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1

In low Mach flight, it can be theoretically demonstrated that an elliptical lift distribution produces the least induced drag for a given span. Induced drag of a lifting surface in incompressible flow can be expressed as (Ref Anderson, Fundamentals of Aerodynamics): $$C_{D_i}=\frac{C_L}{\pi e A}$$ where $C_L$ is the lift coefficient, $A$ is aspect ratio ...


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Winglets are not meaningful- the drag of the wingtip vortices is much less, the vortices are smaller, and they are only useful in cruise flight, where GA planes don't spend too much time.


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Thinking of lift and drag as “causing” each other is—by definition—technically flawed. Lift and drag are the “final” “result” of the magnitude of various pressure forces acting on the airfoil in various directions, resolved into two directions: parallel to the direction of airfoil travel and perpendicular to the direction of airfoil travel. The former is ...


1

One possible explanation is that large amounts of sweep and higher indicated airspeed are less common in "smaller" GA aircraft. Larger and faster aircraft with large amounts of sweep literally plow the air aside, resulting in a significant spanwise airflow at the wingtips. Winglets are touted for reducing the strength of wing tip vortices, and are said to ...


0

My general understanding is that winglets are most beneficial for aircraft that spend a lot of time in a rather narrow window of possible angles-of-attack-- e.g. an airliner in long-range cruising flight. Small aircraft tend not to fit this profile, unless they are flown by really boring pilots.


3

I am working on a project where I have to design a plane which has to cruise at 0.85 Mach at 35,000 ft. While working on the wing design, I quickly discovered that 6 series airfoils, with a good amount of thickness ratio, have a low Critical Mach Number. So, I started exploring Supercritical Airfoils (SC Airfoils). For doing analysis of SC airfoils ...


1

A few constructions, such as the Zenith CH 701 STOL, have horizontal stabs with non-symmetric, inverted airfoils:


2

The cost of approving an STC for an aircraft can be quite expensive and the return on investment may not have been worth it. ------------------------------------------ |Aircraft | # Built | Year Certified | ------------------------------------------ |Learjet 23 | 104 | 1964 | |Learjet 24 | 259 | 1966 to 1976 | (All variants) |...


5

Indeed, the airfoils on many horizontal tail surfaces do have negative camber. This is mostly in combination with powerful flaps on the wing so the tailplane will continue to work with flaps extended, when it needs to develop a relatively high downforce (which is indeed the same as negative lift). The extended wing flaps result in higher wing downwash so the ...


5

Most tailplanes (except for specialist applications, like endurance designs in model airplanes) have a symmetrical airfoil, whether thickened or effectively a flat plate. Camber of any sort is unusual in tailplanes for full size aircraft -- except as it might be incidentally produced by elevator trim, and in that case, it might be either upward or downward, ...


6

The tailplane should produce less lift than the main wing, for pitch stability. That is to say, its lift is negative relative to the wing lift. Its lift need not be wholly negative (pointing down), although it usually is during takeoff and landing. But yes, as a first approximation, the direction of camber matches the direction of lift. Also yes, negative ...


5

The pictures in the question show the normal position of the MiG-29 ailerons. That's how they are unless a roll is commanded. According to Mikoyan Mig-29 Fulcrum Pilot's Flight Operating Manual (google books) the slight upward position is set to improve yaw stability during roll meneuvers: As for whether this angle (neutral position of ailerons) changes in ...


0

On these modern aircraft, there is a thing called flaperons - meaning ailerons and flaps combined, which both move down and up when more lift is needed (TO, LDG and also during some aggressive maneuvers), and are used in order to roll the aircraft. Also- traditionally- you would assume that the plane uses his tail elevators for pitch, but the contrary is ...


3

Reference area for the aerodynamic coefficients (lift, drag, moment) is the planform area. Your picture shows only one wing, while the reference area S would also take into account the fuselage and the other wing: orange times twice blue and then some. In its most generic case, the equation for wing area S is $$\int_{-b/2}^{b/2} c \cdot dy$$ with b = wing ...


2

I implemented a program using Matlab for S.C calculus purposes (I'm actually involved in an aircraft project and, fortunately (or not), I'm the structures guy. I have based the code and the theory in a PDF bibliography that is linked w/ the .zip folder. You'll notice two matlab codes: -One is named "Load_Airfoil_Coordinates_using_MATLAB.m". It loads any ....


4

You'll only get opinions here, but from 40 years in the business, my opinion is not much. Airplanes are a balance of compromises and after much trial and error, dead ends, and false starts, a combination hits a sweet spot in the balancing act and that becomes a near universal configuration. When someone deviates, it MAY create a new configuration paradigm, ...


1

Three definitions first (simply): CoW (Centre of Weight) and CoP (Centre of Pressure). These two govern the aircraft (any) while flying (lets forget about thrust and drag now - the other two). AoA (Angle of Attack) is the anlge between the leading edge and the relative airflow. In case of airplanes CoW and CoP are close together. For a Paraglider, CoW is ...


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