June 15, 2016

Good design pratices

The RNC engineering section incorporates standards containing good practices, resulting from feedback, in terms of design/production/validation of space system onboard and ground segment sub-systems, equipment and instruments. These rules relate both to the development processes and to the technical properties of the products developed. These standards are organised according to the main engineering activities (or disciplines): electrical, structural, thermal, mechanical, propulsion, software, automatics, operations, etc. (see figure below):

 

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The generic requirements of an activity are the subject of a discipline-level standard that makes reference to more specialized standards relating to a process, a type of product, or a specific component/item. These standards are complemented by handbooks. Those handbooks do not contain requirements but elements concerning the implementation, use or justification of standards, in addition to recommendations relating to development processes and product properties.

These generic requirements cover all possible developments from equipment level to space system level. Due to this, the use of RNC standards, including those of the engineering branch, concerning a given development, requires adaptation (also referred to as "tailoring" in ECSS standards) to the project context, depending on:

  • The type of product developed: equipment, instrument, sub-system, satellite, etc.
  • The level of risk tolerated (result of the project risk/cost compromise)
  • The type of orbit and the service life
  • etc.

This adaptation must be carried out in the pre-project phases (phases A/B) by the prime contractor, to draw up the list of standards applicable to the development and to "tailor" the requirements for the selected standards. After tailoring, RNC Engineering standards are made applicable to project developments in one of the following ways:

  • With regards to some projects, the prime contractor produces a unique document (the General Design and Interface Requirement or GDIR) following the tailoring of standards incorporating all generic requirements applicable to equipment/instrument level products. The GDIR therefore replaces all RNC engineering branch requirements and facilitates the application of RNC at this level;
  • With regards to other projects, these generic requirements resulting from the tailoring of RNC Engineering are directly incorporated in the Technical Requirement Specification of the product to be developed.
  • Finally, this constituting the most common method, the RNC Engineering standards are made applicable through an applicability matrix referenced in the Technical Requirement Specification of the product.
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