New answers tagged aircraft-physics
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Circulation may be controlled via either air blown through spanwise slots or horizontal-axis rotors, alone or in combination.
Experiments on wing systems go back at least as far as 1902 and since then almost every variation imaginable has been tried.
The problems come in the engineering implementation. Where investigations have reached the stage of flight ...
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The direct answer to the question as it is ("What´s the relationship between AOA and Airspeed?") is simple: none whatsoever -- that is, until you introduce context and some conditions.
Your context is: we want an airplane to fly. And not just 'fly' but to keep level, at least. For that, you need a certain amount of lift. Lift is used to counteract ...
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A practical answer to help you understand critical angle of attack and stall speeds would be the operation of fast jets. The quickest way to land a jet is to join for a ‘run-in and break’ this could be at any speed but typically 350kts. A high-g turn would be used from overhead the runway at circuit height to the downwind position. The aircraft would be ...
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"Can we get into a stall without reaching the critical AOA?" -- no.
"We know that any aircraft will stall at its stall speed (for a specific weight, CG position, etc.)"-- we need to add "G-loading" to this list of parameters. The "stall speed" we usually talk about is the 1-G stall speed. Change the weight or the G-...
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Most light aircraft sit slightly nose-up in flight. This simplifies the design parameters for the wing mounting, as the wing needs to angle slightly up. The designer seeks to maximise thrust by angling the engine down so it points straight forward.
On a high-wing type, angling the engine down also adjust the thrust line so it passes closer to the centre of ...
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Let us assume level flight. Then the forces acting on the aircraft are shown in the following sketch (not necessarily to scale):
The forces are :
the total aerodynamic force $ F_A $, which is split into two components: lift $L$ (perpendicular to direction of motion) and drag $D$ (parallel to direction of motion)
the weight $W$
the thrust $T$, here acting ...
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If a taildragger is configured and flown properly, actually the result is the same as for a tri-gear.
If you land 3-point, a "full stall" landing, the ideal is for the tailwheel to make contact just before the mains, so that ground contact has the result of reducing AOA (a tiny amount). If you contact mains first you are likely to skip or bounce ...
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First, we must be clear on what exactly is "excess thrust". I will list two possible definitions, although many more may be possible.
Excess thrust is the component of the resultant force in the direction of the flight path. Using this definition, excess thrust and steady state flight are directly at odds (because any net force results in an ...
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When less than full thrust is in use during any steady state phase of flight, it can be considered that excess thrust is available.
Application of some or all of this excess thrust will result in a disturbance to the steady state - either acceleration in level flight, transition to a climb, increased climb rate, reduced descent rate or a combination, ...
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In a steady-state climb, Thrust is not a leg of the closed triangle of force vectors; rather, (Thrust-Drag) is.
See the right-hand vector diagram in this related answer-- Is excess lift or excess power needed for a climb?. The diagram shows that if our definition of "excess thrust" is (Thrust minus Drag), then excess Thrust clearly does exist in a ...
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Yes. With a tailwheel airplane, if you are trying to make a "wheel landing" (on the main wheels only) rather than a 3-point landing, it is critical that the sink rate be very low at the moment of touchdown, or else the plane will tend to pitch nose-up (tail-down) which will make it bounce back into the air. A plane with tricycle gear doesn't have ...
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Agreed. Tail wheel aircraft generally have the required angle of attack on touchdown (for a given landing speed) very close to the angle achieved when all three wheels are in contact with the ground. Hence, if the aircraft is landed at too higher speed the tail will be high, and without care, the touchdown can cause the aircraft to rotate around the main ...
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Yes, it does make sense.
However, the angle of attack increase of the tailwheel airplane would only be possible if it touches down on the main wheels while there still is much clearance of the tail wheel or skid. Normally, the ground attitude of tailwheel airplanes should be very close to their landing attitude, so all three wheels touch down almost ...
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In addition to some excellent content in other answers, it's worth noting that V-bestglide occurs at the angle-of-attack where L/D (and therefore also Cl / Cd) is maximized, while for shallow glide angles, it's a good approximation to say that V-minsink occurs at the angle-of-attack where (Cl^3 / Cd^2) is maximized1. The difference between the two formulae ...
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A. It simply means that the airplane will perform according to the combination of pitch and power control inputs that you make.
B. Yes, why wouldn’t it be? Aircraft are subject to basic laws of physics. These laws are consistent. Every time you pitch nose down and add power you will descend and accelerate. Every time.
C. N/A because it is always true, ...
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In a steady-state climb in an airplane, the basic formula for the magnitude of the Lift vector is Lift = Weight * cosine (climb angle). For much more on this, see the vector diagrams and calculations in this related ASE answer. As long as the Thrust line is aligned with the flight path rather than being tilted up or down, the relationship Lift = cosine (...
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In cruise: No. Less drag means less thrust, which is always beneficial for the practical operation of an airplane.
There is only one condition except for approach and landing where high drag helps, an that is also not during cruise: In aerobatic airplanes during vertical maneuvers.
If, for example, the aerobatic display includes a vertical dive, high drag ...
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The question shows some confusion around the difference between forces and their coefficients.
Let's address forces first.
The key thing about forces is that in an unaccelerated state (which excludes turning flight) we have to be able to rearrange the force vectors into a closed triangle, square, or other closed figure.
As in the vector diagrams shown in ...
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High lift at the expense of even higher drag means that the plane will not be able to fly very fast, as drag rises sharply with speed. But the extra lift is still useful in several situations and is often provided by drag-creating high-lift devices. Some of these situations include:
STOL (short takeoff and landing) and low-speed flight performance, where ...
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Landing phase would benefit from high lift but low lift-to-drag ratio. At most phase of flight you need about the same amount of lift to keep the plane in the air. However during landing you need to slow down to landing speed. Hence you lower lift-to-drag ratio by keep the same amount of lift but increase amount of drag. This is usually accomplish by ...
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I'm trying to understand why does L/D MAX, (the top of the polar curve
that computes CL & CD ratio for any airfoil) is also the lowest point
of the total drag curve.
The graph in another answer shows how to find the max ratio of Cl / Cd, which is arithmetically equal to the max ratio of L/D.
The concept of minimum Drag (as opposed to minimum Drag ...
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Airfoil drag is "parasitic" (or better: everything but induced) drag.
It consists of shear drag and pressure drag, the latter mostly from local flow separation. Both are only present when viscous flow is assumed. Airfoil drag is for the wing section without taking tip effects into account, presuming an infinitely wide wing. This kind of theoretical ...
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