ISO 16694:2024
(Main)Space systems — Measured parameters at firing bench and flight tests of liquid rocket engines
Space systems — Measured parameters at firing bench and flight tests of liquid rocket engines
This document specifies requirements for the list of parameters, measured during firing bench and flight tests. The requirements of the document apply to all the types of expendable liquid rocket engines supplied to the user: a) operating on all types of propellant (including cryogenic); b) with afterburning (with gradual burning) and without afterburning (without gradual burning); c) low-thrust engines: one component (monopropellant) and two-component (bipropellant); d) with a single firing or multiple firings. The document doesn’t specify firing bench test preparation and testing procedure, methods of test results processing and analysis, or requirements to measurement accuracy. The document specifies mandatory and optional parameters.
Systèmes spatiaux — Paramètres mesurés au banc d'allumage et essais de vol des moteurs à propergol liquide
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Standards Content (Sample)
International
Standard
ISO 16694
Second edition
Space systems — Measured
2024-09
parameters at firing bench and
flight tests of liquid rocket engines
Systèmes spatiaux — Paramètres mesurés au banc d'allumage et
essais de vol des moteurs à propergol liquide
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 1
5 General . 2
6 List of parameters, measured during LRE tests . 3
6.1 General .3
6.2 List of parameters, measured during LRE firing bench test .3
6.3 List of parameters, measured during LRE flight test .11
6.4 List of parameters, measured during LTLRE test . 15
Bibliography . 19
iii
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 16694:2015), which has been technically
revised.
The main changes are as follows:
— Clauses 4 and 5 are amended;
— the list of measured parameters is expanded;
— in Tables 1 and 3, the parameter “…pressure pulsation…” is split into two parameters: “…vibration
amplitude…” and “…vibration frequency…”; the parameter “vibro-overloads.” is split into “vibration
acceleration amplitude…” and “vibration acceleration frequency…”;
— certain parameters are moved from the category “mandatory parameters” to the category “optional”;
— superscripts and subscripts of parameter "Letter symbols" are corrected.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
The document provides users, designers, and manufacturers of liquid rocket engines with requirements and
guidance for parameters, measured during firing bench and flight tests. Parameters to be measured are
used for reliability analysis and quality control of liquid rocket engines.
The parameters listed in the document characterize performance of liquid rocket engines and they are used
to evaluate the technical condition of engines (operable, inoperable), their conformity with the specified
requirements and whether engines are available to be delivered to a user and put into operation. ISO 15865
is used to assess conformity of liquid rocket engines to the specified requirements.
Uniform requirements for the parameters, measured during firing bench and flight tests of liquid rocket
engines, ensure the following:
— quality and reliability of developed and operated liquid rocket engines;
— comparison of liquid rocket engine test results;
— end product safety and environmental protection.
The engine developer may identify an additional list of measured parameters for specific items, taking into
account their design features.
This document makes it possible to develop uniform criteria for performance evaluation and comparison of
liquid rocket engines, created by different countries, based on firing bench and flight tests results.
v
International Standard ISO 16694:2024(en)
Space systems — Measured parameters at firing bench and
flight tests of liquid rocket engines
1 Scope
This document specifies requirements for the list of parameters, measured during firing bench and flight
tests. The requirements of the document apply to all the types of expendable liquid rocket engines supplied
to the user:
a) operating on all types of propellant (including cryogenic);
b) with afterburning (with gradual burning) and without afterburning (without gradual burning);
c) low-thrust engines: one component (monopropellant) and two-component (bipropellant);
d) with a single firing or multiple firings.
The document doesn’t specify firing bench test preparation and testing procedure, methods of test results
processing and analysis, or requirements to measurement accuracy.
The document specifies mandatory and optional parameters.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 15864, Space systems — General test methods for spacecraft, subsystems and units
ISO 24917, Space systems — General test requirements for launch vehicles
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Abbreviated terms
AVR apparent velocity regulator
BTP booster turbo pump
CFC component-flow controller
CPT certification periodic test
DD design documentation
EV electric valve
FCR controller of the propellants ratio in a combustion chamber
IpCT in-process control test
LV launch vehicle
LRE liquid rocket engine
LTE low thrust engine
PA pressure alarm
QT qualification test
R&D research and development
SC spacecraft
SPT special periodic test
TDS tank depletion system
TP turbopump
5 General
5.1 The main purpose of LRE and LTLRE parameters measurement while performing ground and flight
tests is to obtain information for assessment of parameter conformity to DD requirements, reliability and
quality analysis of supplied engines.
5.2 Parameters, which should be measured during fire bench and flight tests of LRE, and to which
requirements of this document are applied, fall into the following groups:
a) parameters, characterizing test environment (5.3, 5.4);
b) main parameters (5.5);
c) key performance parameters (5.6);
d) parameters, characterizing the engine ability to operate without any degradation (5.7).
5.3 Parameters, characterizing test environment, include:
a) parameters of natural and artificial environmental impacts;
b) propellants status before and during tests.
5.4 Parameters, characterizing test environment, are used to evaluate conformity of physical environment
and propellants status before and during tests to the requirements of the test specification, and ensure that
the corrected characteristics of an engine (thrust, specific impulse) are identified.
5.5 Main parameters define how the engine performs the specified functions; and they are set by technical
documentation requirements of the engine developer.
5.6 Key performance parameters characterize the engine performance and define whether a test is
passed or not. Key performance parameters may be obtained either directly from measurements or from
calculations. The parameters shall comply with DD requirements of the engine developer.
5.7 Parameters, characterizing the engine ability to operate without any degradation, are used to control
the engine health by estimating values of loads, which act on the engine’s assemblies.
This group comprises parameters, whose values cannot be determined directly by measurements, taken
during assembly manufacturing process. Among these parameters are particularly ones, characterizing
vibration strength and heat-resistance of the combustion chamber and the gas generator and stability of the
assemblies operating process. In case of emergency, these parameters (together with the main parameters
and parameters, characterizing test conditions) are used to analyse causes of emergency.
5.8 It is recommended to use sensors of the same type to measure similar parameters during static fire
and flight tests.
6 List of parameters, measured during LRE tests
6.1 General
Parameters, measured during firing bench and flight tests of the engine, are summarized in the
corresponding tables.
Static fire tests of launch vehicles shall be conducted in accordance with the general requirements in
ISO 24917.
Goals and objectives of flight tests shall be as specified in ISO 15864.
Depending on their importance, parameters, measured during an engine test, fall into the following groups:
a) mandatory;
b) optional;
c) interchangeable.
The term “optional parameter” means (in cases, when a corresponding assembly or a unit is a part of
the engine) that, according to the approved decision of a liquid engine developer, its measurement is not
mandatory, as opposed to a mandatory parameter, which shall be measured and recorded.
Additions may be made to the set of parameters, which are measured during LRE QT, in accordance to the
QT program, agreed upon with the engine developer.
The “Comment” column provides required clarifications and additions to certain parameters.
6.2 List of parameters, measured during LRE firing bench test
The list of optional and mandatory parameters to be measured during in-process control test, certification
periodic test and special periodic test (IpCT, CPT and SPT) of LRE is provided in Table 1.
Table 1 — Parameters, measur
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