch propeller tailored by its pitching moments due to aerodynamic loads setting the blade rotation axis in an offset from the aerodynamic center as shown ...
2
votes
0answers
249 views

Determination of a Joukowski airfoil chord (demonstration)

I'm currently studying Aerodynamics, and one thing that I noticed is that the maximum and minimum $x$ coordinate of the airfoils (which are necessary to compute the chord) on the transformed plane (...
2
votes
0answers
314 views

Where can I find information on dethermalizer aerodynamics?

A dethermalizer is a device that alters the aerodynamics of an airplane, glider etc, allowing it to descend quickly. Are there any sources - including equations and derivations - on dethermalizers, ...
2
votes
0answers
1k views

How does corrugated skin influence the effectiveness of ailerons?

Recently I found a paper about incorporating corrugated skins in aircraft called 'Corrugated composite structures for aircraft morphing skin applications' by C. Thill, J.A. Etches, I.P. Bond, K.D. ...
2
votes
0answers
511 views

What orders of Ram Rise Coefficient (Recovery Factor) are commonly encountered?

The answer to the question about OAT, RAT, TAT, and SAT has the following: Problem is, not all instruments will compress that air in the same way, and not all of them will pick up this Ram Rise ...
1
vote
2answers
68 views

Sub-ideal Autorotation in Rotorcraft

I have another AuRo question for you. When a Helicopter autorotates (ideally) it is in the turbulent wake state and there is virtually no flow through the rotor disk (figure of Leishman attached). Now,...
1
vote
0answers
85 views

Volume of air deflected down by a wing?

When trying to calculate, from first principles, the lift produced by the rotor of an autogyro, I have tried imagining the rotor as a circular flat wing set at an angle to the relative wind. The mass ...
1
vote
0answers
71 views

Is “V/n” geometric or effective pitch in advance ratio formula?

V is the freestream fluid velocity, typically the true airspeed of the aircraft or the water speed of the vessel n is the rotational speed of the propeller in revolutions per unit of time D is ...
1
vote
0answers
37 views

In a gyroplane, how can the angle of attack of the rotor disk be calculated?

In a gyroplane, how can the angle of attack of the rotor disk be calculated as a function of the relevant variables? Those 'relevant variables' are the rotor's angular velocity, the aircraft's ...
1
vote
0answers
41 views

Does momentum theory include deflected slipstream thrust lift at high alpha?

Does momentum theory include deflected slipstream thrust lift of a wing at high alpha? I understand that momentum theory calculates lift due to the angle at which the air is "turned" over ...
1
vote
0answers
65 views

Why does drag coefficient decrease with Mach number in the supersonic regime?

I'm trying to understand why the drag coefficient decreases in the supersonic regime with Mach number. While it is easy show this using supersonic, potential flow theory, I'm looking for a more ...
1
vote
2answers
92 views

Why doesn't a wing in supersonic flow produce a shock that results in flow parallel to the leading edge?

When we look at a wedge in supersonic flow, a shock emanates from the leading edge such that the flow after the shock is turned and is parallel to the airfoil surface. The shock angle is based on the ...
1
vote
1answer
110 views

Does the strength of a wingtip vortex generated by an airfoil peak at the critical angle of attack?

I know that generally, wingtip vortices increase in strength as the angle of attack increases. Is the critical angle of attack/Cl Max the peak strength, or do the vortices generally continue to ...
1
vote
0answers
60 views

Is it true that blowing cannot be used for laminar flow control? Why?

Aerospace Engineering Desk Reference, page 505 Tangential blowing can only be applied to the prevention of separation...The flow caused by blowing tends to be very vulnerable to laminarturbulent ...
1
vote
1answer
174 views

How to find the static stall angle of attack for a given airfoil at given Re?

For vertical axis wind turbines applications I'm wondering how one would find the static stall angle of an airfoil at a given Reynold number? Is it just the critical angle of attach (AoA) where ...
1
vote
0answers
21 views

Are there polar plots and airfoil data points available for the RAF4?

Are there polar plots and airfoil data points available for the RAF4? I understand this is the airfoil used for the horizontal stabilizer of the Zenith 701, which should be similar to a NACA4412 ...
1
vote
0answers
81 views

What factors/equation(s) are used to relate aircraft weights and cruise speeds?

With the recent coronavirus issues, there have been lots of empty seats flying around, especially on long haul flights. I checked the seat map for a recent SFO-SYD flight (777-300) and there were 224 ...
1
vote
0answers
106 views

Carpet Plots for Aircraft Sizing

Generally, Carpet Plots are constructed to find out an optimal design which will satisfy all the performance needs and is least in weight & cost. I want to know how to construct a carpet plot? I ...
1
vote
0answers
61 views

Is there any bibliography for triplane aircraft design?

I've been tasked with designing an RC aircraft that has the greatest lift force for a specified wingspan, total length and takeoff velocity, and thus have been studying the different wing ...
1
vote
0answers
39 views

What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
1
vote
0answers
140 views

If props throw air outwards, why do some prop diagrams show a reduction in airstream diameter behind the prop disc?

If props throw air outwards, why do some prop diagrams show a reduction in airstream diameter behind the prop disc, or are these velocity vectors? Diagram showing airflow outwards as shown on nap.edu ...
1
vote
0answers
141 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 ...
1
vote
0answers
335 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?
1
vote
0answers
30 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?
1
vote
0answers
76 views

Why the lift and drag coefficients for the simulations differ from the experimental value?

I am doing CFD simulations for NACA Airfoil 2415 using K-Omega SST model on ANSYS fluent. I am using an tetrahedral unstructured mesh with 20 Inflation layers on the wall. I have been comparing my ...
1
vote
0answers
90 views

How to choose an angle of incidence?

How to choose an angle of incidence? Looking at typical airfoil polars, it seems most classic NACA GA wing airfoils like the NACA2415, have similar properties: A max Cl/Cd at about 5-7deg Lowest ...
1
vote
0answers
44 views

Do open propellers experience pre-entry drag (additive drag) like an engine in nacelle?

Engines in a nacelle experience pre-entry (also called additive) drag. Do unducted propellers experience it too?
1
vote
0answers
111 views

Is there a relationship between 2D airfoil aerodynamic results and a revolution body from that airfoil?

The airfoil would be symmetric and the axis of revolution would be its chord line. Edit1: To clarify the question, suppose we have a NACA 0010. Then, using for example XFoil, I'm able to get, for ...
1
vote
0answers
87 views

Compute Thrust from RPM and Induced Velocity

I'm attempting to calculate the difference in thrust in a secondary propeller operating in the wake behind a primary propeller, in the context of a trailing quad-copter following a leading quad-copter ...
1
vote
0answers
136 views

What are the effective span and lifting properties of a circular wing?

Today I read an article on FlightGlobal about the Bell air taxi demonstrator. It includes some paraphrased quotes from the Bell VP of innovation, Scott Drennan, among which the following stood out: ...
1
vote
0answers
508 views

What is the relationship between the Center of Pressure and flap deployment?

I have been reading regarding the Center of Pressure of an airfoil (Cp) and the relationship with angle of attack. What is a good way to explain in layman's terms why the pressure changes in such a ...
1
vote
0answers
80 views

What is subcritical and supercritical boundary layer?

What is subcritical and supercritical boundary layer? What is the difference between them?
1
vote
0answers
248 views

How to transform a NACA airfoil into a near-circle using the inverse Karman-Trefftz?

Is there anyway to find the leading-edge's center of curvature of a NACA Airfoil? I'm trying to transform a NACA airfoil into a near-circle using the inverse Karman-Trefftz transformation. the ...
1
vote
0answers
100 views

How much lift can be generated by the intake lip of a duct?

How to calculate the extra lift gained by the intake lip of a duct? Aside from improving efficiency by preventing tip vortices, if a duct has a bell-shaped intake, this lip around the edge creates ...
1
vote
0answers
86 views

What does “lower flatness” mean in airfoil terminology?

What does lower flatness mean in these parameters of a Glenn Martin airfoil?
1
vote
0answers
475 views

What aircraft has the highest critical Mach number?

What aircraft has the highest critical Mach number? The highest I heard of was BAC/English Electric Lightning at Mach 0.95. Are there planes with higher Mcrit. and is it plausible to go higher than ...