2022
Highly Transparent and Conducting Flexible Film for Aircraft Canopy Applications Dr S Parthiban PSG Institute of Advanced Studies, Coimbatore
DRDO Research Project.
2013
New Canopy Manufacturing Technique Could Cut Total JSF Costs by $125 million over 3000 planes.
The U.S. Navy’s Office of Naval Research (ONR) has developed a new manufacturing process to build fighter aircraft canopies. The new technique will be used on the Lockheed Martin F-35 Lightning II Joint Strike Fighter (JSF) in 2014 by GKN Aerospace Transparency Systems.
In the current manufacturing process, technicians have to load preformed acrylic shells into a forming tool and bake it in an autoclave for up to six days. Workers must regularly enter the giant industrial-sized oven to observe the canopy’s progress and manually adjust positioning clamps to control the forming process.
By contrast, the new method employs a control system that uses four cameras to monitor the inside of the autoclave to calculate the rate at which the canopy shape is forming. “The clamps then automatically adjust to ensure the shape remains uniform throughout the process to meet the F-35′s stringent performance requirements. The process takes only four days.
http://news.usni.org/2013/10/21/new-canopy-manufacturing-technique-cut-total-jsf-costs-125-million
2000
GKN Westland Aerospace process for manufacturing the Typhoon canopies.
Billets of modified as-cast acrylic measuring some 2 m square by 50 mm are heated in an oven before being placed in a bi-axial stretching machine. The material is then clamped around its edges and stretched to a finished size of approximately 3 m. The process modifies the material's properties to make it more resilient.
Both sides of the resultant acrylic sheet are then ground and polished to obtain an accurate optical finish. The sheet is then inspected for any optical distortion and any internal material inclusions such as voids or fibers.
Next, the sheets are prepared for forming, a proprietary process developed by ACT. The prepared sheet is formed into the three-dimensional shape of the Eurofighter canopy using specialized tooling also developed by ACT. Following an initial edge profile, the canopy is inspected for optical clarity using an optical collimator. The company said that the optical collimator, installed last year, performs this process in hours instead of the days needed when using previous conventional methods.
The canopy is then moved to a 5-axis, twin-table CNC (computer numerically controlled) machine, which performs detailed machining and edge profiling operations. On completion, the canopy is moved to a coordinate measuring machine (CMM) to inspect the machined hole locations and correct edge profile/tongue thickness, ultimately qualifying the product's interchangeability. From there the canopy enters the polishing bay where it is also given a precoating clean. It enters a clean room for the crucial stages in which ACT's proprietary, low-observable coating system is applied. To maintain an ultra-clean, dust-free environment, ACT has created a clean room within the clean room, housing a coating vacuum chamber and other facilities crucial to maintain the canopy's high optical performance. Once coated, the canopy undergoes final inspection.
ACT: UK company Aerospace Composite Technologies (ACT) has delivered the first production standard canopy to Eurofighter partner BAE Systems.
http://www.sae.org/aeromag/techupdate_6-00/04.htm
Wikipedia
Most modern acrylic canopies are vacuum formed. A sheet of acrylic is secured to a female mould, then the entire assembly is heated in an oven until the acrylic is pliable. The air is then removed from the mould and the acrylic sheet is drawn into it, forming the shape of the canopy. The acrylic is then trimmed to the appropriate shape and attached to an aluminum or composite frame. Some "one-off" canopies are made in a similar fashion, but since a mould would be too time-consuming to make, the acrylic is heated and vacuum formed until it approximates the shape the builder is seeking. This type of construction is less precise, however, and each canopy is unique. If multiple canopies will be needed, a mould is almost always used.
http://en.wikipedia.org/wiki/Aircraft_canopy
The Component
An aircraft canopy is the transparent enclosure over the cockpit of some types of aircraft. The function of the canopy is to provide a weatherproof and transparent environment for the aircraft's occupants. The canopy has to aerodynamically shaped to minimize drag.
Very early aircraft had no canopies at all. The pilots were exposed to the wind and weather. Through World War I most aircraft had no canopy, but they often had a small windshield to deflect the prop wash and wind from hitting the pilot in the face. In the 1920s and 1930s, the increasing speed and altitude of airplanes necessitated a fully enclosed cockpit and canopies became more common.
Early canopies were made of numerous pieces of plate glass held in position by a frame and muntins. The muntins reduced visibility, which was especially problematic for military aircraft. Also, Acrylic canopies lighter than glass canopies were first introduced shortly before World War II. The acrylic bubble canopy was used on aircraft such as the Supermarine Spitfire and Westland Whirlwind, which gave better all-round visibility and reduced weight.
7.4.2023
25.4.2014
