Stack Exchange Network

Stack Exchange network consists of 175 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 [aerodynamics]

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

0
votes
3answers
107 views

Does pumping fuel to each wingtip affect roll trim in a stabilized turn?

If an aircraft is stabilized in a constant-bank, constant rate turn with no sideslip, and then we pump 200 gallons of fuel from a fuselage tank to a tank on the tip of each wing, without changing the ...
0
votes
0answers
44 views

How does the B-2 Spirit fly without a rudder? [duplicate]

On the B-2 Spirit bomber there are no rudders on the back of the aircraft, how does it fly without entering a flat spin or losing control, because when other aircraft like commercial liners lose their ...
0
votes
0answers
24 views

What are typical naca foils for winglets for ultralights/LSA?

What are typical naca foils for winglets for ultralights?
1
vote
2answers
110 views

Need to add elevator downforce to total lift when sizing wing area?

Do I need to add elevator downforce to total lift when sizing wing area? Say a small airplane weighs 1,000 lbs, and both the wing and elevator have a max Cl of 1.5, and my elevator is 20% of my wing ...
1
vote
1answer
81 views

Cp, Cg and Np location of a tandem wing configuration, both have positive lift?

I understand that in a tandem layout( 1 wing at front of plane, 1 wing at rear, both have positive lift) , the Cp has to be ahead of the Cg, and the Np behind the Cg. Is there a rule of thumb how far ...
5
votes
2answers
1k views

The Mig 21 and the Mirage III have been criticized for lack of range, is this a limitation of the wing configuration?

Mig 21 Range: 1,470 km (910 mi; 790 nmi) at 10,000 m (32,800 ft) with 2 × K-13A missiles and 800 l (180 imp gal; 210 US gal) (Wikipeda) J-7 Combat radius: 850 km (459 nmi, 528 mi) (air superiority, ...
0
votes
0answers
52 views

Does anyone recognize this old but good paper in computational aerodynamics? [closed]

I remember that I have seen a paper talking about simulating the flow field among a wing by duplicating this wing and putting wings below and above this wing in an infinite manner. Sorry for the ...
0
votes
1answer
71 views

Do the polar curves have large differences in takeoff than in landing?

I was wondering if the polar curve has differences in the takeoff due to the smaller extension of the flaps (this is half that in the landing) that changes the AOA for $ C_ {la} = 0 $. In addition, ...
0
votes
1answer
52 views

Propeller effect on the L/D of an aircraft (Pusher Propeller configuration)

I recently performed an aerodynamic analysis of a fixed-wing UAV with a pusher propeller configuration. I found out that the L/D reduced by about 15% when compared to the body alone without propeller. ...
0
votes
1answer
53 views

Pitching moment as a pure moment and its measurement with a homemade force balance

In mechanics, we learn that a force $F$ acting at a certain application point $P$ can exert a torque (also called moment of the force) about another arbitrary point $Q$ in the plane, i.e. $\tau= F \...
1
vote
1answer
50 views

Are the pitching moment and pitching moment coefficient of an airfoil given w.r.t. the aerodynamic center?

When the magnitude and sign of the pitching moment and the value of the pitching moment coefficient are communicated, are these values given with respect to the aerodynamic center of the airfoil since ...
0
votes
2answers
175 views

Where can i find aircraft blueprints for study purpose? [closed]

I'm a 3D artist and i want to start my new project. I'm going to create an exact model of the Embraer 190 aircraft. I need this for my graduation project at the university (I chose such a project, ...
3
votes
1answer
44 views

Why do the flap maneuvering speed margins to stick shaker depend on altitude?

Why do the flap maneuvering margins to stick shaker reduce with increasing altitude? Ref: It is written in FCTM of the Boeing 737-800:
0
votes
0answers
18 views

Aerodynamic Pressure Loads in FEA of Lifting Surfaces - Query

Let me give a brief summary of the process involved in the FEA of lifting surfaces with the wing as an example: 1. The wing is modelled as a hollow surface body in Ansys, meaning only the exterior ...
7
votes
3answers
1k views

Why is the tail group of virtually every airplane swept instead of straight?

Even low performance airplanes like ultralights have their tail group (vertical and horizontal stabilizer with rudder and elevator) swept backwards knowing fully well that a straight tail group will ...
4
votes
4answers
180 views

On a constant speed propeller, how is blade pitch related to airspeed and efficiency?

I'm trying to wrap my head around what the PHAK (Pilot's Handbook of Aeronautical Knowledge from the FAA) states for constant speed propellers. First, why is it that if airspeed increases, for a ...
5
votes
1answer
102 views

Do leading edge flaps increase the critical angle of attack?

So from my understanding, trailing edge (TE) flaps increase wing area + camber, effectively increasing the coefficient of lift for a fixed AOA which leads to higher lift at a fixed airspeed and AOA. ...
0
votes
1answer
58 views

What was the decrease in approach speed of the KFIR over the Mirage 5 due to the canards?

The Mirage III approached at 170 knots according to the Dassault. The Mirage NG and the KFIR C2 as well as the Swiss Mirage 5s added canards to the design, what was the decrease in approach speed due ...
1
vote
2answers
64 views

What are the aerodynamic implications of different conditions with the same Mach number?

At a particular Mach number, a fluid behaves similarly, but many other conditions could be different. For example, an aircraft flying at Mach .85 at a low altitude will be in denser, warmer air, and ...
1
vote
1answer
74 views

Boundary layer momentum thickness

Could someone please explain the concept of the boundary layer momentum thickness and its difference to boundary layer thickness calculation? Some explanation about the application of the boundary ...
0
votes
1answer
72 views

Materials for temporary dent repair?

On a recent commercial flight (A320neo), I noticed some materials attached to the leading edge of a slat (no photo available). The attached material was not smooth, it rather looked like a small ball ...
1
vote
4answers
115 views

Constant speed propeller blade pitch compared to fixed-pitch

I just transitioned to a complex airplane (Piper Arrow II). While I get how to use the Manifold Pressure / Propeller levers, I still find myself trying to piece together how all the components would ...
1
vote
3answers
172 views

Is it possible to design a GA plane with a 5' -10' wing span?

We see sparrows with 6" wing span land on a dime, yet it seems there no GA planes you can buy or build from a kit with short bodies, short wing spans, something with a 20' landing/takeoff roll, ...
2
votes
0answers
107 views

Why are the boundary layer suction holes placed far forward from the engine?

Edit: I know that the suction holes reduce the boundary layer; I am wondering if there is a reason why they are placed far ahead of the engine’s intake. My thinking is that the long duct past the ...
1
vote
0answers
29 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.
1
vote
1answer
45 views

What are typical stability analysis dampening values?

I'm not an aerospace engineer, so don't know if I'm asking this correctly. I've been using the new XFLR5 with stability analysis. Just don't know what values are good. What are typical stability ...
3
votes
2answers
76 views

Sensitivity of aircraft stability with respect to the CG location

I am working on the design of an aircraft (2 m long, wingspan = 3 m). The platform is longitudinally stable but it is very sensitive to the variation in CG location. For example, 1) CG_location = 100 ...
2
votes
1answer
97 views

Low speed, low wing loading?

Just looked at the Lamac ( light aircraft manufacturers association of Canada) specs. If I remember correctly, They want to see a maximum of 3 psf wing loading for Vc of 60mph, rising to a maximum of ...
1
vote
1answer
69 views

NACA Airfoil 0005.4

I have come across this NACA profile NACA 0005.4 mod and it is not clear how to interpret this airfoil. Is this considered a 4 digit NACA profile? What does the number after dot mean?
0
votes
1answer
72 views

Are there any full-size airplanes flying with a Selig S1223 airfoil?

Are there any full-size airplanes flying with a Selig S1223 airfoil?
39
votes
4answers
7k views

What does the behaviour of water on the skin of an aircraft in flight tell us?

Sometimes in damp conditions I notice some surprising (surprising to me, anyway) behaviour of water. I'll see moisture glistening in the heads of rivets or bolts on the top of the engine pylons - ...
8
votes
3answers
474 views

Aerodynamic advantage of blunt noses and WHY (subsonic)

Compared to a sharper conical nose, a blunter conical nose is aerodynamically superior in subsonic flight. My question is why. I've read a lot about this and allegedly: A blunter nose accepts a wider ...
1
vote
1answer
37 views

Why is the angle of attack not proportional to the stagnation point?

While I was studying my PPL today, I've encountered a question right below and I wasn't really satisfied with the answer. Which statement about the airflow around an aerofoil is correct if the angle ...
2
votes
1answer
68 views

How do I calculate the total cruise power from the propelers accounting for the losses?

Let's say I have an aircraft with four propellers (see diagram below) and I am supposed to calculate the cruise power required to drive the aircraft forward. The wing creates the lift and propellers ...
5
votes
2answers
276 views

Why do the inlet cones on an SR-71 retract at higher speeds while the one on a MiG-21 extends at higher speeds?

As shown by this illustration in the SR-71 flight manual, its inlet cones (spikes) retract as its speed increases: (source) Meanwhile, the Wikipedia page for the MiG-21 describes the opposite ...
0
votes
1answer
66 views

What are the pros and cons of a straight wing plane? [duplicate]

I need this asap for my folio... Much appreciated. I'm doing a research section on my folio and I need to know the pros and cons for a straight wing in general. Everywhere I've searched doesn't seem ...
3
votes
4answers
281 views

Is it possible for a person to fly with mechanical wings attached to his torso? [closed]

I’ve seen several adaptations of this concept in fiction from the tales of Icarus to Falcon in the MCU. But is it possible in reality for an average human to be able to fly through the air by wearing ...
3
votes
3answers
136 views

Is there a simple relationship between angle of attack and lift coefficient?

Is there an equation relating AoA to lift coefficient? I have been searching for a while: there are plenty of discussions about the relation between AoA and Lift, but few of them give an equation ...
1
vote
3answers
178 views

Why does an increase of airspeed result in a decrease of angle of attack?

In Chapter 02: Aerodynamics of Flight of Helicopter Flying Handbook, on page 10, it says: Induced flow velocity is increased, resulting in a decrease in AOA. I don't understand how airspeed can ...
14
votes
8answers
4k views

Does a windmilling propeller create more drag than a stopped propeller in an engine out scenario?

For this question lets assume that we are talking about a fixed pitch propeller and not a variable pitch propeller. I do understand that variable pitch props should be feathered during an engine ...
2
votes
2answers
140 views

Will creating a strong back pressure within a ducted propeller enable an aircraft to attain a higher altitude?

I would like to know if creating a strong back pressure within a propeller duct will enable an aircraft to attain a higher altitude. Please reference the conceptual drawing below. This is showing a ...
29
votes
6answers
4k views

Would an 8% reduction in drag outweigh the weight addition from this custom CFD-tested winglet?

I'm writing an essay at school about why there is so much variation in winglet design. I am analysing all the primary types of winglets used today in the aviation industry. I'm constructing them in ...
3
votes
2answers
105 views

FAA test question about load factor

The following question is from the FAA PAR (Private Pilot, Airplane) exam : The load factor on an airplane increases with : (A) Any moderate change in pitch attitude, increase in weight, and ...
5
votes
1answer
184 views

What is “Carson cruise” and can I determine it myself?

Mike Y. just posted an answer containing the following: With today’s fuel costs, the Carson cruise angle of attack, which represents the most efficient way to fly fast with the least increase in ...
6
votes
1answer
287 views

Why is a rectangular wing with winglets not better than an elliptical wing?

Why is a simple rectangular wing with winglets not better than an elliptical wing in terms of induced drag and produced lift?
2
votes
1answer
215 views

What is the highest a helicopter can fly?

What is the highest theoretical and current flight a helicopter can achieve?
4
votes
1answer
267 views

How are elliptical winglets better than blended winglets?

I've read in few papers that elliptical winglets give better performance than blended in terms of their L/D ratio. I am not able to find why elliptical winglets are better. the two differ by their ...
11
votes
1answer
339 views

What is the bend in the tip of the blade of the new Black Hawk?

The newer Black Hawks have this angle added to the end of their rotor blades. What is it for? How does it increase or decrease performance? Could this be used on airplane propellers? (...
27
votes
2answers
9k views

What helicopter has the most rotor blades?

I have seen 2 rotor blades up to many and wonder when does having more rotor blades become less efficient? What helicopter has the most rotor blades? Related: Why don't helicopters prefer shorter ...
4
votes
2answers
217 views

Why isn't the bell distribution used?

Why has the bell distribution not become widely used? Is the bell distribution only ideal in inviscid flow scenarios or is there another reason for the lack of use?