These forks are strengthened by aluminum clamps H, Figs. 27 and 28, which keep the tubes from spreading apart. Here, of course, is another call for special castings, but a handy workman may be able to improvise a satisfactory substitute from sheet steel. On each tube there are four fittings: At the bottom, the collar M to which the fork J is attached, and above, the slide G and the clamps K and L, which limit its movement. The collar and slide should be forged, but as this may be impossible, the drawings have been proportioned for castings. The work is simple and may be done by the amateur with little experience. The projecting studs are pieces of 3/4-inch, 14-gauge steel tubing screwed in tight and pinned, though if these parts be forged, the studs should be integral.
The clamps which limit the movement of the slides are to be whittled out of ash or some other hard wood. The upper clamp is held in place by four bolts, which are screwed up tight; but when the machine makes a hard landing the clamp will yield a little and slip up the tube, thus deadening the shock. After such a landing, the clamps should be inspected and again moved down a bit, if necessary. The lower clamps, which, of course, only keep the wheels from hanging down too far, have bolts passing clear through the tubes.
To the projecting lugs on the slides GG are attached the rubber tube springs, the lower ends connecting with eye bolts through the beam E. These rubber tubes, of which four will be needed, are being made by several companies in this country and are sold by supply houses. They should be about 14 inches long, unstretched, and 1 1/4 inches in diameter, with steel tips at the ends for attachment.
Hub Attachments. The hubs of the two wheels are connected with the link P, with universal joints N N at each end. In case the machine lands while drifting sidewise, the wheel which touches the ground first will swing around to head in the direction in which the machine is actually moving, and the link will cause the other wheel to assume a parallel position; thus the machine can run diagonally on the ground without any tendency to upset.
This link is made of the same 1- by 3/8-inch oval tubing used elsewhere in the machine. In the original Bleriot, the joints are carefully made up with steel forgings. But joints which will serve the purpose can be improvised from a 1-inch cube of hard wood and three steel straps, as shown in the sketch, Fig. 27. From each of these joints a wire runs diagonally to the bottom of the tube on the other side, with a spring which holds the wheel in its normal position. This spring should be either a rubber tube, like those described above, but smaller, or a steel coil spring. In the latter case, it should be of twenty 3/4-inch coils of No. 25 piano wire.
Wheels. The wheels are regularly 28 by 2 inches, corresponding to the 700 by 50 mm French size, with 30 spokes of 12-gauge wire. The hub should be 5 1/4 inches wide, with a 5/8-inch bolt. Of course, these sizes need not be followed exactly, but any variations will involve corresponding changes in the dimensions of the forks. The long fork goes on the hub inside of the short fork, so that the inside measurement of the end of the big fork should correspond to the width of the hub, and the inside measurement of the small fork should equal the outside measurement of the large fork.
Rear Skid. Several methods are employed for supporting the rear end of the fuselage when the machine is on the ground. The first Bleriot carried a small wheel in a fork provided with rubber springs, the same as the front wheels. The later models, however, have a double U-shaped skid, as shown in Figs. 23 and 24. This skid is made of two 8-foot strips of ash or hickory 1/2 by 3/4 inches, steamed and bent to the U-shape as shown in the drawing of the complete machine.
Fig. 29. Details of Framework of Bleriot Main Supporting Planes
Wings. Having completed the fuselage and running gear, the wings are next in order. These are constructed in a manner which may seem unnecessarily complicated, but which gives great strength for comparatively little weight. Each wing contains two stout ash beams which carry their share of the weight of the machine, and 12 ribs which give the proper curvature to the surfaces and at the same time reinforce the beams. These ribs in turn are tied together and reinforced by light strips running parallel to the main beams.