Horizontal Launch Research Articles

Dynamics modeling and flight characteristics of folded multi-body aircraft

This paper studies the dynamic modeling method of fold-able multi-body aircraft based on the dynamics theory of multi-body system. Considering the multi-body aircraft as a complete multi-rigid body system, the dynamic model for the free unfolding process of the multi-body aircraft after horizontal launch is established. On the basis of the multi-body dynamics model, the coil spring moment model and the damping moment model for the flexible connection between the flight units are added. Taking a certain type of fold-able three-section wing aircraft as an example, the numerical simulation calculation is carried out. The influence of the flexible connection stiffness coefficient between the flight unit on the dynamic characteristics of the fold-able multi-body aircraft in the free deployment process and the relationship between the stiffness of the flexible connection and the maximum initial folding angle are studied. Finally, the stability envelope between the stiffness coefficient of the flexible connection and the maximum initial folding angle is determined.

Contribution of biological maturation and power of upper and lower limbs to crawl swim performance in adolescent athletes

PurposeThere is no consensus in literature data about the influence of biological maturation (BM) on swim performance in young athletes. We analysed the relationship of BM, upper-limb power (ULP), and lower-limb power (LLP) with adolescent athletes’ performance in crawl swim.MethodsThis observational study determined the BM of 16 competitive swimmers (50% males and 50% females; 12.90 ± 0.88 years) by a mathematical model based on bone age and anthropometric measures. ULP and LLP were established by the horizontal launch test and the vertical and countermovement jump tests on a force platform, respectively. Swim performance was evaluated by the average speed in a 100-m crawl sprint.ResultsBM was related to ULP (males: <i>r</i> = 0.76, <i>p</i> = 0.001; females: <i>r</i> = 0.39, <i>p</i> = 0.02), LLP (males: vertical jump <i>r</i> = 0.80, <i>p</i> = 0.02, countermovement jump <i>r</i> = 0.48, <i>p</i> = 0.02; females: vertical jump <i>r</i> = 0.30, <i>p</i> = 0.04, countermovement jump <i>r</i> = 0.80, <i>p</i> = 0.01), and crawl swim performance (males: <i>r</i> = –0.91, <i>p</i> = 0.001; females: <i>r</i> = –0.72, <i>p</i> = 0.04). BM had a 87% contribution to crawl swim performance in males and a 66% contribution in females. ULP and LLP showed < 50% contribution to crawl swim performance in both females and males.ConclusionsBM was associated with crawl swim performance of adolescent athletes of both sexes. BM exhibited a stronger contribution to crawl swim performance than ULP and LLP in adolescent swimmers at the puberty window.

Multiple-Input/Multiple-Output Random Vibration Control for Simulating a Horizontal Direction Launch Environment

A vibration test system (VTS) consisting of a single shaker and a slip table is the most widely used for a horizontal direction launch environment test. When the single shaker is controlled according to the average of absolute responses at interface points, the payload will have a quite different vibration response, depending on the installation position on its slip table. This paper first discusses the limitation of the conventional VTS. To improve the uniformity of the payload response for each test configuration, an additional shaker can be installed on the opposite side of the slip table. Currently, a multiple-shaker VTS is used for the single-axial launch environment test, where each shaker is controlled by a single drive signal. This approach is effective in increasing the force capability, but it cannot sufficiently reduce the difference of the payload response. Conventional multiple-input/multiple-output control methods have limitations when controlling several interface responses within the tolerance. This study proposes a new control method for the random vibration test; the combination of interface responses is controlled for the high-frequency band and only a single shaker is controlled for the low-frequency band. The proposed method can increase the reliability of the random vibration verification tests for simulation launch environment.

Predefined-time control for a horizontal takeoff and horizontal landing reusable launch vehicle

PurposeThis paper aims to investigate the problem of attitude control for a horizontal takeoff and horizontal landing reusable launch vehicle.Design/methodology/approachIn this paper, a predefined-time attitude tracking controller is presented for a horizontal takeoff and horizontal landing reusable launch vehicle (HTHLRLV). Firstly, the attitude tracking error dynamics model of the HTHLRLV is developed. Subsequently, a novel sliding mode surface is designed with predefined-time stability. Furthermore, by using the proposed sliding mode surface, a predefined-time controller is derived. To compensate the external disturbances or model uncertainties, a fixed-time disturbance observer is developed, and its convergence time can be defined as a prior control parameter. Finally, the stability of the proposed sliding mode surface and the controller can be proved by the Lyapunov theory.FindingsIn contrast to other fixed-time methods, this controller only requires three control parameters, and the convergence time can be predefined instead of being estimated. The simulation results also demonstrate the effectiveness of the proposed controller.Originality/valueA novel predefined-time attitude tracking controller is developed based on the predefined-time sliding mode surface (SMS) and fixed-time disturbance observer (FxTDO). The convergence time of the system can be selected as a prior control parameter for SMS and FxTDO.

Accelerated Landweber iteration based control allocation for fault tolerant control of reusable launch vehicle

This paper presents a novel Fault Tolerant Control (FTC) scheme based on accelerated Landweber iteration and redistribution mechanism for a horizontal takeoff horizontal landing reusable launch vehicle (RLV). First, an adaptive law based on fixed-time non-singular fast terminal sliding mode control (NFTSMC), which focuses on the attitude tracking controller design for RLV in the presence of model couplings, parameter uncertainties and external disturbances, is proposed to produce virtual control command. On this basis, a novel Control Allocation (CA) based on accelerated Landwber iteration is presented to realize proportional allocation of virtual control command among the actuators according to the effective gain as well as the distance from the current position of actuator to corresponding saturation limit. Meanwhile a novel redistribution mechanism is introduced to redistribute oversaturated command among healthy actuators (non-faulty or redundant). The proposed method can be applied to a real-time FTC system so that the controller reconfiguring is not required in case of actuator faults. Finally, the effectiveness of the proposed method is demonstrated by numerical simulations.

Space launches and the UK marine environment

Government’s vision is for the UK to be at the global forefront of small satellite launch and emerging space transportation markets. The UK Spaceflight Programme, LaunchUK, aims to establish commercial vertical and horizontal small satellite launch from UK spaceports, with the first launches taking place from the early 2020s. This will support the Government’s aim of growing the UK’s global market share of the space sector to 10% by 2030. To meet this vision and aim, the UK Government is funding a range of industry-led projects including funding to support a new spaceport in Sutherland, Scotland, and a horizontal launch site at Cornwall Airport Newquay. The potential environmental risks of such spaceports, and their ancillary activities, need to be fully assessed under the Space Industry Act 2018, since it is envisaged that various stages of the launch vehicles will be jettisoned into the marine environment. However, it is unknown whether these will be in UK territorial, other countries exclusive economic zones (EEZ), or international waters. Here we set out the regulatory context of these activities, provide an initial assessment of the potential marine impacts from such launches and the potential jettisoned debris that may be generated and highlight any unaddressed regulatory issues.

Sharing airspace: Simulation of commercial space horizontal launch impacts on airlines and finding solutions

Commercial space transportation is becoming more affordable and accessible. Consequently, we expect to see significant expansion of commercial space launch activities in the coming decade. As space vehicles travel through airspace during the launch and re-entry stages, they potentially disrupt the regular operations of traditional users. This paper estimates the potential economic and operational impacts of commercial space horizontal launch activities on airlines under various launch scenarios using predictive fast-time simulation modeling, focusing on Cecil Air and Space Port in Jacksonville (Florida) and the rules governing the national airspace system (NAS) in the United States. Our results indicate that the existing 4-hour airspace closure rule impacts a significant number of flights, resulting in flight time delays, additional flight distance and fuel burn, as well as other direct operating costs. Safely reducing the duration of airspace closures could serve as a simple solution to mitigate the impacts on airlines and other traditional NAS users. More importantly, treating our studied launch vehicle as an aircraft and opening its departure/arrival corridor to air traffic during a horizontal launch and return would potentially reduce the impacts on airlines significantly, depending on the location of the spaceport, planned flight paths and the trajectory of the launch.

Analysis of microsphere oblique impact with planar surfaces based on the independent friction-restitution approach

The independent friction restitution closure (IFR) previously applied to describe planar oblique impact of a homogeneous sphere on an infinitely massive rough plane is applied here to microsphere collisions and is extended to describe horizontal launch experiments. The model provides analytical solutions of the motion equations based on a unique set of values of the coefficients of normal and tangential restitution and friction. Comparison with experimental data in literature for the impact of microspheres of diameter <100 μm yields a satisfactory agreement between experimentation and theory.

Measurements and modeling of acoustic propagation in a scale model canyon.

Two scale-model acoustic propagation experiments were conducted in a laboratory tank to investigate three-dimensional (3D) propagation effects induced by range-dependent bathymetry. The model bathymetry, patterned after measured bathymetric data, represents a portion of the Hudson Canyon at 1:7500 scale. The bottom condition in the scale model is nearly pressure release, and as a result, the bottom reflection and backscattering are stronger than that of the real ocean environment. Measurements are presented for propagation paths oriented along and across the axis of the canyon. The measured data are interpreted using both 3D adiabatic-mode and 3D ray models. For propagation along the canyon axis, horizontal focusing is observed, and the out-of-plane arrivals are identified using the vertical mode/horizontal ray analogy to determine which wall or walls of the canyon refracted the sound. For the across-canyon propagation, out-of-plane arrivals are observed for both forward scattered and backward scattered sound. Using the 3D ray model, an investigation of the horizontal and vertical launch angles is used to identify features on the canyon walls responsible for the measured out-of-plane propagation. For both the along- and across-canyon experiments, the 3D ray model produced a solution that was more accurate and less computationally intensive.

Integrating Air and Near Space Traffic Management for aviation and near space

Commercial space transportation is becoming more affordable and accessible. Consequently, we expect to see significant expansion of commercial space launch activities in the coming decade. As space vehicles travel through airspace during the launch and re-entry stages, they potentially disrupt the regular operations of traditional users. This paper estimates the potential economic and operational impacts of commercial space horizontal launch activities on airlines under various launch scenarios using predictive fast-time simulation modeling, focusing on Cecil Air and Space Port in Jacksonville (Florida) and the rules governing the national airspace system (NAS) in the United States. Our results indicate that the existing 4-hour airspace closure rule impacts a significant number of flights, resulting in flight time delays, additional flight distance and fuel burn, as well as other direct operating costs. Safely reducing the duration of airspace closures could serve as a simple solution to mitigate the impacts on airlines and other traditional NAS users. More importantly, treating our studied launch vehicle as an aircraft and opening its departure/arrival corridor to air traffic during a horizontal launch and return would potentially reduce the impacts on airlines significantly, depending on the location of the spaceport, planned flight paths and the trajectory of the launch.

Evaluation of electron cyclotron current drive performance for CFETR

A number of simulations of electron cyclotron current drive (ECCD) have been carried out for the China Fusion Engineering Test Reactor (CFETR) using the C3PO/LUKE code to investigate the performance and optimize schemes of power injection for the design of the launcher. The operation ranges of the toroidal field, cutoff density, and resonance layer location are given at different source frequencies in CFETR phases I and II. A comparison of ECCD performance between the horizontal and top port launch is presented. ECCD efficiency estimated for CFETR phase I is for top port launch and for horizontal port launch. The ECCD efficiency and second-harmonic absorption is calculated at different wave frequencies (from 170 to 230 GHz) in CFETR phase II. It is found that the highest driven efficiency is obtained at 210 GHz with the toroidal field of 6.5 T, and the second-harmonic absorption increases rapidly with the increase of frequency.

Horizontal Backward Launch Dynamics Modeling and Analysis

Fighters’ air strikes play a vital role in modern warfare. But, with the development of fighters, the amount of bombs will inevitably become a major disadvantage due to the limitations of the invisible design and other functions, so a combination of the old model bombers and the advanced fifth-generation fighters has been proposed. This paper takes the aircraft missile horizontal backward launch system as the research object; firstly, the finite element model of the missile’s off-track is established, and the simulation calculation under the fixed platform is tested to verify the correctness of the finite element model. Meanwhile, the simulation parameters of the initial trajectory are obtained. Then, by establishing the separation model of the machine under the open state of the aircraft’s rear launcher, the variation of the flow field during the separation process of the missile is analyzed, and the variation of the force and the attitude of the missile is studied. It is found that the pitching motion of the missile is greatly affected by the initial pitch angle, it is always in the heading state during the whole separation process, and the yaw motion is not obvious.

Visual dependency and postural control on swing performance in golf players

Individuals have to reweight the respective contribution of the different sources of sensorial information for regulating posture and balance, especially during fine task execution. Given the evidences indicating strategy during swing performance as associated with prioritization of task-relevant visuospatial information for skill execution, the aim of the present work is to assess differences in visual dependency (VD) and postural control in a population of expert (EXP) and non-expert (NEXP) golfers when compared with healthy subjects (HC) and to discover possible relationships between these outcomes and swing performance. Thus, 15 golfers (EXP = 7; NEXP = 8) and 32 matched HC underwent otoneurological testing including video Head Impulse Test, posturography and Rod and Disk Test (RDT). Golf players also underwent a swing session procedure, which performance was measured by means of the Flightscope X2 Doppler-radar launch monitor system. EXP subjects demonstrated significant (p < 0.05) lower values in i) counter-clockwise (CCW) and clockwise (CW) dynamic conditions when compared with both NEXP and HC subjects RDT outcome measures and ii) surface and length posturography values as compared with HC subjects. When treating golf players outcomes as ‘a continuum’, CCW and CW scores were found to positively correlate with both lateral distance and horizontal launch angle and to negatively correlate with spin rpm. In conclusion, the present study suggests that the high-level of visual-independency demonstrated by EXP subjects may be functionally related in expert golfers to an effective motor strategy preferentially not referring to an inappropriate reliance on visual input.

Performance and Technological Feasibility of Aerospace Plane Horizontal Launch and Landing with Ekranoplane Assistance

Numerous attempts to reduce the cost of launching a satellite into low Earth orbit (LEO) were undertaken in many countries and characterize the current trend to make space projects economically viable and less costly. This is necessary for the progress of the development of our earthly civilization, its evolution according to the plans of the outstanding Russian thinker, the founder of cosmonautics Konstantin E. Tsiolkovsky. Mastering of the Moon and Mars are the necessary steps in the cosmic evolution of earthlings. Unfortunately, this process has not led presently to a sharp decrease in the specific launch cost. The concepts of such task solving are considered in this paper.

The effect of movement variability on putting proficiency during the golf putting stroke

Movement variability has been considered important to execute an effective golf swing yet is comparatively unexplored regarding the golf putt. Movement variability could potentially be important considering the small margins of error between a successful and a missed putt. The aim of this study was to assess whether variability of body segment rotations influence putting performance (ball kinematic measures). Eight golfers (handicap range 0–10) performed a 3.2 m level putt wearing retro-reflective markers which were tracked using a three-dimensional motion analysis system sampling at 120 Hz. Ball roll kinematics were recorded using Quintic Ball Roll launch monitor. Movement (segment) variability was calculated based on a scalene ellipsoid volume concept and correlated with the coefficient of variation of ball kinematics. Statistical analysis showed no significant relationships between segment variability and putting proficiency. One significant relationship was identified between left forearm variability and horizontal launch angle, but this did not result in deficits in putting success. Results show that performance variability in the backswing and downswing is not related to putting proficiency or the majority of ball roll measures. Differing strategies may exist where certain golfers may have more fluid movement patterns thereby effectively utilising variability of movement. Therefore, golf instructors should consider movement variability when coaching the golf putt.

The effect of dimple error on the horizontal launch angle and side spin of the golf ball during putting

ABSTRACTThis study aimed to examine the effect of the impact point on the golf ball on the horizontal launch angle and side spin during putting with a mechanical putting arm and human participants. Putts of 3.2 m were completed with a mechanical putting arm (four putter-ball combinations, total of 160 trials) and human participants (two putter-ball combinations, total of 337 trials). The centre of the dimple pattern (centroid) was located and the following variables were measured: distance and angle of the impact point from the centroid and surface area of the impact zone. Multiple regression analysis was conducted to identify whether impact variables had significant associations with ball roll variables, horizontal launch angle and side spin. Significant associations were identified between impact variables and horizontal launch angle with the mechanical putting arm but this was not replicated with human participants. The variability caused by “dimple error” was minimal with the mechanical putting arm and not evident with human participants. Differences between the mechanical putting arm and human participants may be due to the way impulse is imparted on the ball. Therefore it is concluded that variability of impact point on the golf ball has a minimal effect on putting performance.

Reusable Space Planes Challenges And Control Problems

The possible directions of development of space launch technology, including space launch to suborbital trajectory, in order to reduce the specific cost of launch at the expense of the majority of reusable carrier components, are analyzed. Opportunities of providing reusability for horizontal and vertical launch are compared. The experience of soft landing of the first stage of Falcon 9-R rocket of US firm SpaceX is taken into account. The requirements to the air breathing engine, which could provide an economical horizontal launch, are considered. The requirements for the engine could be reduced for suborbital launch, and in this simplified case they could be fulfilled well already at the present stage of development of aerospace technologies. The proposed principles of reusable HTHL system "WIG-craft +Aerospace Plane" are described and its advantages over the vertical launch systems are considered.

Water injection pre-compressor cooling assist space access

AbstractAdvances in space activity are linked to reductions in launch cost. Air-breathing propulsion-assisted flight systems offer the potential for revolutionary change of the space operations paradigm. Horizontal launch of a space-access system provides mission flexibility, responsiveness, and affordability. One way to reduce launch cost is to increase the Mach number at which a launch vehicle is staged from a carrier aircraft. Without exceeding the engine and airframe design limits, the pre-compressor cooling technology allows an operational aircraft to operate at Mach numbers and altitudes beyond its basic operational limits. This is an essential, near-term technology for reducing launch cost to place small-weight payloads in low Earth orbit. The advantage of this technology is assessed with a modified McDonnell Douglas QF-4C aircraft. Payloads are unachievable or marginal with an unmodified QF-4C. However, payloads weighing around 150 pounds are plausible with this aircraft when incorporating the water injection pre-compressor cooling (WIPCC) technology.

Air Breathing Rocket Engines and Sustainable Launch Systems

An air-breathing rocket engine inhales oxygen from the air for about half the flight, so it doesn't have to store the gas onboard. So at take-off, an air-breathing rocket weighs much less than a conventional rocket, which carries all of its fuel and oxygen onboard. Air breathing rockets, combine the performance characteristics of both rocket and ramjet engines. An air-breathing engine gets its initial take-off power from specially designed rockets, called air-augmented rockets, that boost performance about 15 percent over conventional rockets. When the vehicle's velocity reaches twice the speed of sound, the rockets are turned off and the engine relies totally on oxygen in the atmosphere to burn the hydrogen fuel. Once the vehicle's speed increases to about 10 times the speed of sound, the engine converts to a conventional rocket-powered system to propel the vehicle into orbit. And therefore reducing a vehicle's weight decreases cost significantly. And since an air breathing engine cannot get required initial take off thrust, various launch types like air augmented rockets, horizontal launch mode courtesy hybrid engine, magnetic levitation launch systems are used for initial thrust requirements ,thus reducing fuel emissions and increases net efficiency of rockets. Hence air breathing engines can be implemented to address energy considerations and reduce costs.

Control Strategies of Spaceplane Docking and Undocking with Other Winged Vehicle

AbstractThe concept of aerospace plane (ASP) horizontal launch and landing with the assist of heavy plane or ekranoplane is analyzed1. It is shown, that their docking at a final stage of aerospace plane alighting is favorable to expansion of functional capacity of this space transportation system. Ekranoplane with mass of 1500 ton or more is capable to carry ASP with initial mass of 500 ton and landing mass of 60-70 ton. Ekranoplane can provide ASP with the primary speed of Mach 0.5-0.65 in required direction that allows the lowering of the requirements to ASP wing area and its engines. A number of other advantages of the offered transport system are connected with the possible use of an ekranoplane at ASP launch and landing. Undocking and docking are the important stages of ASP flight which require the perfect automatic control. The requirements to corresponding systems of motion control of both winged crafts are presented, the structure of the integrated system of relative motion control is offered.