The present application claims priority to Application No.  101 57 752.4, filed in the Federal Republic of Germany on Nov. 27, 2001, which is expressly incorporated herein in its entirety by reference thereto. 
The present invention relates to a nozzle extension made of carbon ceramics for a rocket propulsion unit. 
A method for manufacturing combustion chambers and nozzle extensions of carbon ceramics is based on the use of prefabricated fabric layers of carbon filaments.  The fabric layers are placed on a form and make up the carbon-fiber structure for the combustion chamber or nozzle extension.  Following placement of the fabric layers, a precursor polymer is injected into the carbon-fiber structure, and the infiltrated carbon-fiber structure is subjected to a pyrolysis.  During the pyrolysis, the precursor matrix decomposes, and a fiber-reinforced carbon structure is formed.  In a further step, the fiber-reinforced carbon structure is infiltrated with liquid silicon and hardened to form a ceramic silicon-carbide matrixxe2x80x94also described as carbon ceramics or, in short, as xe2x80x9cC/SiCxe2x80x9d (German Published Patent Application No.  197 30 674).  It is relatively expensive to manufacture C/SiC nozzle extensions using the above described placement method, and required flange joints and other force-application or fastening elements are only able to be integrated with difficulty, with adequate strength into the nozzle extension. 
It is an object of the present invention to provide a nozzle extension having flange elements of C/SiC which is able to be manufactured relatively simply and which provides sufficient physical properties. 
The above and other beneficial objects of the present invention are achieved by providing a nozzle extension as described herein. 
The design approach in accordance with the present invention for fabricating the carbon-fiber structure of the nozzle extension utilizes the winding technique known from carbon-fiber technology, in combination with a reshaping technique, to manufacture integrated flange elements. 
In the context of the application of the winding technique in accordance with the present invention, besides attaining economic advantages with respect to the manufacturing outlay, the load specifications of the nozzle extension and of its interface elements may also be considered by adapting the fiber orientation and the layer structure.  It is possible, e.g., to reinforce the material by using the winding technique in the critical flange regions of the conical nozzle extension. 
A further reinforcement of such locations is possible, if required, in that, additionally during the winding process, fabric layers of carbon filaments are applied and integrated between the winding layers. 
In accordance with the present invention, the flanges of the nozzle extension are conically curved toward the outside and arranged as a reinforced flaring of the nozzle bushing.  In this manner, there is no interruption in the fiber flow at the flange locations, so that the best possible physical properties may be derived for the thus integrated flange.  The reshaping technique is thereby rendered possible without entailing substantial outlay, and a flange that is bent upwardly with an acute bending angle has elastic properties, depending on the particular form, which may be able to compensate for thermal expansions in the flange joint. 
Further example embodiments of the present invention relate to engaging springs of C/SiC for locking an extensible or retractable part of a nozzle extension and to the formation of a stability ring at the outlet of a nozzle extension. 
Exemplary embodiments of the present invention are described in the following on the basis of the figures.