National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

Lateral-directional aerodynamics parameter estimation using neural partial differentiation

Abstract: In this paper, application of neural networks combined with partial differentiation of the neural outputs has been discussed to estimate lateral-directional flight stability and control parameter. A neural model capable of predicting generalized force and moment coefficients using measured motion and control variables can be employed to extract aerodynamic parameters from flight data. The Neural Partial Differentiation method is used for this purpose. The estimated results are compared with the parameter estimates obtained from Output Error Method. The validity of estimates has been verified by the model validation method, wherein the estimated model response is matched with the flight-test data that are not used for estimating the parameter.

Shape Memory Alloy Based Smart Landing Gear for an Airship

Abstract: The design and development of a shape memory alloy based smart landing gear for aerospace vehicles is based on a13; novel design approach. The smart landing gear comprises a landing beam, an arch, and a superelastic nickeltitanium shape memory alloy element. This design is of a generic nature and is applicable to a certain class of light13; aerospace vehicles. In this paper a specixFB01;c case of the shape memory alloy based smart landing gear design and13; development applicable to a radio controlled semirigid airship (radio controlled blimp) of 320 m3 volume is13; presented.Ajudicious combination of carbon xFB01;ber reinforced plastic for the landing beam, cane (naturally occurring13; plant product) wrapped with carbon xFB01;ber reinforced plastic for the arch, and superelastic shape memory alloy is13; used in the development. An appropriate sizing of the arch and landing beam is arrived at to meet the dual requirement of low weight and high-energy dissipation while ndergoing x201C;large elasticx201D; (large nonlinear recoverable13; elastic strain) deformations to ensure soft landings when the airship impacts the ground. The soft landing is required13; to ensure that shock and vibration are minimized (to protect the sensitive payload). The inherently large energydissipating character of the superelastic shape memory alloy element in the tensile mode of deformation and the superior elastic bounce back features of the landing gear provide the ideal solution.Anonlinear analysis based on the classical and xFB01;nite element method approach is followed to analyze the structure. Necessary experiments and tests have been conducted to check the veracity of the design. Good correlation has been found between the analyses and testing. This exercise is intended to provide an alternate method of developing an efxFB01;cient landing gear with satisfactory geometry for a x201C;certain class of light aerospace vehiclesx201D; such as airships, rotorcraft, and other light unmanned air vehicles.

Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

Abstract: This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm−1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm−1 to 3.39 dB cm−1.

Blowdown tunnel application of pressure sensitive paint

Abstract: A pressure sensitive paint (PSP) and a temperature sensitive paint (TSP) were applied to large blowdowntype supersonic wind tunnel testing of an SST model to expand the paint technique beyond usual continuous wind tunnel application. Bach paint was applied on each side of the wing, and luminescence data of both paints were captured by a CCD-camerabased imaging system at the same time. A PSP/TSP combined calibration which requires no pressure tap information and solves both temperature and pressure simultaneously was applied to compensate for unfavorable temperature sensitivity of the PSP. Even there was continuous drop of the surface temperature which was more than 10K during 40 seconds blow of the tunnel at M=2, the pressure data showed little change among the measurements conducted more than 15 seconds after the uniform flow was established. The paint data clearly captured a complex shockinteractive pressure field around a typical nacelleintegrated SST configuration. However, detailed comparisons with the pressure tap data showed the PSP data had about 0.1 shift in Cp toward a higher pressure direction at M=2. In addition, as the first step of the secondary use of the continuous pressure field data, a hinge-moment of an aileron was computed from the paint data.