Questions tagged [aerodynamics]
Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design.
2,341
questions
0
votes
1
answer
44
views
How do I get rid of this weird line along the x-axis when importing an airfoil into XFLR5?
Whenever I try to import an airfoil into XFLR5, I always notice this weird line along the x-axis as you can see in the picture.
Is there a way to somehow get rid of this line?
I'd be thankful for any ...
1
vote
1
answer
92
views
Why is spanwise flow more prevalent in the boundary layer?
Spanwise flow is stronger in the boundary layer, but to me it's kind of counterintuitive because the BL flow is slowed down by friction, experiencing less of a pressure gradient over the wing, ...
- 435
0
votes
1
answer
257
views
Does the air in the region of pressure recovery over a wing decelerate in the vertical axis?
In this answer, it states that the deceleration of air in the region of pressure rise over a wing acts in a direction perpendicular to the lines of relative chord, explaining spanwise flow.
To be ...
- 435
0
votes
1
answer
36
views
Are there any sources that contain information on the airfoils of the Boeing 737-500 and 737NG Aircraft?
I have found some information about this on airfoiltools.com (http://airfoiltools.com/airfoil/details?airfoil=b737a-il) but it doesn't specify the exact version of the aircraft, as the generations ...
- 1
3
votes
2
answers
481
views
Why does the nose pitch up during power reduction in a T-tail with rear mounted engines?
For the CRJ700 for example, reducing thrust causes a pitch up. Why is that?
- 31
0
votes
0
answers
107
views
Why does the F/A-18 use external aileron and flap hinges?
As seen in the picture, the legacy Hornet uses ailerons and flaps with external hinges, and I was wondering what were the advantages of external hinges compared to flush hinges in the land-based ...
- 11
1
vote
2
answers
169
views
Is this "separation" caused by the boundary layer?
I was wondering if the void seen in this picture (on top of airfoil, not the wake from the airfoil) is from the boundary layer thickening, or from the fact that as you go further back on an airfoil, ...
- 435
2
votes
1
answer
114
views
Does the pressure recovery on the rear side of an airfoil recover all of the pressure?
I was wondering if all of the low pressure created by the airfoil gets recovered on the rear side of the wing. (I know during a stall or flow separation, this doesn’t happen, I think)
My main question ...
- 435
1
vote
2
answers
88
views
Type of airfoil used by Briggs, Hull, and Dryden
What airfoil do Briggs, Hull, and Dryden use in NACA Report No. 207: https://ntrs.nasa.gov/api/citations/19930091273/downloads/19930091273.pdf
They mention it a few times:
"The airfoils tested ...
- 111
1
vote
0
answers
91
views
How does more lift help during a stall (ex. flaps deployed) [duplicate]
How does more lift help in a stall? For flaps, I thought the effective increase in camber of the wing would make the wing have a higher AoA, therefore making a stall happen sooner.
Thanks!
- 435
2
votes
1
answer
105
views
Why does a helicopter that uses the Coandă effect need a direct jet thuster aswell
Why does a helicopter that uses the Coandă effect instead of a tail rotor need a direct jet thruster as well. Why couldn't they just vary the pitch of the ducted fan used for the Coandă effect?
- 313
0
votes
0
answers
80
views
Chord Wise Load Distribution
I'm looking for some guidance on how to compute the chord-wise lift distribution of the wing using Xflr5 or OpenVsp or any analytical method. This is for designing the internal structure of the wing.
...
4
votes
2
answers
197
views
Why does the turn tighten in a Spiral Dive as it progresses? Even without applying any elevator control?
Why does the turn keeps getting tighter as the spiral dive develops?
Use of elevator control makes sense as it would increase the horizontal lift vector inside the turn. But even without any elevator ...
- 609
0
votes
0
answers
134
views
How exactly does the startup vortex form, and why does it occur when circulation around the wing changes?
So I was wondering how exactly the startup vortex forms, why it dissipates, and where it's located in relation to the trailing edge of the wing. Also, why does a startup vortex form when circulation ...
- 435
2
votes
1
answer
163
views
For a fixed density altitude, how does climb performance depend on pressure altitude?
Below is the climb performance from the 1978 Cessna 152 POH, which I've plotted as climb rate versus density altitude. It shows that higher pressure altitude gives decreased performance even when the ...
- 12k
0
votes
0
answers
54
views
Deriving Accurate Exit air velocity of rotor
My goal is to derive the equation for exit air velocity as a function of:
Pitch angle
RPM
Rotor Radius
Constants like ρ
Assumptions:
Vc is relative velocity of air upstream, and is = 0
Inflow is ...
0
votes
0
answers
75
views
Why does Aerodynamic Center move to 50% chord when supersonic?
There are several sources available that state that when an airfoil is fully supersonic, the Aerodynamic Center will move to the 50% chord location. Some of these sources, the ANA shown above being ...
3
votes
2
answers
263
views
Is blade flapping "fully automatic"?
I have a rather simple question just to "double check" if I understood blade flapping right. So, I understand that a helicopter, in forward flight faces an asymmetric lift. Blade flapping is ...
- 173
0
votes
1
answer
150
views
How does speed and angle of attack affect pressure distribution at the wingtip?
So I was wondering how speed and AoA affect lift distribution at the tip of a wing. For example, if you are flying level and at a high speed, does that mean your wing has more even lift distribution ...
- 435
2
votes
4
answers
195
views
Moving from 2D wing to 3D wing design
In terms of the design perspective of an Aircraft, once we decide on the airfoil that would be used for the wing, how would an Aerodynamics Engineer (or you) proceed to construct the wing? The ...
- 21
0
votes
1
answer
63
views
Sources for Python Codes to do some aerodynamic Calculations [closed]
I am currently working to design a wing. I basically want the Python code which would take the coordinates of the airfoil (.dat file), freestream velocity, Span (b), planform of the wing as input, and ...
- 21
6
votes
2
answers
482
views
Why don't modern military aircraft typically keep their guns covered?
Back in the 1940s, it was common to cover gun ports with tape. As well as improving streamlining, it would presumably help keep them clean.
Spitfire Mk 1, with all eight .303 inch Browning machine ...
- 11.8k
2
votes
2
answers
200
views
Do winglets change the lift distribution of a wing?
In this answer, it claims that the reason for lift decreasing at the wingtips is due to airflow around the wingtips. If I'm thinking correctly, that is due to the air below the wing spilling on to the ...
- 435
0
votes
3
answers
64
views
How does changes in Power vary the aerodynamic forces on an aircraft?
When we make changes to the Thrust by adding or removing power. In what way does it affect the other forces? As Power controls Rate of Climb or Descent of an aircraft, How is it acting on the other ...
- 609
0
votes
0
answers
65
views
pressure wave propagation of shockwaves? [duplicate]
I can’t find a simple explanation of how the pressure waves propagate that leads to a shock over an aerofoil online.
How does this happen with upstream flow that is high speed but subsonic?
- 87
2
votes
1
answer
99
views
How does a shockwave form from a subsonic upstream?
How does a shockwave form over say an aerofoil from a subsonic upstream?
Wouldn’t the flow have to be supersonic before it ‘shocks’?
Also, does the flow in a shockwave jump from let’s say it is at M=1....
- 87
2
votes
5
answers
259
views
Can an airplane propeller become supersonic?
Is it possible for an aircraft propeller to become supersonic?
I am not referring as for the aircraft, only the rotating blade.
I know it is extremely unlikely for a propeller plane to go supersonic, ...
- 21
1
vote
2
answers
237
views
How does aspect ratio affect stall speed and stall AoA?
I've read a few answers on here but they didn't really tell me what I wanted to know. So I get that high AR wings will stall before low AR wings but what makes that true? Higher AR wings have a higher ...
- 435
0
votes
1
answer
85
views
what is the cross section of an elevator and trailing edge flap?
Is the cross section of both a Trailing edge flap and elevator an aerofoil please or, like i've shwon in in image below? I tried to find a side view of an elevator and TE deflected to see this for ...
- 53
1
vote
1
answer
64
views
What is monotonous and non-monotonous flow?
I'm not an engineering graduate so I'm learning as I go along. I've just read a sentence that states:
The transition shapes are identical, while the variety of growth rates of intermittency
are non-...
- 113
1
vote
1
answer
90
views
How do I know which outer grid shape is best for CFD?
I’m looking into running a CFD simulation on an aerofoil in transonic flow (M=0.8) but am unsure about what external grid shape to choose for my computational domain?
I read into 3 main types:
C-grid
...
- 53
2
votes
1
answer
72
views
If I know both Re number and Mach, how do I incorporate both into my simulation?
I’m trying to simulate an aerofoil based on experimental data with flow in the following conditions:
Mach=0.84
Reynolds number (Re) = 3*10^6
I wanted to keep my chord length at 1unit but then what ...
- 53
3
votes
1
answer
158
views
Is the AOA on the horizontal stabilizer positive?
I am making a flight sim and would like some help.
If I am correct, the angle of attack on the horizontal stabilizer should look something like this:
aoa(Hstab) = aoa(Wing) - downwash + Hstab ...
- 69
5
votes
3
answers
3k
views
Why is it that when autopilot is maintaining cruise, we don’t feel the changes when lift increases?
When we’re inside an aeroplane, when we’re in cruise, why is it that we don’t feel the changes in altitude, lift and the adjustments for example from the elevator on the plane as the weight is burned ...
- 87
-2
votes
1
answer
160
views
How is an airliner trimmed nose-down or up? [duplicate]
so when a plane is in cruise, it loses weight and then the weight begins to exceed lift.when this happens, the plane begins to climb.
My question is this please:
The plane would be trimmed up or down ...
- 87
3
votes
7
answers
586
views
If in a coordinated turn, the horizontal lift vector is equal to the Centrifugal force. Then how is the aircraft still turning?
Image source
How does the Aircraft continue to turn when the both the Horizontal component of lift and the centrifugal force are equal?
- 609
0
votes
2
answers
75
views
What is aeroplane trim and how does it control/adjust the elevator in cruise?
so in my last question, ‘trim’ popped up a lot and after reading up on it I got this: it’s used to adjust the forces on the control surfaces so that the aircraft maintains like a set input
But what I ...
- 87
3
votes
0
answers
56
views
How do Antishock Bodies / Cuchemann Carrots delay shock-induced flow separation?
There are several online resources that describe these aerodynamic devices as either "Antishock Bodies" or "Kuchemann Carrots" and that they are used to produce some combination of ...
0
votes
2
answers
69
views
"Pure" Aerospace engineering vs mechanical engineering/pathway aerospace?
Does "pure" aerospace engineering give better aero-knowledge then mechanical engineering/pathway aerospace?
What is point of specialization aerospace at mechanical engineering, isn't ...
- 1,648
0
votes
1
answer
87
views
What are the effects of whiteout (snow) and brownout (sand/dust) on helos?
Is there any other effect besides low visibility?
Both seem to show very similar conditions.
0
votes
0
answers
28
views
Is the Lift required for a steady-state climb and descent equal for the same absolute value of the kinematic climb angle? [duplicate]
Here is my confusion :
I found in my lecture script the following equation for the steady-state climb and descent (wings level)
...
1
vote
2
answers
141
views
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 ...
1
vote
1
answer
141
views
What are the effects of wing washout and anhedral on induced drag?
I am studying for my ATPL and was curious if and how induced drag varies based on wing anhedral and geometric washout.
I have a basic understanding that spanwise flow affects induced drag since there'...
- 111
6
votes
2
answers
3k
views
Why is a flat turn less efficient than a coordinated turn?
How I understand a flat (rudder-only) turn:
AOA between relative wind and the fuselage of the airplane causes a sideslip in the direction of yaw.
Vertical stabilizer weathervanes into the relative ...
- 75
0
votes
1
answer
58
views
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 ...
- 23
0
votes
1
answer
105
views
Pressure coefficient over a flat plate against its length/width ratio
We conducted an experiment to measure the surface pressure distribution around a flat plate (dimensions below). The plate has 104 equally distributed tappings as shown below.
Where the arrows ...
3
votes
1
answer
184
views
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 ...
- 4,454
8
votes
1
answer
4k
views
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 ...
- 183
1
vote
3
answers
105
views
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 ...
0
votes
3
answers
190
views
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 ...
- 609