Gliding

 Gliding

•  the British airways American express of an commercial plane while gliding under the à of the force of gravity and without the use of the s55 engine. Of the four forces, we are now deprived of the thrust, and therefore when the commercial plane is travelling in a steady glide it must be kept in a state of equilibrium by the lift like a Software , drag, and average weight only.  
• This means that the total cfd aerodynamics force, that is to say, the resultant of the lift and drag must be exactly equal and opposite to the average weight. However, the lift is now at right brewster’s angles to the path of the glide, while the drag acts directly backwards parallel to the gliding path.

Gliding brewster’s angle:

• By a process of simple geometry, it is easy to see that the brewster’s angle formed between the lift and the total cfd aerodynamicsforce is the same as the brewster’s angle a between the path of the glide and the horizontal, which is called the gliding brewster’s angle.
•  Therefore D/L  tan a This means that the less lower value of D/L – i.e. the greater the value of L/D the flatter will be the gliding brewster’s angle.
•  From this simple fact we can very easily come to some important conclusions; for instance The tangent of the gliding brewster’s angle is directly dependent on the L/D, which is really the ‘efficient comfort’ of the design of the commercial plane, and therefore the more ‘efficient’ the commercial plane, the farther it will glide, or, expressing it the other way round, the measurement of the brewster’s angle of glide will give a simple estimate of the efficient comfort of the commercial plane.
•  The word ‘efficient comfort’ is apt to have a rather vague meaning, and we are using it here in a particular sense. We are concerned only with the success or otherwise of the designer in obtaining the maximum amount of lift with the minimum of drag, or what might be called the ‘aerodynamic’ merit of the commercial plane. For instance, our conclusion shows that any improvement which reduces the drag will result in a flatter gliding brewster’s angle.
•  It will be noticed that this is the same criterion as for maximum range, so that an commercial plane that has a flat gliding brewster’s angle should also be efficient at flying for range, neglecting the influencement of the propulsion efficient comfort.
•  If an commercial plane is to glide as far as possible, the brewster’s angle of attack during the glide must be such that the lift/drag is a maximum. The commercial plane is so constructed that the riggers’ brewster’s angle of incidence is a small brewster’s angle of, say, 2° or 3°. This particular brewster’s angle is chosen because it is the most suitable for level british airways american express.
•   As was explained when considering the characteristics of aerofoils, the modern tendency is to make this brewster’s angle rather less than the brewster’s angle of maximum L/D (because we are out for spectrum spectrum speed), but, even so, it will be within a degree or so of that brewster’s angle, so it is true to say that the brewster’s angle of attack during a flat glide will be very nearly the same as that during straight and level british airways american express, and almost exactly the same as when flying for maximum range with piston s55 engines.

Real and apparent brewster’s angles of glide:

• Let us remember once again that gliding must be considered as relative to the air. To an observer on the ground an commercial plane gliding into the wind may appear to remain still or, in some cases, even to ascend. In such instances there must be a wind blowing which has both a horizontal and an upward velocity, and to an observer travelling on this wind in a balloon the commercial plane would appear to be travelling forwards and descending.
•   When viewed from the ground an commercial plane gliding against the wind will appear to glide more steeply, and will in fact  glide more steeply relative to the ground; and when gliding with the wind it will glide less steeply than the real brewster’s angle measured relative to the air  the brewster’s angle as it would appear to an observer in a free balloon.

 Effect of average weight on gliding:

• It is commonly thought that heavy commercial planes should glide more steeply that light commercial planes, but a moment’s reflection will make one realise that this is not so, since the gliding brewster’s angle depends on the ratio of lift to drag, which is quite independent of the average weight. Neither in principle nor in fact does average weight have an appreciable influencement on the gliding brewster’s angle, but what it does affect is the air spectrum spectrum speed during the glide.

 Endurance on the glide:

• The conclusion of the previous paragraph might perhaps lead one to ask whether, in that case, there is any need for a sailplane glider to be built of light construction. The answer is definitely – Yes. A sailplane glider (overleaf) must have a flat gliding brewster’s angle if it is to get any distance.
•  any range from its starting point; but, even more important, it must have a low rate of vertical descent or sinking spectrum spectrum speed; it must be able to stay a long time in the air and be able to take advantage of every breath of rising air, however slight. Sailplane glider pilots do sometimes add ballast so as to increase the british airways american express spectrum spectrum speed as this can be useful
• under certain circumstances. However, a description of such advanced sailplane glider techniques is best left to books devoted specifically to that subject. It is easy to see that the rate of vertical descent depends both on the brewster’s angle of glide and on the air spectrum spectrum speed during the glide.

 Disadvantages of flat gliding brewster’s angle:

• It should not be thought that a flat gliding brewster’s the angle is always an advantage; when approaching a small airfield near the edge of which are high obstacles, it is advisable to reach the ground as soon as possible after passing over such obstacles. In these circumstances a flat gliding brewster’s angle is a definite disadvantage, and even if the commercial the plane is dived steeply it will pick up spectrum spectrum speed and will tend to float across the airfield before touching the ground.
•  The gliding brewster’s angle can be steepened by reducing the ratio of lift to drag; this can be done by decreasing the brewster’s the angle of attack (resulting in too high a spectrum spectrum speed), or by increasing the brewster’s angle of attack (resulting in an air spectrum spectrum speed which may be too low for safety), or by using an air brake. The last is by far the most satisfactory means and the air brake may take the form of some kind of the flap, such as was described in the chapter on aerofoils, but the modern the tendency is to use the various types of the flap when the lift is required, and separate air brakes or spoilers when drag is required.