Aircraft Canopies Research Articles

Transparent and hard TiO2/Au electromagnetic shielding antireflection coatings on aircraft canopy PMMA organic glass

This research addresses the critical need for a highly stable and transparent electromagnetic shielding coating for aircraft PMMA windows and canopies, crucial for safeguarding against electromagnetic interference and enhancing aircraft stealth capabilities. The study presents the novel design, deposition and investigation of transparent coatings, specifically TiO2/Au, on PMMA organic glass cockpit canopies. Optimization of TiO2 and Au film thicknesses is achieved through simulation using TFcalc software, incorporating polarization and optical constants data obtained in this study. The experiments reveal that the deposition of TiO2/Au/TiO2 on PMMA results in fogging, reducing transparency, while novel TiO2/Au coating does not exhibit this issue. The TiO2/Au configuration, featuring a TiO2 layer approximately 30 nm thick and an Au film ranging from 11 to 15 nm in thickness, demonstrates outstanding attributes, including a remarkable transparency level of approximately 70–80% and robust electromagnetic interference shielding efficiency within the range of 19–29 dB across S, C, X, and Ku bands of electromagnetic waves. These exceptional performance characteristics position it as an ideal choice for aviation applications. The synergy of the stable Au and durable TiO2 components, with their high hardness and self-cleaning properties, extends its potential utility to a diverse array of applications.

Highly stable, ultra-thin Au embedded zinc tin oxide multilayer transparent conductive thin films

Transparent conducting thin films (TCFs) with excellent stability and good mechanical properties, room temperature processing, as well as owing high transparency and conductivity, have become an essential requirement in numerous applications. Here, we report the fabrication of room temperature processed Au-embedded zinc tin oxide (ZTO) multilayer transparent conducting thin films on glass and polycarbonate substrates by radio frequency magnetron sputtering. A detailed investigation on the correlation of optical and electrical properties of the ZTO/Au/ZTO (ZGZ) multilayer thin films, with the thickness of individual layers was carried out. The ZGZ thin films showed excellent performance under various stability tests. To evaluate the commercial application capabilities in aircraft canopies and other optoelectronic devices, the fabricated ZGZ multilayer TCFs was subjected to electromagnetic interference (EMI) shielding studies. The ZGZ thin film exhibited EMI shielding effectiveness of 24.75 dB in the X-band region, yielding 99.66% power attenuation.

Electrohydrodynamic lithography of metallic mesh for optically transparent flexible and conformal antennas

The optically transparent antenna is becoming a very attractive proposition for various applications, such as wearable devices and vehicle radars. The fabrication of transparent flexible/conformal antennas is a long-lasting interest in academia and industry. However, the preparation of radio-frequency radiators with excellent conductivity and optical transmittance is still quite challenging. Herein, we introduce a facile approach to directly fabricate optically transparent flexible and conformal coplanar waveguide-fed antennas using programmable electrohydrodynamic lithography. Metallic meshes with transmittance above 90% have been successfully created based on the conformal electrohydrodynamic printing of high-viscosity photoresist masks, and the corresponding sheet resistance can be tuned down to ∼2 Ω/□. Then, the geometrical structure of the proposed transparent antenna has been systematically optimized because of the basic radio frequency components, including the radiator, feeder line, ground plane, and size of metallic meshes. Optically transparent flexible and conformal antennas are finally obtained, presenting an optical transmittance of 92% and 55%, respectively. The simulated and measured results demonstrate that the transparent antennas with a good optoelectronic performance indeed exhibit a nice electromagnetic behavior. We believe that this newly developed conformal electrohydrodynamic lithography method can be utilized to fabricate a variety of other transparent electronic devices, such as transparent electromagnetic shielding meshes on aircraft canopies, in the future.

Radiation Exposure at Aircraft Altitudes Using DYASTIMA-R and HZETRN Simulations

Radiation exposure and its harmful effects on the human body are explored with the use of two simulation codes: DYnamic Atmospheric Shower Tracking Interactive Model Application (DYASTIMA)-R and high-charge-and-energy transport computer program (HZETRN). Absorbed and equivalent dose values for 17 different altitudes between 31,000 ft (9.5 km) and 85,000 ft (26 km) were simulated. Comparisons were made between HZETRN, which uses the deterministic method, and DYASTIMA-R, which uses the Monte Carlo method; all results were then compared to published data from International Commission on Radiation Units and Measurements Report 84. Unlike DYASTIMA-R results, HZETRN results did not converge; this could be due to the user-input source particle spectrum and the need to provide an extrapolated data set for HZETRN to base its simulations. HZETRN also neglected neutron particle influence on absorbed and equivalent dose that likely caused HZETRN dose values to undershoot. A third data set was introduced, combining HZETRN dose equivalent values with DYASTIMA-R neutron contribution. These neutron-adjusted HZETRN runs were used to then analyze the effect of aircraft canopies on equivalent dose values at flight altitudes.

Prospects for Using Different Types of Transparencies in the Manufacture of Aircraft Canopies (Review)

The prospects for using aircraft transparency parts based on silicate, organic, or polycarbonate glasses from the standpoint of strength, the primary sources of loading, and the most vulnerable locations are reviewed. Suggestions for increasing their strength reliability are described.

Polymer based aerospace structures under high velocity impact applications; experimental, constitutive and finite element analysis

Polymethyl methacrylate (PMMA) and Polycarbonate (PC) are two famous optically clear thermoplastic polymers widely used in various aeronautical and astronatucial applications. Owing to their exceptional transparency, process shape adaptability, low density and high impact strength they find particular attention in aerospace industry where they are used to manufacture air craft canopies, windshields, impact resistant windows, visors and safety glasses. The design and manufacturing of the satisfied polymeric structures involve accurate modeling of the material behavior and detailed analysis of their service behavior under extreme loading conditions. In order to evaluate the material behavior under these loading conditions, extensive work in terms of experimental characterization and material constitutive modeling is required. A systematic research methodology including the material characterization, material constitutive modeling, constitutive model implementing and finite element prediction of mechanical behaviors is proposed in this work. The material characterization tests were performed by means of universal testing machine and Split Hopkinson pressure bar (SHPB) setup. On the basis of performed tests and using phenomenological approach, a constitutive model was proposed to successfully predict the entire deformation behavior of polymers under various loading conditions with sufficient accuracy. The model was implemented numerically by establishing a User-defined material subroutine (UMAT) in explicit Finite element (FE) solver LS-DYNA. The model successfully ascertained the dynamic behavior of PMMA based aircraft windshield and PC based astronaut helmet visor under application of high velocity projectile impact. A number of FE simulations were carried out to determine the critical impact energy, maximum deformation and stress level in these structures. The simulations results help to evaluate various design approaches to optimize the structural response prior to preliminary experimentations and therefore provide an alternative to costly and time consuming extensive experimental tests.

Effect of Scratch Depths on Tensile Strength of PMMA for Aircraft Canopies

Static tensile tests of polymethyl methacrylate (PMMA) specimens without scratches and containing a scratch whose depth was set to be 0.2mm, 0.3mm and 0.4mm, respectively, were carried out to explore effect of scratch depths on tensile strength of PMMA. Based on the experimental load-displacement curves, the specimens without scratches deform most severely when the failure comes forth. The failure deformation declines gradually with higher scratch depth, namely higher scratch depth leads to lower plastic deformation. It thus follows that the scratch significantly reduces the tensile strength of PMMA while the variation of the scratch depth from 0.2mm to 0.4mm has negligible influence on the tensile strength of PMMA.

A high precision instrument to measure angular and binocular deviation introduced by aircraft windscreens by using a shadow casting technique

Objects viewed through transparent sheets with residual non-parallelism and irregularity appear shifted and distorted. This distortion is measured in terms of angular and binocular deviation of an object viewed through the transparent sheet. The angular and binocular deviations introduced are particularly important in the context of aircraft windscreens and canopies as they can interfere with decision making of pilots especially while landing, leading to accidents. In this work, we have developed an instrument to measure both the angular and binocular deviations introduced by transparent sheets. This instrument is especially useful in the qualification of aircraft windscreens and canopies. It measures the deviation in the geometrical shadow cast by a periodic dot pattern trans-illuminated by the distorted light beam from the transparent test specimen compared to the reference pattern. Accurate quantification of the shift in the pattern is obtained by cross-correlating the reference shadow pattern with the specimen shadow pattern and measuring the location of the correlation peak. The developed instrument is handy to use and computes both angular and binocular deviation with an accuracy of less than ±0.1 mrad (≈0.036 mrad) and has an excellent repeatability with an error of less than 2%.

Artificial Glass—The Versatility of Poly(methyl methacrylate) from Its Early Exploitation to the New Millennium

Poly(methyl methacrylate) (PMMA) has been exploited as a material for over 60 years. More commonly recognized under trade names such as Lucite, Perspex or Plexiglas, it was originally developed during the 1930s as a safe replacement for glass in aircraft canopies. PMMA has the important advantages of being lighter and less brittle than glass; it is more easily fabricated and is much less likely to cause cuts and lacerations when broken. Nowadays, these advantages and others are exploited in applications ranging from hospital incubators to automotive rear light clusters. The development of means to toughen and increase the glass transition temperature (Tg) of PMMA has further enhanced its utility.

Aerospace notes

Engineers have developed an injection‐moulding process for producing aircraft canopies and windshields much more cheaply than with current techniques. The new fabrication method, developed in a research project sponsored by the US Air Force's Wright Laboratory Flight Dynamics Directorate outside Dayton, Ohio, cuts the cost of these “transparencies” by 90 per cent.

Measurement and prediction of dynamic temperatures in unsymmetrically cooled glass windows

Semitransparent materials such as glass have many applications in high-temperature environments such as supersonic aircraft canopies and spacecraft windows. At elevated temperatures, the energy transfer within semitransparent materials is dominated by radiation, making both the prediction and measurement of internal temperatures substantially more difficult than for opaque substances. Experimental measurement of the dynamic internal temperature distribution in soda-lime glass plates cooling from an initial temperature of about 550 C was carried out. The boundary conditions on the plates were established using the laboratory ambient for the front surface and employing a radiant heater at the rear surface. The surface and internal plate temperatures were measured using thermocouples fused in the glass. The temperature data are compared to predictions obtained from the solution of the transient energy equation where the internal radiative transfer has been accounted for using rigorous radiative transfer theory. The predicted and measured temperatures, the experimental method, the process used to fuse the thermocouples in the test plates, and the formulation of the energy equation for semitransparent materials are discussed. 18 refs.

Simulation of a birdstrike impact on aircraft canopy material

The simulation of a birdstrike on a material used in aircraft canopies is performed using the ABAQUS finiteelement code. The results of the simulation are compared to the response of a test coupon struck by a rubber ball with properties that provide a load on the coupon comparable to a bird. The displacement-time history of the test coupon is recorded using a high-speed camera. The results of the impact test are compared to the finite-element results. One of the major tasks in developing the simulation was obtaining a load history to apply to the model. The impact load associated with a birdstrike is hydrodynamic, time dependent, and decreases exponentially from the centerline of the impact region. The velocity of impact indicates that material properties at high-strain rates would be required for the simulation. Published material properties at lower strain rates provided adequate information to demonstrate good correlation for the loads examined. Good correlation was achieved in comparing the centerline deflection time histories recorded in the impact test and obtained from the finite-element simulation.

Pyrolysis‐evolved gas‐infrared spectroscopic characterization of poly(methyl methacrylate) copolymer glazing materials

AbstractThe linear temperature programmed pyrolysis of some commercial crosslinked poly(methyl methacrylate) copolymers has been examined by the technique of pyrolysis‐evolved gas‐infrared analysis. Methyl methacrylate monomer, methanol, and carbon dioxide were detected in the pyrolysis gases. The profiles of rate of evolution against temperature were used to identify the presence of occluded monomer and thermally unstable and groups such as unsaturation. The evolution profiles for methyl methacrylate and methanol were found to be characteristic for each type of crosslink. Evolution of methanol between 250°C and 300°C, and between 300°C and 350°C has been attributed to condensation reactions of carboxylic acid and primary amide groups, respectively, with adjacent ester groups. The evolution profiles were used to distinguish between samples from different manufacturers, and to identify material in aircraft canopies.

All Weather Cockpit Canopies … 1

A new generation of advanced, supersonic, fighter aircraft windshields and canopies is taking shape at the Sylmar, California facility of Sierracin Corporation under the impetus of an Air Force search for the ideal transparencies for current and future US fighters.

Around the industry

ICI at Oyannax. For the first time, ICI have exhibited at the Oyannax, France, Plastics Exhibition. Unable to obtain space in the Exhibition Hall because of priority bookings by regular exhibitors, the company secured the agreement of the organisers to the erection of a 34‐ft‐diam. inflatable air house in the exhibition grounds. The air house was fabricated by Gordon Low (Plastics) Ltd., of Horsham, from Plastolene made by Storeys of Lancaster. Plastolene is a vinyl laminate reinforced with Terylene ICI polyester fibre. The products displayed in the air house were the plastics materials made by ICI in England and sold by ICI (France) S.A. They included Perspex acrylic sheet used for signs, lighting fittings, aircraft canopies and windows, sanitary ware and catering equipment; Diakon acrylic moulding materials used for domelights, telephones and motor car equipment; Alkathene (polyethylene) used for cable insulation, packaging film manufacture and the moulding of domestic ware; the Butakon range of synthetic resins, rubbers and latices; Fluon PTFE, and Maranyl glass‐filled nylon, a new plastics with great potential as an engineering material for the replacement of metals in gears, housings and general die‐casting.