Aircraft-Structure-and-Repair-Lec-13.pptx

Structure

1. Chapter 3: Airplane Fuselage Structure (Continued) Aircraft Structure and Repair

2. The portion of the windshield that can be opened in flight for the purpose of giving pilot vision in case the windshield wiper and/or windshield heating system becomes inoperable during stormy conditions. The storm window must be so arranged that the airstream and the snow or rain are deflected across the opening. The windows and windshield sections for the pilot s compartment must be installed in such manner that there will be no glare or reflections which will interfere with the Vision of the pilot particularly at night. The windshield panes which the pilots will be directly behind in the normal conduct of their duties must have sufficient strength to withstand without penetration the impact of a 4-Ib bird when the velocity of the airplane relative to the bird along the flight path of the airplane. 2 W indshield Construction

3. The function of a radome is to provide protection for an antenna and it must also be capable of providing a clear, undistorted, antenna view, with minimum reflection. In addition, a radome must be structurally sound, since structural failure can result in aircraft damage. Although radomes are generally thought of as curved structures (e.g. a nose radome for protecting a weather radar antenna), they can also be flat or slightly curved coverings as those used for the protection of Doppler equipment. 3 Radomes

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5. In general, the radomes used on aircraft may be classified as either 'sandwich' or 'thin wall' and can be regarded as "tuned" or 'untuned' respectively. To minimize power losses the thickness ofa sandwich (tuned) radome proportional to the frequency of the associated radar system, whereas a thin wall radome , being untuned, is made as thin as structural limitations permit. 5 Radome Construction

6. Sandwich Construction The sandwich type of radome consists of a dielectric core of glass-fiber honey comb, expanded nitrite ebonite, expanded PVC or polyurethane foam, which is supported on each side by a skin comprising three or more layers of glass-fiber cloth impregnated and bonded with resin. Nose-mounted radomes are generally protected from erosion by covering nose with a neoprene overshoe, or by a polyurethane coating. 6

7. Honeycomb Construction This type of construction is often used in the manufacture of flying control surfaces. The interior structure, aft of the spar, consists mainly of honeycomb-shaped matrix, which is bonded edgewise to the outer stressed skins. Both matrix and stressed skin are made from aluminum alloy and are bonded together by the Redux process. If this form of construction is used for a control surface which is affected by heat from the engine, the honeycomb matrix and stressed skin may be made from stainless steel bonded together by brazing. Due to great strength in compression, Honeycomb construction is also used in aircraft flooring. 7

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9. Honeycomb Construction Both aluminum honeycomb and fiber glass honeycomb sandwich material are commonly used the construction of wing and stabilizer surfaces, bulk-heads, floors, control surfaces, and trim tabs. In the construction of large aircraft structures, and in some small aircraft as well the honeycomb sandwich structure employs either aluminum or reinforced plastic materials. Aircraft honeycomb material is manufactured in various shapes, but is usually of the constant thickness or tapered core types. 9