Take-off Speed Research Articles

A Novel Method for Obtaining the Electrical Model of Lithium Batteries in a Fully Electric Ultralight Aircraft

This article introduces a novel approach for developing an electrical model of the lithium batteries used in an electric ultralight aircraft. Currently, no method exists in the technical literature for accurately modeling the electrical characteristics of batteries in an electric aircraft, making this study a valuable contribution to the field. The proposed method was validated with an all-electric ultralight aircraft designed and constructed at the Pascual Bravo University Institution. To build the detailed model, a kinematic analysis was first conducted through takeoff tests, where data on the speed, acceleration, time, and distance required for takeoff were collected, along with measurements of the current and power consumed by the batteries. The maximum speed and acceleration of the aircraft were also recorded. These kinematic results were obtained using two batteries made from Samsung INR-18650-35E lithium-ion cells, and different wing configurations of the aircraft were analyzed to assess their impacts on the battery energy consumption. Additionally, the discharge cycles of the batteries were evaluated. In the second phase, laboratory tests were performed on the individual battery cells, and the Peukert coefficient was estimated based on the experimental data. Finally, using the Peukert coefficient and the kinematic results from the takeoff tests, the electrical model of the battery was fine tuned. This model allows for the creation of charging and discharging equations for ultralight lithium batteries. With the final electrical model and energy consumption data during takeoff, it becomes possible to determine the energy usage and flight range of an electric aircraft. The model indicated that the aircraft did not require a long distance to takeoff, as it reached the necessary takeoff speed in a very short time. The equations used to simulate the discharge cycles of the batteries and lithium cells accurately described their energy capacities.

PLR and take-off speed implications on noise contours and local gaseous emissions for SST business jet concept aircraft

DLR has established a simulation process to evaluate the landing and take-off of novel civil supersonic transport (SST) aircraft. This process was applied to two business jet concept aircraft in order to assess the certification noise levels according to novel regulations under discussion at ICAO CAEP. It has to be noted, that neither of the concept aircraft is optimized for low noise nor for low boom. At DLR, modifications to departure flight procedures are under investigation, i.e., an automated thrust reduction referred to as Programmed Lapse Rate and an increased take-off speed. These measures as proposed by NASA promise to reduce the certification noise levels for the two departure locations. For the two considered concept aircraft, promising procedures with reduced noise at the certification locations have been identified previously. This paper now addresses the impact of these promising departure procedures on noise contour areas and local gaseous emissions. Impact on EPNL and SEL contours and differences in CO2 and NOX are assessed along the simulated flights. It is demonstrated, that the proposed procedures do not only reduce noise at the certification locations but also noise contour areas and gaseous pollutants.

Numerical-physical modelling of the long jump flight of female athletes: Impact of jump style, hairstyle and clothing

The long jump is a track and field event in which the athlete sprints down a runway and tries to leap as far as possible from a take-off line. To the best of our knowledge, there are no published studies on the aerodynamic impact of jump style, hairstyle and clothing on the long jump distance. This paper presents a numerical-physical model of the long jump flight. It allows to predict flight distance and the impact of jump style, hairstyle and clothing. It consists of five submodels: an existing model of the sprint before take-off, a computational fluid dynamics (CFD) model of different body postures in flight, a set of physical wind tunnel models for CFD validation, a full-scale wind tunnel manikin with different hairstyles and clothing and a numerical model of the flight trajectory. Jump style only impacts flight distance by 1 cm or less. Hairstyle and clothing however can cause drag to vary by more than 25% and flight distance by more than 10 cm, mostly by impacting the take-off speed. In the long term, long jump events might see the introduction of hair caps and low-drag clothing to reduce aerodynamic resistance and level the playing field.

Development of a Finishing Process for Imbuing Flame Retardancy into Materials Using Biohybrid Anchor Peptides

Flame retardants are commonly used to reduce fire risk in various products and environments, including textiles. While many of these additives contain harmful substances, efforts are underway to reduce their usage. Current research aims to minimize flame-retardant quantities and enhance durability against external factors. This involves utilizing anchor peptides or material-binding peptides (MBPs), which are versatile molecules that bind strongly to surfaces like textiles. MBPs can be equipped with functional molecules, e.g., flame-retardant additives, by chemical or enzymatic bioconjugation. In this research, biohybrid flame retardants and an adapted finishing process are developed. Specifically, biobased adhesion promoters, the so-called MBPs, are used to finish textiles with flame-retardant additives. To date, there is no finishing process for treating textiles with MBPs and so a laboratory-scale finishing process based on foulard was developed. Necessary parameters, such as the take-off speed or the contact pressure of the squeezing rollers, are determined experimentally. In order to develop an adapted finishing process, various trials are designed and carried out. Part of the trials is the testing and comparison of different textiles (e.g., glass woven fabrics and aramid woven fabrics) under different conditions (e.g., different ratios of MBPs and flame retardants). The finished textiles are then analysed and validated regarding their flammability and the amount of adhered flame retardants.

Pes planus level affects counter movement jump performance: A study on amateur male and female volleyball players.

The aim of this study was to investigate the effect of pes planus level on counter movement jump (CMJ) performance parameters in amateur female and male volleyball players. In this context, amateur volleyball players aged between 18 and 23 years actively playing in the university school volleyball team were included in the study. Pes planus levels of the participants were analyzed using the navicular drop test (NDT). My Jump Lab application was used for CMJ measurement. Within the scope of CMJ, the participants' jump height, force, relative force, power, relative power, average speed, take-off speed, impulse, and flying time were analyzed. According to the linear regression results between NDT and CMJ parameters, force in males (t = 12.93, P = .049) and average speed in females (t = -3.52, P = .017) were significantly associated with NDT. NDT was similar in men and women (P > .05). However, all CMJ parameters were highly different between genders (P < .001). In the correlation analysis between sport age and physical characteristics and CMJ parameters; height (r = .386, P = .046), weight (r = .569, P = .002), leg length (r = .389, P = .045), foot length (r =. 558, P = .005), foot width (r = .478, P = .018), force (r = .407, P = .039), impulse (r = .460, P = .018) parameters, and sport age. The results suggest that the average speed in females and force in males both significantly influenced NDT, highlighting the significance of both factors in predicting NDT scores. Moreover, all CMJ measures showed significant variations between genders, although the NDT scores did not. Furthermore, the correlation analysis demonstrated a strong correlation between a number of physical attributes and CMJ parameters, highlighting the multifaceted nature of athletic performance and indicating the possible impact of these attributes on CMJ results.

Clustering technical approaches of elite and world-class pole vaulters based on 10 years of measurement during competitions

ABSTRACT Recently, a variety of technical approaches in world-class pole-vaulters’ behaviour have been observed. The aim of this study was to investigate the presence of subgroups using different technical approaches and to compare biomechanical performance differences. Biomechanical analysis of performances over 5.00 metres from 99 athletes were clustered with K-means methodology based on the relative position of the top hand at take-off and the direction of the top of the pole from take-off to the maximal pole bending. Analysis revealed four subgroups that were distinguished by higher and lower direction angle and relative position values. Despite differences in technique, the analysis did not reveal significant differences between these four groups in performance, take-off speed, or athlete anthropometrics. Nevertheless, these clusters showcased variations in pole–athlete interactions and pole bending, suggesting different strategies and physical requirements associated with each approach. Cluster 2 characterised the classical technique with a high direction angle and a take-off position close to the vertical plane. Cluster 4 displayed a technique with a low take-off angle, suggesting the influence of athletes like Lavillenie, in deviating from the conventional model. Understanding and categorising athletes based on their preferred technique can aid coaches in providing tailored instructions, leading to performance improvements.

Performance and jump-to-jump development in the first female ski flying competition in history.

In 2023, for the first time in history, the international ski and snowboard federation (FIS) arranged an official ski flying competition where the 15 highest ranked women were allowed to participate. This study investigated jump-to-jump performance development in female ski flying, with men's results used as reference data. Official FIS data from all six jumps of women were evaluated together with the eight jumps by men. Performance was evaluated by a score, where the distance points compensated by wind were divided by take-off speed, enabling performance to be evaluated across jumps and sexes. Women improved performance by 96% from the first to the sixth jump, with two major leaps; from the first to the second jump and from the first to the second day. In contrast, men mainly improved from training to competition. The best women had performance scores equivalent to the 10-20 best ranked men and the sex-difference between the top 3 athletes was 26.2%. This difference was thereafter compared to similar results in the normal and large hill World championship in Planica 2023, in which sex-differences between the top 3 were 8.6% and 14.6% in normal and large hill. This historical competition showed the importance of gaining practical experience with ski flying on performance, exemplified by the large improvement of female athletes. This, together with the enlarge sex-differences in large compared to normal hills, indicates that female ski jumpers have a particularly large improvement-potential in ski flying and must gain specific experience on this through traning and competitions.

Reduced-Order Model for Supersonic Transport Takeoff Noise Scaling with Cruise Mach Number

The recent interest in the development of supersonic transport raises concerns about an increase in community noise around airports. As noise certification standards for supersonic transport other than Concorde have not yet been developed by the International Civil Aviation Organization, there is a need for a physics-based scaling rule for supersonic transport takeoff noise performance. Assuming supersonic transport takeoff noise levels are dominated by the engine mixed jet velocity and the aircraft-to-microphone propagation distance, this paper presents a reduced-order model for supersonic transport takeoff noise levels as a function of four scaling groups: cruise Mach number, takeoff aerodynamic efficiency, takeoff speed, and number of installed engines. This paper finds that, as cruise Mach number increases, supersonic transport takeoff noise levels increase while their thrust cutback noise reduction potential decreases. Assuming constant aerodynamic efficiency, takeoff speed, and number of installed engines, the takeoff noise levels and noise reduction potential of a Mach 2.2 aircraft are found to be ∼15.3 dB higher and ∼19.2 dB less compared to a Mach 1.4 aircraft, respectively. This scaling rule can potentially yield a simple guideline for estimating an approximate noise limit for supersonic transport, depending on their cruise Mach number.

Study on the startup-shutdown performance of gas foil bearings-rotor system in proton exchange membrane fuel cells

The startup-shutdown behavior of the gas foil bearings-rotor system is vital for proton exchange membrane fuel cells due to the inherently frequent start-stop of hydrogen fuel cell vehicles, which significantly affects the sustainable power generation and efficiency of the fuel cells. In this paper, the effects of three systematic factors including bump foil structure, nominal clearance, and coating on the dynamic response of the bearings-rotor system are first investigated based on startup-shutdown experiments. The mathematical model considering both gas film and thermo-hydrodynamic characteristics is presented to investigate the startup-shutdown behavior further. The influencing mechanisms of the factors on performance are analyzed. The energetic results demonstrate that the bearing structure parameters have a significant influence on the startup-shutdown performance and energy consumption. Considering optimal startup-shutdown performance, a better bearings-rotor system is proposed. Compared to the average values in all cases, the take-off speed, temperature rise, and average energy consumption of the system are decreased by 51.3%, 16.2%, and 60.7%, respectively. This indicates that the startup-shutdown improvement of the bearing-rotor system has great significance for enhancing the energy efficiency of the fuel cell.

BIOKINEMATIC CHARACTERISTICS OF THE TRIPLE JUMP TECHNIQUE IN QUALIFIED ATHLETES

The purpose of the study is to investigate the biokinematic characteristics of the triple jump technique in qualified athletes. Material and methods. The technique of the final attempts of qualified triple jumpers during the 2023 World Athletics Championships was analyzed. The following methods were used in the work: analysis and synthesis of scientific and methodological literature, analysis of video materials, methods of mathematical statistics. The video of the final attempts was used, provided for public use by the International Athletics Federation (World Athletics). The attempts were recorded by four video cameras installed on the side of the treadmill at a distance of 2,5 m, the height of the video camera mounted on a tripod was 1,5 m. Two of the four video cameras recorded video at a frequency of 25 frames per second, the other two video cameras recorded video at a frequency of 1300 frames per second. Video analysis of the final attempts and processing of biokinematic parameters of the technique were determined using the Dartfish and Kinovea programs. All statistical data were processed in the statistical analysis program IBM SPSS Statistics version 28.0.1.0. Results. The metric, time, angular, and speed characteristics of the take-off technique are determined; push-off; jump; step; jump for highly skilled triple jumpers. Based on the analysis of the triple jump technique indicators, the optimal biokinematic parameters of the technique that athletes need to have in order to achieve high competitive results were obtained. Conclusions. To achieve high competitive results in the triple jump, the following technical parameters must be used. The take-off speed should reach 10.40 m s-1 or more, the length of the last take-off step should be 2,20-2,40 m; the pace of the last step is 4-5 steps/s. The push-off; from the bar should last 0.100-0.133 s; the push-off; angle reaches 65-70 ̊; the speed of departure of the general center of mass of the body is 9.60 m s-1 and more. The jump should last no more than 0,660 s. During the jump, the high height of the overall center of body mass should be 1.30-1.45 m; upon landing, the speed of the general center of mass of the body is 9,20 m s-1 or more. The second push-off should last 0,160-0,180 s, the push-off angle is 60-65°. The take-off speed of the general center of body mass in a step should be 8,80 m s-1 or more. The optimal step duration is 0.450-0.520 s, step length is 5.20-5.50 m, the maximum height of the overall center of body mass is 1.24-1.30 m; upon landing, the speed of the general center of mass of the body is 8.50 m s-1 or more. The third push-off should last 130-166 s. The push-off angle is 63-70°. The take-off speed of the general center of mass of the body in a jump is from 8 m s-1 and more. The optimal duration of the jump is 0.750-0.780 s; maximum height of the overall center of body mass 1,10-1,22 m; upon landing, the speed of the general center of mass of the body is 7 m s-1 or more. When taking off and landing, the angle in the supporting leg throughout all three jumps should be 163-170 ̊.

Permanent Magnet Electrodynamic Suspension System Integrated With a Car: Design, Implementation, and Test

In this paper, a permanent magnet electrodynamic suspension (PMEDS) system integrated with a car has been developed by our group, along with a 100-m-long test track made of copper. The entire vehicle weighs 2.8 ton and is freely suspended in air over 35 mm without a lateral constraint on guideway. The car uses its own wheels and engine to provide a take-off speed for the PMEDS system, eliminating the excessive costs of the motor, with a maximum speed of 70 km/h. Firstly, a new topology structure equipped with the damping magnets is presented. Afterward, the onboard magnets and guideway are designed via the simulation method verified by the high-speed rotary experiment platform with a diameter of 2500 mm, clarifying the mapping between the electromagnetic forces and structure parameters. The suspension frame and gap adjustment mechanism are developed, and a complete test system is built to monitor the levitation gap, accelerations and deflection angle. Lastly, the integrated PMEDS system is implemented and tested. In-house experiment and line test results not only reveal that the PMEDS has a significant weak guidance capability, but also confirm the effectiveness of the proposed damping magnets. Through the damping magnets, the maximum lateral deflection is limited to less than 11°. The tested levitation-drag-ratio is in general agreement with the simulation results. The great suspension capacity of the PMEDS system can be visually demonstrated. This paper conducts the free suspension test of the PMEDS system for the first time in China, which can open up prospects for further engineering applications.

Startup optimization of gas foil bearings-rotor system in proton exchange membrane fuel cells

The startup performance is crucial to the high-efficient operation of the sustainable power generation system. Current literature usually focuses on catalysts and startup strategy to improve startup performance of the proton exchange membrane fuel cell, which ignores the gas foil bearings-rotor system that directly affects startup response. Therefore, in this paper, the effects of bump foil structure, coating, and nominal clearance on the startup response of the bearings-rotor system are first investigated experimentally. Multi-objectives optimization mathematical model considering simultaneously lower power consumption, takeoff speed, and vibration is presented based on grey relational analysis. The optimal bearings-rotor system with radial trisection bump foil, coating MoS2, and nominal clearance of 50 μm is identified. Compared to average values, the power consumption of the optimal system is diminished by 27.2% while the takeoff speed and nonlinear vibration are reduced by 16.2% and 47.3%, respectively. These findings can be used to improve energy efficiency and startup performance for fuel cells. The systematic methodology proposed in this study can be extended to other investigations about the startup.

Moderate mass loss enhances flight performance via alteration of flight kinematics and postures in a passerine bird.

Many birds experience fluctuations in body mass throughout the annual life cycle. The flight efficiency hypothesis posits that adaptive mass loss can enhance avian flight ability. However, whether birds can increase additional wing loading following mass loss and how birds adjust flight kinematics and postures remain largely unexplored. We investigated physiological changes in body condition in breeding female Eurasian tree sparrows (Passer montanus) through a dietary restriction experiment and determined the changes in flight kinematics and postures. Body mass decreased significantly, but the external maximum load and mass-corrected total load increased significantly after 3days of dietary restriction. After 6days of dietary restriction (DR6), hematocrit, pectoralis and hepatic fat content, take-off speed, theoretical maximum range speed and maximum power speed declined significantly. Notably, the load capacity and power margin remained unchanged relative to the control group. The wing stroke amplitude and relative downstroke duration were not affected by the interaction between diet restriction and extra load. Wing stroke amplitude significantly increased after DR6 treatment, while the relative downstroke duration significantly decreased. The stroke plane angle significantly increased after DR6 treatment only in the load-free condition. In addition, the sparrows adjusted their body angle and stroke plane angle in response to the extra load, but stroke amplitude and wingbeat frequency remained unchanged. Therefore, birds can maintain and even enhance their flight performance by adjusting flight kinematics and postures after a short-term mass loss.

Modeling the soil-machine response of secondary tillage: A deep learning approach

Seedbed preparation constitutes a highly important step in the crop establishment process since it directly influences both quality and yield expectation in crop fields. The quality of seedbed preparation is usually assessed by the operator of the tractor or a supervising farmer and thus dependent on qualified field personnel which are scarce today. Subsequent to the visual assessment of the current seedbed structure, a qualified operator can manually adapt the secondary tillage machine in order to optimize resource efficiency (e.g., fuel consumption) while maintaining optimal seedbed preparation according to local soil conditions. In this work, we propose to use an automated approach for real-time in-situ measurement of seedbed quality. Stereo cameras mounted in the front and the back of the tractor provide images and depth-information. Additionally, telemetry data such as working speed, power take-off (PTO) speed, fuel consumption and engine torque utilization of the tractor are logged. Based on this data, we develop a Deep-Learning-based model to predict seedbed quality (measured in form of the Roughness Coefficient), engine torque utilization and engine fuel rate. Thus, we model the interaction of the soil and the machine (soil-machine response) when preparing the seedbed with different machine configurations and environment states. For training and evaluating our model, we collected data from 16 field runs with varying soil types ranging from loamy sand to silty clay in Baden-Württemberg, Germany. Based on this data, we demonstrate that our novel model is able to predict the soil-machine response on previously unseen fields with high accuracy – in our setting with a relative root mean squared error (rRMSE) between 12.2 and 14.4 %. Our proposed model has two main advantages: (1) it allows farmers to plan the optimal machine configuration in advance by simulating different machine configurations and thus reduce the complexity for the operator and (2) it can serve as a basis for the training of intelligent control agents.

Automatic Continuous Thrust Control for Supersonic Transport Takeoff Noise Reduction

Advanced takeoff trajectories are proposed for supersonic transport noise reduction by capitalizing on excess engine thrust and improved aerodynamic efficiency at higher takeoff speeds. These novel trajectories use i) automatic continuous control of thrust, ii) increased takeoff speed, and iii) reduced cut-back altitude, compared to conventional pilot-initiated discrete thrust cut-back procedures currently used for subsonic transport. In this paper, we develop an optimal control framework to assess the attributes of effective takeoff trajectories for supersonic transport that yield minimum noise levels. We quantify the noise reduction potential of advanced takeoff trajectories for the eight-passenger, 55-metric-ton, Mach-1.4 NASA Supersonic Technology Concept Airplane. For the aircraft examined, these advanced takeoff trajectories enable a cumulative certification noise reduction of 10.6 EPNdB, which is insufficient to meet current subsonic transport noise limits.

Design Optimization of a Cavitating 2D Profile in Proximity of the Free Surface

The appearance of AC72 foiling catamarans in the scenario of sailing yacht competitions in 2013 raised attention to this ship design concept, although not brand new in the yacht design history. The drastic drag reduction connected with the elevation of the ship hull outside the water is obtained by the use of a foil, or a system of foils, acting as the wings of a plane, providing a lift force balancing the weight of the ship. Since this lift is proportional (non-linearly) to the ship hull speed, the take-off speed of the hull cannot be low. As a result, since we are travelling in water at high speeds, the occurrence of the phenomenon of cavitation cannot be completely avoided, and the performance of the ship undergoes deterioration. Shaping of the foil profile must consider this peculiar situation, so the design tools commonly adopted for the aero-hydrodynamic hull design optimization are no longer adequate. In this paper, we are considering the optimization of the 2D profile of a foil in three different physical conditions: single fluid, two fluids and two fluids with cavitation. The first is typical of aeronautic wing design, the second of the appendages of a displacement ship, and the third of a foiling ship. Results give evidence of the different requirements for the three different conditions.

Advanced Hypersonic Transportation Perspectives

High-speed transportation design concepts are examined for advanced civil aviation and space transportation applications. The design concept of transatmospheric vehicles, flying directly from earth to orbit, will enable launching and recovery of small telecommunication and remote sensing satellites, harvesting solar energy from space, and space tourism.Commonality of flight regimes in atmospheric flight, the similarity of fuels, propulsion technology, aerodynamic configuration design, and airframe structure materials used in these high-speed flight regimes for air and space transportation are discussed in detail.A single, Integrated Hypersonic Transport Programme, is recommended, based on small size, low risk, and low cost vehicles. A dual fuel, kerosene-hydrogen system meets the needs of such an Integrated Hypersonic Transportation Programme, with kerosene for take-off, powered landing and low speed ascent/descent flight. Hydrogen is used for high-speed cruise flight. India would greatly benefit by an Integrated Hypersonics Transportation Programme, with leading institutions like ISRO, NAL and ADA working together to jointly study, design and build a strong technology base for small, unmanned hypersonic flight demonstrators. This project could then lead on, safely and economically, to hypersonic Executive Jet aircraft, and small fully Reusable Trans-Atmospheric Vehicles for direct ascent of the hypersonic aerospacecraft to earth orbit.

Two different jumping mechanisms of water striders are determined by body size

Current theory for surface tension-dominant jumps on water, created for small- and medium-sized water strider species and used in bioinspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the takeoff delay without breaking the water surface. Here, we use empirical observations and theoretical modeling to show that large species (heavier than ~80 mg) could theoretically perform the surface-dominated jumps according to the existing model, but they do not conform to its predictions, and switch to using surface-breaking jumps in order to achieve jumping performance sufficient for evading attacks from underwater predators. This illustrates how natural selection for avoiding predators may break the theoretical scaling relationship between prey size and its jumping performance within one physical mechanism, leading to an evolutionary shift to another mechanism that provides protection from attacking predators. Hence, the results are consistent with a general idea: Natural selection for the maintenance of adaptive function of a specific behavior performed within environmental physical constraints leads to size-specific shift to behaviors that use a new physical mechanism that secure the adaptive function.

Caenorhabditis elegans transfers across a gap under an electric field as dispersal behavior

Interactions between different animal species are a critical determinant of each species' evolution and range expansion. Chemical, visual, and mechanical interactions have been abundantly reported, but the importance of electric interactions is not well understood. Here, we report the discovery that the nematode Caenorhabditis elegans transfers across electric fields to achieve phoretic attachment to insects. First, we found that dauer larvae of C.elegans nictating on a substrate in a Petri dish moved directly to the lid through the air due to the electrostatic force from the lid. To more systematically investigate the transfer behavior, we constructed an assay system with well-controlled electric fields: the worms flew up regardless of whether a positive or negative electric field was applied, suggesting that an induced charge within the worm is related to this transfer. The mean take-off speed is 0.86m/s, and the worm flies up under an electric field exceeding 200kV/m. This worm transfer occurs even when the worms form a nictation column composed of up to 100 worms; we term this behavior "multiworm transfer." These observations led us to conclude that C.elegans can transfer and attach to the bumblebee Bombus terrestris, which was charged by rubbing with flower pollen in the lab. The charge on the bumblebee was measured with a coulomb-meter to be 806 pC, which was within the range of bumblebee charges and of the same order of flying insect charges observed in nature, suggesting that electrical interactions occur among different species.

Experimental investigation on the start-stop performance of gas foil bearings-rotor system in the centrifugal air compressor for hydrogen fuel cell vehicles

The start-stop performance of gas foil bearings (GFBs)-rotor system directly affects the operation range and energy consumption of the air compressor for hydrogen fuel cell vehicles which has the inherent characteristic of frequent start and stop. In this paper, the effects of three factors including cooling gas flow, cooling gas pressure, and cooling gas type on the start-stop performance of the GFBs-rotor system are experimentally investigated for the first time. Based on the start-stop response analysis, the take-off speed of 6576 rpm and power consumption of 0.61 kW for the optimum GFBs-rotor system are obtained. The performance of the proposed system for the centrifugal air compressor is compared with the commercial products. The comparison shows that the lowest speed can be decreased by 34.2% while the operating range is expanded by 8.6%, which can in turn improve the performance of the centrifugal air compressors in hydrogen fuel cell vehicles.