Showing papers on "Rocket published in 2018"
TL;DR: In this paper, a mathematical model is developed accounting for the peculiarities of diffusion combustion of fuel in the flow of oxidant, which is composed of oxygen-nitrogen mixture.
109 citations
08 Jan 2018
TL;DR: In this article, the authors proposed a successive convexification framework to solve the minimum-time 6-DoF rocket powered landing problem, where the trajectory is subject to a variety of convex and non-convex state and control-constraints, and aerodynamic effects are assumed negligible.
Abstract: In this paper, we employ successive convexification to solve the minimum-time 6-DoF rocket powered landing problem. The contribution of this paper is the development and demonstration of a free-final-time problem formulation that can be solved iteratively using a successive convexification framework. This paper is an extension of our previous work on the 3-DoF free-final-time and the 6-DoF fixed-final-time minimum-fuel problems. Herein, the vehicle is modeled as a 6-DoF rigid-body controlled by a single gimbaled rocket engine. The trajectory is subject to a variety of convex and non-convex state- and control-constraints, and aerodynamic effects are assumed negligible. The objective of the problem is to determine the optimal thrust commands that will minimize the time-of-flight while satisfying the aforementioned constraints. Solving this problem quickly and reliably is challenging because (a) it is nonlinear and non-convex, (b) the validity of the solution is heavily dependent on the accuracy of the discretization scheme, and (c) it can be difficult to select a suitable reference trajectory to initialize an iterative solution process. To deal with these issues, our algorithm (a) uses successive convexification to eliminate non-convexities, (b) computes the discrete linear-time-variant system matrices to ensure that the converged solution perfectly satisfies the original nonlinear dynamics, and (c) can be initialized with a simple, dynamically inconsistent reference trajectory. Using the proposed convex formulation and successive convexification framework, we are able to convert the original non-convex problem into a sequence of convex second-order cone programming (SOCP) sub-problems. Through the use of Interior Point Method (IPM) solvers, this sequence can be solved quickly and reliably, thus enabling higher fidelity real-time guidance for rocket powered landings on Mars.
69 citations
TL;DR: In this article, the authors reviewed the research progress of mostly used elastomers, and a circumstantial understanding about the features of ablation and insulation has been validated, especially in the elastomeric heat shielding materials with various reinforcing agents.
Abstract: Catastrophic breakdown that occurs during the flight of supersonic vehicles demands more focused research in the insulation of rocket engines. At present, optimization of polymeric ablatives as viable insulation for solid rocket motor casing has a prominent role in the successful mission of rockets. Among polymers, elastomer serves an imperative part. Comprehensive investigations were disclosed, especially in the elastomeric heat shielding materials with various reinforcing agents. In this paper, research progress of mostly used elastomers is reviewed, and a circumstantial understanding about the features of ablation and insulation has been validated.
58 citations
TL;DR: Researchers are working to reduce the threats posed by more than 20,000 objects in space by identifying and reducing the risks ofombie satellites, rocket shards and collision debris.
Abstract: Zombie satellites, rocket shards and collision debris are creating major traffic risks in orbits around the planet. Researchers are working to reduce the threats posed by more than 20,000 objects in space. Zombie satellites, rocket shards and collision debris are creating major traffic risks in orbits around the planet. Researchers are working to reduce the threats posed by more than 20,000 objects in space.
37 citations
TL;DR: In this paper, a model of a small-scale deep mesoscale convective "rocket dust storm" was used to simulate the formation and evolution of the detached dust layers on Mars.
Abstract: The origin of the detached dust layers observed by the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter is still debated. Spiga et al. (2013, https://doi.org/10.1002/jgre.20046) revealed that deep mesoscale convective “rocket dust storms” are likely to play an important role in forming these dust layers. To investigate how the detached dust layers are generated by this mesoscale phenomenon and subsequently evolve at larger scales, a parameterization of rocket dust storms to represent the mesoscale dust convection is designed and included into the Laboratoire de Météorologie Dynamique (LMD) Martian Global Climate Model (GCM). The new parameterization allows dust particles in the GCM to be transported to higher altitudes than in traditional GCMs. Combined with the horizontal transport by large-scale winds, the dust particles spread out and form detached dust layers. During the Martian dusty seasons, the LMD GCM with the new parameterization is able to form detached dust layers. The formation, evolution, and decay of the simulated dust layers are largely in agreement with the Mars Climate Sounder observations. This suggests that mesoscale rocket dust storms are among the key factors to explain the observed detached dust layers on Mars. However, the detached dust layers remain absent in the GCM during the clear seasons, even with the new parameterization. This implies that other relevant atmospheric processes, operating when no dust storms are occurring, are needed to explain the Martian detached dust layers. More observations of local dust storms could improve the ad hoc aspects of this parameterization, such as the trigger and timing of dust injection. Plain Language Summary On Mars, dust is of major importance to the Martian atmosphere, analogous to the importance of water to the Earth’s atmosphere. But unlike the water on Earth, the distribution of dust on Mars is still not well understood, particularly the vertical distribution. The Mars Climate Sounder aboard the Mars Reconnaissance Orbiter found that the dust on Mars is detached at ∼20–40 km in altitude in the Martian atmosphere, rather than concentrated in the near-surface atmosphere and decreasing as the pressure decreases, as scientists have thought since the 1980s. The reason for the detached dust layers is still debated. In this paper, we implemented a modeling study by simulating the small-scale deep rocket dust storm in a Global Climate Model to explore the origins of the detached dust layers. We found that when the Global Climate Model included rocket dust storms, the simulations produced the detached structures of dust on Mars. This suggests that the rocket dust storm is responsible for the formation of the detached dust layers. Meanwhile, the rocket dust storms cannot reproduce all the detached dust layers observed by Mars Climate Sounder. This implies that some unknown atmospheric processes can also contribute to the existence of the detached dust layers.
36 citations
TL;DR: In this article, a flamelet-based combustion model is proposed for the prediction of wall heat transfer in rocket engines and confined combustion systems to account for convective heat loss due to the interaction of the flamelet and the combustion medium.
Abstract: A flamelet-based combustion model is proposed for the prediction of wall heat transfer in rocket engines and confined combustion systems. To account for convective heat loss due to the interaction ...
34 citations
08 Jan 2018
33 citations
TL;DR: In this article, the authors examined the thermoacoustic oscillations of a full-scale solid rocket motor (SRM) by means of nonlinear time-series analysis, namely phase portraits, Poincare maps and recurrence plots.
33 citations
TL;DR: In this article, the regression characteristics of axial-injection end-burning hybrid rocket were experimentally investigated using a laboratory-scale motor, and the axialinjection engine and fuel grains were evaluated.
Abstract: The regression characteristics of axial-injection end-burning hybrid rocket were experimentally investigated using a laboratory-scale motor. The axial-injection end-burning type fuel grains were ma...
32 citations
TL;DR: In this paper, the launch of a SpaceX Falcon 9 rocket with Taiwan's Formosat-5 Earth observation satellite was reported to have induced a massive circular shock acoustic wave (SAW) in total electron content (TEC).
Abstract: The launch of SpaceX Falcon 9 rocket delivered Taiwan’s FORMOSAT-5 satellite to orbit from Vandenberg Air Force Base in California at 18:51:00 UT on 24 August 2017. To facilitate the delivery of FORMOSAT-5 to its mission orbit altitude of ~720 km, the Falcon 9 made a steep initial ascent. During the launch, the supersonic rocket induced gigantic circular shock acoustic waves (SAWs) in total electron content (TEC) over the western United States beginning approximately 5 min after the liftoff. The circular SAWs emanated outward with ~20 min duration, horizontal phase velocities of ~629–726 m/s, horizontal wavelengths of ~390–450 km, and period of ~10.28 ± 1 min. This is the largest rocket-induced circular SAWs on record, extending approximately 114–128°W in longitude and 26–39°N in latitude (~1,500 km in diameter), and was due to the unique, nearly vertical attitude of the rocket during orbit insertion. The rocket-exhaust plume subsequently created a large-scale ionospheric plasma hole (~900 km in diameter) with 10–70% TEC depletions in comparison with the reference days. While the circular SAWs, with a relatively small amplitude of TEC fluctuations, likely did not introduce range errors into the Global Navigation Satellite Systems navigation and positioning system, the subsequent ionospheric plasma hole, on the other hand, could have caused spatial gradients in the ionospheric plasma potentially leading to a range error of ~1 m. Plain Language Summary On 24 August 2017, a SpaceX Falcon 9 rocket departed from Vandenberg Air Force Base in California, carrying Taiwan’s FORMOSAT-5 Earth observation satellite into orbit. The lightly weighted solo payload enables the rocket to fly a lofted trajectory for direct insertion at the mission altitude of 720 km. This unique nearly vertical trajectory is different from the usual satellite launches that the rockets fly over horizontal trajectory and insert satellites at 200 km altitude followed by orbit maneuvers to its mission altitudes. Consequently, the rocket launch generated a gigantic circular shock wave in the ionosphere covering a wide area four times greater than California. It is followed by ionospheric hole (plasma depletions) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. The ionospheric hole causing large spatial gradients could lead to ~1 m range errors into GPS navigation and positioning system. Understanding how the rocket launches affect our upper atmosphere and space environment is important as these anthropogenic space weather events are expected to increase at an enormous rate in the near future.
31 citations
TL;DR: In this article, a laser absorption sensor was developed for carbon monoxide (CO) sensing in high-pressure, fuel-rich combustion gases associated with the internal conditions of hydrocarbon-fueled liquid bipropellant rockets.
Abstract: A laser absorption sensor was developed for carbon monoxide (CO) sensing in high-pressure, fuel-rich combustion gases associated with the internal conditions of hydrocarbon-fueled liquid bipropellant rockets. An absorption feature near 4.98
$$\upmu$$
m, comprised primarily of two rovibrational lines from the P-branch of the fundamental band, was selected to minimize temperature sensitivity and spectral interference with other combustion gas species at the extreme temperatures (> 3000 K) and pressures (> 50 atm) in the combustion chamber environment. A scanned wavelength modulation spectroscopy technique (1f-normalized 2f detection) is utilized to infer species concentration from CO absorption, and mitigate the influence of non-absorption transmission losses and noise associated with the harsh sooting combustor environment. To implement the sensing strategy, a continuous-wave distributed-feedback (DFB) quantum cascade laser (QCL) was coupled to a hollow-core optical fiber for remote mid-infrared light delivery to the test article, with high-bandwidth light detection by a direct-mounted photovoltaic detector. The method was demonstrated to measure time-resolved CO mole fraction over a range of oxidizer-to-fuel ratios and pressures (20–70 atm) in a single-element-injector RP-2-GOx rocket combustor.
TL;DR: The ILR-33 sounding rocket for microgravity experiments has been developed at the Institute of Aviation in Warsaw, Poland as discussed by the authors, which enables performing experiments in microgravity for almost 150 seconds with an apogee over 100 km.
09 Jul 2018
TL;DR: In this article, the authors present results of optimisation of sounding rockets using hybrid propulsion and provide insight into the sensitivity of different design parameters on performance of hybrid sounding rockets and delve into the potential and challenges of using hybrid rocket technology for expendable suborbital applications.
TL;DR: Using the proposed convex formulation and successive convexification framework, the original non-convex problem is converted into a sequence of convex second-order cone programming (SOCP) sub-problems, which can be solved quickly and reliably, thus enabling higher fidelity real-time guidance for rocket powered landings on Mars.
Abstract: In this paper, we employ successive convexification to solve the minimum-time 6-DoF rocket powered landing problem. The contribution of this paper is the development and demonstration of a free-final-time problem formulation that can be solved iteratively using a successive convexification framework. This paper is an extension of our previous work on the 3-DoF free-final-time and the 6-DoF fixed-final-time minimum-fuel problems. Herein, the vehicle is modeled as a 6-DoF rigid-body controlled by a single gimbaled rocket engine. The trajectory is subject to a variety of convex and non-convex state- and control-constraints, and aerodynamic effects are assumed negligible. The objective of the problem is to determine the optimal thrust commands that will minimize the time-of-flight while satisfying the aforementioned constraints. Solving this problem quickly and reliably is challenging because (a) it is nonlinear and non-convex, (b) the validity of the solution is heavily dependent on the accuracy of the discretization scheme, and (c) it can be difficult to select a suitable reference trajectory to initialize an iterative solution process. To deal with these issues, our algorithm (a) uses successive convexification to eliminate non-convexities, (b) computes the discrete linear-time-variant system matrices to ensure that the converged solution perfectly satisfies the original nonlinear dynamics, and (c) can be initialized with a simple, dynamically inconsistent reference trajectory. Using the proposed convex formulation and successive convexification framework, we are able to convert the original non-convex problem into a sequence of convex second-order cone programming (SOCP) sub-problems. Through the use of Interior Point Method (IPM) solvers, this sequence can be solved quickly and reliably, thus enabling higher fidelity real-time guidance for rocket powered landings on Mars.
01 Jan 2018
TL;DR: A high length-to-diameter ratio of a rocket leads to unstable flight performance, affects structural loads, and makes a high dry mass of the rocket with a diameter constraint as mentioned in this paper.
Abstract: A high length-to-diameter ratio of a rocket leads to unstable flight performance, affects structural loads, and makes a high dry mass of the rocket with a diameter constraint. To improve the volume...
TL;DR: For an adequate understanding of the broadband acoustic phenomena generated by a rocket exhaust jet impinging on a flame deflector, the authors experimentally clarifies the factors that cause the di...
Abstract: For an adequate understanding of the broadband acoustic phenomena generated by a rocket exhaust jet impinging on a flame deflector, this study experimentally clarifies the factors that cause the di...
TL;DR: In this article, the authors present the state-of-the-art of Microwave Rocket development and related researches on atmospheric discharge in a high-power millimeter-wave beam.
Abstract: This paper presents the state of art of Microwave Rocket development and related researches on atmospheric discharge in a high-power millimeter-wave beam. Its operational mechanisms, thruster design, history of development, and flight path and cost analyses are introduced along with millimeter-wave discharge observations and numerical simulations. A thruster model of 126 g weight with no on-board propellant was launched to 1.2 m altitude using a 1 MW class gyrotron. A flight analysis that shows 77% cost reduction is possible using Microwave Rocket as the first stage of H-IIB heavy. A millimeter-wave discharge with unique plasma structure such as a quarter-wavelength microstructure and a comb-shaped filamentary structure was observed and reproduced by a two-dimensional numerical model.
TL;DR: In this article, the authors used time-resolved synchrotron x-ray imaging (with both absorption and phase contrast) to view aluminum agglomerate formation in situ at relevant rocket pressures.
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TL;DR: In this paper, the authors showed that the maximum velocity of a photon propulsion rocket is a function of the reduced Compton wavelength of the heavy subatomic particles in the rocket, which is the same as the maximum velocities of a Planck mass particle.
Abstract: In this paper we look at the ultimate limits of a photon propulsion rocket. The maximum velocity for a photon propulsion rocket is just below the speed of light and is a function of the reduced Compton wavelength of the heaviest subatomic particles in the rocket. We are basically combining the relativistic rocket equation with Haug's new insight on the maximum velocity for anything with rest mass.
An interesting new finding is that in order to accelerate any subatomic "fundamental" particle to its maximum velocity, the particle rocket basically needs two Planck masses of initial load. This might sound illogical until one understands that subatomic particles with different masses have different maximum velocities. This can be generalized to large rockets and gives us the maximum theoretical velocity of a fully-efficient and ideal rocket. Further, no additional fuel is needed to accelerate a Planck mass particle to its maximum velocity; this also might sound absurd, but it has a very simple and logical solution that is explained in this paper.
09 Jul 2018
TL;DR: In this paper, the effect of the heat release distribution on the component matching is analyzed on an integrated rocket-based combined cycle (RBCC) model through three-dimensional numerical simulations and the freejet tests under Ma∞ = 4 and Ma∩∞=5 conditions, and the results indicate that the increasing precombustion shock strength during the movement can balance the pressure difference between air intake and combustion effectively.
TL;DR: A NASA sounding rocket for high-contrast imaging with a visible nulling coronagraph, the Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) payload, has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani as mentioned in this paper.
Abstract: A NASA sounding rocket for high-contrast imaging with a visible nulling coronagraph, the Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) payload, has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. The first flight in 2011 demonstrated a 5 mas fine pointing system in space. The reduced flight data from the second launch, on November 25, 2015, presented herein, demonstrate active sensing of wavefront phase in space. Despite several anomalies in flight, postfacto reduction phase stepping interferometer data provide insight into the wavefront sensing precision and the system stability for a portion of the pupil. These measurements show the actuation of a 32 × 32-actuator microelectromechanical system deformable mirror. The wavefront sensor reached a median precision of 1.4 nm per pixel, with 95% of samples between 0.8 and 12.0 nm per pixel. The median system stability, including telescope and coronagraph wavefront errors other than tip, tilt, and piston, was 3.6 nm per pixel, with 95% of samples between 1.2 and 23.7 nm per pixel.
TL;DR: In this paper, a multi-stage hydrogel rocket with precise control of the step-by-step detachment of the hydrogels stage and tunable cargo release ability is presented.
Abstract: The emerging micromotors have shown great potential as delivery vehicles due to their promising transport capacity and ability to dynamically respond to the environment. We report here a multi-stage hydrogel rocket with precise control of the step-by-step detachment of the hydrogel stage and tunable cargo release ability. The hydrogel rocket, constructed from driving hydrogel blocks alternating with sacrificial hydrogel blocks, could propel itself fast driven by the Marangoni effect and drops off self-propelled small rockets by thermal/light stimulation. Furthermore, the tunable release of the payload in the hydrogel rocket was demonstrated. This multi-stage hydrogel rocket may provide new insight into the design of micromotors with on-demand cargo transport and delivery capabilities.
08 Jan 2018
TL;DR: In this article, a simplified double-frequency scheme has been developed to obtain high-frequency detonations for pulse detonation rocket engines based on the valved and valveless schemes.
TL;DR: In this paper, the authors present a tool for hydrogen peroxide/hydrocarbon bipropellant rocket propulsion system optimisation in terms of given requirements and design constraints, which may enable the development of advanced, environmentally-friendly satellites and highly efficient architectures utilizing storable green propellants.
09 Jul 2018