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Aviation History
1910
1910 - 0537.PDF
Sir Hiram Maxim, speaking of his paradox aeroplane says:— " When the aeroplane is made very thick in the middle, and sharp at the edges (see sketch), with the bottom side dead level, it produces a decided lifting effect, no matter which way it is being propelled through the air. This is not because the bottom side produces any lifting effect of itself, but because the air running over the top follows the surface. The aeroplane encounters air which is not moving at all. The air is first moved upwards slightly, but i also has to run down the incline to the rear edge of the aeroplane so that when it is discharged it has a decided downward trend A. ANGLE OF DEFLECTION IF THE INCIDENT WIND 15 HORIZONTAL WINOv_ A ANC,LE OF DEFLECTION \ F THE RELATIVE WIND IS TAN^ENTICAL TO LEADINC^ E-DCjE. therefore, the air passing over the top side instead of under the bottom side produces the lifting effect, showing that the top side of an aeroplane as well as the lower side should be considered.'' Now Sir Hiram Maxim satisfied himself by experiment that lift existed, and the above is his explanation of the phenomenon, which, in the light of more satisfactory evidence to the contrary, we accept as descriptive of the physical conditions obtaining, in spite of the fact that many who experiment in this direction seem to find it easier to produce vortex disturbances on the upper surface than stream-line flow. The point to which we specially wish to draw attention in this connection is the absence of a positive angle of incidence, and the necessity therefore of explaining the phenomenon of lift by recognising the primary importance of the angle of deflec tion. If those of our readers who are interested in this subject will again refer to page 238 of our current volume they will find diagrams illustrating this point, and also several remarks relating to the sub ject. In connection with the angle of incidence, too, it is of interest to refer to one of the conclusions in Lanchester's " Aerodynamics," where it is shown that an aerofoil, having a section represented by the arc of a circle and an attitude in which the chord is horizontal, satisfies the "essential" conditions. (See Lanchester's "Aero dynamics," pp. 275-281.)—ED.] CYCLE-AEROPLANE. [598] I have been studying your papers for some considerable time, and found it a very interesting subject to take up, since the London to Manchester has attracted so much public attention. I am now starting as a beginner, and I wish to know what is the difference between the following planes :—Aeroplane, monoplane, biplane, and a glider. I am making a model aeroplane, which is 45 in. long, 12 in. high, and 18 in. wide. Its weight is about 34 lbs. at the most, and I wish to know whether you think it advisable to have an electric motor to work it, and how many revolutions per minute would you think suitable for working the propeller or propellers, sufficient enough to take it up. With regard to using propellers, if one propeller is only used to work a machine, is it much longer and wider than as if three were in use ? I am thinking of constructing a cycle-aeroplane, and could you tell me the most suitable wood for the framework, and what kind of wood is used for propellers. Has a cycle-aeroplane been invented yet, and if you were making one would you consider 16 ft. long, 14 ft. wide, and about 4 it. to 5 ft. high too much ? Hoping to see your valuable information in your paper. Balham. B. BAKER. [The meaning of the terms mentioned will be found in the glossiry of the " Flight Manual." Monoplanes, biplanes and gliders are all aeroplanes. The former are single and double-deck machines respectively, while the last-mentioned implies a motorless device. It would be preferable to commence experiments with an elastic motor. One propeller capable of exerting the same thrust as three propellers would either be of a larger diameter or rotate at a higher speed. A cycle aeroplane has been invented, but we have not heard of its success.—ED.] THE CYCLOPLA.NE. [599] Your correspondent " O. D. A." (letter No. 551) confuses my " Cycloplane " shown in the first Aero Show at Olympia with another man's " Cycle aeroplane," shown in the second Aero Show, having a notice affixed, " If this machine fails to fly at the Crystal Palace befoie the end of the month, all orders for it will be auto matically cancelled." The Cycloplane is an aeroplane attached to a cycle to relieve the tyres of some of the rider's weight. There is no propeller fixed, and the fact that the cycle's tyre adhesion to the road is essential for pro pulsion should dispel the idea that the Cycloplane is intended for flight. From a scientific point, the Cycloplane is a great dodger of wind currents ; no matter how quickly you turn a corner of the road the Cycloplane automatically veers into a new and correct position. Two years ago I tried about forty different shapes and constructions, but found the inverted dihedral the only safe type in a side wind, because the weight is so far below the centres of pressure and lift. In side winds the other shapes quickly took me into hedges, but the inverted dihedral rather draws the aeroplane into the wind. The Cycloplane on the market is only one application ot the patents covering it. I shall have a flying machine shortly finished embodying another application of the inverted dihedral, and shall be pleased to give your readers the benefit of any further results after getting over the initial engine and other troubles, and hope it will turn out to be the two-speed machine you have so strenuously advocated in FLIGHT. Gargrave. JOHN GADNT. STEERING CONTROL. [600] I am sending a diagram with description of a novel steering control, for insertion in your useful paper. There are three motions from this control: — 1. The wheel can be turned, the steering column being kept in the same straight line. This turns the spindle through the universal- joint, N. There is a wooden drum on the spindle, between the two supports, M and P. This has a wire round it which can be led to operate the vertical rudder for hori zontal steering. 2. If, however, the whole steering column is swung right or left, sliding along a wooden quadrant- rest, and pdvoted about the joint, N, then a tiller motion at R results. This can be made to operate wires by a ring, R, sliding between two collars, 1 and 2, the wires operating ailerons. 3. If the wheel and column are thrust away from or drawn towards the aviator, the spindle (cross- section shown at AB) will slide through the drum without moving it, and will not affect the ring, R, as it has a space to slide between I and 2. A ring, S, loose between two collars, operates two wires, as shown, which are led to the elevator or horizontal rudders. The tiller motion has little or no effect on these last-mentioned All three motions, or any two, can be combined at will. Dartmouth. N. F. WHEELER, Naval Cadet. DIHEDRAL ANGLE. [601] Rd Mr. R. C. Clinker's reply (No. 502) to Mr. Flight's letter (No. 410), might I be permitted to make a few remarks ? Surely the machine has a tendency to regain the horizontal position as soon as it has left it, as while the machine is progressing forward it is virtually continually ascending, though it actually keeps in the same plane, therefore there must be an even pressure on the planes in the direction Pj, P2. This pressure is equal for any given distance along the vertical line, A, B, from the centre ; to be more explicit, if OX, OY, are equal, the pressure is equal, then points may be projected on to the planes giving the points, Z, V. So on the equal portions of the planes, OZ, OV, there is equal pressure. Is that not so? Now, when the machine tilts, what do we get ? If the machine is still travelling at the same speed, &c, the pressure for unit length of A B will be still the same, namely, OX = OV. But now 535
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