Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [drag]

Aerodynamic drag is the fluid drag force that acts on any moving solid body in the direction of the fluid freestream flow. Part of the drag is the direct consequence of the wing generating lift.

3
votes
1answer
67 views

How does a weak shock-wave boundary-layer interaction create wave drag (other than through direct shock losses)?

I'm trying to understand the physical cause of wave drag, beyond the simple statement "the presence of shockwaves increases the drag". As far as I understand, in the case of a weak BLSWI (so without ...
2
votes
4answers
205 views

Why are the leading edges of wings not always made as 'sharp' as possible?

Why is an airplane's wing (the leading edge) not made as sharp as possible to break the air, in the same way that a ship's hull is made sharp to easily break the water? This is unlike Concorde's nose ...
1
vote
2answers
65 views

How does wing aspect ratio influence lift and drag?

I know simmilar questions are all over the internet (and this website too), but there's one thing that i just cannot comprehend and none of the articles i read could explain it properly. According to ...
0
votes
0answers
20 views

Determine “basic lift distribution” over a wing that has a circulation distribution

I don't understand what they mean with basic lift distribution. I have calculated C_L which is 5a (a is alpha in radians). I added the relevant equations here.
2
votes
2answers
82 views

How do endplates reduce induced drag?

I have heard the explanation which states that the endplates reduce the tip vortex formation thereby reducing induced drag. From what I understand induced drag is the backwards component of the total ...
0
votes
2answers
94 views

What is the relationship between drag and sink rate?

I was just brushing up on basic aerodynamics and I have something I want to clarify about flying in the region of reverse command. I went up in my 172 the other day and noticed the following while ...
0
votes
0answers
14 views

What is a typical Cd0 value for single-slotted flaps?

I've been having trouble finding any source for what a typical value would be for single-slotted flaps. I haven't been able to find any information within Anderson's Aircraft Performance and Design or ...
0
votes
1answer
67 views

What is the first cause of induced drag changes?

What causes induced drag to change with speed: speed itself or angle of attack? I have found in different sources 2 versions: 1). Most cited version according to which, with ↑ speed in straight and ...
5
votes
5answers
219 views

How to recognize the horizontal winglet in the Horten design, or the experimental glider in this video?

Comments below the NASA Armstrong Flight Research Center video Proving Prandtl- With A Twist! incclude: This video is entirely a hidden jewel in youtube, it deserves much more attention than ...
6
votes
2answers
371 views

What prevents BFS from becoming unstable when pitching from horizontal to vertical?

In this video from (SpaceX's BFS landing) there is a point where the ship tilts from horizontal « belly first » terminal velocity freefall, to vertical « engine first » landing position. The graph ...
3
votes
4answers
144 views

How can drag induced by the landing gear be reduced?

What are some of the methods used to reduce the drag caused by the landing gear for aircraft with non-retractable landing gear?
0
votes
0answers
48 views

Calculating induced drag approximation using XFoil generated parasitic drag

I am trying to do rough predictions of induced drag using the XFoil results for parasitic drag. To do so, I am using the lifting line equation for induced drag and the Oswald efficiency number: $C_D=...
0
votes
1answer
83 views

How to calculate the induced drag coefficient?

In an exercice of Flight mechanic, I have to compute the drag coefficient at zero lift: $C_{D0}$.We saw in class two ways to find it : $$ C_{D0} = \frac{\pi AR e}{4E_{max}^2} $$ With $AR$ the aspect ...
2
votes
3answers
170 views

What is compressibility drag?

I don't mean wave drag here. What is compressibility drag, which is understood to be a form of miscellaneous drag?
0
votes
3answers
156 views

How can pilots minimize parasite drag?

What can pilots do to minimize parasite drag? As far as I know the effect of parasite drag really depends on the manufacturer of the airplane, but can pilots do anything about it?
0
votes
0answers
50 views

Is winglet height equivalent to duct height?

Winglets increase effective wingspan by causing vorticies to be generated further away from the wing root in proportion to the height of the winglet (if vertical), likewise with winglets on propellers....
0
votes
0answers
81 views

What is the drag (or $C_D$ vs $C_L$) of the Airbus A320 in cruise flight?

Is there any website or data-sheet that I can find drag of airplane for cruise conditions. $C_D$ vs $C_L$ graph is also acceptable. To be more specific I am searching drag values of A320 in cruise ...
0
votes
1answer
83 views

Why do I see moisture coming from the middle of the wing as well as wingtip vortices? [duplicate]

A lot of times I see small tube like streams of visible moisture training from the middle of an airliners wing. I assume this is induced drag created by wingtip vortices, when the aircraft is heavy, ...
8
votes
3answers
215 views

Why does a turbulent boundary layer cause more friction drag than a laminar boundary layer?

From what I understand, friction is caused by viscosity and a bigger Reynolds number signifies lower viscosity. Thus, a higher Reynolds number(i.e. turbulent flow) results in lower friction. But, ...
39
votes
3answers
8k views

How is it possible for supersonic aircraft to push air out of the way?

If the force (pressure) can be transferred/propagated only at the speed of sound, how are supersonic aircraft able to move air out of their way/do work on the air? It seems that they must transfer the ...
2
votes
1answer
115 views

How can one approximately guesstimate wave drag?

Wave drag is an especially high drag that affects supersonic vehicles above mach 1, but I've found it hard to find source materials to estimate wave drag. I'm looking at the transonic region till Mach ...
1
vote
2answers
151 views

What are the two turning tendencies that occur during a steep turn?

A question has come up in preparation for a Block exam. what are the two turning tendencies that occur during steep turn? If you know this may you please explain to me, why these tendencies occur. ...
1
vote
1answer
81 views

Lift and Drag Coefficients using load cell data

I have a MAV and I need to find out the lift and drag coefficients for the wing and tail. I am not available with a wind tunnel so I will be using a load cell along with a separate wind source. Now I ...
0
votes
0answers
235 views

Why don't more airplanes incorporate spiroid winglets? [duplicate]

In typical airplanes, lift induced drag can account for the majority of the overall drag. Why don't more aircraft employ methods to reduce this and specifically why not spiroid winglets? From every ...
1
vote
1answer
152 views

How does drag change with Reynolds number?

If you want to scale down an airframe, i.e., for wind tunnel testing, you have to adjust for the Reynolds number. I want to ask if in case I forgot to adjust the Reynolds number, would the drag on the ...
14
votes
6answers
3k views

Is lift in fact a kind of drag?

Given the similarities between Lift and drag and their very similar relationships to the density, surface area, and airflow velocity, could one, in theory, describe aerodynamic lift as a kind of drag ...
8
votes
1answer
77 views

Is aspect ratio efficiency related to the momentum added to the air?

Many years ago I was taught that for generating lift or propulsion, lower losses were associated with imparting less momentum change to a larger volume of air, and higher losses were seen when ...
0
votes
0answers
69 views

How do I find experimental Cp, Cd and Cl values for a NACA0012 airfoil? [duplicate]

How can I get experimental Cp, Cd and Cl values for a NACA0012 airfoil where Chord length=240mm and Re=4.6e5? I'm looking for both 2D and 3D airfoil/wing (infinite span). I understand that plenty of ...
1
vote
2answers
131 views

Is it possible to eliminate induced drag completely?

According to Wikipedia an airfoil of infinite length would create zero induced drag. Therefore, would it be possible to make a wing that creates no drag if you ignore viscous effects (skin friction) ...
32
votes
5answers
8k views

Why, until recently, were smooth nose sections not popular?

Why, until recently, were smooth nose sections not popular? By smooth I mean without a break between the nose and windshield. (The question focuses on airliners.) Seeing the Starliner (left) and DC-7 ...
3
votes
2answers
141 views

How significant is the lift induced drag contribution to total drag of aircraft at cruise speed?

How significant is the lift induced drag contribution to total drag of aircraft at cruise speed? From what I've learned so far it seems to be around 10 to 15 percent of total drag. I suspect the ratio ...
2
votes
2answers
143 views

Hypothetical aircraft drag reduction

What would happen if I mounted a system dumping hydrogen (sound velocity 1310 m/s) at the leading edges of an aircraft flying at i.e. mach 2 (ignore all practicality issues)? What would happen at the ...
3
votes
1answer
260 views

When are winglets most effective?

If winglets reduce induced drag, induced drag is greatest at slow speeds. When are winglets most effictive?
3
votes
5answers
333 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 ...
8
votes
2answers
208 views

Would a lighter aircraft require the same amount of power than a heavier one to fly at the same speed?

I had a question come up: If aircraft A is identical to aircraft B, except that aircraft B weighs 200 kg more. Which of the following statements are true? The answer I selected was wrong: ...
0
votes
2answers
243 views

Winglet design and airfoil selection

I'm currently in the process of designing a winglet for my low speed aircraft in xflr. While researching about winglets I read in a Boeing article that if the baseline outboard wing is relatively ...
6
votes
2answers
217 views

Can quadcopters save energy by flying in formation?

If two or more quadcopters are aligned, would the effect of drag due to the lead quadcopter's slipstream lead to measurable energy savings? And if so, how would one determine the optimal distance ...
4
votes
2answers
182 views

How would the wave drag of an elongated Sears–Haack body change with a cylindrical mid section?

Would a Sears–Haack body have the same wave drag as the same body with cylinder of the same diameter placed in the middle, between two halves of the Sears–Haack?
1
vote
0answers
57 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 ...
1
vote
0answers
119 views

When rearranging the lift force equation to solve for lift coefficient instead of lift force, why is the numerator often given as F not 2F?

the standard description of the Lift force affecting the lift surface is: $$ F={\dfrac{1}{2}}\rho v^{2} SC_{L} $$ the basic rearrangement gives the following definition of the lift coefficient: $$ C_{...
0
votes
1answer
68 views

What is the ideal volume distribution for minimization of transonic drag?

I am aware what the area rule states - my question is what is defined as "as smooth as possible area distribution" - Is there a formula for the curve?
8
votes
2answers
343 views

What is purpose of engine pylon airfoils on the Hondajet HA-420?

The engine pylons on the Hondajet are aerodynamically shaped so as to provide a lift force laterally and outwardly. Engine pylon as viewed from rear Engine pylon as viewed from front Are these for ...
7
votes
3answers
3k views

At what rpm does the tip of a 54" propeller start to incur mach losses?

At what rpm does the tip of a 54 inches propeller start to incur mach losses? The max rpm of my engine is 3600.
0
votes
2answers
234 views

How much more economical are planes with retractable gears vs. those with fixed gears?

Many small planes have fixed gears, some have retractable gears. All things being equal, the plane with retractable gears would have to be more expensive than fixed gears, as the mechanisms involved ...
0
votes
0answers
94 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. ...
0
votes
2answers
228 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 ...
3
votes
1answer
150 views

Why is the thrust/drag increase much lower at a lower FL with weight the only variable?

From and related to: What is the relation between drag and weight? Friction drag is not affected by the angle of attack change. The [induced] drag will increase with the square of the mass ...
0
votes
1answer
192 views

Do wingtip vortices cause a decrease in the lift component of aerodynamic force, and do planes need to pull more AoA to compensate?

So, from what I know about wingtip vortices, they shift the angle of the relative airflow to where the effective angle of attack of the airfoil is lowered. Since the aerodynamic force is always ...
0
votes
2answers
296 views

Does an aircraft with higher aspect ratio wings produce more wingtip vortices in a turn than one with lower aspect ratio wings?

The Ta-152H was well-known for having very high-aspect ratio wings: 8.94, if I'm not mistaken. Now, compare this to the P-51 which had, if I'm not mistaken, an aspect ratio of 5.86. Does this mean ...
0
votes
3answers
198 views

If we use upper surface blowing and externally blown flap on the same wing will lift correspondingly be very high?

With two engines, one above and one below the wing, will the lift be the sum of two lift increments (produced by upper surface blowing and external blowing)? I am trying to make a jet suit and I am ...