In the former two articles on constructing the Knight Twister, we have told you how the fuselage and wings are built.
I am now building one of the latest types of the Knight Twister and drawings are included in this story that show some features of the construction of this ship. You may have noticed that the fairing on the fuselage will give a finished appearance similar to a monocoque fuselage. That is, every section of the fuselage is elliptical in shape.
In the first article describing the fuselage, I showed the cross-sections of the forward part of the fuselage, but not of the rear part.
Note Drawing 300, which is shown here. It shows and instructs you how to draw an ellipse. There are also drawings of the cross-sections of the fuselage at the various stations, numbered 1 to 4 inclusive, also a cross-section at the tail-post. The shape at the tail-post is carried out to the rudder.
The head-rest, shown at station No. 3 is gradually tapered down into the vertical fin, as shown in both cross-sections of stations Nos. 1 and 2.
In drawing Number 110, I show many fuselage steel fittings and controls that are within the fuselage. Notice in the drawing of the side of the fuselage (Drg. 110) that the elevator cable leading from the top control horn goes through the stabilizer (not crossed). The elevator cables pass under two pulleys placed under the pilot's seat. These are shown in a detail drawing No. 4.
This (No. 4) appears under the fuselage and also in the corner of the detail drawing. One of the elevator cables passes through the center of the torque tube. This is the tube that has the joystick attached to it.
The torque tube is 7/8 inch diameter as shown in the detail drawing (No. 2). The control horn that connects to the push-tubes, coming from the ailerons, is welded to the torque tube.
A 3/8 inch bushing, with 16 gauge wall, is welded under the torque tube and is reamed for a 1/4 inch bolt. This is for the joy-stick pivot. When making the bracket that holds the pulley in the front end of the torque tube, be sure that the pulley extends down into the torque tube just far enough to hold the cable in the center of the torque tube and so that it will not allow the cable to rub on the wall.
There are two collars or rings that are tack welded on the torque tube, to locate and keep the torque tube from shifting forward or backward in the front bearing. These collars are called "1 inch by 16 gauge bushings" in the detail drawing (No. 2). This means that they are one inch in diameter and have a wall thickness of 16 gauge which is .065 inch. They are 3/8 inch wide.
The torque-tube bearings are shown in Detail Drawing (No. 3) and the joystick is shown in Detail Drawing, (No. 1). The joy-stick diameter is 7/8 inch.
Take particular notice of Detail Drawing (No. 4). There is a note, stating that four tubes of 1/4 inch diameter are used as braces for the pulley housings, two to the side and two to the front or forward to the next station.
In Detail Drawing (No. 5) is shown the pedals that control the rudder. The pedals should be made and slipped on the 1/2 inch cross-tube with the narrow 5/8 inch by 16 gauge collars. After the pedals are properly spaced, these collars are tack welded to the cross-tube and then the cross-tube is welded into the fuselage.
A slight tension is kept on the rudder cables by two short coil springs, one on each pedal and they are fastened to the front part of the fuselage. Notice that the rudder cables pass through two fiber guides as shown in Detail (No. 6). The cables can not go straight back to the rudder, for they would then pass through the cock-pit, therefore these rudder cables must be deflected to the side of the fuselage by means of the fiber guides.
In Drawing No. 400, is shown the landing-gear of the Knight Twister, as well as a sketch of the landing-gear leg pants and also the wheel fairings.
When this landing-gear is complete and covered with sheet aluminum, it appears to be what is known as a Mono-Strut Type of Landing-Gear. The drawing shows that this type is really made of three struts, heavy enough to stand the shocks of severe landings. In this type of landing-gear we place the shock-absorber under compression instead of tension.
Some types have the shock-absorber in the bottom center of the fuselage and pulls out and down as the wheels come up. Notice, to change a tire, the short axle is pushed out and the whole wheel is dropped out of the fork, as with a motorcycle.
Detail (No. 1) shows the fitting in the fuselage that supports the top end of the shock-absorber. These fittings are made of 16 gauge steel and welded in. Drawing (No. 2) shows the shock-absorber. It shows a wrapped type of rubber shock-absorber. Some of you may wish to design a spring or oleo-type of shock for this ship. It would take less room.
Detail Drawing (No. 3) shows the upper end of the largest strut in the landing-gear that connects with the shock-absorber. Detail Drawing (No. 4) shows the fittings for the landing-gear on the fuselage and also on the front strut of the landing-gear.
Those fuselage landing-gear fittings are 3/8 inch by 16 gauge tubes welded to the lower longerous and are also reinforced with steel gusset plates to keep these fittings from being torn out of the longerons when a severe landing is made. The 3/8 inch by 16 gauge tube that is welded across the front and rear landing-gear struts is also re-inforced with a strap of steel that is welded to the side of the strut and over the top end.
Notice the partial side view of the fuselage. It shows the landing-gear fittings on the fuselage. The front fitting is on the longeron, but the rear fitting (at station No. 6) is ahout 3 inches down from the lower fitting. The center-lines of the bolts in both the front fitting and the rear are in line, just the same as the two bolts of two widely separated hinges on a door that may lead to your cellar or private stock.
Being that the rear landing-gear fitting on the fuselage is so far away from the longeron, it must be braced by a tube running in from this fitting to the center of the fuselage at the center front wing fitting.