The Theory and Practice of Model Aeroplaning Part 19

[Ill.u.s.tration: FIG. 57.--THE G.P.B. SMITH MODEL.]

The model shown in Fig. 57 has won more compet.i.tion medals than any other. It is a thoroughly well designed[54] and well constructed model. Originally a very slow flyer, the design has been simplified, and although by no means a fast flyer, its speed has been much accelerated. Originally a one-propeller machine, it has latterly been fitted with twin propellers, with the idea of obtaining more directional control; but in the writer's opinion, speaking from personal observation, with but little, if any, success. The steering of the model is effected by canting the elevator. Originally the machine had ailerons for the purpose, but these were removed owing, I understand, to their r.e.t.a.r.ding the speed of the machine.

In every compet.i.tion in which this machine has been entered it has always gained very high marks for stability.

[Ill.u.s.tration: FIG. 58.--THE GORDON-JONES DIHEDRAL BIPLANE.]

Up to the time of writing it has not been provided with anything in the nature of fins or rudder.

Fig. 58 is a biplane very much after the type of the model just alluded to, but the one straight and one curved aerofoil surfaces are here replaced by two parallel aerofoils set on a dihedral angle. The large size of the propeller should be noted; with this the writer is in complete agreement. He has not unfortunately seen this model in actual flight.

The scientifically designed and beautifully made models ill.u.s.trated in Fig. 59 are so well known that any remarks on them appear superfluous. Their efficiency, so far as their supporting area goes, is of the highest, as much as 21 oz. per square foot having been carried.

[Ill.u.s.tration: FIG. 59.--MESSRS. T.W.K. CLARKE AND CO.'S MODEL FLYERS.]

For ill.u.s.trations, etc., of the Fleming-Williams model, _see_ ch. v., -- 23.

(Fig. 60.) This is another well-constructed and efficient model, the shape and character of the aerofoil surfaces much resembling those of the French toy monoplane AL-MA (see -- 4, ch. vii.), but they are supported and held in position by quite a different method, a neat little device enabling the front plane to become partly detached on collision with any obstacle. The model is provided with a keel (below the centre of gravity), and rudder for steering; in fact, this machine especially claims certainty of directional control. The writer has seen a number of flights by this model, but it experiences, like other models, the greatest difficulty in keeping straight if the conditions be adverse.

The model which will do this is, in his opinion, yet to be evolved.

The small size of the propellers is, of course, in total disagreement with the author's ideas. All the same, the model is in many respects an excellent one, and has flown over 300 yards at the time of writing.

[Ill.u.s.tration: FIG. 60.--THE DING SAYERS MONOPLANE.]

More than a year ago the author made a number of models with triangular-shaped aerofoils, using umbrella ribs for the leading edge and steel piano wire for the trailing, but has latterly used aerofoils of the elongated ellipse shape.

Fig. 61 is an ill.u.s.tration of one of the author's latest models which won a Bronze Medal at the Long Distance Open Compet.i.tion, held at the Crystal Palace on July 27, 1910, the largest and most keenly contested compet.i.tion held up to that date.

The best and straightest flight against the wind was made by this model.

On the morning of the compet.i.tion a flight of about 320 yards (measured in a straight line) was made on Mitcham Common, the model being launched against the wind so as to gain alt.i.tude, and then flying away with the breeze behind the writer. Duration of flight 50 seconds. The following are the chief particulars of the model:--Weight, 7 oz. Area of supporting surface, 1-1/3 sq. ft.

Total length, 4 ft. Span of main aerofoil, 25 in. Aspect ratio, 4 : 1.

Diameter of propeller, 14 in. Two strand geared rubber motor, carrying altogether 28 strands of 1/16 square rubber cord 43 in. long. The propeller was originally a Venna, but with the weight reduced by one-third, and considerable alteration made in its central contours.

The front skid of steel pianoforte wire, the rear of jointless cane wire tipped; the rear skid was a necessity in order to protect the delicate gearing mechanism, the weight of which was reduced to a minimum.

[Ill.u.s.tration: FIG. 61.--THE AUTHOR'S "GRa.s.sHOPPER" MODEL.]

The very large diameter of the propeller should be noted, being 56 per cent. of the span. The fin, high above the centre of gravity, was so placed for transverse stability and direction. At the rear of the fin was a rudder. The small amount of rubber carried (for a long distance machine) should also be noted, especially when allowing for friction in gearing, etc.

The central rod was a penny bamboo cane, the large aerofoil of jointless cane and Hart's fabric, and the front aerofoil of steel wire surfaced with the same material.

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, GREAT WINDMILL STREET, W., AND DUKE STREET, STAMFORD STREET, S.E.

FOOTNOTE:

[54] The design is patented.

_October, 1910_

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PAGE AERONAUTICS 2 AGRICULTURE 2 ARCHITECTURE 3 ARTILLERY 5 BRIDGES AND ROOFS 5 BUILDING 3 CEMENT AND CONCRETE 7 CIVIL ENGINEERING 8 DICTIONARIES 11 DOMESTIC ECONOMY 12 DRAWING 13 ELECTRICAL ENGINEERING 14 FOREIGN EXCHANGE 19 GAS AND OIL ENGINES 20 GAS LIGHTING 20 HISTORICAL; BIOGRAPHICAL 21 HOROLOGY 22 HYDRAULICS 22 INDUSTRIAL CHEMISTRY 24 IRRIGATION 27 LOGARITHM TABLES 28 MANUFACTURES 24 MARINE ENGINEERING 28 MATERIALS 30 MATHEMATICS 31 MECHANICAL ENGINEERING 33 METALLURGY 36 METRIC TABLES 38 MINERALOGY AND MINING 38 MUNIc.i.p.aL ENGINEERING 45 NAVAL ARCHITECTURE 28 ORGANISATION 40 PHYSICS 41 PRICE BOOKS 42 RAILWAY ENGINEERING 43 SANITATION 45 STRUCTURAL DESIGN 45 TELEGRAPH CODES 47 WARMING; VENTILATION 47 WATER SUPPLY 48 WORKSHOP PRACTICE 49 USEFUL TABLES 52 MISCELLANEOUS 53

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=The Atmosphere=: its characteristics and dynamics. By F.J.B.

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