Filament Winding Plant Builds Propulsion Rockets
Close Cooperation between Roth and Avio
As regards the aerospace technology, in modern rockets fibre solids are used more and more often for the lightweight composite casings of the engines and for other components. Their manufacture is effected in Filament Winding or Prepreg processes. Owing to the lightweight construction, for example, the weight of the booster stages of Ariane 6 can be reduced by up to 35 %. As to the operation of the rocket, the expenses per load-ton are thus supposed to be reduced by up to 50 %.
Avio S.p.A., Colleferro/Italien und Roth Composite Machinery GmbH, Steffenberg, utilized their common experience from the former projects referring to Ariane 5 and Vega as well as the technology and application know-how built up for decades for developing the new Filament Winding Plant. Having a weight of 100 tons, it is one of the world’s largest plants of Roth Composite Machinery. With a maximum length of 17 metres and a diameter of 3.6 metres, the winding mandrel weighs around 120 tons. The plant is equipped with three carriages for three different winding processes – each carriage has a length of 7.4 metres and is moving up to 90 metres per minute.
Three Carriages for Three Different Winding Processes
As to the necessary heat resistance of the boosters, the first carriage is used for winding heat protection tape onto the mandrel in moldless composite construction (first layer inside the booster). After the vulcanization of the tape, the Towpreg winding process is effected by using the second carriage. “In this case pre-impregnated bundles of fibres are wound onto the winding reel. Due to the prior separate impregnation of the fibres resulting in Towpregs with a very constant quality, a highly homogeneous composite structure of high-quality is originated", stated Bernd Fischer, Sales Director of Roth Composite Machinery. "Therefore, the Towpreg winding is particularly used in the aerospace industry".
The third carriage is equipped with a fibre delivery head for automated tape laying (ATL) being patented by Avio. This technology enables the exact laying of the tape resulting in complex geometrical shapes for the attachment parts of the boosters. The trimming of the tape is carried out by means of an ultrasonic cutting head. The ATL technology was developed by Avio together with Roth and a further Italian partner.
Boosters Resist Extreme Force Loads
The boosters of Ariane 6 are about 15 mentres long and have a diameter of up to 3.6 meters. Depending on the weight of the freight, two or four boosters per rocket are used. They are filled with solid fuel and ensure the enormous boost when firing the rocket as well as in the first flight phase in order to reach the thinner air layers as quickly as possible. The booster case is completely made of carbon fibres and replaces the steel casing of the previous version being used at Ariane 5. The boosters have to resist high temperatures when the fuel is burned and extreme force loads during the acceleration of the rocket without any damages. Components made of fibre composites have these ideal mechanic characteristics such as high tensile strength and high force absorption.