Learning to fly in the U.S. Army

by E. N. Fales

1. Landing Gear Assembly to Fuselage.—The landing gear is assembled by mounting the wheels on the axle, and bolting wheels in place. The fuselage should now be elevated to receive the landing gear. This may be accomplished in one of two ways—either by tackle or by shims and blocking. For either method, first connect up the tail skid. This is accomplished by pinning up the front end of the skid to the spring-fitting, and then pinning in the other end to the tail-post socket.

If block and tackle are used to raise the fuselage, pass a line under the engine-bed supports or sills just to the rear of the radiator. To this line attach hook of block. To avoid damaging or crushing some part do not attach lifting device to any other point. With the fuselage now resting on its attached tail skid, lift the front end until the lower longeron clips clear the landing gear. When the clips on the longerons line up with the clips on the ends of the struts of the landing gear the bolts are passed down through the holes thus aligned. This places the nuts on the down side of the connection thus facilitating assemblies and inspection of connections. The castellated nuts are then put on the bolts and drawn up tight, until the drilled hole in the bolt is visible through the castle of the nut. Then insert cotter-pin and spread the two leaves backward over the nut. This locks the nut in place. When the landing gear has been completely assembled to the fuselage, the tail of the machine should be elevated and supported by a horse and blocking until the upper longeron is level. This can be determined by placing a spirit level on the upper longeron at the tail or on the two engine-bed sills in machines where these sills are parallel to the top longeron, as in Curtiss JN-4B.

2. Horizontal Stabilizer.—After the upper longeron is levelled up, the horizontal stabilizer is assembled to the tail of the fuselage. The horizontal stabilizer is fastened by means of bolts in the top longeron and the tail post. The nuts are all drawn up tight and cotter-pinned. The vertical stabilizer is next erected in place.

3. Vertical Stabilizer.—The vertical stabilizer is now fastened to the horizontal stabilizer, first by means of the bolt which passes up through the forward part of the horizontal stabilizer and then by means of the flexible stay lines running from the top of the vertical stabilizer. The forward bolt passes through the clip at the lower front point of the vertical stabilizer. Draw the nuts up tight and lock with cotter-pins. Flexible wire cables are attached to vertical stabilizer, and turnbuckles are used to align and tighten cables. The vertical stabilizer is further aided in its alignment by the bolt clip at its toe and by the double clip at its heel. This rear double clip passes over the two bolts which are attached to the tail post and which hold down the horizontal stabilizer.

4. Rudder.—The control braces are first attached to the rudder. These braces are so placed that the upper tips point toward the hinge line. In this fashion the holes will match up. The rudder is mounted on the tail post and vertical stabilizer by means of the hinges. The hinge pins are inserted in the hinges, and cotter-pins passed through the drilled holes in the bottom of the pins. The cotter-pins should be spread backward as usual.

5. Elevators or Flaps.—These are first equipped with the control braces which are also arranged so that the upper tips point toward the hinge line. The elevators are mounted to the horizontal stabilizer by means of the hinges and hinge pins. The hinge pins are kept in their bearings by the cotter-pins, inserted through the drilled holes in the bottom of the hinge pins.

6. Panel Assembly.—The panels are now to be assembled. Before the main panels can be connected to the fuselage, the engine section panel must be erected.

Engine Section Panel.—The engine section struts are first set into place in their sockets on the engine section. Then the whole thing is lifted up to place and the four struts are set into their sockets on the upper longeron. The bracing wires are attached and the engine section aligned by means of them (see alignment).

7. Main Panels.—The main panels are now to be assembled to the machine. There are two methods for accomplishing this: first, assemble panels, struts and wires, before attaching to fuselage; second, assemble the upper plane to the engine section, and complete assembly. The first method is the most advantageous, since it permits the setting of the main panels at the correct stagger and dihedral, and does not require as much adjustment as the second method, which will be omitted.

Assembling Panels Together Before Fastening Them to Fuselage.—All the main struts will be found to bear a number. These numbers run from 1 to 8, on Curtiss JN-4. The numbers on the Standard run from 1 to 12 including the center section struts. The method used in numbering the posts is as follows: Starting at post No. 1, with the outer post, on the left-hand side of the pilot, as he faces his direction of travel, the posts are numbered successively from No. 1 to No. 4; Nos. 1 and 2 being on the left side and Nos. 3 and 4 being on the right side. The rear posts are similarly numbered from No. 5 to No. 8, Nos. 5 and 6 being on the left and Nos. 7 and 8 being on the right. This system of numbering does not include the engine section struts. The plan shows the system graphically (see Fig. [39]).