Search Results

This document provides background information on the design, application, repair and inspection of composite structures, including metal bonding, used on civil transport aircraft. The objective of this document is to assist inspectors to know where to expect composite and metal bonded parts on the aircraft, to understand the capabilities of current NDT methods and to aid interpretation of inspection results. ...The objective of this document is to assist inspectors to know where to expect composite and metal bonded parts on the aircraft, to understand the capabilities of current NDT methods and to aid interpretation of inspection results.

Two tests of composite shells loaded under half-cosine impulsive loadings are discussed. One cylinder which included no other materials was modeled successfully such that calculated results matched test results out to late times. ...The other cylinder, which included an inner annulus of an elastomeric material, was less successfully modeled, even though the composite material was modeled similarly in both instances. A viscoelastic model and an elastic model were both used to model the elastomeric material, and the viscoelastic model produced significantly better results.

Bell Helicopter Textron has used fiber reinforced plastic materials in many applications since the earliest appearance of these materials. An overview of past, present and future usage is presented. The discussion includes examples of fuselage, control system, main rotor, energy attenuator and engine cowling/firewall applications.

Manufacturing readiness of composite rotors and certification of flywheels depend in part on the maturity of nondestructive evaluation (NDE) technology for process optimization and quality assurance, respectively. ...Examples of possible occurring flaws or anomalies in composite rings as detected by NDE and validated by destructive metallography are shown. The general NDE approach to ensure quality of composite rotors and to help in the certification of flywheels is briefly outlined. ...The general NDE approach to ensure quality of composite rotors and to help in the certification of flywheels is briefly outlined.

Design and fabrication of a titanium matrix composite (TMC) F-15 nose landing gear (NLG) outer cylinder is discussed. Results of a field experience survey examining landing gear (LG) operations are also discussed.

The testing of a titanium matrix composite (TMC) F-15 nose gear outer cylinder is discussed. Two cylinders were fabricated. An entire F-15 nose gear was assembled using the first cylinder.

In this study, lightning effects on hydraulic transport elements in composite aircraft have been considered for the first time. Based on recent test results and analysis, several forms of possible structural damage and system component failures are presented. ...A new trend in the aerospace industry is the use of composite materials in the construction of aircraft wings and fuselages. This has brought about new technologies, with a reduction in weight being a major advantage. ...Due to the low conductivity of the composite structures, in the case of direct lightning strike, high currents will flow through the conductive structural elements.

A high potential to reach this goals is offered by textile structural composites. Textile fibre performs for composite reinforcement can be manufactured automatically with an optimized fibre architecture in 3D space. ...Composite materials offer a high potential for realizing high performance light weight structures for aerospace applications. ...In the paper the overall performance of textile structural composites based on braiding will be evaluated and first exemplary applications, especially in the aerospace field will be presented (stiffened profiles, engine components).

To achieve the demonstrated energy density of greater than 310 kJ/kg in a volume of less than 0.05 m3, the rotors utilize flexible composite arbors to connect a composite rim to a metallic shaft, resulting in compact, lightweight, high energy density structures. ...Flywheel energy storage systems employing high speed composite flywheels and advanced electric motor/generators are being evaluated by the Department of Defense (DoD), NASA [1], and firms [2,3] to replace electrochemical battery banks in satellites and manned space applications. ...This paper describes the design, fabrication, and spin testing of two 10 MJ composite flywheel energy storage rotors. To achieve the demonstrated energy density of greater than 310 kJ/kg in a volume of less than 0.05 m3, the rotors utilize flexible composite arbors to connect a composite rim to a metallic shaft, resulting in compact, lightweight, high energy density structures.

This paper describes a segment of research activities involving composite materials under a joint University-Industry project sponsored by NASA-Lewis for more general investigation on an Electro-Impulse De-icing method for aircraft. ...The application of EIDI system to the Lear Fan Kevlar Composite leading edge has been successfully tried in the icing tunnel.

An analysis has been conducted to determine the feasibility of composite fan blade for meeting impact resistance requirements for turbo-fan engines. This report describes the effect of centrifugal force on the impact response of fan blades. ...For the blade made of light materials, e.g. polymer matrix composites, the effect of centrifugal force is less appreciable than for the blade made of heavy materials. ...Maximum stress generated by 1.5 lb (680 gram) bird strike is large enough to generate local permanent deformation in the metal blades and to generate global delamination in the polymer matrix composite blades.

In this study, a new hydrophilic, composite membrane has been developed for passage of the coolant fluid and retention of gas bubbles. ...The resulting composite membranes have shown repeatable decrease in nitrogen permeability, which is indicative of a decrease in membrane pore size.

This report discusses the design implications for spacecraft radiators made possible by the successful fabrication and proof-of-concept testing of a graphite-fiber-carbon-matrix composite (i.e., carbon-carbon (CC)) heat pipe. The prototype heat pipe, or space radiator element, consists of a C-C composite shell with integrally woven fins. ...The prototype heat pipe, or space radiator element, consists of a C-C composite shell with integrally woven fins. It has a thin-walled furnace-brazed metallic (Nb-1%Zr) liner with end caps for containment of the potassium working fluid. ...From geometric and thermal transport properties of the C-C composite heat pipe tested, a specific radiator mass of 1.45 kg/m2 can be derived. This is less than one-fourth the specific mass of present day satellite radiators.

Oven and flame tests were designed and conducted to evaluate the heat resistance of a ceramic coating material, Cerakote C-7700Q, and evaluate its viability to replace the intumescent coating as one painting material for helicopter engine cowlings. The test results showed that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. This study explained why serious appearance defects occurred in the inner skin of the engine cowling when the aircraft is hovering and suggested that one most time- and cost-effective solution is to repaint the current engine cowlings with a new three coating system of Cerakote, surface protection HS7072-622, and intumescent paint as a fireproof lacquer.

Abstract A large amount of heat generated in the engineering compartment in a hovering helicopter may lead to premature degradation of inner skin of its engine cowling and cause serious failure on the engine cowling. This study proposes a solution of improving heat resistance of the helicopter engine cowlings by replacing the currently used intumescent coating with a ceramic coating material, Cerakote C-7700Q. Oven and flame tests were designed and conducted to evaluate the heat resistance of Cerakote C-7700Q. The test results show that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. Based on that, a new painting scheme with C-7700Q implemented was recommended.

Abstract Piston internal combustion engines used in the propulsion of ultralight aircraft are characterized by special operating conditions, especially an increased engine oil temperature. Most of the engines intended for the drive of the propeller drivetrain are air cooled. Failure to introduce an additional cooling agent so as to absorb and remove heat from the running engine makes the average lubricating oil temperature rise to about 140°C in the pistohn ring part. With such a thermal load, changes in the moments of resistance to motion of the engine are difficult to determine in the conditions of engine tests due to difficulties in temperature stabilization. The performance of aircraft engines requires taking into account many variables that are difficult to determine, which may affect changes in the moment of resistance to movement of the engine, especially when using oils of low dynamic viscosity.

Thermal imaging data obtained from a FLIR high-performance camera shows that the expected turbine output temperature is approximately 285°C when the helicopter is in forward flight. However, during hover operations a steady state temperature of about 343°C will be reached.

Light weight, low cost, composite pressure vessels, fabricated by over-wrapping thin metal liners with continuous high strength fibers embedded in resins, have been developed as a result of transferring aerospace technology to commercial products. ...With their advanced technology but lower cost, composite tanks are perfect for military and aerospace applications - as evidenced by the recent selection of commercial filament wound cylinders for the Manned Maneuvering Unit thruster for Space Shuttle astronauts.

This document provides guidance for a means of showing compliance with regulations for protection against lightning direct effects for aircraft of conventional design, as well as for those involving advanced composite structures or other new technologies. This guidance also applies to those aspects of aircraft systems and components not addressed in the regulations covering the protection of electrical/electronic systems (for example, FAR/JAR xx.1316) or fuel systems (for example, xx.954).