Casting process effect on composite solid propellant burning rate

Small-scale rocket motors are widely used by propulsion industries to carry out burn rate measurement for a variety of needs. Several automated data-reduction procedures have been implemented to derive burn rate from pressure-time profiles resulting from experimentation. Even if these are easy and fast to use, these procedures are not completely reliable in that these measure only the average behaviour of a motor. A new model has recently been proposed to overcome this problem. However, it was soon noticed that the results depend on the propellant grain production and forming processes even if the motor hardware is the same. A series of propellant grains has been produced to be sampled to map the local ballistic behaviour and changes introduced by the manufacturing process. In this study, sampling and testing procedures are reported and the results of an almost complete grain mapping are discussed.

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“…The variation of burn rate along the radius is expected to be very small (less than 5% in some cases reported in literature [10][11] ) .…”

Section: Radial Burn Rate Profilesmentioning

confidence: 99%

Burn-rate Measurement on Small-scale Rocket Motors

Maggi

Luca

Bandera

et al. 2006

DSJ

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“…The study of the burning rate and its optimization can increase the impulse generated, improving the motor's performance [14]. Different studies have dealt with the burning rate [15][16][17][18][19][20][21]. (2)…”

Section: Ballistic Propertiesmentioning

confidence: 99%

A Study of the Influence of Storage Time of Uncured Propellants on the Final Properties of the Composite in Multi‐Batch Processes on an Industrial Scale

Cunha

Rocco

2021

Propellants Explo Pyrotec

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In the Brazilian Aerospace Program, even though all developed rocket motors are manufactured in the same plant of the Department of Aerospace Science and Technology, differences are observed in the magnitude of the masses applied in each motor. Thus, depending on the volume of the combustion chamber, it is common for the casting to carry out multi-batch processes when a required mass of solid propellant is greater than the maximum capacity of the reactor. In this context, the studies that systematically evaluate multi-batch processes on an industrial scale of composite propellants based on polyurethanes obtained from HTPB are incipient. Furthermore, each batch preparation of the casting process for large motors is carried out on different days, so that each of these has a different storage time until the day of the effective casting. As a result, this wait can generate changes in the properties of the propellant grain as a whole, which can modify the motor's performance. Thusly, through the analysis of data of multi-batch processes, the present study evaluated the influence of the storage time in the preparation of the propellant and on the final properties of the grain. It was concluded that the grain becomes softer with a reduction in its hardness, greater elongation at break, and less modulus for batches with longer storage times before casting.

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“…Some process parameters in the production and casting of rocket motors can significantly affect the final propellant properties. The temperature, the sequence of material addition, the mixer blades speed, the mixing cycle duration, the mixer power during mixing, the casting duration (mass flow during casting), the vacuum level in the mixing and casting, the duration and curing conditions are examples of important process parameters that have been investigated [19][20][21][22][23][24][25][26][27]. The equipment design parameters, such as the size of the mixer [28] and the mixer type, have also a fundamental importance.…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Level of Load in the Mixer on the Processability and Mechanical Properties of the Solid Composite Propellant

Cunha

Rocco

2021

Propellants Explo Pyrotec

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The present study evaluated the influence of the level of load in the mixer on the processability and mechanical properties of the solid composite propellant. The mixtures were processed with the same composition and process conditions but using different percentages of levels of the maximum mixing capacity of the mixer. Both vertical and horizontal types of mixers were used to verify the existence of an optimal level of operation and whether it would depend on the type of mixer adopted. Levels of 50 %, 60 %, 70 %, 80 %, and 90 % were adopted in each macerator. In terms of processability, the 70 % level for the hori-zontal macerator and the 60 % level for the vertical macerator was the most suitable ones. Regarding the mechanical properties, the optimal operating level to obtain propellants with better properties would be 60-70 % in the horizontal macerator and 70 % in the vertical macerator. The results were interesting as they demonstrated the influence of the level adopted on the final grain. In addition, it is necessary to avoid using the mixers close to their maximum capacity. Therefore, the mixer level should be considered in any rocket motor casting project, both in single-batch and multi-batch processes.

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Casting process effect on composite solid propellant burning rate

Cited by 7 publications

References 3 publications

Burn-rate Measurement on Small-scale Rocket Motors

Burn-rate Measurement on Small-scale Rocket Motors

A Study of the Influence of Storage Time of Uncured Propellants on the Final Properties of the Composite in Multi‐Batch Processes on an Industrial Scale

The Influence of the Level of Load in the Mixer on the Processability and Mechanical Properties of the Solid Composite Propellant

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