Rocket Sled Research Articles

Wear mechanism study of rocket sled shoe material 30CrMnSiNi2A

The material used for the rocket sleds in this study was 30CrMnSiNi2A. The research focused on examining the wear patterns and elemental distribution of the 30CrMnSiNi2A alloy under high-speed (34.56 m/s, 69.12 m/s, 101 m/s) and heavy-load (150–600 N) conditions through both experimental and simulation methods. A conceptual wear model was developed by integrating experimental results with numerical outcomes. At speeds of 34.56 m/s and 69.12 m/s, the friction coefficient and wear rate decreased with increasing applied pressure. At 101 m/s, the friction coefficient was less influenced by pressure, whereas the wear rate increased with increasing pressure. Simulation results show that under a load of 600 N, the von Mises stress consistently increased with increasing speed.

Sensors Layout Optimization Design of Rocket Sled Test System.

The rocket sled, as a ground dynamic test system, combines the characteristics of the wind tunnel test and the flight test. However, some practical factors, such as shock wave interference, ground effect, and high-intensity aerodynamic noise will cause serious interference and even failure of the uniformly distributed sensors during horizontal sliding in a wide speed range. The AGARD HB-2 standard model is employed as the payload to simulate the aerodynamic and aeroacoustic characteristics during the variable acceleration period, aiming to optimize the test sensors layout. It is observed that in the high Mach number flow fields, strong coupling behaviors among complex waves will occur. The peak of wake vortex strength will appear at 1.5 s and gradually diminish over time. In addition, when the vortex between the load and the booster is monitored, its position shifts forward in the subsonic stage, then gradually moves backward and expands in the supersonic stage. Acoustic directivity is pronounced at subsonic and transonic speeds, pointing towards 75° and 135° relative to the sliding speed, respectively. These results can provide technical support for sensor layout and high-precision testing in rocket sled tests.

Research on Deceleration Technology of Rocket Sled Double Track Sled

Aiming at the shortcomings of water brake in the deceleration recovery test of double-track sled, the reverse rocket deceleration was applied to the recovery of double-track sled. A deceleration scheme of rocket sled double track sled car is designed to improve the safety of double track sled car. Firstly, according to the requirements of sliding distance and water entry speed of sled, the deceleration resistance is designed and calculated, and the reverse rocket is selected. However, the sled car is designed according to the dimensions of the reverse thrust rocket, and the installation position and way of the reverse thrust rocket are determined. At last, according to the deceleration trajectory and the parameters of recoil rocket, the control mode and ignition position of recoil rocket are designed. The simulation results show that the deceleration effect of reverse rocket is obvious. This control method is simple and feasible. The reverse rocket deceleration method can be applied to the recovery of double track sled.

Terminal Ballistic Design of Guided Bomb in Rocket Sled Test

In order to meet the impact attack angle demand of 3°±1° of the guided bomb in the terminal effect rocket sled test, the dual-track rocket sled was designed as the research object, based on the simulation analysis of bomb-sled separation and factors that interfere with impact attack angle of the guided bomb. The terminal ballistic scheme was created with the guided bomb was preset to 2° and through 3m straight track, 6m curved track with a radius of 40m, 3m free flight, and the impact attack angle would be within the range of 2.12°~2.72°. In the test, impact attack angle of the guided bomb was 2.2°, which verifies the correctness of the design method.

Mechanistic Study of Rail Gouging during Hypersonic Rocket Sled Tests

Gouging—an obstacle to the development of hypersonic rocket sled test techniques—was mechanistically investigated through experimental and theoretical analyses. Typical gouges were analyzed using macroscopic and microscopic experiments to investigate the evolution of gouging. Quasistatic compression and Hopkinson bar experiments were performed to systematically study the thermoviscoplastic properties of U71Mn rail steel under wide ranges of the strain rate and temperature. The critical condition for gouging was derived based on a thermoviscoplastic constitutive model supplemented by a three-variable criterion for an adiabatic shear instability. The results showed the following. (1) Adiabatic shear bands (ASBs) form when stress reduction under the combined action of frictional heating and high-speed deformation exceeds the strain-hardening effect of the rail material. (2) The nonuniform deformation of the edges of ASBs leads to the generation of cracks that split the rail surface. As the ASBs expand, the cracks grow and coalesce, eventually causing the material to peel off, forming gouges. (3) The relationships among the temperature, strain rate, and strain at the onset of gouging can be determined based on the critical condition for the formation of ASBs in rail steel.

Rocket Sled Based High Speed Rail Track Test Facilities

The present study introduces and compares several high-speed track based ground test facilities available all over the world to simulate high-speed dynamic events for selected portions of flight trajectories. The scope of performing high speed flight-testing is addressed, which is followed by the requirements of these track based test facilities. The facilities deliver flight test articles under controlled conditions to achieve high velocity impact, acceleration, aerodynamic and other related testing for small and large test articles depending upon the requirements. Sled is designed in such a way so that it can carry the test articles like aircrafts, payloads, warheads, missiles and many other ballistic systems to achieve high velocities ranging from subsonic to hypersonic by accelerating these sleds using solid rocket motors over the rail track. Such facilities provide instrumentation for large set of trial data acquisition and offline analysis for both recovery and non- recovery (impact) trials, which makes such facilities important for test, research and evaluation purposes.
 Here, the detailed description of test facilities, which are available in many countries such as India, United States (US), Japan, United Kingdom (UK), France, and others countries based on their technical characteristics is presented. Additionally, a brief history and introduction into basic rocket sled test facility aspects, essential technical characteristics and major features to support high speed testing at these facilities as an accurate testing technique based on quality of construction and engineering design are also covered in this paper. Compilation of available or under development facilities is done in one place which provides the information about facilities’ technological gaps. The paper concludes with an explanation of the role, major capabilities and limitations of these test facilities in the present global scenario.

Dynamic Response of a Hypersonic Rocket Sled Considering Friction and Wear

The dynamic response of a hypersonic rocket sled was studied by considering the time-varying friction coefficient and the gap caused by wear between the slipper and track. A multibody dynamic model for a hypersonic rocket sled system was established by considering the time-varying mass and moment of inertia, nonlinear aerodynamic loads, engine thrust, track irregularity, and nonlinear contact force. As for the wear calculation, the ductile and shear criteria were used as the material damage criteria, and slipper wear was determined by the number of damaged elements. A rocket sled test was also carried out, and the dynamic response of the sled was measured. The results showed that the computational sliding displacement and velocity of the third-stage sled matched well with the test values. The computational root mean square (RMS) values of the vertical acceleration of the third-stage sled front slipper considering friction and wear matched better with the test values than with the case without considering friction and wear, which underestimated the RMS value by approximately 20.1% at Mach 5. The importance of considering friction and wear and the correctness of the computational method were validated. It is also found that the kinetic friction coefficient decreased with an increase in the product of the pressure and velocity. The wear height of the slipper increased almost linearly with the sliding displacement. The test results showed that the vertical acceleration power spectral density of the third-stage sled front slipper increased with time in the full frequency band below 2000 Hz. This study will guide the design and optimization of hypersonic rocket sleds.

Numerical simulation of aerodynamic and aeroacoustic characteristics of subsonic rocket sled

Rocket sled is the main equipment for horizontal launching and ground test equipment for high-speed aircraft. The aerodynamic characteristic analysis of a rocket sled is not only the object of experimental research, but also a way to avoid the potential safety hazard in the ground test which may cause the aircraft to overturn or even get out of its rail. Severe aerodynamic noise may damage the precise instruments during high-speed rocket sleds experiments. In order to instruct the design of aeroacoustics protection, numerical simulations are conducted based on computational fluid dynamics and computational acoustics. The distribution of velocity and pressure has been analyzed. Diagram of sound pressure level on the symmetric face under different situations has been compared. Characteristic frequencies and the directivity of aeroacoustics under three conditions with different Mach numbers are investigated. It can be found that the characteristic frequency and sound pressure level increases with the Mach number of the incoming flow. The directivity of noise at characteristic frequency also changed with the incoming flow’s Mach number. Characteristic frequency under three conditions are revealed. Some suggestions have been put forward to reduce the influence of aeroacoustic noise. The conclusions may guide the design of aeroacoustics protection for the rocket sled test.

Thrust Validation of Rotating Detonation Engine System by Moving Rocket Sled Test

This Paper presents the results of a rotating detonation engine rocket sled test demonstration on a 127 mm gauge rail at 100 m long high-speed running track test equipment to evaluate the thrust performance of a stand-alone rotating detonation engine propulsion system. The developed sled test demonstrator contained all onboard subsystems, including engine, gas cylinders, valves, controller, and a data logger. The sled test demonstrator successfully generated thrust, and three or four detonation waves of 1460 to were observed during the 2.0 s burn time. The measured specific impulse in the sled test was 144 s as estimated from the acceleration of the demonstrator and the mass decrease in the onboard cylinders. The test results were compared with the data from a laboratory-stand firing test using a load cell, and the specific impulses of the sled test were found to be comparable to the results of the stand firing test.

Study on Full Time Dynamics Simulation of Two-track Rocket Sled

Study on Full Time Dynamics Simulation of Two-track Rocket Sled

Shock-Wave/Rail-Fasteners Interaction for Two Rocket Sleds in the Supersonic Flow Regime

Rocket sleds belong to a category of large-scale test platforms running on the ground. The applications can be found in many fields, such as aerospace engineering, conventional weapons, and civil high-tech products. In the present work, shock-wave/rail-fasteners interaction is investigated numerically when the rocket sled is in supersonic flow conditions. Two typical rocket sled models are considered, i.e., an anti-D shaped version of the rocket sled and an axisymmetric slender-body variant. The dynamics for Mach number 2 have been simulated in the framework of a dynamic mesh method. The emerging shock waves can be categorized as head-shock, tailing-shock and reflected-shock. An unsteady large-scale vortex and related shock dynamics have been found for the anti-D shaped rocket sled. However, a quasi-steady flow state exists for the slender-body shaped rocket sled. It indicates that the axisymmetric geometry is more suitable for the effective production of rocket sleds. With the help of power spectral density analysis, we have also determined the characteristic frequencies related to shock-wave/rail-fasteners interaction. Furthermore, a harmonic phenomenon has been revealed, which is intimately related to a shock wave reflection mechanism.

Brake Force Calculation for Water-Brake Device in High Speed of Doub1e Track Rocket Sled Test

According to the recovery requirement of high-speed double-track sled, the horizontal momentum conversion type water brake structure is designed, the brake resistance is calculated. The brake resistance under six working conditions is calculated by using the calculation model of horizontal momentum conversion water brake force. The brake resistance is calculated by using FLUENT software. The force is simulated and checked. The results show that the brake resistance calculated by the two methods are basically identical, which provides support for the development of high-speed double-track sled.

Analysis of Rocket Sled Vibration Signal Transmission Based on Zigbee Application

Multi-path effecting and Dopplereffecting on missile-borne tester signal transmission based onZigbee application was researched. The maximum transmission distance was derived based on communication channel loss model and multi-path model. The effecting of multi-path on transmission distance was discussed. The effecting of Doppler shift was researched by speed of rocket sled and receiver position. Transmission speed and error rate of missile-borne tester was studied by Doppler effecting. The measure which reduced multi-path fading and Doppler effecting was gained. These can advance signal transmission quality and improve revamping of equipment.

Design of Single Layer Vibration Damping System for Rocket Sled

Design of Single Layer Vibration Damping System for Rocket Sled

Analysis of Wear for a Rocket Sled Slipper

This study analyzed the thermal and stress field of a rocket sled slipper by establishing a thermal-mechanics coupling model. The temperature field and thermal stress field were obtained. The results are compared with real rocket sled run test. It shows that there is an agreement of wear distance between the test and simulation. However, the real test local temperature which is above 1470 °C, in evidence of detected Cristobalite-high SiO2, is much higher than simulation result which is 818 °C, due to high vibration impact load in real run test.

The Sliding Contact Condition in Stability Analysis of Stage Motion for a Rocket Sled Track Facility

Variations in the mechanical characteristics of a material, intense plastic deformations, and the ablation of the material of working surfaces during high-speed sliding of loads along the rails of a rocket sled track facility are studied.

An Analysis of Dynamic Response of a Rocket Sled

The prediction of dynamic response of the rocket sled before the detailed design process would be beneficial as it can help optimize the structure, thereby increasing the reliability, shortening the development cycle, and reducing the risk of developing. However, it is very difficult to accurately simulate the dynamic response of a rocket sled considering the additional elastic deformation and the irregularity of the track surface. A calculation of the difference between the value of track-sled gap and the irregularity of the track surface for estimating elastic deformation can improve the simulation accuracy, but this method does not apply to lower speed, as the impact speed would not cause the same amount of additional deformation calculated. In light of this, an appropriate interpolation method is developed to determine the additional elastic deformation value in lower speed. The results of dynamic response are provided comparing with real test data and it proves that this method is very effective.

ПОСТАНОВКА ИСПЫТАНИЙ ТОПЛИВНЫХ УПАКОВОЧНЫХ КОМПЛЕКТОВ НА РАКЕТНОМ ТРЕКЕ

ПОСТАНОВКА ИСПЫТАНИЙ ТОПЛИВНЫХ УПАКОВОЧНЫХ КОМПЛЕКТОВ НА РАКЕТНОМ ТРЕКЕ

Evaluation of Thermomechanical Damage of a Slipper and Rail in a Rocket Sled System

Abstract During the rocket sled test, slippers and rail experience high-speed sliding contact causing critical damage on the surfaces. Because of the significant temperature rise on the contacting surfaces, its fracture mechanism relies on the temperature-dependent material properties. In this study, the thermomechanical damage of the slipper and the rail is systematically investigated through 3D finite-element analysis (FEA) model and simulations. The sliding velocity consisted of 20 m/s, 200 m/s, and 1500 m/s, whereas the vertical velocity (bouncing speed of the slippers) was assumed to be 1.1 m/s. The unique method of including the aerodynamic bounce by allowing the rail to move vertically is quite different from other models explored by collaborating authors. The process of material thermal softening by adiabatic and frictional heat generation is applied to the modeling. From the simulation results, it is found that the damage process and pattern of the slipper and the rail asperity is very dependent upon the sliding velocity and the slipper temperature. For the sliding velocity of 20 m/s, the damage rate of the slipper gradually increases with the elapsed contact time, where the slipper surface produces a plowing type of damage pattern (continuous scratch). However, when the sliding velocity increases beyond 200 m/s, the slipper surface starts showing a gouging type of damage pattern along with a chopping material removal in the rail asperity.

Quantification and Mitigation of Errors in the Inertial Measurements of Distance

The accurate measurement of the distance travelled, velocity and acceleration at low velocities to supersonic speeds is an active area of research. The captive flight at Rail Track Rocket Sled (RTRS) facility provides a unique environment for kinematic testing at supersonic speeds. Using RTRS facility, an accurate distance measurement method is developed, tested and experimentally verified. Three accelerometers, with different noise density, identically moving, have been chosen for sensing forward motion. A number of measures such as different mountings, bias correction, capping, digital filtering and position fix have been tried in a practical implementation. To keep the measurement error within tolerable limits a novel method of obtaining position fix is proposed by using a pair of magneto-inductive sensors. The bias correction is applied in the position to derive corrected velocity and acceleration. To know the truthfulness of results and to validate the proposed methods, a system has been developed to generate reference values for computation of error. This reference system has an error of 0.046 % which is much better than reported in previous study. After mitigation of various errors using proposed methods, an error within 1.5 % was attained with one of the sensors used in trials. The proposed work identifies the elements which contribute in errors and quantify the mitigated errors in some cases and highlights the measures which bring about significant improvement in error. It also suggests how to obtain more accurate results using economical MEMS accelerometers.