A survey of development test programs for LOX/kerosene rocket engines

Emdee, Jeffery L.

doi:10.2514/6.2001-3985

Cited by 9 publications

(11 citation statements)

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“…Only two recommendations are published for new engine designs by comparing previous hot fire test programs, however, without any obvious justification. The two recommendations are -a test program should consist of 400 tests with 40,000 s of accumulated firing spread over approximately 15 prototypes(see [8]), or -a minimum of 150 tests with 50,000 s of accumulated firing should be performed (see [9]). …”

Section: Scope and Effort Of Engine Testing During Developmentmentioning

confidence: 99%

Reusability aspects for space transportation rocket engines: programmatic status and outlook

Preclik¹,

Strunz²,

Hagemann³

et al. 2011

CEAS Space J

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Rocket propulsion systems belong to the most critical subsystems of a space launch vehicle, being illustrated in this paper by comparing different types of transportation systems. The aspect of reusability is firstly discussed for the space shuttle main engine, the only rocket engine in the world that has demonstrated multiple reuses. Initial projections are contrasted against final reusability achievements summarizing three decades of operating the space shuttle main engine. The discussion is then extended to engines employed on expendable launch vehicles with an operational life requirement typically specifying structural integrities up to 20 cycles (start-ups) and an accumulated burning time of about 6,000 s (Vulcain engine family). Today, this life potential substantially exceeds the duty cycle of an expendable engine. It is actually exploited only during the development and qualification phase of an engine when system reliability is demonstrated on ground test facilities with a reduced number of hardware sets that are subjected to an extended number of test cycles and operation time. The paper will finally evaluate the logic and effort necessary to qualify a reusable engine for a required reliability and put this result in context of possible cost savings realized from reuse operations over a time span of 25 years.

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Section: Scope and Effort Of Engine Testing During Developmentmentioning

confidence: 99%

Reusability aspects for space transportation rocket engines: programmatic status and outlook

Preclik¹,

Strunz²,

Hagemann³

et al. 2011

CEAS Space J

View full text Add to dashboard Cite

show abstract

“…The F-1 hot-fire testing groups, with the corresponding EQMs, are based on the matching of the weighting factor for hot-fire tests that are shorter than full mission duration that were given in Worland et al [22] and a Bayesian solution for the parameters of the likelihood function of the model introduced by Lloyd and Lipow [20]. The resulting accumulated hot-fire test time is about 111,000 s, with the average HFTD of around 100 s that can be compared with the data given in Emdee [9], which result in the average HFTD of roughly 90 s. Likewise, the RS-68 hot-fire testing groups are based on a test allocation that resulted in the accumulated HFTD that is given by Wood [6]. The weighting factors for the hotfire tests that were shorter than full mission duration were also calculated with the Bayesian solution for the parameters of the likelihood function of the model introduced by Lloyd and Lipow [20].…”

Section: B Express Hot-fire Tests As Mission Equivalentsmentioning

confidence: 99%

“…POF models, covariate models, or expert opinions can be used to provide credible figures. Table 13 lists the bogey or design cycles and bogey or design life for the F-1 [9] and SSME [7]. The bogey cycles and bogey life for the Valves on oxidizer side Main oxidizer valve, preburner oxidizer valves To provide energy to ignite 8 Igniters for preburners and TCA To heat oxidizer 9 Heat exchanger to pressurize tank Heat exchanger to pressurize tank RS-68 were defined through the RAIV methodology.…”

Section: E Express Hardware Reliability As Life Capabilitymentioning

confidence: 99%

“…Table 13 lists the bogey or design cycles and bogey or design life for the F-1 [9] and SSME [7]. The bogey cycles and bogey life for the Valves on oxidizer side Main oxidizer valve, preburner oxidizer valves To provide energy to ignite 8 Igniters for preburners and TCA To heat oxidizer 9 Heat exchanger to pressurize tank Heat exchanger to pressurize tank RS-68 were defined through the RAIV methodology. Only realistic hardware reliability levels should be stated during the requirement development process, as will be seen for the SSME in the next step of the RAIV methodology.…”

Section: E Express Hardware Reliability As Life Capabilitymentioning

confidence: 99%

“…The surveys performed by Emdee [8,9] and Pempie and Vernin [10] provide further details about the variety of current best practices by recommending the scope of hot-fire test programs and highlighting the lack of an industry or government standard or guideline. The recommendations vary from 400 hot-fire tests with 40,000 s accumulated test duration spread over 15 hardware sets to 150 hot-fire tests with at least 50,000 s of accumulated test duration but without a statement about a required number of hardware sets.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reliability as an Independent Variable Applied to Liquid Rocket Engine Hot Fire Test Plans

Strunz¹,

Herrmann²

2011

Journal of Propulsion and Power

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Manufacturers lack an adequate method to balance performance, reliability, and affordability. The reliability-asan-independent-variable methodology is the solution proposed by expressing quantitatively the reliability trade space as ranges of a number of hardware sets and a number of hot-fire tests necessary to develop and qualify/certify a liquid rocket engine against a stated reliability requirement. Therefore, reliability-as-an-independent-variable becomes one of the key decision parameters in early tradeoff studies for liquid rocket engines because the reliability trade space directly influences the performance requirements and, as a result, the affordability. The overall solution strategy of reliability-as-an-independent-variable is based on the Bayesian statistical framework using either the planned or actual number of hot-fire tests. The planned hot-fire test results may include test failures to simulate the typical design-fail-fix-test cycles present in liquid rocket engine development programs in order to provide the schedule and cost risk impacts for early tradeoff studies. The reliability-as-an-independent-variable methodology is exemplarily applied to the actual hot-fire test history of the F-1, the space shuttle main engine, and the RS-68 liquid rocket engine, showing adequate agreement between computed results and actual flight engine reliability.Nomenclature Beta = Beta probability density function Bi = Binomial probability density function C = level of confidence (credibility bound) c = number of cycles CTD = cumulated test duration, s F X = cumulative density function HW = number of hardware L = likelihood function n = number of trials, i.e., hot-fire tests p = probability of success q = failure fraction q ind = candidate probability density function R = reliability r = number of failures t = hardware life, s tp = hot-fire test proportion T 50 = median lifetime, s w = weighting factor x = number of successes, i.e., hot-fire tests = shape parameter 1 , 2 = weighting factors = shape parameter = median regression coefficients = integration domain = parameters to be estimated = acceptance rate = Gamma function = parameter of Poisson probability mass function = probability of success of a functional node = posterior probability 0 = prior probability = standard deviation

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Liquid Propulsion: Systems Engineering, Design Trades, and Testing

Emdee

2010

Encyclopedia of Aerospace Engineering

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Liquid rocket engine design, manufacturing, and testing require implementation of a robust systems engineering process to be successful. In addition to propulsion, there are multiple disciplines involved, including thermal, structures, structural dynamics, electrical engineering, and fluid dynamics. There are also significant interface challenges when integrating the engine system with the launch vehicle. The overall process requires a balance of often competing requirements, including cost, schedule, performance, and reliability. Application of the systems engineering process to liquid rocket engine system design and test evaluation is described in this chapter. Considerations for several system design requirements are covered, including human rating and reliability. After an engine is designed and manufactured, extensive testing and evaluation are required to confirm analytical model predictions and assumptions. Engine testing processes are described to provide an overview of test objectives and requirements. Development testing is used to characterize engine operation and to identify failure modes before qualification begins. Qualification test requirements and flight test demonstration goals will also be reviewed. Finally, systems engineering tools, which are available to prevent and resolve failures, are summarized with specific application to liquid rocket propulsion systems described.

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A survey of development test programs for LOX/kerosene rocket engines

Cited by 9 publications

References 10 publications

Reusability aspects for space transportation rocket engines: programmatic status and outlook

Reusability aspects for space transportation rocket engines: programmatic status and outlook

Reliability as an Independent Variable Applied to Liquid Rocket Engine Hot Fire Test Plans

Liquid Propulsion: Systems Engineering, Design Trades, and Testing

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