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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23 votes
1 answer
3k views

How would a belt sander wing perform?

This is a theoretical question, the belt sander is an analogy to help visualize. How would a rectangular wing that is able to make its outer skin circulate around the airfoil perimeter perform? ...
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1 vote
1 answer
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Effect of Vortex Shedding in lift and drag coefficient?

I want to calculate lift and drag coefficient of a airfoil at multiple using CFD simulation. I am using steady state simulation to run analysis. However I am worried about results. Does steady state ...
-3 votes
4 answers
364 views

How can ground speed be higher than airspeed? [duplicate]

I've heard that ground speed is higher than air speed when the plane is being pushed by wind wind. But how is this possible? Wouldn't your AirSpeed also increase since you're going faster?
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-1 votes
2 answers
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Why airflow travels faster on upper wings?

I have been looking for solutions and come up with two popular explanations: Conservation of mass / Continuity For a positive-cambered wing, the streamlines would be compressed/converged at the ...
0 votes
1 answer
141 views

What is max angle of surface without stall?

AoA is by defintion angle between choord line and airflow, here is 25°. But max effective AoA here is 60°, so flow will separate for sure here.. What is max lets call it "effective AoA" that ...
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3 votes
3 answers
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Power calculation of propeller

This is probably a very simple question, but I have been really struggling and need your help. I have simulated a propeller with these parameters on Ansys: Thrust: 2000 N Angular Velocity: 314 rad/s ...
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10 votes
2 answers
469 views

Why is this angle of attack sensor tab not symmetrical between the leading and trailing edges?

Here is an Angle of Attack (AoA) sensor I took from here. If you are interested to know the AoA detail, just click the link. You may see what is inside it. But not sure what airplane's AoA sensor it ...
0 votes
3 answers
325 views

What is the AeroVironment Helios' Kármán line?

If it's true that the NASA/AeroVironment Helios maintained level flight 96,000 ft above sea level at a maximum airspeed of 23.5 kts (43.5 km/h) I assume it must have a very high Kármán altitude, the ...
0 votes
2 answers
263 views

How to calculate lateral velocity of a turning aircraft

An aircraft in a 45 degree banked turn has a horizontal lift force vector equal to the weight of the aircraft. Although the Coefficient of Drag is much larger for the aircraft profile, it seems there ...
-1 votes
1 answer
100 views

Effect of velocity of air on stagnation pressure

Why does stagnation pressure remain unchanged when velocity of air increases if the formula is: stagnation pressure = static pressure + (1/2×density×velocity$^2$)
5 votes
3 answers
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What is a spool in any jet engine, what is its funtion?

I am a student and I'm trying to determine how a spool works in an engine. What effect does it have depending on the number of spools on the performance of the engine? I tried to find it on Google but ...
3 votes
2 answers
184 views

Is a wing lift distribution smooth in the presence of a prop?

Wings designed to minimize induced drag have a smooth distribution of lift from root to tip. Whether elliptical for span constrained wings or more bell shaped to minimize structural weight, ideal ...
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5 votes
4 answers
746 views

Why does static directional stability decrease with altitude?

At constant CAS, high altitude means lower air density and therefore higher TAS: this decreases the aerodynamic damping during a rotation. For this reason, I cannot understand why directional ...
0 votes
0 answers
63 views

What is the effect of aspect ratio on cruise velocity?

Does the Aspect ratio affect the Maximum cruise velocity please? I was thinking it wouldn’t as Aspect ratio= b^2/S. If I wanted to go quicker I could just increase my span and decrease S?
2 votes
2 answers
140 views

why normal surface pressure over wedged cone is greater than freestream pressure

I came across this question in "Fundamentals of Aerodynamics" by John Anderson, although I knew how to solve the question, I didn't understand why we had the surface pressure on the wedge 1....
1 vote
1 answer
90 views

Is this description of lift and drag coefficients correct?

In my course (Principles of Flight) written: The effect of CLift is not linear. This means that Lift doubles for double the lift coefficient. And The effect of CDrag is linear. This means that for ...
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13 votes
2 answers
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Can free fall velocity be used to start a ramjet?

A comment to this question suggested, followed by a smiley, that dropping it [a ramjet engine] from orbit might start it. This got me thinking if this really would be possible. This Skybrary article ...
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3 votes
1 answer
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How to calculate the inaccuracy in the "standard" turn radius equation, for supersonic airspeeds

I learned to calculate the radius of a level turn (r) using the function $ r = \frac{V^2} {g . tan(bank angle)}$. V is true airspeed, g is the local gravity constant. But now I have seen in the ...
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17 votes
6 answers
3k views

Is the Centre of Gravity moved by an aircraft travelling at “High Speeds”?

The following quote is from G. Bristol’s book, Ace the Technical Piloting Interview: [The] movement of the centre of gravity is due to a change in weight. The distribution of the aircraft’s weight ...
1 vote
1 answer
479 views

Aspect ratio of an elliptical wing

I am looking into elliptical wings at various aspect ratios and my intuition tells me that an elliptical wing with aspect ratio of one is a circle, meaning the chord and the span will be equal. But, ...
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0 votes
1 answer
242 views

Are there retractable, compact hang gliders?

I was wondering if there were hang gliders that you could, say wear on your back, in which the wings would retract into the suit. Kind of like the falcon in the mcu? If they aren't there, why not?
2 votes
5 answers
367 views

What is the indicated airspeed necessary to exit ground effect on takeoff?

I always thought that a plane needed to be at stall speed or greater to be able to exit ground effect on takeoff. However, after seeing the YouTube video in the link below I am not so sure. ...
2 votes
2 answers
488 views

Reference area in lift coefficient calculation

Does the reference area changes with angle of attack? Most sources says it is projected area. If it is projected area then it should depend on Angle of attack. I want to calculate Lift and drag ...
7 votes
2 answers
2k views

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 ...
3 votes
2 answers
363 views

In the context of aerodynamics, what is a polar?

Many aerodynamics discussions (including several on this site) talk about "polars" without ever explaining what they actually are. As with any technical term common to a field, once the ...
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3 votes
0 answers
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Maneuvering Speed Discrepancy

In this page from the limitations section of the Extra Flugzeugbau 330SC, it states I’m curious as to the discrepancy between maneuvering speeds Va between operation in the Normal Category and the ...
1 vote
1 answer
116 views

Could the center of pressure be not on an aircraft?

I have created the outer mold line of a blended wing body drone and have put it through Ansys Fluent. Using SST k-omega turbulence model and 40 m/s of airspeed. However, the output from the program ...
0 votes
2 answers
82 views

How does the velocity of a turboprop engine relative to the airplane change when a plane is banking?

I saw this YouTube video recently: And in it, a turboprop engine propeller and gearbox comes out and slashes across the underbelly of the plane, crippling the aircraft....
1 vote
3 answers
600 views

Why does power go up with the cube of the airspeed?

If i have an airplane with over 100 kN of thrust, and i want to accelerate from a velocity at which drag force is 25kN to a velocity twice higher, is it possible that i wont be able to do this because ...
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1 vote
3 answers
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What's the relationship between mach number and drag force on an airplane?

From what i've read drag coefficient at mach 1 is several times (up to 10x) the drag coefficient below drag divergence mach number. It drops as the mach number increases. It's easy to find plots ...
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4 votes
3 answers
332 views

How do you maximize lift while keeping span as short as possible?

This weekend I saw the Fly Baby at the Smithsonian Air & Space Museum at the Washington Dulles Airport, and it was at some point the smallest airplane (since surpassed by the Bumble Bee II, if I ...
7 votes
1 answer
2k views

What is the difference between Vs and Vs1g?

As the name suggests, what is the difference between Vs1g and Vs? If both of them are referring to the stall condition, why they aren't the same? Which one is usually greater and why? Why do we need a ...
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2 answers
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If Navier-Stokes equations are unsolvable how does CFD software calculate simulation? [closed]

Navier-Stokes equations are one of the problems of the millennium. How, then, are CFD programs doing simulation, calculating forces, etc if these equations are unsolvable?
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5 votes
4 answers
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Why does lift decrease and drag increase when approaching the stall condition?

This is an ECQB-PPL question specifically asking what happens before the stall. I do understand that after the critical angle has been reached, the airfoil is no longer generating lift (so obviously ...
4 votes
1 answer
226 views

Can a jet-engine aircraft fly all the way to its service ceiling at its maximum takeoff weight? [closed]

I am trying to understand how high an aircraft can get to at its maximum takeoff weight (minus whatever fuel is consumed in getting to that altitude). Can it make it all the way to its service ceiling?...
1 vote
2 answers
280 views

Is aerodynamics science still being discoverd? [closed]

Is aerodynamics science still being discovered(like mathematics for example) or everything has already done?
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11 votes
2 answers
3k views

Why is the ball no longer centred in a multi-engine airplane with inoperable engine?

I'm currently working on my PPL, and whilst trying to understand fully how the turn coordinator works, I got down a rabbit hole that makes me question my understanding, and that I can't dig myself out ...
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7 votes
4 answers
747 views

Why do smaller RC helicopters have visible twist in their rotors, and slightly bigger ones do not?

Smaller, cheap, RC helicopters generally have very pronounced twist in their blades, and also vary their chord - slightly larger, slightly more expensive RC helicopters have no visible twist or chord ...
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-4 votes
1 answer
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Would blade-less (Dyson style) jet engines work? [duplicate]

Is it possible to design an aircraft with blade-less (same concept as Dyson) design to generate thrust? What are some of the key benefits, drawbacks and examples of attempts (if any) at this kind of ...
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3 votes
3 answers
772 views

What causes ram air turbines with more blades to spin slower than turbines with two blades? [closed]

Lets say aircraft has two ram air turbines that work as generators to produce electricity on each wing. One has two blades and one has 8 blades, both with the same diameter. What is the aerodynamic ...
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1 vote
1 answer
225 views

What is the difference between buffeting and wake galloping?

I am interested in flow-induced vibration and confused between buffeting and wake galloping. As far as I have studied, both phenomena are the vibration of an object with another object in front of it. ...
1 vote
2 answers
184 views

Does closed oval wing produce two vortex and downwash between them, like normal wing? [duplicate]

Does closed oval wing like this in video produce two vortex and air between them goes in downward direction like on normal wing? I think yes ,because cause for downwash is wing that push air down, not ...
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0 votes
1 answer
172 views

Can a fixed pitch propeller be designed to act as both a propeller and a generator?

The angle of attack (AoA) plays a major role in designing a propeller for specific uses, such as if it is to be designed for aircraft propulsion the AoA must be high, while the AoA must be low if it ...
3 votes
2 answers
189 views

Does tailless delta configuration retain any advantage over conventional configuration with straight wings at high subsonic speeds?

For a model aircraft designed for cruise at say 0.75 Mach, do delta wings offer any benefit over straight wings. Is drag saving from elimination of the tail large enough to consider a delta ...
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4 votes
1 answer
179 views

What is the reason that the Russian flying wing UCAV does not have sharp leading edges?

The new Russian UCAV sports a fairly blunt leading edge while all the other UAVs in the same category have sharp leading edges.
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2 votes
1 answer
158 views

What means when center of pressure is out of physical dimension of wing?

Center of pressure(CoP) is point where total force vector acting at. If you hold wing at this point, wing will not rotate(moment=0). Example hanging point at hanglider. I see at some diagrams for very ...
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2 votes
3 answers
305 views

How the AOA, Pitch and FPA are changing during a flight maneuver

For a steady state flight, there is a equation that FPA + AOA = Pitch, but how these three variables are correlated during a flight maneuver like currently I am in a leveling flight and then I want to ...
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-3 votes
1 answer
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Why the European Eurofighter Typhoon did not have pitot tube in front of the radome? [closed]

The layout of the aircraft does not have the proper pitot tube. I believe that the aircraft needs clean airflow for its instruments .
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7 votes
2 answers
1k views

G Load during payload drop

Some days ago I saw the accident of the airtractor that, just after a drop, suffered a spar failure in both the wings. Luckily the pilot survived. If load factor in his simplest formula is: n=lift/...
1 vote
2 answers
511 views

How calculate lift/drag using static pressure taps in wind tunnel test?

An airfoil section in a wind tunnel has many static taps on its upper and lower surface. These static ports can only read static pressure which acts perpendicularly to the local airfoil surface. In ...
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