## Flight Without Formulae: Simple Discussions on the Mechanics of the Aeroplane |

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already angle of incidence assume attained ballast biplane Bleriot XI Breguet cambered plane centre of gravity centripetal force Chapter chord climbing corresponding detrimental surface diameter directional stability displacement effect disturbing dive drag efficiency elevator engine equal exerted fact flight-path force forward travel gliding angle gliding path greater gust head-resistance Hence horizontal flight hour increase inverted dihedral keel surface lateral stability lift coefficient lift values longitudinal dihedral longitudinal equilibrium longitudinal stability lowered axis machine main plane Maurice Farman maximum mechanical efficiency monoplane motor normal angle normal flight number of revolutions obtained optimum angle oscillation pilot pitch ratio plane area position possess power required pressure Q produce propeller propeller-thrust raised axis relative action relative wind remains result revolutions per minute righting couple rolling axis rotary effect rotation rudder sheaf of total shown in fig speed of flight speed variation tail plane thrust total pressures turning movement useful-power vertical weight

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Page 154 - FIG. 70. not take place mathematically about this axis ; but at the same time, as further investigations would show, the true rolling axes only differ from it to a very slight extent, and are always slightly more raised than the rolling axis. This brings us to the moment of rolling inertia. In Chapter VII. was defined the moment of inertia of a body about any axis ; in the examination of longitudinal stability the moment of inertia of an aeroplane about its pitching axis was considered as the moment...

Page 184 - ... waves comparable to the waves of the sea. The regular mean wind which reigns there may therefore be considered as possessing atmospheric pulsations, propagated at a speed differing from the speed of the wind itself, comparable to the ripples produced by throwing a stone in flowing water—ripples which move at a speed differing from that of the current itself. This comparison of a regular wind with a flowing stream enables the effect of such a wind on an aeroplane to be studied in a very simple...

Page 41 - Therefore, in theory at all events, the optimum angle is not necessarily the most advantageous from the point of view of the least expenditure of power to obtain speed. But in practice the small saving in power would probably be neutralised owing to the difficulty of constructing two aeroplanes of the same type with a plane area of 30 and 40 sq.

Page 3 - ... diagrams or curves, which give, for each type of wing, the values of the lift and drag corresponding to the various angles of incidence. The following curves are here reproduced from M. Eiffel's work, and relate to: A flat plane (fig. 1). A slightly cambered plane, a type used by Maurice Farman (fig. 2). A plane of medium camber, adopted by Breguet (fig. 3). A deeply cambered plane, used by Bleriot on his No. XI. monoplanes, cross-Channel type (fig. 4.) * The word " drag " is here adopted, in...

Page 193 - ... duction of the lift coefficient by 0-005 would be 80 kg. instead of 40 kg. These results hold good irrespectively of the area and the speed. Finally, if both the speed and the angle of wind vary at one and the same time, both results are added to one another. From this it may be deduced that for an aeroplane to experience the least possible loss of lift owing to an atmospheric disturbance, it should be light, fly at a high speed, and possess a big lift coefficient. These two latter conditions...

Page 188 - ... would be zero. For any craft possessing mass the primary gust effect would at first be zero and the relative action at a maximum; but, as the machine gradually yields to the gust, the relative action grows smaller and finally vanishes altogether when the aeroplane has completely conformed to the new wind. The greater the inertia of the machine, the longer will be the transition period. Still keeping to our hypothesis of an instantaneous change of condition, an anemometer fixed in space and another...

Page 88 - This study of the power-plant may now be rounded off with a few remarks on static propeller teats, or bench tests. These consist in measuring, with suitable apparatus, on the one hand, the thrust exerted by the propeller turning at a certain speed without forward motion, and, on the other, the power which has to be expended to obtain this result. Experiment has shown that a propeller of given diameter, driven by a given expenditure of power, exerts the greatest static thrust if its pitch ratio is...

Page 107 - ... which would again pass through the centre of gravity. A fourth arrangement (fig. 38), and the first to be adopted in practice—since the 1903 Wright and the 1906 SantosDumont machines were of this type—is also possible. It has lately been made use of again in machines of the " Canard" type (eg in the Voisin hydro-aeroplane), and consists in placing the tail, which must of course be a lifting tail, in front of the main plane. The conditions of equilibrium are the same as in fig. 36. In an aeroplane,...

Page 91 - ... position of the body in question, through the same point G, termed the centre of gravity of the body. The effect of gravity on any body, in other words, the FIG. 24. force termed the weight of the body, therefore always passes through its centre of gravity, whatever position the body may assume. Another principle is also of the greatest importance in considering stability; namely, the turning action of forces. When a force of magnitude F (fig. 25), exerted in the direction XX, tends to make a...

Page 50 - ... always met with whatever the vehicle of locomotion under consideration, and their combination enables us to determine as the most efficient from a mechanical point of view that vehicle or machine which requires the least power to attain, for a constant weight, the same speed. Hence, what we may term the mechanical efficiency of an aeroplane may be measured through its weight multiplied by its normal speed and divided by the motivepower. If the speed is given in metres per second and the power...