第22章

In laying out plans for a flying machine the first thing to decide upon is the size of the plane surfaces. The proportions of these must be based upon the load to be carried. This includes the total weight of the machine and equipment, and also the operator. This will be a rather difficult problem to figure out exactly, but practical approximate figures may be reached.

It is easy to get at the weight of the operator, motor and propeller, but the matter of determining, before they are constructed, what the planes, rudders, auxiliaries, etc., will weigh when completed is an intricate proposition.

The best way is to take the dimensions of some successful machine and use them, making such alterations in a minor way as you may desire.

Dimensions of Leading Machines.

In the following tables will be found the details as to surface area, weight, power, etc., of the nine principal types of flying machines which are now prominently before the public:

MONOPLANES.

Surface area Spread in Depth in Make Passengers sq. feet linear feet linear feet Santos-Dumont . . 1 110 16.0 26.0Bleriot . . . . . 1 150.6 24.6 22.0R. E. P . . . . . 1 215 34.1 28.9Bleriot . . . . . 2 236 32.9 23.0Antoinette. . . . 2 538 41.2 37.9No. of Weight Without Propeller Make Cylinders Horse Power Operator Diameter Santos-Dumont. . 2 30 250 5.0Bleriot. . . . . 3 25 680 6.9R. E. P. . . . . 7 35 900 6.6Bleriot. . . . . 7 50 1,240 8.1Antoinette . . . 8 50 1,040 7.2BIPLANES.

Surface Area Spread in Depth in Make Passengers sq. feet linear feet linear feet Curtiss . . . 2 258 29.028.7

Wright. . . . 2 538 41.030.7

Farman. . . . 2 430 32.939.6

Voisin. . . . 2 538 37.939.6

No. of Weight Without Propeller Make Cylinders Horse Power Operator Diameter Curtiss . . . 8 50 600 6.0Wright. . . . 4 25 1,100 8.1Farman. . . . 7 50 1,200 8.9Voisin. . . . 8 50 1,200 6.6In giving the depth dimensions the length over all--from the extreme edge of the front auxiliary plane to the extreme tip of the rear is stated. Thus while the dimensions of the main planes of the Wright machine are 41 feet spread by 6 1/2 feet in depth, the depth over all is 30.7.

Figuring Out the Details.

With this data as a guide it should be comparatively easy to decide upon the dimensions of the machine required.

In arriving at the maximum lifting capacity the weight of the operator must be added. Assuming this to average 170 pounds the method of procedure would be as follows:

Add the weight of the operator to the weight of the complete machine. The new Wright machine complete weighs 900 pounds. This, plus 170, the weight of the operator, gives a total of 1,070 pounds. There are 538square feet of supporting surface, or practically one square foot of surface area to each two pounds of load.

There are some machines, notably the Bleriot, in which the supporting power is much greater. In this latter instance we find a surface area of 150 1/2 square feet carrying a load of 680 plus 170, or an aggregate of 850pounds. This is the equivalent of five pounds to the square foot. This ratio is phenomenally large, and should not be taken as a guide by amateurs.

The Matter of Passengers.

These deductions are based on each machine carrying one passenger, which is admittedly the limit at present of the monoplanes like those operated for record-making purposes by Santos-Dumont and Bleriot. The biplanes, however, have a two-passenger capacity, and this adds materially to the proportion of their weight-sustaining power as compared with the surface area. In the following statement all the machines are figured on the one-passenger basis. Curtiss and Wright have carried two passengers on numerous occasions, and an extra 170pounds should therefore be added to the total weight carried, which would materially increase the capacity.

Even with the two-passenger load the limit is by no means reached, but as experiments have gone no further it is impossible to make more accurate figures.

Average Proportions of Load.