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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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5answers
365 views

Is wing sweep needed on supersonic aircraft?

Area rule states that bodies with the same crossectional area distribution have the same drag. Does that mean I could use a straight wing on mach 1.2 aircraft with performance as high as sweep winged ...
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1answer
109 views

Twist optimization for a low speed aircraft

I'm currently designing an aircraft with the following specifications- s=1.8m^2, AR=7-8, trapezoidal planform with a taper ratio of about 0.45, a load of 25KGs and a cruising speed of 13-15m/s. I'm ...
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2answers
337 views

Why do compressors constrict flow if this decreases pressure?

An axial compressor (and a ramjet intake, for that matter) is commonly depicted as decreasing the volume of air travelling through as we move closer to the combustion chamber. In axial compressors, ...
2
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3answers
260 views

How does the wraparound wing design reduce drag?

How does the wraparound wing in this AOPA article reduce drag? One would think all that extra leading edge and surface area would make it worse. One more link also. The Parsifal Project has ...
4
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1answer
353 views

Could Mach 1.4 be a better design point for SST?

There's been a number of recent proposals for design work on low-supersonic bizjets that would cruise at Mach 1.1-1.6, the common theme being avoiding a sonic boom. I'm wondering if this range of ...
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0answers
35 views

If elliptical lift distribution is considered in every case, does the induced velocity change based on the shape of the wing?

Shapes like rectangular, curved, trapezoidal etc. Here I mean rectangular or curved when viewed from the top. The sectional airfoil shape is the same in each case.
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3answers
411 views

How does the nozzle diameter affect the thrust of a ducted propeller?

I currently do some experiments with ducted propellers in which I try to figure out which effect a nozzle has on the thrust produced. My theory goes like this: If I reduce the exit diameter of the ...
1
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1answer
199 views

Why are some Tomahawk missiles' nose duck-nose shaped?

Why there is a duck-like shape in this Tomahawk missile's nose? I see this shape in most Tomahawk images; however, not every Tomahawk's nose is shaped like this. If it is an aerodynamic feature, ...
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2answers
408 views

Is there a downwash equation?

I need to find an equation for the following problem: Suppose a full-size glider passes 10 feet over my head at high speed. No doubt I will feel the downward air pressure (downwash) caused by the ...
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0answers
91 views

Hovering propeller: how to calculate Chord length and Advance ratio? [duplicate]

friends ! I would like to design a propeller for my drone with specific weight and power requirements. The drone will either hover or fly slowly. It is kind of clear how to select an angle of attack ...
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0answers
106 views

Why double delta wing is used over delta wing? [duplicate]

I was thinking about delta wing then I saw the picture of double delta wing and thinking about its significance over delta wing.
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5answers
389 views

Why wing ribs have diagonal struts

Why do ribs have diagonal struts,why not vertical as seen in airfoils of Citabria airplane?
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0answers
142 views

Why don't helicopter rotors use curved blades? Curved from the top view. [duplicate]

I'm studying blade element analysis and I tried applying it to curved rectangular blades instead of straight ones. It doesn't really show any significant changes in the inflow ratio computation. Why ...
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3answers
614 views

What is the relationship between Angle of Attack and Angle of Incidence?

The Angle of Incidence (AoI) of most GA planes is 6°. During takeoff, the Angle of Attack (AoA) is often 11° or more; does the 11° AoA include the initial 6° AoI in it i.e, 11 - 6 = 5 ? Meaning the ...
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1answer
58 views

How do we choose a frequency range of interest for flutter prediction?

I'm trying to perform some flutter and dynamical (gust etc.) calculations with Nastran. It has been told to use a range up to 30 Hz for an aircraft I'm working with, but why the upper limit is so ...
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3answers
2k views

Why do aircraft need Mach number? [duplicate]

Why don't aircraft operates with IAS only? Is there any other usage of Mach number except monitoring of shock waves formation? How Mach number is calculated?
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2answers
763 views

How to realistically model propeller static thrust?

I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and ...
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0answers
116 views

Is there a fixed ratio between highest L/D and max endurance L/D?

It can be demonstrated that, for any airplane, there is a fixed ratio between the maximum range and maximum endurance speeds (1.31607...). Does another, fixed ratio exist between highest L/D and L/D ...
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2answers
111 views

What are technical and aerodynamical limitations to blown wings main propulsion?

Why wouldn't some blown flap or blown wing device (suppressing propeller or fan or jet exhaust from aircraft design) produce sufficient thrust needed for takeoff and cruise flight, opposed to "only" ...
2
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1answer
255 views

How does the Coanda effect help some aircraft produce more lift?

How exactly does the Coanda effect affect the air stream on the wing of, e.g., an AN-72? The Coanda effect makes an air stream flow on the curved (outboard) surface object which it has produced from ...
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0answers
58 views

What is formula for induced drag in stalling regime?

I'm wondering what is the formula for induced drag in a stalled regime, i.e. in a regime where the $C_L$ (coef. of. lift) has started to decrease but is still nonzero. I've a feeling that the ...
6
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1answer
358 views

Is there any way to reduce the noise and vibration in a C-130 Hercules?

We are using C-130 B and E Models with T-56 A-15 engines and Hamilton Sundstrand 54H60-91/117 propellers. A lot of vibration and resonance are felt on these military version aircraft even after using ...
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0answers
41 views

Why are CP and AC of a symmetrical aerofoil coincidental? [duplicate]

Considering symmetrical aerofoil CP is located some distance back AC along the chord, and will move forward as the AOA increases within the limits of normal range. But for symmetrical aerofoil it has ...
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1answer
344 views

Why does stall speed decreases with increasing aspect ratio?

As I have found Cl(max) doesn't change with changing AR. Is it true? Therefore stall speed which corresponds to Cl(max) and crit AOA must remain constant regardless of AR. Where am I mistaken?
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2answers
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Do negative angles-of-attack create lift?

(wikimedia.org) A typical curve showing section lift coefficient versus angle of attack for a cambered airfoil. Based on the graph above, do negative angle-of-attack values create lift? How?
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2answers
662 views

Why is the velocity squared in the lift equation?

Why is the velocity $v$ squared in the lift equation? $$L=C_L\cdot\frac{1}{2}\cdot\rho\cdot v^2\cdot S$$
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1answer
329 views

will a Sears-Haack body straighten itself out if “launched” sideways?

I'm asking this here not because it's a question about flying a plane but because I read some engineering questions that said to bring aerodynamics questions to aviation.se for the best results. Will ...
3
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1answer
490 views

How is shear stress distributed on an airfoil?

I know the pressure distribution on an airfoil but not shear stress. How is shear stress distributed on an airfoil?
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3answers
430 views

What is the “Centre of Pressure”?

This question may sound naive but surprisingly it puzzles me. A wing has a centre of pressure, does it mean that lift acts on point and not on the whole chord of an airfoil?
2
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1answer
112 views

Why did a circular paper aeroplane of larger diameter fly further than one of a smaller diameter?

http://www.10paperairplanes.com/how-to-make-paper-airplanes/07-the-ring.html I am not an expert at this- just a high school student, so please explain this in fairly simple terms. Thank-you very much ...
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2answers
864 views

How does rudder lock occur?

Citing Wikipedia article on the Vertical Stabiliser: Rudder lock occurs when the force on a deflected rudder (in a steady sideslip) suddenly reverses as the vertical stabilizer stalls. This may ...
3
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1answer
126 views

Why would lift coefficent change with weight on swept-wing aircraft?

Today I encountered a problem. There is a book saying, "Why does the lift coefficient of a swept-wing airplane decrease with the increase in the weight of the airplane?" I cannot think of the reason. ...
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2answers
119 views

What are the methods of reducing vortex? [closed]

I have tried reading the notes on the wing tip, but didn't understand well. How will the vortex be reduced on the wing tip.
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1answer
405 views

How does angle of incidence affect an aircraft's stability?

How does angle of incidence affect an aircraft's stability? I've tried searching the web for the simplest answer that makes sense but so far I've come up with nothing as yet. I know it sounds simple, ...
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1answer
113 views

How much speed is required to achieve lift on something that weighs 1000lbs? [closed]

I was wondering how much speed would be needed to get an object that weighs about 1000 pounds to generate enough lift to get off the ground and achieve flight?
2
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1answer
763 views

How I determine numerically the roll rate of an aircraft?

I'm a Spanish student of aerospace engineering and I'm doing my final bachelor work that consists in designing an unlimited aerobatic plane, and I wonder if it is possible to calculate an ...
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1answer
208 views

How do I calculate the lift force on an aileron?

How do I calculate the force of lift acting on an aileron with a deflection of 8° and a flight speed of 40km/h?
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1answer
75 views

Is it possible to embed CL, CD, dCLda, etc, into a tensor?

Is it possible to form a tensor (i.e. matrix) such that this tensor applied to the apparent wind vector produces a vector representing the resulting aerodynamic force?
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4answers
1k views

How can I find the optimum chord wing length for this wing?

This Aviation SE forum looks the perfect place to ask this question: people here usually make maths the root of most solutions and I think this may solve my aerodynamic optimization problem! I am ...
3
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2answers
360 views

Does anyone know an equation relating wingspan to gliding distance for a glider?

I found this equation online but it is not from a reputable source and has no derivation. Could anyone help me by deriving this equation or even verifying its accuracy? I would love to cite and use ...
2
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1answer
198 views

how do we determine whether the airfoil trailing edge is CUSPED or POINTED?

I'm working on a project and I need to decide whether an airfoil has a cusped or pointed trailing edge given the x and y coordinates of the airfoil. I'm familiar with the kutta condition, but I could ...
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2answers
329 views

Could a blimp maneuver using a sail? [closed]

How do you build a sail for a blimp/hybrid airship and what would it look like? Similar to a sail boat how could a blimp maneuver without propellers? Can a blimp sail against the wind? Wind can travel ...
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0answers
95 views

In theory which causes more parasitic drag? A large smooth wing or a small, rough exhaust port?

I'm new to aviation and I have a basic, mechanical question. Wings produce a lot of lift-induced drag, especially at lower speeds. But according to this chart that drops off as velocity increases. ...
5
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2answers
291 views

Where can I find a cross sectional area plot for the A320 or other modern airliners?

I'm studying to become a pilot and stumbled upon the Raptor Aircraft a while ago. In one of our subjects we briefly discussed the concept of the area rule but did not get into much detail since our ...
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2answers
313 views

Would An-72-like (or any anhedral wing multi-engine aircraft) cruising at high speed, roll counter intuitively right, if left engine suddenly dies?

Assuming low angle of attack & anhedral wing configuration. (and as a consequence of natural left yawing moment)
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2answers
232 views

Are high-frequency flapping wings efficient and scalable at high Reynolds numbers?

Is high-frequency flapping (similar to how dragonflies fly) an efficient lift production method at high Reynolds numbers? I have not seen anyone develop wing suits with high frequency flapping, is ...
2
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1answer
385 views

What factors are included in the moment coefficient of a wing?

I am trying to make sure I correctly understand the moment coefficient. Both the lift and the drag coefficients vary with angle of attack and can be either positive, negative or zero. The moment ...
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2answers
169 views

Are aircraft wings airtight?

Is there any no air proof design for the wings? Or are some of the parts are equivalent to outside pressure and some have gauge pressures? Are some parts airtight and others not?
4
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1answer
132 views

How to handle the formula for computing net thrust of closely coupled engine systems for an engine with a nacelle that has non-circular dimensions?

I am working on a paper and I wish to use this equation for calculating the thrust of an engine in a nacelle: $$ Fn= \displaystyle \oint V_x\rho\vec V\cdot\vec n \ dA + \displaystyle \oint(P-P_{\infty}...
17
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1answer
2k views

What is the aerodynamic advantage to a cuffed wing like the Cirrus SR-22?

What is the aerodynamic advantage to a cuffed wing like this Cirrus?