Roxel through its versatile panel of in-house casing technologies can design and propose the best compromise (cost, performance, IM properties) to fulfil the customer’s requirements.
Metal cases offer a high stiffness and maintain strength up to high temperature.
- Flowformed structures are made from a metal tube formed over a mandrel. A very high pressure roller is used to shear the metal, forcing it against the mandrel, at the desired shape and thickness. During this process, the structure is cold worked, offering a strengthened metal case.
Composite structures offer a lower mass and enable high constructive figures. They are highly attractive for fire and bullet impact IM requirements.
- Steel strip laminate (SSL)
SSL cases are a metal form of composite structure. These cases are made by helically winding a number of very thin layers of maraging steel strip coated with a suitable adhesive onto a mandrel of diameter equal to the desired bore of the finished tube. It is then bonded on the end rigs by heat treatment. SSL cases are a world leading contender for IM rocket motor solutions; they have been subjected to very demanding structural testing & fatigue testing. This type of motor case is not susceptible to cumulative damage or stone chip/tool damage in the same way as carbon fibre composite cases. SSL cases have been used in-service for air carriage.
SSL cases can be lighter than the equivalent homogenous steel or Aluminium case & are well suited to small production volumes.
Hybrid cases are composite case that incorporate fibres, resin and a metallic structure. It’s a compromise between the monolithic metallic case and composite case
This is normally the lowest price structure if a large scale production run is required. However, IM properties are undesirable so grooves & other mitigation methods may be added to improve the IM response.
- Filament winding over propellant
Since the propellant grain (charge) acts as the mandrel the motor case can be constructed, with low polar opening diameter, around a non-castable type charge.
- Kevlar overwound aluminium (KOA)
KOA cases allow the rocket motor to have a high operating pressure with a low mass and improved IM signature. Such cases have been used in several rocket motors that are in-service.