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First, analyzing the data shows some lift and drag benefits at low AOA but much worse performance at higher AOA. Why? Because with undercambered wings, at higher AOA the concave bottom creates a higher pressure lifting "bubble" which a "permeable" area hurts. At lower AOA, a little "bleed" through the wing may enhance lift and ...


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Just ask the people at Fairey how well their Rotodyne succeeded. Wikipedia article Overly complex, heavy, and expensive.


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In some aircraft, such as the Canadair CP-107 Argus, the control yoke is not actually connected to the ailerons. Rather, they are connected to servo tabs, which are basically small ailerons attached to the rear of the actual ailerons (not to be confused with trim tabs, which look exactly the same but are controlled differently). Turning the yoke left causes ...


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There are 2 major problems. First is the weight you'd incur from: Extra rotors/propellers Transmission components (the V22 already has a transmission in case of an engine failure, it's already more complex than you'd ideally want but it's necessary for safety) Structural components to support the forces from the propellers and extra transmission It's ...


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What you describe is effectively a "compound helicopter" -- an inefficient design used only when you must combine hovering flight with maximum forward speed -- but with hovering managed by tilt rotors (adds complexity and weight for the shafts and transmission) and lift in forward flight handled by the fixed wings. The simple reason this hasn't ...


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Most likely the adverse yaw effect (due to the induced drag of the increased lift on the down-aileron side) is causing the wing to yaw the opposite direction from the intended roll, and the yaw causes the dihedral induced roll (proverse to the yaw) to override the aileron input. This situation is very commonly seen with very slow flying model aircraft -- ...


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When doing "bunts", it's about the oil, not the fuel. The airframe doesn't care; it's in a ballistic arc and is completely unloaded, like some trash you launched into a neighbor's yard with your Yard-A-Pult. Overall, the main risk is of a temporary drop in engine oil pressure when oil in the sump turns to globs and floats around, potentially ...


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Also, you have to think that the air does not hit the wing at a 90* angle to the leading edge on a swept wing. The shape of the wing ribs is not necessarily the shape that the air is being in contact with. It is probably going to be a longer trip than the shape of the rib in certain areas of the wing, like close to the tip, where both leading and trailing ...


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No, there isn't. Weight (which is a result of mass and gravity) is not related to mach number (which depends on velocity and the local speed of sound). You are comparing apples and oranges.


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If it's for something like an airplane or powered glider, for best thrust efficiency and noise level, you want the prop on the front. If behind, the turbulence from the pylon causes both efficiency loss and a loud buzz as the blades pass through the pylon's wake. This is a bigger deal than the effect of the prop's wake hitting the pylon when mounted forward. ...


2

The airflow downwind of the propeller will be moving significantly faster than upwind, since the incoming air is drawn over a wider angle than the outgoing air, which is more or less a cylinder. Also bear in mind that the outgoing airflow will be rotating in a helix and so will impart a sideways force to the pylon. If the pylon isn’t circular in cross-...


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Yes, sweep makes a wing heavier and less efficient. But making the airfoil of a straight wing thinner runs into diminishing returns and also will drive up mass. Since a thin wing needs to create the same lift as a thicker one, only the local speed increase from thickness can be tackled by making the airfoil thinner. The speed increase necessary for lift ...


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In order to measure yaw derivatives, the airplane has to yaw when in the tunnel. If you mount it at the center of gravity, which should be reasonably close to the geometric center, it will stay in the center of the tunnel section. In the old times, windtunnel models were mounted on strings. I expect that your model sits on a long sting. This sting sits on a ...


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The downwash is about as high as wide, and angled only by a few degrees (more at slow speed). So the longitudinal distance needs to be many times longer than the wing span to make the wings independent. And it would still be less efficient than increasing the span: If you double the span, you will decrease induced drag four times. If you half the lift, you ...


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It's done sometimes, for ultralight aircraft and paramotors. Like this:


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Any propeller 'unit' has been designed for a certain set of conditions: rotational-speed/air-speed/power/etc. If you then double-up in any way, then you can be assured that for the same conditions, the new unit will be less efficient. Also, the most efficient unit, all things being equal is a single-bladed propeller - some small model airplanes use this ...


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Sure, this is not only possible, but even has some advantages over single-plane propellers. The catch is you ideally want the two to spin in opposite directions to cancel out torque and vibration. You're building a contra-rotating propeller: Pictured is a Sun Flightcraft contra-rotating gearbox kit for Rotax 503 and Rotax 582 engines. Although more ...


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This arrangement is for a better fulcrum (not pun intended here) in pitching. Advantage is that they hide the plum of exhaust heat at some angle of view form the enemie aircraft


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There are the right way and the easy way. Rigorous way would be to use the ICAO Standard Atmosphere (Doc 7488-CD in 1993) a link for document Then your code looks for temperature gradient (Table D) and uses eq.12 or 13 for pressure calculation. It depends on the temperature gradient. Then you can easily compute the density eq.14. Easy way would be ...


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Let's imagine 2 theoretical wings, both of which have the same area, but differ in aspect ratio. Then the wing with the higher aspect ratio also has more span. This is what counts. If induced drag depends on the downwash angle, why would a longer wingspan reduce the angle? Because the wider wing will affect more air. Think of the air affected by the wing ...


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Your understanding of induced drag is correct. It is caused by turning the air flow and the force that does it must be tilted, otherwise conservation of energy would be violated. The stream ‘tube’ affected by the wing is obviously as wide as the wing, and always considered to be roughly as high as wide. That is, wings with higher span affect air to greater ...


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This is my interpretation. See if it helps. Induced drag can be thought of as the energy consumed in making lift, in other words, the energy consumed in inducing a package of air to move down as a result of the wing's passage. It's the energy consumed in accelerating a mass; wing, propeller, helicopter rotor, it's all the same. Vortices are just a ...


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As already done in this answer, we can calculate the True Air Temperature (TAT) that the aircraft's skin will feel from the Static Air Temperature (SAT) and the Mach number: $$ \frac{\text{TAT}}{\text{SAT}} = 1 + \frac{\gamma - 1}{2} M^2 = 1 + \frac{1}{5} M^2 $$ (using $ \gamma = 1.4 $ for air). For different SATs the curves then look like this: I added a ...


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The root bending issue has been well answered. Ultralights and hang gliders often have tailless swept wings. Such a wing with an elliptical distribution can be unstable in pitch, especially if the aerofoil is cambered. The bell distribution effectively puts a "tail at the tips of the wings", making the plane stable. The rule of thumb is that ...


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I don't think any kinds of external wires are going to affect the aerodynamic properties of the zero-lift tip, they will just add their own independent effects. For a straight wing the benefits are as already described. You note minimal root stress, hence light weight, hence minimal induced drag. A previous answer notes improved stall characteristics at slow ...


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Root bending isn't an issue for braced structures using wires or struts. The root fitting is just a pin joint on most wire and strut braced aircraft, and even if there is a one piece beam going across, like some hang gliders, it's not under significant bending, except at the point where the wires/struts attach outboard. Root bending only matters on ...


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Let me use the following graph to try to clarify your confusion, which is excerpted from Etkins, Dynamics of Flight: The body axis is rotated from the [flat] Earth axis via a series of Euler angle rotations, $\psi$ (heading), $\theta$ (pitch), $\phi$ (roll), in this sequence. In the nomenclature of the graph, we've rotated from $(x_E, y_E, z_E)$ (Earth axis)...


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Twofold (at least): firstly it results in less energy going into the tip vortices, secondly, is the reduction in lift is gradual towards the wingtip then it tends to reduce the spin tendency - the angle of attack of the tip is typically lower than at the root and so it will stall later than the root. In a slow-flying aircraft such as a paraglider the ...


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