SIST EN 16603-35-02:2014
(Main)Space engineering - Solid propulsion for spacecrafts and launchers
Space engineering - Solid propulsion for spacecrafts and launchers
General requirements applying to all type of Propulsion Systems Engineering are defined in ECSS-E-ST-35. For solid propulsion activities within a space project the standards ECSS-E-ST-35 and ECSS-E-ST-35-02 are applied together. This Standard defines the regulatory aspects that apply to the elements and processes of solid propulsion for launch vehicles and spacecraft. It specifies the activities to be performed in the engineering of these propulsion systems and their applicability. It defines the requirements for the engineering aspects such as functional, physical, environmental, quality factors, operational, and verification.
Raumfahrttechnik - Feststoffantriebe für Raumfahrzeuge und Trägerraketen
Ingénierie spatiale - Propulsion solide pour satellites et lanceurs
Vesoljska tehnika - Trdna pogonska goriva za vesoljska plovila in lansirnike
Splošne zahteve, ki veljajo za vse vrste inženiringa pogonskih sistemov, so opredeljene v standardu ECSS-E-ST-35. Za dejavnosti, povezane s trdnimi pogonskimi gorivi v okviru vesoljskega projekta, skupaj veljata standarda ECSS-E-ST-35 in ECSS-E-ST-35-02. Ta standard opredeljuje regulatorne vidike, ki se nanašajo na elemente in postopke za trdna pogonska goriva za vesoljska plovila in lansirnike. Določa dejavnosti, ki se izvajajo v tehničnem delu teh pogonskih sistemov in njihovo uporabnost. Določa zahteve za tehnične vidike, kot so funkcionalni, fizikalni, okoljski, kakovostni dejavniki, zahteve med delovanjem in verifikacijo.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Vesoljska tehnika - Trdna pogonska goriva za vesoljska plovila in lansirnikeRaumfahrttechnik - Feststoffantriebe für Raumfahrzeuge und TrägerraketenIngénierie spatiale - Propulsion solide pour satellites et lanceursSpace engineering - Solid propulsion for spacecrafts and launchers49.140Vesoljski sistemi in operacijeSpace systems and operationsICS:Ta slovenski standard je istoveten z:EN 16603-35-02:2014SIST EN 16603-35-02:2014en,fr,de01-november-2014SIST EN 16603-35-02:2014SLOVENSKI
STANDARD
SIST EN 16603-35-02:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16603-35-02
September 2014 ICS 49.140
English version
Space engineering - Solid propulsion for spacecrafts and launchers
Ingénierie spatiale - Propulsion solide pour satellites et lanceurs
Raumfahrttechnik - Feststoffantriebe für Raumfahrzeuge und Trägerraketen This European Standard was approved by CEN on 23 February 2014.
CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2014 CEN/CENELEC All rights of exploitation in any form and by any means reserved worldwide for CEN national Members and for CENELEC Members. Ref. No. EN 16603-35-02:2014 E SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 2 Table of contents Foreword . 4 Introduction . 5 1 Scope . 6 2 Normative references . 7 3 Terms, definition and abbreviated terms . 8 3.1 Terms from other standards . 8 3.2 Abbreviated terms. 9 4 Solid propulsion engineering activities . 10 4.1 Overview . 10 4.2 Functional . 10 4.2.1 Mission . 10 4.2.2 Functions . 10 4.3 Constraints . 12 4.3.1 Dynamic phenomena . 12 4.3.2 External loads during the life cycle of the propulsion system . 12 4.3.3 Thrust centroid time . 12 4.3.4 Acoustic noise . 12 4.3.5 Pollution . 12 4.3.6 Ejected parts . 13 4.3.7 Safety. 13 4.4 Interfaces . 13 4.4.1 General . 13 4.4.2 Induced and environmental temperature . 14 4.4.3 General environment . 14 4.5 Design . 14 4.5.1 Overview . 14 4.5.2 Propulsion system selection and design process . 15 4.5.3 Global performance . 17 4.5.4 Ignition and tail-off . 17 SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 3 4.5.5 Solid rocket motor components . 18 4.6 Ground support equipment (GSE) . 20 4.7 Materials . 21 4.8 Verification . 21 4.8.1 Verification by analysis . 21 4.8.2 Verification by test . 21 4.9 Production and manufacturing . 24 4.10 In-service . 26 4.10.1 General . 26 4.10.2 In-flight operations. 26 4.11 Deliverables . 27 Annex A (normative) Dynamic analysis report (AR-DY) - DRD . 28 Annex B (normative) Material Safety Data Sheet
(AR-MSDS) - DRD . 32 Bibliography . 35
Tables Table 4-1: Coefficient values . 18 Table 4-2: Test for qualification of solid propulsion systems, subsystems and components . 22 Table 4-3: Examples of mission dependent verification tests for qualification . 24 Table 4-4: Test for acceptance of solid propulsion systems, subsystems and components . 25 Table 4-5: Examples of mission dependent verification tests for acceptance . 26
SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 4 Foreword This document (EN 16603-35-02:2014) has been prepared by Technical Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN. This standard (EN 16603-35-02:2014) originates from ECSS-E-ST-35-02C. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2015, and conflicting national standards shall be withdrawn at the latest by March 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This document has been developed to cover specifically space systems and has therefore precedence over any EN covering the same scope but with a wider domain of applicability (e.g. : aerospace). According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 5 Introduction The requirements in this Standard ECSS-E-ST-35-02C (and in the 3 other space propulsion standards ECSS-E-ST-35, ECSS-E-ST-35-01 and ECSS-E-ST-35-03) are organized with a typical structure as follows: • functional; • constraints; • development; • interfaces; • design; • GSE; • materials; • verification; • production and manufacturing; • in-service (operation and disposal); • deliverables.
This standard forms parts of ECSS-E-ST-35 series which has the following structure; • ECSS-E-ST-35
Propulsion general requirements • ECSS-E-ST-35-01
Liquid and electric propulsion for spacecraft • ECSS-E-ST-35-02 Solid propulsion for spacecraft and launchers • ECSS-E-ST-35-03 Liquid propulsion for launchers • ECSS-E-ST-35-06 Cleanliness requirements for spacecrafts propulsion hardware • ECSS-E-ST-35-10 Compatibility testing for liquid propulsion components, subsystems, and systems ECSS-E-ST-35 contains all the normative references, terms, definitions, abbreviated terms, symbols and DRD that are applicable for ECSS-E-ST-35, ECSS-E-ST-35-01, ECSS-E-ST-35-02 and ECSS-E-ST-35-03. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 6 1 Scope General requirements applying to all type of Propulsion Systems Engineering are defined in ECSS-E-ST-35. For solid propulsion activities within a space project the standards ECSS-E-ST-35 and ECSS-E-ST-35-02 are applied together. This Standard defines the regulatory aspects that apply to the elements and processes of solid propulsion for launch vehicles and spacecraft. It specifies the activities to be performed in the engineering of these propulsion systems and their applicability. It defines the requirements for the engineering aspects such as functional, physical, environmental, quality factors, operational, and verification. NOTE 1 Some solid propulsion systems use hot gas valves, for thrust or pressure modulation. The requirements applicable to these systems are not covered by the present document. NOTE 2 For SRM with TVC, only moveable nozzle with flexseal are addressed. This standard may be tailored for the specific characteristic and constrains of a space project in conformance with ECSS-S-ST-00. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 7 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this ECSS Standard. For dated references, subsequent amendments to, or revision of any of these publications, do not apply. However, parties to agreements based on this ECSS Standard are encouraged to investigate the possibility of applying the more recent editions of the normative documents indicated below. For undated references, the latest edition of the publication referred to applies.
EN reference Reference in text Title EN 16601-00-01 ECSS-S-ST-00-01
ECSS System- Glossary of terms EN 16603-20 ECSS-E-ST-20 Space engineering - Electrical and electronic EN 16603-20-07 ECSS-E-ST-20-07 Space engineering - Electromagnetic compatibility EN 16603-32 ECSS-E-ST-32 Space engineering - Structural general requirements EN 16603-32-08 ECSS-E-ST-32-08 Space engineering - Materials EN 16603-32-10 ECSS-E-ST-32-10 Space engineering - Structural factors of safety for spaceflight hardware EN 16603-33-11 ECSS-E-ST-33-11 Space engineering - Explosive systems and devices EN 16603-35 ECSS-E-ST-35 Space engineering - Propulsion general requirements EN 16602-20 ECSS-Q-ST-20 Space product assurance – Quality assurance EN 16602-40 ECSS-Q-ST-40 Space product assurance - Safety EN 16602-70 ECSS-Q-ST-70 Space product assurance - Materials, mechanical parts and processes
SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 8 3 Terms, definition and abbreviated terms 3.1 Terms from other standards For the purpose of this Standard, the terms and definitions from ECSS-S-ST-00-01, ECSS-E-ST-35, ECSS-E-ST-32, and ECSS-E-ST-32-10 apply, in particular for the following terms: ECSS-E-ST-32 maximum design pressure (MDP) maximum expected operating pressure (MEOP) test factors (KA and KQ)
ECSS-E-ST-35 ablated thickness (ea) burning time charred thickness (ec) corridor hump effect ignition time (tign)
insulation thickness (ei) non affected thickness(es) pre-heating time solid rocket motor thrust centroid time SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 9 3.2 Abbreviated terms For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01 and the following apply:
Abbreviation Meaning AIV assembly, integration and verification COG centre of gravity COM centre of mass DLAT destructive lot acceptance test EMC electromagnetic compatibility EMI electromagnetic interference ESD electrostatic discharge GSE ground support equipment HCl chloride acid
MCI mass, centre of mass, inertia MDP maximum design pressure MEOP maximum expected operating pressure NDI non-destructive inspection OBDH on-board data handling SRM solid rocket motor TBPM to be provided by manufacturer TBPU to be provided by user TM/TC telemetry/telecommand TVC thrust vector control SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 10 4 Solid propulsion engineering activities
4.1 Overview A solid propulsion system comprises the following main subsystems: • The gas generating system consisting of a solid propellant contained in a thermally protected case. • A nozzle with or without TVC. • An ignition system to ignite the solid propellant. This document applies to large and small systems; the latter usually have some different requirements to the large systems. Solid propulsion systems can either deliver a velocity increment in a fixed direction (with respect to the launcher or spacecraft) or in a variable direction, depending on whether TVC is present or not. Most solid propulsion systems use a single nozzle and roll control is usually provided by a separate system. Solid propulsion systems are “one-shot” systems and do not need a lot of preparation before use. Because a solid propellant motor is a ‘one shot’ item, an acceptance firing test cannot be performed with the actual flight motor.
4.2 Functional 4.2.1 Mission a. ECSS-E-ST-35 clause 4.2 ‘mission’ shall apply. 4.2.2 Functions
4.2.2.1 Steady state a. The propulsion system shall: 1. conform to the interfaces (see “interfaces” clause 4.4), 2. provide the specified total impulse, a thrust profile (nominal and dispersion) versus time. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 11 b. The overall thrust profile shall be defined, taking into account the following launcher or spacecraft system constraints: 1. the general loads on the launcher or spacecraft (due to aerodynamics, thermal fluxes and guidance or attitude control), 2. the induced accelerations. c. To conform to 4.2.2.1a and 4.2.2.1b, the following aspects shall be covered: 1. thrust level and orientation versus time; 2. burning time; 3. total impulse; 4. reliability level. 4.2.2.2 Transients a. The initial and final transient thrusts shall conform to the lift-off and separation constraints and requirements. 4.2.2.3 End-of-flight mass a. The mass of the motor shall conform to the system requirements. NOTE
The “end-of-flight” mass of solid motors strongly depends on the internal ballistics, functional parameters and the applied technologies. 4.2.2.4 First stage a. The first stage configuration and thrust profile shall be thoroughly analysed and a trade-off made against system constraints and requirements. 4.2.2.5 Electrical a. The propulsion system shall have electrical continuity, including grounding and bonding. 4.2.2.6 Thrust orientation a. The propulsion system shall provide TVC or a thrust in a fixed orientation (with respect to the launcher or spacecraft) according to the system requirements. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 12 4.3 Constraints 4.3.1 Dynamic phenomena
a. Pressure or thrust oscillation levels vs frequency range shall be specified at system and subsystem level. b. Pressure or thrust oscillation vs frequency range shall be characterised. c. The maximum allowable dynamic mechanical loads induced by the solid rocket motor during transient phases shall be specified vs frequency.
NOTE
For example shock during ignition and pressure wave. d. The dynamic mechanical loads induced by the solid rocket motor during transient phases shall be characterised. e. The Report for dynamic phenomena shall be delivered in conformance with the DRD of Annex A. 4.3.2 External loads during the life cycle of the propulsion system a. All external loads, static and dynamic (including mechanical, thermal, electrical, magnetic, humidity and radiation) shall be specified as input for the design. 4.3.3 Thrust centroid time a. For solid thrusters that provide thrust impulsion, the thrust centroid time shall be characterized.
NOTE
Examples of solid thrusters: separation or braking rockets, control systems. 4.3.4 Acoustic noise
a. The acoustic noise generated by the motor operating in the atmosphere shall be characterised. b. The Report for acoustic noise phenomena shall be delivered in conformance with the DRD of Annex A. 4.3.5 Pollution
a. Pollution constraints shall be specified.
NOTE
For example propellant without HCl emissions, space debris mitigation. b. The propulsion system shall conform to the pollution constraints specified in 4.3.5a. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 13 4.3.6 Ejected parts a. Constraints on parts foreseen to be ejected during the missions by the solid rocket motor shall be specified. NOTE
For example nozzle plugs and igniters. b. The propulsion system shall conform to the constraints specified in 4.3.6a. c. The ejected parts shall be characterized. 4.3.7 Safety a. For safety aspects, ECSS-Q-ST-40 shall apply. b. Constraints on safety due the regulation shall be specified. c. The propulsion system shall conform to the constraints specified in 4.3.7b. d. The propulsion system safety parameters shall be characterized and delivered in conformance with the DRD of Annex B. 4.4 Interfaces 4.4.1 General
a. All the following interfaces shall conform to the propulsion system requirements during the whole life of the system or subsystems and include the following: 1. Other stages of the launcher. 2. The launcher or spacecraft spaceonics. 3. Stage or spacecraft components: (a) skirts; (b) spaceonics (including hardware, OBDH, TM/TC, wiring and tunnels); (c) separation devices; (d) TVC; (e) explosive devices; (f) stage or spacecraft thermal protection; (g) contamination (e.g. plume effects); (h) termination and destruction devices; (i) environmental protection devices (e.g. rain, dust, and Sun). SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 14 4. The nature of the interfaces, i.e.: (a) geometry, including the analysis of the dimensions for all phases of life (e.g. assembly or AIV, transport, integration on the spacecraft and flight); (b) mechanical, including induced loads, static and dynamic; (c) thermal, including thermal fluxes; (d) electrical, including ensuring continuity, preventing ESD, EMI, and EMC; (e) materials, including ensuring compatibility. NOTE
Refer to ECSS-E-ST-32-08. 5. Interfaces with GSE and transport, including: (a) definition of interfaces for launcher or spacecraft GSE and transport, with the launch authorities for safety; (b) capability for the electrical grounding of the systems and subsystems. 4.4.2 Induced and environmental temperature a. The temperature range during the mission shall be specified. b. The number and amplitude of the temperature variations (thermal cycling) during the motor life shall be specified. NOTE 1 E.g. motors which have a long in-orbit life before being operated. NOTE 2 The operating range of the motor can require a thermal control system. 4.4.3 General environment a. The motor shall comply with the specified and its self–induced loads (thermal, dynamic) environment. b. Measurement and control devices shall be protected against specified and self-induced adverse effects. 4.5 Design
4.5.1 Overview The following clauses define requirements applicable to the overall propulsion system derived from specific characteristics of each component of the system itself. Therefore they do not intend to cover the mayor requirements applicable to each component. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 15 4.5.2 Propulsion system selection and design process 4.5.2.1 General a. ECSS-E-ST-35 clause 4.3 (Development) shall apply. b. All components of a solid rocket motor shall:
1. demonstrate compatibility with materials, propellants and fluids; 2. be selected assessing safety, economics, reliability and environmental considerations and restrictions. NOTE
E.g. debris, pollution. c. The design and dimensioning of the SRM and the components shall be compliant with the manufacturing capabilities (available facilities, and processes, and reproducibility). d. The causes for potential dispersions shall be analysed in the project phases A and B. NOTE
Reproducibility requirements are provided by the customer. e. For PDR the following characteristics shall be provided: 1. the mass and COM of the propulsion system; 2. performance; 3. type of ignition system; 4. nozzle structure and configuration (e.g. thrust orientation); 5. propellant type. NOTE
If the requirements given by customer cannot be met, (including. target cost and industrial feasibility) either: • the requirements are reconsidered,
• the system or subsystem design modified, or • the manufacturing and control processes modified (see ECSS-E-ST-10). f. For PDR the technological choices of the design shall be performed, justified, and documented, assessing the mission requirements, interface with other systems or subsystems, lifetime, safety, availability, manufacturing process, performance, cost, environmental considerations and restrictions (e.g. pollution). g. It shall be ensure that the solid propulsion components, subsystems and systems can sustain without degradation the loads during manufacturing, handling, test and transport. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 16 4.5.2.2 MEOP and MDP a. The MEOP shall be calculated as specified in ECSS-E-ST-32 clause 4.2.7 ‘Limit loads’. NOTE 1 The MDP is calculated as defined in ECSS-E-ST-32 clause 3.2.27 ‘MDP’. NOTE 2 If model uncertainties are included in the MEOP determination, Km is 1 for the calculation of MDP. b. Dedicated MEOP and MDP may be calculated for each component to take into account the axial gradient of pressure in the bore. c. During the development phase, it shall be verified for each component that the MDP remains higher than the one determined by calculation of the internal ballistics of the motor updated on the basis of the development tests results. 4.5.2.3 Electrical a. Electrical bonding between all SRM components shall be ensured in compliance with ECSS-E-ST-20-07 clause 4.2.11 ‘Electrical bonding requirements’. b. Electrical grounding shall be ensured in conformance with ECSS-E-ST-20-07 clause 4.2.10 ‘Grounding’. c. The propulsion system shall have electrical continuity, including grounding. 4.5.2.4 Contamination a. The motor shall be protected against external contaminants (including moisture) which can enter the motor. 4.5.2.5 Detonation risk a. It shall be demonstrated that failures in the motor do not lead to detonation during the mission. 4.5.2.6 Testing a. The motor shall be designed to undergo firing static tests according to the development plan. 4.5.2.7 Leak tightness a. ECSS-E-ST-35 clauses 4.5.11.1 ‘Risks of accidental fire or explosion’ and 4.5.11.2 ‘External leakage’ shall apply. b. The motor shall conform to the system requirements on leak tightness during the mission life. c. Under pressure loads mechanical assembly tightness shall be guaranteed.
NOTE
This is performed with an appropriate design of seals and mechanical parts. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 17 4.5.2.8 Adhesive bonding a. For adhesive bonding mechanical dimensioning ECSS-E-ST-32 clause 4.5 ‘Design’ shall apply. b. It shall be ensured that, if a bonded assembly fails under loads, the rupture is within one of the constitutive materials and not at the interface (cohesive rupture). 4.5.2.9 Ageing a. For ageing, ECSS-E-ST-35 clause 4.5.13 ‘Impact of ageing on sizing and dimensioning’ shall apply. 4.5.3 Global performance a. ECSS-E-ST-35 clause 4.5.2 ‘Global performance‘ shall apply. b. The SRM parameters shall be identified by the supplier and reported in conformance with the AR-P DRD in Annex A of ECSS-E-ST-35 to the customer, covering at least the following; 1. ejected mass flow rate (propellant and inert mass), vacuum thrust vs time, including during tail-off;
2. non ejected mass vs time; 3. MCI (mass, COM, inertia,) vs time; 4. thrust centroid time; 5. motor dynamic behaviour; 6. pressure and thrust oscillations; 7. plume effects to be reported in conformance with Annex D ‘Plume analysis report’ DRD in ECSS-E-ST-35; 8. interfaces with TVC; 9. thrust imbalance for multiple motors functioning simultaneously (including ignition and tail off). NOTE
Nominal values, uncertainties and dispersions in the specified operational conditions shall be provided. 4.5.4 Ignition and tail-off a. For ignition phase, the percentage of the theoretical pressure defining tign shall be defined in the motor or system specification. NOTE
tign is defined in ECSS-E-ST-35 clause 3.2.1.32. b. The pressure and mass flow rate corridor shall be defined in the motor specifications for ignition and tail-off phases. c. The operating time of the igniter shall exceed the ignition time tign. SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 18 4.5.5 Solid rocket motor components 4.5.5.1 Motor case
a. Elements that are connected to the case shall be dimensioned by cumulating the forces due to internal pressure and other forces such as external loads, inertial forces and local loads. NOTE
e.g. skirts, mounting parts and interface connectors.
b. If dimensional variation constraints are given for the propulsion systems, the dimensioning of the case shall be performed to comply with these constraints. 4.5.5.2 Internal thermal protection
4.5.5.2.1 Thermal dimensioning a. The temperature of the interface between the thermal protection and the propellant shall be defined and justified such that the propellant combustion rate increase remains consistent with SRM safety and reliability requirements. b. To design the thermal insulation thickness, e, the coefficients of Table 4-1 shall be used and the following formula met:
eKpKaeaKcecKiei≥××+×+× where: ea = ablated thickness ec = charred thickness ei = insulation thickness Ka = ablation coefficient Kc
= char coefficient Ki
= isolation coefficient Kp
= factor project NOTE 1 See ECCS-E-ST-32-10 definition 3.2.4. NOTE 2 Kp is applied only on ea due to uncertainty on ablation phenomena. Table 4-1: Coefficient values
Ka Kc Ki Spacecraft 1,3 1,25 1 Launcher 1,3 1,25 1 Man rated S/C 1,7 1,25 1
SIST EN 16603-35-02:2014
EN 16603-35-02:2014 (E) 19 c. Dimensioning shall be done with the combustion duration at the lower temperature of the operational envelope, including the expected combustion duration deviation (n x s), n being a real number determined by the supplier in accordance with the reliability allocation. d. Radiative and conductive thermal loads during pre-heating time shall be determined and used for the dimensioning of the floater and inhibitor areas. NOTE
For floater and inhibitor see ‘pre-heating time’ definition in ECSS-E-ST-35. e. If requirements 4.5.5.2.1b, 4.5.5.2.1c, and 4.5.5.2.1d are not applied an alternative methodology may be used under customer approval. 4.5.5.2.2 Mechanical dimensioning a. After having dimensioned the thermal protection on thermal loads and ablation, it shall be verified that the dimensioning satisfies the mechanical system requirements (i.e. expansion-contraction and transfer of loads, ageing effect) during the whole mission. b. For mechanical dimensioning, ECSS-E-ST-32 clause 4.5 ‘Design’ shall apply. 4.5.5.3 Propellant grain
4.5.5.3.1 Ballistics
a. For th
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