Lift-off Time Research Articles

Future sustainable space exploration: Space conditions adaptation and self-sustaining system

Creating regenerative systems onboard space vehicles is the next technological breakthrough to reduce cost, efficiency, and sustainability of space exploration. Near future projects include NASA’s plan to set up moon base as soon as 2028 in one of the Artemis missions. Upon architectural and structural maturation, focus is shifted to maintaining presence. This includes minimising astrological impacts on the crew and building self-sustaining systems that would be the key to a new era of ambitious missions. ALS and HLS will provide transportation for the missions from the Earth to destinations, with impacts on the crew during journey discussed. Ways of minimising effects are vital to missions in the long run. Process of activation and operating core modules is portrayed on blueprints. Details of development and current technological advances that could be utilised may offer potential on the system, new advancements by the time of liftoff is expected for taking pioneering space missions to a new level.

A catalogue of observed geo-effective CME/ICME characteristics

One of the goals of Space Weather studies is to achieve a better understanding of impulsive phenomena, such as Coronal Mass Ejections (CMEs), to improve our ability to forecast their propagation characteristics and mitigate the risks to our technologically driven society. The essential part of achieving this goal is to assess the performance of forecasting models. To this end, the quality and availability of suitable data are of paramount importance. In this work, we merged publicly available data of CMEs from both in-situ and remote observations in order to build a dataset of CME properties. To evaluate the accuracy of the dataset and confirm the relationship between in-situ and remote observations, we have employed the Drag-Based Model (DBM) due to its simplicity and modest consumption of computational resources. In this study, we have also explored the parameter space for the drag parameter and solar wind speed using a Monte Carlo approach to evaluate how efficiently the DBM determines the propagation of CMEs for the events in the dataset. The geoeffective CMEs selected as a result of this work are compliant with the hypothesis of DBM (isolated CME, constant solar wind speed beyond 20 R⊙) and also yield further insight into CME features such as arrival time and arrival speed at L1 point, lift-off time, speed at 20 R⊙ and other similar quantities. Our analysis based on the acceptance rate in the DBM inversion procedure shows that almost 50% of the CME events in the dataset are well described by DBM as they propagate in the heliosphere. The dataset includes statistical metrics for the DBM model parameters. The probability distribution functions (PDFs) for the free parameters of DBM have been derived through a Monte Carlo-like inversion procedure. Probability distribution functions obtained from this work are comparable to PDFs employed in previous works. The analysis showed that there exist two different most probable values (median values) of solar wind speed for DBM input based on slow (wslow ≈ 386 km/s) and fast (wfast ≈ 547 km/s) solar wind type. The most probable value for the drag parameter (γ ≈ 0.687 × 10−7 km−1) in our study is somewhat higher than the values reported in previous studies. Using a data-driven approach, this procedure allows us to present a homogeneous, reliable, and robust dataset for the investigation of CME propagation. Additionally, possible CME events are identified where the DBM prediction is not valid due to model limitations and higher uncertainties in the input parameters. These events require further thorough investigation in the future.

Coupled bubble dynamics and interaction mechanisms of adjacently nucleated vapor bubbles under subcooled pool boiling regime

The present work investigates the plausible modes of interaction between two adjacently located vapor bubbles growing on high wettability surface during subcooled nucleate pool boiling. The study becomes important as the phenomenon of bubble interaction has a significant impact on the resulting bubble dynamic parameters as well as on microlayer dynamics of the respective vapor bubbles. As against the symmetric growth of microlayer in the case of isolated pool boiling, microlayers of mutually interacting vapor bubbles no longer remain symmetric and tend to deplete relatively faster, thereby influencing the resulting wall heat transfer rates. Toward this, the microlayers and dynamics of adjacently located interacting vapor bubbles have been mapped in a simultaneous manner using thin-film interferometry and high-speed rainbow schlieren deflectometry as a function of varying subcooling levels. Results of the experiments revealed that parameters such as non-dimensional spacing between the two vapor bubbles, supplied heat flux, and degree of subcooling have a strong impact on the mechanism of bubbles' interaction, which, in turn, influence the bubble departure frequency, bubble diameter, and microlayer dynamics. Three dominant modes of bubble interaction, hydrodynamic interaction (HI), thermal interaction (TI), and coalescence (C), were identified as a function of the level of subcooling. Quantification of the experimental data showed that the equivalent diameter of the vapor bubble increases with an increase in the level of heat flux, while it decreases with an increase in the subcooling level. Additionally, the secondary nucleation affects the liftoff time and movement of the primary bubble and can hydrodynamically deplete the microlayer of the first bubble even when the bubbles are far apart, with the depletion rates showing a strong dependence on the growth rate and location of the secondary nucleation.

Microlayer dynamics of hydrodynamically interacting vapour bubbles in flow boiling

Nucleate boiling, a ubiquitous heat transfer mode, involves multiple vapour bubble nucleations on the heater surface and offers high heat transfer coefficients. The bubble growth process on a heating substrate involves the formation of microlayer, a thin liquid film trapped between the growing bubble and the heating substrate, and contributes to the bubble growth phenomenon through evaporation. Microlayer dynamics for a single bubble have been widely investigated in the pool and flow boiling conditions. However, the literature on multiple bubbles interactions and their associated microlayer information is scarce. Notably, in the case of flow boiling, where the microlayer dynamics are not symmetric due to the bubble's movement, the bubbles’ interaction and its influence on associated microlayer dynamics have never been reported. Therefore, microlayer and bubble dynamics in multiple interactions have been investigated experimentally using simultaneous application of thin-film interferometry and high-speed videography techniques in flow boiling with water as the working fluid. Our experimental investigation revealed that the secondary nucleation could cause a reduction in lift-off time and may assist or hinder the movement of the first bubble. The experimental results also demonstrated that the secondary nucleation could deplete the microlayer of the first bubble hydrodynamically even when the bubbles are far apart. Furthermore, it has been found that the microlayer depletion rate depends on the growth rate and the location of the secondary nucleation. Hence, this experimental study emphasises the need to consider the interaction of bubbles while modelling boiling flows to avoid overestimating the contribution of microlayer evaporation.

Theoretical Investigations on Tribological Properties of Air Foil Thrust Bearings during Start-Up Process

During the start-up process, air foil thrust bearings (AFTBs) come into contact and are prone to localized overheating and even failure. Frequent starts and stops are the major sources of wear. In this study, a transient mixed lubrication model considering the air rarefaction effect is established. In the model, asperity contact between the top foil of the air foil thrust bearing (AFTB) and the rotor surface is considered using a deterministic approach, and the deformation of the foil structure is considered using the elastic-aerodynamic coupling. The influences of bearing compliance, external load, acceleration time and contact stiffness on the tribological properties during the start-up process are investigated. The results show that the lift-off speed increases with the increase of the bearing compliance and of the external load. Specifically, the lift-off speed of AFTBs increases from 1950 rpm to 5325 rpm when the bearing compliance increases linearly from 0.2 to 1.0. When the external load increases from 10 N to 80 N, the lift-off speed is increased by approximately 30 times, from 450 rpm to 13,575 rpm. Furthermore, a decrease in the acceleration time of the rotor generates a decrease in the lift-off time and an increase in the contact stiffness of the bearing leads to a decrease in the lift-off speed of the bearing. By exploring the effects of the bearing parameters and working conditions on the tribological performance of AFTBs during start-up, the results presented in this study can provide theoretical support for improving start-up performance and designing high-reliability and long-life AFTBs.

Computing the viscous effect in early-time drop impact dynamics

The impact of a liquid drop on a solid surface involves many intertwined physical effects, and is influenced by drop velocity, surface tension, ambient pressure and liquid viscosity, among others. Experiments by Kolinski et al. (Phys. Rev. Lett., vol. 112, no. 13, 2014b, p. 134501) show that the liquid–air interface begins to deviate away from the solid surface even before contact. They found that the lift-off of the interface starts at a critical time that scales with the square root of the kinematic viscosity of the liquid. To understand this, we study the approach of a liquid drop towards a solid surface in the presence of an intervening gas layer. We take a numerical approach to solve the Navier–Stokes equations for the liquid, coupled to the compressible lubrication equations for the gas, in two dimensions. With this approach, we recover the experimentally captured early time effect of liquid viscosity on the drop impact, but our results show that lift-off time and liquid kinematic viscosity have a more complex dependence than the square-root scaling relationship. We also predict the effect of interfacial tension at the liquid–gas interface on the drop impact, showing that it mediates the lift-off behaviour.

Biomechanics of Volleyball Players' Run-Up and Take-Off Link under Deep Learning.

In volleyball, the correct approach and start (including the number of steps and stride speed) are a prerequisite for all technical movements to attack. It can not only improve the horizontal speed of the athlete, but also properly convert the total speed into vertical speed, so that the hitting point is improved and the ball speed is accelerated. To explore the biomechanical characteristics of lower limb movements in the run-up and take-off stage of volleyball spiking, this paper takes four male volleyball players from the Physical Education College of X University as the research objects to analyze the kinematics and dynamics of the run-up process and the take-off process. This paper uses the precise recognition method under the background of deep learning to accurately capture the movements of the research object. This paper discusses the effects of time, speed, distance, knee, and hip parameters (angle, joint muscle torque, and power) on the effect of spiking techniques. It is expected to provide reference for the diagnosis, guidance, and muscle strength training of this special technical movement. The research results show that the horizontal speed of No. 2 athlete is 3.62 m/s and the vertical speed is 2.71 m/s when he takes off. The landing time is 0.375 s and the lift-off time is 0.16 s. The torque and power of the knee joint changed greatly during the take-off process, and the change of the hip joint was small.

Stereopsis contributes to the predictive control of grip forces during prehension.

Binocular viewing is associated with a superior prehensile performance, which is particularly evident in the latter part of the reach as the hand approaches and makes contact with the target object. However, the visuomotor mechanisms through which binocular vision serves prehension are not fully understood. This study assessed the role of stereopsis in the predictive control of grasping by measuring grip force. Twenty participants performed a precision reach-to-grasp task in four viewing conditions: binocular, monocular, and with reduced stereoacuity (200 arc sec, > 400 arc sec). Monocular, compared to binocular viewing, was associated with a fourfold increase in grasp errors, a 56% increase in grasp duration, 22% decrease in grip force at 50ms following grasp initiation, and the time of peak force occurred 40% later after grasp initiation (all p < 0.05). Grasp performance was also disrupted when viewing with reduced stereoacuity. Notably, grip force at the time of object lift-off was comparable between all viewing conditions. These results demonstrate that binocular stereopsis contributes to the efficient programming of grip forces. Specifically, stereopsis may provide important sensory information that enables the central nervous system to engage in predictive control of grasping.

Predicting Lift-Off Time When Deep-Frying Potato Dough Snacks

When frying potato snacks, it is typically observed that the dough, which is submerged in hot oil, after some critical time increases its buoyancy and floats to the surface. The lift-off time is a useful metric in ensuring that the snacks are properly cooked. Here we propose a multiphase mathematical model for the frying of potato snacks, where water inside the dough is evaporated from both the top and bottom surfaces of the snack at two receding evaporation fronts. The vapor created at the top of the snack bubbles away to the surface, whereas the vapor released from the bottom surface forms a buoyant blanket layer. By asymptotic analysis, we show that the model simplifies to solving a one-dimensional Stefan problem in the snack coupled to a thin-film equation in the vapor blanket through a nonlinear boundary condition. Using our mathematical model, we predict the change in the snack density as a function of time and investigate how lift-off time depends on the different parameters of the problem.

Exhaustive study of three-time periods of solar activity due to single active regions: sunspot, flare, CME, and geo-effectiveness characteristics

In this paper, we present the multi-wavelength study of a high level of solar activity during which a single active region produced multiple flares/CMEs. According to the sunspot observations, the current solar cycle 24 manifest to be less intense in comparison with the previous recent sunspot cycles. In the course of the current sunspot cycle 24, several small and large sunspot groups have produced various moderate and intense flare/CME events. There are a few active regions with a large number of flaring activities passed across the visible disk of the Sun during 2012-2015. In this study, we consider the three periods 22-29 Oct 2013, 01-08 Nov 2013, and 25 Oct-08-Nov 2014, during which 228 flares have been observed. Considering only active regions near the central part of the disk, 59 CMEs (halo or partial) have been reported among which only 39 events are associated with flares. We conclude that an active region with a larger area, more complex morphology and stronger magnetic field has a comparatively higher possibility of producing extremely fast CMEs (speed $>1500$ km/sec). So that among the 5 X class flares of the reported periods, 3 of them (60%) are associated with a CME. The lift-off time for CME-flare associated events has a +15 to +30 minute time interval range after the occurrence time of associated flares suggesting that the flares produce the CMEs. Additionally, we compiled the geomagnetic storms occurring within 1-5 days after the CME onset. 10% of the 59 CMEs are related to a magnetic storm but all are moderate storms.

Numerical simulation of sliding bubbles in saturated flow boiling

This paper presents a numerical study of the heat transfer associated with multiple sliding bubbles in saturated flow boiling. We develop a stagnant micro-layer model, which is subsequently validated with an existing experimental study. We employ the said model to simulate flow boiling with shear rates γ̇ ranging from 0.02 s−1 through 0.17 s−1, for bubble spacing s=2.5 mm and 5 mm. We observe that for a fixed s, the heat transfer coefficients for all values of γ̇ deviate from one another after a certain time. For cases with s=5.0 mm, we observe a distinct bubble growth period prior to bubble sliding. For cases with s=2.5 mm, we observe a relatively short growth period followed by prolonged sliding. The micro-layer contributes up to 65% of the total latent heat absorbed. Cases with s=2.5 mm yield a better heat transfer coefficient than those with s=5 mm. The improvement in the heat transfer coefficient correlates linearly with the lift-off time.

Water takeoff performance calculation method for amphibious aircraft based on digital virtual flight

Owing to the strong coupling among the hydrodynamic forces, aerodynamic forces and motion of amphibious aircraft during the water takeoff process, the water takeoff performance is difficult to calculate accurately and quickly. Based on an analysis of the dynamics and kinematics characteristics of amphibious aircraft and the hydrodynamic theory of high-speed planing hulls, a suitable mathematical model is established for calculating the hydrodynamics of aircraft during water takeoff. A pilot model is designed to illustrate how pilots are affected by the lack of visual reference and the necessity to simultaneously control the pitch angle, flight velocity and other parameters during water takeoff. Combined with the aerodynamic model, engine thrust model and aircraft motion model, a digital virtual flight simulation model is developed for amphibious aircraft during water takeoff, and a calculation method for the water takeoff performance of amphibious aircraft is proposed based on digital virtual flight. Typical performance indicators, such as the liftoff time and liftoff distance, can be obtained via digital virtual flight calculations. A comparison of the measured flight test data and the calculation results shows that the calculation error is less than 10%, which verifies the correctness and accuracy of the proposed method. This method can be used for the preliminary evaluation of airworthiness compliance of amphibious aircraft design schemes, and the relevant calculation results can also provide a theoretical reference for the formulation of flight test plans for airworthiness certification.

Dynamics of impact cratering on granular bed by hydrogel sphere

A lot of studies on the dynamics of a granular impact cratering by a liquid drop have been carried out. However, the results so far are controversial due to the complex impact dynamics of a liquid drop, such as deformation, splash, and penetration into the granular bed. In this study, we focused on the dynamics of the granular impact cratering by a hydrogel sphere, which deforms without splashing and penetrating. We investigated the maximal deformation time of the sphere and the lift-off time of the grains. Both the maximal deformation time and the lift-off time are similar to each other and depend on the −1/2 power of the Young’s modulus of the hydrogel sphere. This power law of the maximum deformation time is the same as an impact of a gel sphere on a flat solid surface. The angle of the ejected curtain was evaluated. The angle is larger for the impact with small deformation of the sphere than that for the impact with large deformation, and the angle is less dependent on the free-fall height. We also investigated the distributions of the ejected grains using the grains dyed by a fluorescent dye. The distribution was visualized by the fluorescent images captured before and after the impact. At the crater rim, the number of the dyed grains flying to and away are balanced. The number of the dyed grains gathered at the dimensionless distance from the crater center of 1.15, where the distance is nondimensionalized by the crater radius, is the largest. This maximum value for the number of the gathered grains is larger for the impact with small deformation than that with large deformation. This result is consistent with the dependence of the impact mode on the angle of the ejected curtain.

Handle-Hand Compatibility Effects for the Right and Left Hand Using Reach-to-Touch Movements.

In stimulus-response compatibility tasks, performance is better when the handle of an object is oriented on the same side of the response than when the handle is oriented on the opposite side. Two major alternative accounts, the motor affordance and spatial accounts, have been proposed to explain this handle-hand compatibility effect. In two experiments, we tested between these two accounts by administering a go/no-go task to right-handed participants. Handled objects presented on a touchscreen were used as stimuli. Half of the participants had to reach-to-touch the stimuli by using their dominant hand, the other half by using their nondominant hand. Liftoff times (LTs), movement times (MTs) and spatial coordinates of the movement endpoints were recorded. Results from the LTs and MTs analyses showed no evidence of handle-hand compatibility effects. In contrast, the analyses of the spatial coordinates revealed that participants' touches were shifted more laterally towards the handle when the handles were oriented on the same side of the responding hand (Experiments 1 and 2). Furthermore, the right-hand touches landed higher (towards the handle) than the left-hand touches, especially when the vertical object dimension was particularly salient (Experiment 1). Overall, these results are in line with the activation of hand motor programs to reach and grasp the object as predicted by the motor account, at least for the right/dominant hand.

Numerical and experimental investigation on dynamic performance of bump foil journal bearing based on journal orbit

Widespread usage of bump-type foil journal bearing (BFJB) in oil-free micro-turbomachinery requires accurate predictions of dynamic performance characteristics, although it remains a challenging issue because BFJB reflects nonlinear both structurally and aerodynamically. This paper presented a simple experimental method to semi-directly obtain the minimum film thickness and dynamic stiffness of BFJB using the journal orbit. Numerical calculations and simulations are conducted to validate the experimental method. The micro-deformation and interaction of various foils are taken into consideration to improve the model precision. The results from the numerical model regarding the BFJB dynamic characteristics are compared with the experimental results coming from a dedicated test rig, which shows that the experimental results fluctuate obviously and agree not well with the numerical results at the start stage due to the presence of dry friction at that time, nevertheless, they show fantastic agreement as soon as a gas film is gradually generated to separate the shaft from the top foil. Therefore, the proposed experimental method is effective to predict film thickness and dynamic characteristics during the period from the lift-off time to the land-off time. The dynamic characteristics, along with the journal orbits also can be used to rapidly predict the dynamics behavior of rotor-bearing systems.

An experimental study on the influence of radial pressure gradient on bubbles dynamic behavior in subcooled flow boiling

It is well aligned with the general consensus that the quality of boiling heat transfer is heavily dependent upon bubbles characteristics. Moreover, the accuracy of various numerical models developed to simulate flow boiling on a heated wall heavily depends on empirical data on bubbles dynamic behavior. In this paper, the influence of radial pressure gradient on bubbles dynamic behavior characteristics in upward subcooled flow boiling of water is experimentally investigated using high-speed photography. Thereby, a comparative study on bubbles characteristics is conducted between a vertical U-shaped channel, where flow experiences the radial pressure gradient, and a straight channel under the same geometrical and flow conditions. Since the bubbles of three different locations having wall inclination angles of roughly 0°, 45°, and 90° are captured in the U-shaped channel, the straight channel is tested in horizontal, 45-degree oriented, and vertical positions, and the results are compared. In this way, not only, is the effect of wall inclination on bubble characteristics eliminated, i.e. the comparisons merely distinguish the effect of radial pressure gradient, but also the influence of this phenomenon is examined in different wall inclinations. All the experiments are performed at atmospheric pressure with heat flux in the range of 36.3–61.5 kW.m-2, flow velocity in the range of 0.132–0.265 m.s-1, and inlet subcooling ranging from 1.7 to 5.7 °C. The comparisons reveal that departure diameter and nucleation frequency are two characteristics affected the most by the radial pressure gradient. Furthermore, bubble mean departure and lift-off diameters and nucleation frequency in the U-shaped channel are shown to be on average 127.05%, 66.80%, and 73.19% greater than those of the straight one. The results also indicate that on average, bubble mean departure, lift-off, and waiting times are, respectively, 41.52%, 59%, and 41.18% lower in the vertical U-shaped channel compared to the straight one. Additionally, it is found that excluding the lift-off time, bubble characteristics are more influenced by radial pressure gradient for the case of vertical channel (90° inclination angle).

Takeoff and Performance Trade-Offs of Retrofit Distributed Electric Propulsion for Urban Transport

While vertical takeoff and landing aircraft have shown promise for urban air transport, distributed electric propulsion on existing aircraft may offer immediately implementable alternatives. Distributed electric propulsion could potentially decrease takeoff distances enough to enable thousands of potential intercity runways. This conceptual study explores the effects of a retrofit of open-bladed electric propulsion units. To model and explore the design space, blade element momentum method, vortex lattice method, linear-beam finite element analysis, classical laminate theory, composite failure, empirically based blade noise modeling, motor and motor-controller mass models, and gradient-based optimization are used. With liftoff time of seconds and the safe total field length for this aircraft type undefined, this paper focused on the minimum conceptual takeoff distance. It was found that 16 propellers could reduce the takeoff distance by over 50% compared with the optimal 2-propeller case. This resulted in a conceptual minimum takeoff distance of 20.5 m to clear a 50 ft (15.24 m) obstacle. It was also found that, when decreasing the allowable noise by approximately 10 dBa, the 8-propeller case performed the best with a 43% reduction in takeoff distance compared with the optimal 2-propeller case. This resulted in a noise-restricted conceptual minimum takeoff distance of 95 m.

Assessing Lift-Off Times for a Hospital-Based Helicopter Transport Program

Hospital-based helicopter transport programs must define and track their own lift-off times (LOTs). The goal of this quality improvement study was to evaluate LOTs, identify factors influencing LOTs, and implement changes to improve LOTs without compromising safety. A retrospective evaluation of 248 flights during 2016 was completed using recorded times from our dispatch center. Actual LOTs were compared with policy LOT goals. Tasks for flight departure were identified, timed, and sorted into those that should not be pressured and those amenable to process change. Five tasks were identified as being amenable to process change. The average LOT for scene calls was 10.56 minutes (range, 1-22 minutes) and met our 10-minute policy goal 59% of the time. The average LOT for interfacility flights was 13.2 minutes (range, 4-76 minutes) and met the policy goal of 15 minutes 76.5% of the time. We identified tasks amenable to safe process change to decrease LOTs. The data supported LOT policy change to a single LOT goal of 13 minutes for all flights. This change represents an acceptable goal for all LOTs without compromising safety to our patients and teams.

The influence of fuel type and partial premixing on the structure and behaviour of turbulent autoigniting flames

This paper explores turbulent autoignition and flame stabilisation for a range of fuels, utilising a jet in a hot coflow burner. Jet fuels including: hydrogen, dimethyl ether and hydrocarbons ranging from CH4 to C4H8 are investigated with the influence of partial premixing, dilution and hot coflow temperature. Simultaneous acoustic emission measurements and high-speed chemiluminescence imaging at 10 kHz are performed; investigating the flame lift-off dynamics and to study the initiation and evolution of autoignition kernels. For all fuels studied, a common trend is found for increasing coflow temperatures; where a transition from high lift-off flames exhibiting an autoignition kernel dominated flame stabilisation mechanism, to lower lift-off flames exhibiting a premixed flame propagation stabilisation mechanism. Three key findings are reported: (i) common to all fuels studied for the high lift-off flames, the lift-off height vs. time follows a sawtooth-like trend. The leading edge of the main flame body (flame base) drifts downstream with near constant velocity, whilst upstream of the flame base autoignition kernels form and grow rapidly merging with the flame base; thereby lowering the tip of the flame base. (ii) High amplitude acoustic emission events correlate well with auto-ignition kernel flame base merging events for high lift-off flames, for the fuels studied. The ethylene flames produced the highest sound levels for a given mean lift-off height. (iii) In the high lift-off height regime, the lift-off height for all fuels scales well with corresponding simple 0-D auto-ignition delay calculations. The good correlation of the lift-off height scaling with the computed autionition delay implies that chemical kinetics, rather than turbulent mixing controls the processes at the base of these flames for higher lift-off height flames, indicating that autoignition is the dominant stabilising mode.

Low-dose hip abductor-adductor power training improves neuromechanical weight-transfer control during lateral balance recovery in older adults

BackgroundAge-related neuromuscular changes in the hip abductor-adductor muscles lead to reduced performance, especially in the rate of force development and power production. These alterations may impair weight transfer control and lateral balance recovery through protective stepping. This study compared the effects of eight weeks of low-dose hip abductor-adductor power and strength training on the performance of isometric maximal voluntary contractions, and lateral balance recovery at different initial weight-bearing conditions in older individuals. MethodsEighteen healthy older adults (71.3 (0.9) years) underwent eight weeks of low-dose hip abductor-adductor exercise training involving either power training (n = 10) or lower velocity strength training (n = 8). Outcomes were assessed for hip abductor-adductor isometric maximal voluntary contractions and lateral waist-pull balance perturbations with three initial stepping limb-load conditions (50%, 65%, or 80% body mass). FindingsPower training increased isometric maximal voluntary contractions abductor-adductor peak torque (14%–18%, p < 0.05), rate of torque development (31%–39%, p < 0.05) and rate of neuromuscular activation (37%–81%, p < 0.05). During lateral balance recovery, power training increased the incidence of stabilizing single lateral steps at 80% body mass pre-load (by 43%, p < 0.05), reduced step lift-off time by 27 ms at 50% body mass (p < 0.05) and decreased downward momentum of the body center of mass at 80% body mass (32%, p < 0.05). Power training also increased in task hip abductor net joint torque (49%–61%, p < 0.05), power (21%–54%, p < 0.05), and abductor-adductor rate of neuromuscular activation (17%–62%, p < 0.05). InterpretationLow-dose hip abductor-adductor power training was more effective than strength training at eliciting improvements in maximal neuromuscular performance and enhanced medio-lateral balance recovery.