A project of spacecraft “moonplane” for regular delivery of astronauts onto the Moon is considered. At the first stage of flight by using a carrier rocket, equipped with a chemical rocket engine, the astronauts are ...A project of spacecraft “moonplane” for regular delivery of astronauts onto the Moon is considered. At the first stage of flight by using a carrier rocket, equipped with a chemical rocket engine, the astronauts are delivered on the international space station ISS. For flights from Earth orbit into Moon orbit, the design of a moonplane “MOND”, consisting of an interorbital module and a lunar module, has been developed. The interorbital module is an electric rocket, equipped with four superconductive magnetoplasma engine MARS. To power supply of the electromotors, a solar battery of gallium arsenide is used. The design of the lunar module with cabin astronauts, which is equipped with a chemical rocket engine for landing and take-off from the surface of the Moon, is developed. A method and a device for refuelling of the electrical rocket engines with nitrogen and for refuelling of the chemical rocket engines with oxygen and hydrogen, which are stored in cryogenic tanks of the moonplane in the liquid state is developed. The developed spacecraft is capable to regularly transport four astronauts off a moorage of ISS onto the surface of the Moon and back during 6 days. The total cost delivery of one astronaut is 4 million US dollars.展开更多
Spinsonde is a chute-free vertical retardation technique specifically developed for fixed-wing unmanned aircraft to acquire accurate measurement of vertical wind speed profile for meteorological applications. Key adva...Spinsonde is a chute-free vertical retardation technique specifically developed for fixed-wing unmanned aircraft to acquire accurate measurement of vertical wind speed profile for meteorological applications. Key advantages of spinsonde over the expendable chute-operated dropsondes are the ability to acquire multi-cycle measurement, efficient use of payload capacity and cost-effectiveness. This work proposes the concept of “rotosonde”, which is the spinsonde equivalent for unmanned helicopters. Computer simulations are carried out to evaluate the performance of the rotosonde and results indicate that the measured speed generally correlates with the wind speed to within ±3 km·h﹣1 even for intensities in excess of 180 km·h﹣1. The profound implication of this work is that unmanned helicopters can now be considered for important field of studies such as cyclogenesis given their reliability to operate in gusty wind conditions in remote oceans, particularly during docking and launching from carriers.展开更多
The transmission system is a critical power component of helicopters, playing an indispensable role in power transmission. Among its key elements, the planetary gear system is an essential part of the helicopter trans...The transmission system is a critical power component of helicopters, playing an indispensable role in power transmission. Among its key elements, the planetary gear system is an essential part of the helicopter transmission architecture. Establishing a dynamic model of the helicopter transmission system and analyzing the dynamic response of the planetary gear system under varying flight conditions are crucial for enhancing the system’s performance and safety. In this study, the transmission system is modeled comprehensively using the lumped mass method and the finite element method, and the dynamic characteristics of the planetary gear system, as reflected on the main gearbox casing under different flight scenarios, are examined. The findings reveal that the resonance frequencies of the planetary gear system remain consistent across various flight conditions, indicating that these frequencies are governed by the inherent structural and dynamic properties of the system. However, the vibration amplitudes at resonance points differ depending on the flight condition. Specifically, the resonance amplitudes at 0.057 kHz and 0.093 kHz during Hovering are significantly lower than those in other conditions, demonstrating that operational scenarios directly influence vibration response.展开更多
This paper is focused on a higher-level report of a new generation of Unmanned Aerial Vehicle (UAV) technologies. Starting from the structural scalability of civil tiltrotors, design strategy and requirements for UAVs...This paper is focused on a higher-level report of a new generation of Unmanned Aerial Vehicle (UAV) technologies. Starting from the structural scalability of civil tiltrotors, design strategy and requirements for UAVs, and advanced composite materials, the increased speed and productivity requirements for tiltrotors have spawned several investigations associated with proprotor aero elastic stability augmentation and aerodynamic performance enhancements. The research emphasized the Large Civil Tilt Rotor as the configuration with the best potential to meet the technology goals, and the design, including the challenges of the Large Civil Tilt Rotor (LCTR). The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The research includes some manufacturers of helicopters, drones and tiltrotors carrying out design studies and production of prototypes, as well as research projects aimed at designing, manufacturing, qualifying, and flight-testing the new wing of the Next-Generation Civil Tiltrotor Technology Demonstrator. Promises of Vertical Take-off and Landing (VTOL) aircraft, UAVs, Digitalization of Urban Air Mobility (UAM), and the “U-space” concept are discussed in the paper. The eight SUMP principles and possibilities of future advancements are emphasized.展开更多
Stabilizers and their control surfaces are vital components in maneuvering an airplane during flight. However, a shortcoming of stabilizers is that they require airstream or propeller wash for them to work properly. I...Stabilizers and their control surfaces are vital components in maneuvering an airplane during flight. However, a shortcoming of stabilizers is that they require airstream or propeller wash for them to work properly. In this work, we propose the concept of roto-stabilizer as viable substitution for conventional horizontal stabilizer. A key benefit of the proposed technique is its ability to exert powerful moment in the absence of forward airspeed or propeller wash. Proof of principle is demonstrated via computer simulations. Results reveal that new aerobatic maneuvers are made possible. Furthermore, when implemented in canard configuration, it is possible to achieve ultra-STOL and VTOL.展开更多
A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produc...A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.展开更多
In this paper, a real-time online data-driven adaptive method is developed to deal with uncertainties such as high nonlinearity, strong coupling, parameter perturbation and external disturbances in attitude control of...In this paper, a real-time online data-driven adaptive method is developed to deal with uncertainties such as high nonlinearity, strong coupling, parameter perturbation and external disturbances in attitude control of fixed-wing unmanned aerial vehicles (UAVs). Firstly, a model-free adaptive control (MFAC) method requiring only input/output (I/O) data and no model information is adopted for control scheme design of angular velocity subsystem which contains all model information and up-mentioned uncertainties. Secondly, the internal model control (IMC) method featured with less tuning parameters and convenient tuning process is adopted for control scheme design of the certain Euler angle subsystem. Simulation results show that, the method developed is obviously superior to the cascade PID (CPID) method and the nonlinear dynamic inversion (NDI) method.展开更多
In this paper, the method of reliability test profile construction for air-launched spacecraft is analyzed, in order to effectively carry out air-launched spacecraft flight reliability test. The flight mission profile...In this paper, the method of reliability test profile construction for air-launched spacecraft is analyzed, in order to effectively carry out air-launched spacecraft flight reliability test. The flight mission profile and environment profile of air-launched spacecraft are formed. Meanwhile, the method of temperature stress, vibration stress, electronic stress and humidity stress of external spacecraft under different mission profiles are calculated. Finally, this paper takes an airborne electronic product as an example, and a reliability test profile is designed by correction of the experimental section with measured data.展开更多
For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of...For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.展开更多
A project of the expedition to the north pole of Mars, which is carried out in two stages, has been developed. In the first stage, a space refueller and a mobile solar battery are delivered to the icy surface of the n...A project of the expedition to the north pole of Mars, which is carried out in two stages, has been developed. In the first stage, a space refueller and a mobile solar battery are delivered to the icy surface of the north pole of Mars. The delivery is carried out with the help of electric rocket ER-7, driven by the electric rocket engine “MARS”, and the source of electricity is a solar battery from gallium arsenide. In the second stage, the space train is formed from two interconnected ER-7 rockets and an orbital takeoff-landing capsule TLC-2, in which three astronauts land on the surface and carry out a complex of physical, biological and geological researches on Mars surface. The space refueller has been developed, which melts the water ice on the surface of Mars and with the help of an electrolyser and a liquefier produces fuel and oxidizer for the operation of the chemical rocket engine of the takeoff-landing capsule. To move astronauts from the north pole to the equator, a spacecraft—?marsoplane, which consists of the electric rocket ER-7 and the takeoff-landing capsule TLC-1 is developed. The duration of the expedition is 110 days at a cost of 2 billion dollars.展开更多
Shock wave is a detriment in the development of supersonic aircrafts;it increases flow drag as well as surface heating from additional friction;it also initiates sonic boom on the ground which precludes supersonic jet...Shock wave is a detriment in the development of supersonic aircrafts;it increases flow drag as well as surface heating from additional friction;it also initiates sonic boom on the ground which precludes supersonic jetliner to fly overland. A shock wave mitigation technique is demonstrated by experiments conducted in a Mach 2.5 wind tunnel. Non-thermal air plasma generated symmetrically in front of a wind tunnel model and upstream of the shock, by on-board 60 Hz periodic electric arc discharge, works as a plasma deflector, it deflects incoming flow to transform the shock from a well-defined attached shock into a highly curved shock structure. In a sequence with increasing discharge intensity, the transformed curve shock increases shock angle and moves upstream to become detached with increasing standoff distance from the model. It becomes diffusive and disappears near the peak of the discharge. The flow deflection increases the equivalent cone angle of the model, which in essence, reduces the equivalent Mach number of the incoming flow, manifesting the reduction of the shock wave drag on the cone. When this equivalent cone angle exceeds a critical angle, the shock becomes detached and fades away. This shock wave mitigation technique helps drag reduction as well as eliminates sonic boom.展开更多
This paper is an eye opening to the new horizon of the design of operational Compressors in our jet engines. That are compressors usually perform an operation called isentropic process and which levitate the pressure ...This paper is an eye opening to the new horizon of the design of operational Compressors in our jet engines. That are compressors usually perform an operation called isentropic process and which levitate the pressure and temperature to the optimum level which require for effective ignition. Basically, our compressors have several sets of blades to perform this function, more precisely saying Rotor and stator blades. Where rotor blade provides air molecule to push at very high velocity to the Stationary blade and when the air Enders to the Stator, the stator races its pressure to move on to the next stage. And we call this set of Stator and rotor as a stage ref [1]. However, in this work, I consider the geometry of the incoming air molecule and how it transforms its physical quantities such as Pressure and temperature ref [2]. For that I tie the concept of Thermodynamic and mechanics on the platform of Tensor analysis ref [3]. That is, I consider the quantities like Pressure, Temperature and rate of flow are their corresponding vector spaces and energy related quintets like heat, work as the scaling elements on the above vector space. And quantities such as entropy enthalpy and specific heat capacity are corresponding physics of it. Considering the advantages, one of the important advantages of this approach is the applicability of results of this work to the formulation of blade less compression Example: Ram and Scram jet engine. Again, the relevant upgrading which is essential for future hypersonic air crafts can achieve from this study and this will be a mile stone for bright air and space travel. To conclude, this approach will be a great transformation on the conventional idea for realization of compression for operational Scram and Ram jet engines ref [4] [5].展开更多
A project of elimination of potentially dangerous asteroid Apophis which April 13, 2029 year approaches to Earth at a distance of 36,000 km is considered. The elimination is carried out by means of asteroid disintegra...A project of elimination of potentially dangerous asteroid Apophis which April 13, 2029 year approaches to Earth at a distance of 36,000 km is considered. The elimination is carried out by means of asteroid disintegration into small fragments as a result of nuclear explosion, which is produced 133 days before the moment of maximal convergence of the asteroid Apophis with Earth. In the project, a method of phased timely delivery of nuclear charge on the surface of the asteroid is proposed. In the first stage, the nuclear charge using carrier rocket “Delta” is delivered into Earth orbit. In the second stage, the charge using electric rocket is transferred from Earth orbit into the orbit of asteroid Apophis and is descended onto its surface. For implementation of the project, the design of electric rocket ER-7, which uses electric rocket engines type MARS and solar panels based on gallium arsenide is developed. Design of landing capsule, which has a chemical rocket engine and the container in which located the nuclear charge of 6 megaton is developed.展开更多
A project of the space cruise over the route “Earth-Mars-Earth” is considered. Design of electric rocket train, whose energy source is a semiconductor solar panel and a superconducting electrorocket engine (MARS) of...A project of the space cruise over the route “Earth-Mars-Earth” is considered. Design of electric rocket train, whose energy source is a semiconductor solar panel and a superconducting electrorocket engine (MARS) of new design is used as a mover, is developed. The concept of the cruise, which allows to reduce time of interorbital flight in twice, owing to refueling with working body on orbit of Mars, is developed. Development of the space locomotive with 4 MARS engines rated at 600 kW in which nitrogen is used as working substance, was being carried out. A new design of takeoff-landing capsule, in which cabin can be placed 10 space tourists, is developed. The studies carried out on the mathematical model, which takes into account the changing of power provided by onboard power plant, depending on the distance from the Sun, has shown that cruise may be done within 77 days including the stay of tourists on the Martian surface during 7 days. The project provides for implementation three cruises on the surface of Mars and 15 cruises on the lunar surface during two years with total cost of 2.2 billion dollars.展开更多
Our study identifies a subtle deviation from Newton’s third law in the derivation of the ideal rocket equation, also known as the Tsiolkovsky Rocket Equation (TRE). TRE can be derived using a 1D elastic collision mod...Our study identifies a subtle deviation from Newton’s third law in the derivation of the ideal rocket equation, also known as the Tsiolkovsky Rocket Equation (TRE). TRE can be derived using a 1D elastic collision model of the momentum exchange between the differential propellant mass element (dm) and the rocket final mass (m1), in which dm initially travels forward to collide with m1 and rebounds to exit through the exhaust nozzle with a velocity that is known as the effective exhaust velocity ve. We observe that such a model does not explain how dm was able to acquire its initial forward velocity without the support of a reactive mass traveling in the opposite direction. We show instead that the initial kinetic energy of dm is generated from dm itself by a process of self-combustion and expansion. In our ideal rocket with a single particle dm confined inside a hollow tube with one closed end, we show that the process of self-combustion and expansion of dm will result in a pair of differential particles each with a mass dm/2, and each traveling away from one another along the tube axis, from the center of combustion. These two identical particles represent the active and reactive sub-components of dm, co-generated in compliance with Newton’s third law of equal action and reaction. Building on this model, we derive a linear momentum ODE of the system, the solution of which yields what we call the Revised Tsiolkovsky Rocket Equation (RTRE). We show that RTRE has a mathematical form that is similar to TRE, with the exception of the effective exhaust velocity (ve) term. The ve term in TRE is replaced in RTRE by the average of two distinct exhaust velocities that we refer to as fast-jet, vx<sub>1</sub>, and slow-jet, vx<sub>2</sub>. These two velocities correspond, respectively, to the velocities of the detonation pressure wave that is vectored directly towards the exhaust nozzle, and the retonation wave that is initially vectored in the direction of rocket propagation, but subsequently becomes reflected from the thrust surface of the combustion chamber to exit through the exhaust nozzle with a time lag behind the detonation wave. The detonation-retonation phenomenon is supported by experimental evidence in the published literature. Finally, we use a convolution model to simulate the composite exhaust pressure wave, highlighting the frequency spectrum of the pressure perturbations that are generated by the mutual interference between the fast-jet and slow-jet components. Our analysis offers insights into the origin of combustion oscillations in rocket engines, with possible extensions beyond rocket engineering into other fields of combustion engineering.展开更多
This article discusses the kinematics of a parachutist making a very-high-altitude jump. The effect of altitude on the density of air, on the gravitational field strength of the Earth, and on the atmosphere’s tempera...This article discusses the kinematics of a parachutist making a very-high-altitude jump. The effect of altitude on the density of air, on the gravitational field strength of the Earth, and on the atmosphere’s temperature has been taken into account in our analysis. The well-known equations of classical mechanics governing the selected topic have been solved numerically by using the mathematical software Mathcad. Especially, the possibility of a person exceeding the speed of sound during their fall has been considered in our analysis. The effect of the sound barrier is taken into account so that the shape factor of the falling body is given as a speed-dependent function, which reaches its maximum value at Mach 1.0. The obtained results have been found to be highly consistent with the available experimental data on some high-altitude jumps. The data published on the famous jump of Captain Joseph Kittinger has been analyzed very carefully, and although our calculations reproduced the reported values for most parts, some interesting inconsistencies were also discovered. Kittinger jumped from a gondola attached to a helium-filled balloon from a record-high altitude of 102,800 ft, or 31,330 m, in August 1960. We also made numerical analysis on the high-altitude jump of Felix Baumgartner. He bailed out from his gondola at the record-high altitude of 39.0 km in October 2012.展开更多
The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and p...The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and pop versus-times curves for each weld. Titanium alloys and their mechanical properties are known to be highly sensitive to strain rate as the material is deformed, though nothing has ever been considered in terms of the higher-order time-derivatives of position. These curves have been studied and analysed further, for a more complete understanding of the derivative trends. Rotational acceleration and jerk traces both display behavior patterns across the two welds as the part rotates under action from the flywheel. The rotational snap also displays a pattern in this derivative during the final approximately 0.5 s of welding, as the energy dissipates. Evidence of a distinct oscillatory pattern in the rotational crackle and pop terms was noted for one weld when differentiating over a larger time-base, though could not be replicated in the 2<sup><span style="font-family:Verdana;">nd</span></sup><span style="font-family:Verdana;"> weld. The </span><span style="font-family:Verdana;">higher derivative curves allow distinction of different process regimes, indi</span><span style="font-family:Verdana;">cat</span><span style="font-family:Verdana;">ing that inertial energy mostly influences the time-base of dynamically</span><span style="font-family:Verdana;"> steady-</span><span style="font-family:Verdana;">state phase. Qualitative differences between initial energies are evident in</span><span style="font-family:Verdana;"> higher derivatives.</span>展开更多
Examples of changes in the magnitude of the <b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;"><span style="font-family:Verda...Examples of changes in the magnitude of the <b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">-</span></b></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">field after the heliosphere termination shock (TS) with both Voyager spacecraft (SC) are presented. The work focuses on similarities and differences in the observations at their </span><i><span style="font-family:Verdana;">in-situ</span></i><span style="font-family:Verdana;"> measurements along divergent paths. The presented results were collected where the accuracy of the magnetometer is the highest. These locations are those wherein, four to seven times during the year, the SC performs about 330 minutes of slow rotations identified in the SC language as MAGROLs. They are next reviewed, with the understanding that after the TS, at MAGROLs, the solar wind (SW) flows appear to be mostly sub-magnetosonic and compressional in this region, region named helio-sheath (HS). This is a preliminary survey that uses </span><span style="font-family:Verdana;">48 sec</span> <b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;">-field averages. The time-intervals in this work fill gaps in the currently available studies for longer time intervals. The present study reinforces the view that in the HS after the TS the SW is most likely strongly compressional. </span><span style="font-family:Verdana;">Further</span><span style="font-family:Verdana;"> we discuss the fact that observed fluctuation intensity-modes of the </span><b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;">-field in our time-ranges appear to be much more pronounced at the Voyager 2 path than at the Voyager 1 path.</span></span></span></span>展开更多
As an indispensable part of </span><span style="font-family:Verdana;">global</span><span style="font-family:Verdana;"> satellite navigation system, the frequency band of DME...As an indispensable part of </span><span style="font-family:Verdana;">global</span><span style="font-family:Verdana;"> satellite navigation system, the frequency band of DME will overlap with that of the navigation signal, which will cause the signal from the DME platform to be accepted by the Global Navigation Satellite System receiver and form interference. Therefore, it is of great significance to study an effective algorithm to suppress DME pulse interference. This paper has the following research on this problem. In this paper, wavelet packet transform is used to solve for the suppression of </span><span style="font-family:Verdana;">DME</span><span style="font-family:Verdana;"> pulse interference method, wavelet packet analysis belongs to the linear time-frequency analysis method, it has good time-frequency localization characteristics and the signal adaptive ability, due to the function of wavelet packet and parameter selection of DME will affect the ability of interference suppression, combining with the theory of wavelet </span><span style="font-family:Verdana;">threshold</span><span style="font-family:Verdana;">, function type and decomposition series are discussed to prove the validity of the selected parameters on the pulse interference suppression</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.展开更多
This research focuse<span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> on multiple facts regard</span><span style="font-family:Verdana;&q...This research focuse<span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> on multiple facts regard</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> the earth gravity and the space mechanism, mainly on the solar systems including the Sun and the planets belonging to it. Our solar system consists of our star, the Sun, and everything bound to it by gravity based on Albert Einstein and Isaac Newton theories. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">dozens of moons, millions of asteroids, Comets and meteoroids </span><span style="font-family:Verdana;">[<a href="#ref1">1</a>]</span><span></span><span><span></span></span><span style="font-family:Verdana;">. Also, </span><span style="font-family:Verdana;">it </span><span style="font-family:Verdana;">will discuss about The Geocentric model and how scientifically proofed that the Earth is not orbiting the sun as it has a fixed position in the universe with the rotation around its axis and the sun is orbiting the Earth in one solar year. The output of the Geocentric model led to that the gravity is a feature generated by the planet itself to be measured reference to the weight granted to the matter.</span>展开更多
文摘A project of spacecraft “moonplane” for regular delivery of astronauts onto the Moon is considered. At the first stage of flight by using a carrier rocket, equipped with a chemical rocket engine, the astronauts are delivered on the international space station ISS. For flights from Earth orbit into Moon orbit, the design of a moonplane “MOND”, consisting of an interorbital module and a lunar module, has been developed. The interorbital module is an electric rocket, equipped with four superconductive magnetoplasma engine MARS. To power supply of the electromotors, a solar battery of gallium arsenide is used. The design of the lunar module with cabin astronauts, which is equipped with a chemical rocket engine for landing and take-off from the surface of the Moon, is developed. A method and a device for refuelling of the electrical rocket engines with nitrogen and for refuelling of the chemical rocket engines with oxygen and hydrogen, which are stored in cryogenic tanks of the moonplane in the liquid state is developed. The developed spacecraft is capable to regularly transport four astronauts off a moorage of ISS onto the surface of the Moon and back during 6 days. The total cost delivery of one astronaut is 4 million US dollars.
文摘Spinsonde is a chute-free vertical retardation technique specifically developed for fixed-wing unmanned aircraft to acquire accurate measurement of vertical wind speed profile for meteorological applications. Key advantages of spinsonde over the expendable chute-operated dropsondes are the ability to acquire multi-cycle measurement, efficient use of payload capacity and cost-effectiveness. This work proposes the concept of “rotosonde”, which is the spinsonde equivalent for unmanned helicopters. Computer simulations are carried out to evaluate the performance of the rotosonde and results indicate that the measured speed generally correlates with the wind speed to within ±3 km·h﹣1 even for intensities in excess of 180 km·h﹣1. The profound implication of this work is that unmanned helicopters can now be considered for important field of studies such as cyclogenesis given their reliability to operate in gusty wind conditions in remote oceans, particularly during docking and launching from carriers.
文摘The transmission system is a critical power component of helicopters, playing an indispensable role in power transmission. Among its key elements, the planetary gear system is an essential part of the helicopter transmission architecture. Establishing a dynamic model of the helicopter transmission system and analyzing the dynamic response of the planetary gear system under varying flight conditions are crucial for enhancing the system’s performance and safety. In this study, the transmission system is modeled comprehensively using the lumped mass method and the finite element method, and the dynamic characteristics of the planetary gear system, as reflected on the main gearbox casing under different flight scenarios, are examined. The findings reveal that the resonance frequencies of the planetary gear system remain consistent across various flight conditions, indicating that these frequencies are governed by the inherent structural and dynamic properties of the system. However, the vibration amplitudes at resonance points differ depending on the flight condition. Specifically, the resonance amplitudes at 0.057 kHz and 0.093 kHz during Hovering are significantly lower than those in other conditions, demonstrating that operational scenarios directly influence vibration response.
文摘This paper is focused on a higher-level report of a new generation of Unmanned Aerial Vehicle (UAV) technologies. Starting from the structural scalability of civil tiltrotors, design strategy and requirements for UAVs, and advanced composite materials, the increased speed and productivity requirements for tiltrotors have spawned several investigations associated with proprotor aero elastic stability augmentation and aerodynamic performance enhancements. The research emphasized the Large Civil Tilt Rotor as the configuration with the best potential to meet the technology goals, and the design, including the challenges of the Large Civil Tilt Rotor (LCTR). The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The research includes some manufacturers of helicopters, drones and tiltrotors carrying out design studies and production of prototypes, as well as research projects aimed at designing, manufacturing, qualifying, and flight-testing the new wing of the Next-Generation Civil Tiltrotor Technology Demonstrator. Promises of Vertical Take-off and Landing (VTOL) aircraft, UAVs, Digitalization of Urban Air Mobility (UAM), and the “U-space” concept are discussed in the paper. The eight SUMP principles and possibilities of future advancements are emphasized.
文摘Stabilizers and their control surfaces are vital components in maneuvering an airplane during flight. However, a shortcoming of stabilizers is that they require airstream or propeller wash for them to work properly. In this work, we propose the concept of roto-stabilizer as viable substitution for conventional horizontal stabilizer. A key benefit of the proposed technique is its ability to exert powerful moment in the absence of forward airspeed or propeller wash. Proof of principle is demonstrated via computer simulations. Results reveal that new aerobatic maneuvers are made possible. Furthermore, when implemented in canard configuration, it is possible to achieve ultra-STOL and VTOL.
文摘A generic approach to model the kinematics and aerodynamics of flapping wing ornithopter has been followed, to model and analyze a flapping bi- and quad-wing ornithopter and to mimic flapping wing biosystems to produce lift and thrust for hovering and forward flight. Considerations are given to the motion of a rigid and thin bi-wing and quad-wing ornithopter in flapping and pitching motion with phase lag. Basic Unsteady Aerodynamic Approach incorporating salient features of viscous effect and leading-edge suction are utilized. Parametric study is carried out to reveal the aerodynamic characteristics of flapping bi- and quad-wing ornithopter flight characteristics and for comparative analysis with various selected simple models in the literature, in an effort to develop a flapping bi- and quad-wing ornithopter models. In spite of their simplicity, results obtained for both models are able to reveal the mechanism of lift and thrust, and compare well with other work.
文摘In this paper, a real-time online data-driven adaptive method is developed to deal with uncertainties such as high nonlinearity, strong coupling, parameter perturbation and external disturbances in attitude control of fixed-wing unmanned aerial vehicles (UAVs). Firstly, a model-free adaptive control (MFAC) method requiring only input/output (I/O) data and no model information is adopted for control scheme design of angular velocity subsystem which contains all model information and up-mentioned uncertainties. Secondly, the internal model control (IMC) method featured with less tuning parameters and convenient tuning process is adopted for control scheme design of the certain Euler angle subsystem. Simulation results show that, the method developed is obviously superior to the cascade PID (CPID) method and the nonlinear dynamic inversion (NDI) method.
文摘In this paper, the method of reliability test profile construction for air-launched spacecraft is analyzed, in order to effectively carry out air-launched spacecraft flight reliability test. The flight mission profile and environment profile of air-launched spacecraft are formed. Meanwhile, the method of temperature stress, vibration stress, electronic stress and humidity stress of external spacecraft under different mission profiles are calculated. Finally, this paper takes an airborne electronic product as an example, and a reliability test profile is designed by correction of the experimental section with measured data.
文摘For the quad tilt rotor aircraft, a computational fluid dynamics method based on multiple reference frames (MRF) was used to analyze the influence of aerodynamic layout parameters on the aerodynamic characteristics of the quad tilt rotor aircraft. Firstly, a numerical simulation method for the interference flow field of the quad tilt rotor aircraft is established. Based on this method, the aerodynamic characteristics of isolated rotors, rotor combinations at different lateral positions on the wing, and rotor rotation directions under different inflow velocities were calculated and analyzed, in order to grasp their aerodynamic interference laws and provide reference for the design and control theory research of such aircraft.
文摘A project of the expedition to the north pole of Mars, which is carried out in two stages, has been developed. In the first stage, a space refueller and a mobile solar battery are delivered to the icy surface of the north pole of Mars. The delivery is carried out with the help of electric rocket ER-7, driven by the electric rocket engine “MARS”, and the source of electricity is a solar battery from gallium arsenide. In the second stage, the space train is formed from two interconnected ER-7 rockets and an orbital takeoff-landing capsule TLC-2, in which three astronauts land on the surface and carry out a complex of physical, biological and geological researches on Mars surface. The space refueller has been developed, which melts the water ice on the surface of Mars and with the help of an electrolyser and a liquefier produces fuel and oxidizer for the operation of the chemical rocket engine of the takeoff-landing capsule. To move astronauts from the north pole to the equator, a spacecraft—?marsoplane, which consists of the electric rocket ER-7 and the takeoff-landing capsule TLC-1 is developed. The duration of the expedition is 110 days at a cost of 2 billion dollars.
文摘Shock wave is a detriment in the development of supersonic aircrafts;it increases flow drag as well as surface heating from additional friction;it also initiates sonic boom on the ground which precludes supersonic jetliner to fly overland. A shock wave mitigation technique is demonstrated by experiments conducted in a Mach 2.5 wind tunnel. Non-thermal air plasma generated symmetrically in front of a wind tunnel model and upstream of the shock, by on-board 60 Hz periodic electric arc discharge, works as a plasma deflector, it deflects incoming flow to transform the shock from a well-defined attached shock into a highly curved shock structure. In a sequence with increasing discharge intensity, the transformed curve shock increases shock angle and moves upstream to become detached with increasing standoff distance from the model. It becomes diffusive and disappears near the peak of the discharge. The flow deflection increases the equivalent cone angle of the model, which in essence, reduces the equivalent Mach number of the incoming flow, manifesting the reduction of the shock wave drag on the cone. When this equivalent cone angle exceeds a critical angle, the shock becomes detached and fades away. This shock wave mitigation technique helps drag reduction as well as eliminates sonic boom.
文摘This paper is an eye opening to the new horizon of the design of operational Compressors in our jet engines. That are compressors usually perform an operation called isentropic process and which levitate the pressure and temperature to the optimum level which require for effective ignition. Basically, our compressors have several sets of blades to perform this function, more precisely saying Rotor and stator blades. Where rotor blade provides air molecule to push at very high velocity to the Stationary blade and when the air Enders to the Stator, the stator races its pressure to move on to the next stage. And we call this set of Stator and rotor as a stage ref [1]. However, in this work, I consider the geometry of the incoming air molecule and how it transforms its physical quantities such as Pressure and temperature ref [2]. For that I tie the concept of Thermodynamic and mechanics on the platform of Tensor analysis ref [3]. That is, I consider the quantities like Pressure, Temperature and rate of flow are their corresponding vector spaces and energy related quintets like heat, work as the scaling elements on the above vector space. And quantities such as entropy enthalpy and specific heat capacity are corresponding physics of it. Considering the advantages, one of the important advantages of this approach is the applicability of results of this work to the formulation of blade less compression Example: Ram and Scram jet engine. Again, the relevant upgrading which is essential for future hypersonic air crafts can achieve from this study and this will be a mile stone for bright air and space travel. To conclude, this approach will be a great transformation on the conventional idea for realization of compression for operational Scram and Ram jet engines ref [4] [5].
文摘A project of elimination of potentially dangerous asteroid Apophis which April 13, 2029 year approaches to Earth at a distance of 36,000 km is considered. The elimination is carried out by means of asteroid disintegration into small fragments as a result of nuclear explosion, which is produced 133 days before the moment of maximal convergence of the asteroid Apophis with Earth. In the project, a method of phased timely delivery of nuclear charge on the surface of the asteroid is proposed. In the first stage, the nuclear charge using carrier rocket “Delta” is delivered into Earth orbit. In the second stage, the charge using electric rocket is transferred from Earth orbit into the orbit of asteroid Apophis and is descended onto its surface. For implementation of the project, the design of electric rocket ER-7, which uses electric rocket engines type MARS and solar panels based on gallium arsenide is developed. Design of landing capsule, which has a chemical rocket engine and the container in which located the nuclear charge of 6 megaton is developed.
文摘A project of the space cruise over the route “Earth-Mars-Earth” is considered. Design of electric rocket train, whose energy source is a semiconductor solar panel and a superconducting electrorocket engine (MARS) of new design is used as a mover, is developed. The concept of the cruise, which allows to reduce time of interorbital flight in twice, owing to refueling with working body on orbit of Mars, is developed. Development of the space locomotive with 4 MARS engines rated at 600 kW in which nitrogen is used as working substance, was being carried out. A new design of takeoff-landing capsule, in which cabin can be placed 10 space tourists, is developed. The studies carried out on the mathematical model, which takes into account the changing of power provided by onboard power plant, depending on the distance from the Sun, has shown that cruise may be done within 77 days including the stay of tourists on the Martian surface during 7 days. The project provides for implementation three cruises on the surface of Mars and 15 cruises on the lunar surface during two years with total cost of 2.2 billion dollars.
文摘Our study identifies a subtle deviation from Newton’s third law in the derivation of the ideal rocket equation, also known as the Tsiolkovsky Rocket Equation (TRE). TRE can be derived using a 1D elastic collision model of the momentum exchange between the differential propellant mass element (dm) and the rocket final mass (m1), in which dm initially travels forward to collide with m1 and rebounds to exit through the exhaust nozzle with a velocity that is known as the effective exhaust velocity ve. We observe that such a model does not explain how dm was able to acquire its initial forward velocity without the support of a reactive mass traveling in the opposite direction. We show instead that the initial kinetic energy of dm is generated from dm itself by a process of self-combustion and expansion. In our ideal rocket with a single particle dm confined inside a hollow tube with one closed end, we show that the process of self-combustion and expansion of dm will result in a pair of differential particles each with a mass dm/2, and each traveling away from one another along the tube axis, from the center of combustion. These two identical particles represent the active and reactive sub-components of dm, co-generated in compliance with Newton’s third law of equal action and reaction. Building on this model, we derive a linear momentum ODE of the system, the solution of which yields what we call the Revised Tsiolkovsky Rocket Equation (RTRE). We show that RTRE has a mathematical form that is similar to TRE, with the exception of the effective exhaust velocity (ve) term. The ve term in TRE is replaced in RTRE by the average of two distinct exhaust velocities that we refer to as fast-jet, vx<sub>1</sub>, and slow-jet, vx<sub>2</sub>. These two velocities correspond, respectively, to the velocities of the detonation pressure wave that is vectored directly towards the exhaust nozzle, and the retonation wave that is initially vectored in the direction of rocket propagation, but subsequently becomes reflected from the thrust surface of the combustion chamber to exit through the exhaust nozzle with a time lag behind the detonation wave. The detonation-retonation phenomenon is supported by experimental evidence in the published literature. Finally, we use a convolution model to simulate the composite exhaust pressure wave, highlighting the frequency spectrum of the pressure perturbations that are generated by the mutual interference between the fast-jet and slow-jet components. Our analysis offers insights into the origin of combustion oscillations in rocket engines, with possible extensions beyond rocket engineering into other fields of combustion engineering.
文摘This article discusses the kinematics of a parachutist making a very-high-altitude jump. The effect of altitude on the density of air, on the gravitational field strength of the Earth, and on the atmosphere’s temperature has been taken into account in our analysis. The well-known equations of classical mechanics governing the selected topic have been solved numerically by using the mathematical software Mathcad. Especially, the possibility of a person exceeding the speed of sound during their fall has been considered in our analysis. The effect of the sound barrier is taken into account so that the shape factor of the falling body is given as a speed-dependent function, which reaches its maximum value at Mach 1.0. The obtained results have been found to be highly consistent with the available experimental data on some high-altitude jumps. The data published on the famous jump of Captain Joseph Kittinger has been analyzed very carefully, and although our calculations reproduced the reported values for most parts, some interesting inconsistencies were also discovered. Kittinger jumped from a gondola attached to a helium-filled balloon from a record-high altitude of 102,800 ft, or 31,330 m, in August 1960. We also made numerical analysis on the high-altitude jump of Felix Baumgartner. He bailed out from his gondola at the record-high altitude of 39.0 km in October 2012.
文摘The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and pop versus-times curves for each weld. Titanium alloys and their mechanical properties are known to be highly sensitive to strain rate as the material is deformed, though nothing has ever been considered in terms of the higher-order time-derivatives of position. These curves have been studied and analysed further, for a more complete understanding of the derivative trends. Rotational acceleration and jerk traces both display behavior patterns across the two welds as the part rotates under action from the flywheel. The rotational snap also displays a pattern in this derivative during the final approximately 0.5 s of welding, as the energy dissipates. Evidence of a distinct oscillatory pattern in the rotational crackle and pop terms was noted for one weld when differentiating over a larger time-base, though could not be replicated in the 2<sup><span style="font-family:Verdana;">nd</span></sup><span style="font-family:Verdana;"> weld. The </span><span style="font-family:Verdana;">higher derivative curves allow distinction of different process regimes, indi</span><span style="font-family:Verdana;">cat</span><span style="font-family:Verdana;">ing that inertial energy mostly influences the time-base of dynamically</span><span style="font-family:Verdana;"> steady-</span><span style="font-family:Verdana;">state phase. Qualitative differences between initial energies are evident in</span><span style="font-family:Verdana;"> higher derivatives.</span>
文摘Examples of changes in the magnitude of the <b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">-</span></b></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">field after the heliosphere termination shock (TS) with both Voyager spacecraft (SC) are presented. The work focuses on similarities and differences in the observations at their </span><i><span style="font-family:Verdana;">in-situ</span></i><span style="font-family:Verdana;"> measurements along divergent paths. The presented results were collected where the accuracy of the magnetometer is the highest. These locations are those wherein, four to seven times during the year, the SC performs about 330 minutes of slow rotations identified in the SC language as MAGROLs. They are next reviewed, with the understanding that after the TS, at MAGROLs, the solar wind (SW) flows appear to be mostly sub-magnetosonic and compressional in this region, region named helio-sheath (HS). This is a preliminary survey that uses </span><span style="font-family:Verdana;">48 sec</span> <b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;">-field averages. The time-intervals in this work fill gaps in the currently available studies for longer time intervals. The present study reinforces the view that in the HS after the TS the SW is most likely strongly compressional. </span><span style="font-family:Verdana;">Further</span><span style="font-family:Verdana;"> we discuss the fact that observed fluctuation intensity-modes of the </span><b><span style="font-family:Verdana;">B</span></b><span style="font-family:Verdana;">-field in our time-ranges appear to be much more pronounced at the Voyager 2 path than at the Voyager 1 path.</span></span></span></span>
文摘As an indispensable part of </span><span style="font-family:Verdana;">global</span><span style="font-family:Verdana;"> satellite navigation system, the frequency band of DME will overlap with that of the navigation signal, which will cause the signal from the DME platform to be accepted by the Global Navigation Satellite System receiver and form interference. Therefore, it is of great significance to study an effective algorithm to suppress DME pulse interference. This paper has the following research on this problem. In this paper, wavelet packet transform is used to solve for the suppression of </span><span style="font-family:Verdana;">DME</span><span style="font-family:Verdana;"> pulse interference method, wavelet packet analysis belongs to the linear time-frequency analysis method, it has good time-frequency localization characteristics and the signal adaptive ability, due to the function of wavelet packet and parameter selection of DME will affect the ability of interference suppression, combining with the theory of wavelet </span><span style="font-family:Verdana;">threshold</span><span style="font-family:Verdana;">, function type and decomposition series are discussed to prove the validity of the selected parameters on the pulse interference suppression</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">.
文摘This research focuse<span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> on multiple facts regard</span><span style="font-family:Verdana;">ing</span><span style="font-family:Verdana;"> the earth gravity and the space mechanism, mainly on the solar systems including the Sun and the planets belonging to it. Our solar system consists of our star, the Sun, and everything bound to it by gravity based on Albert Einstein and Isaac Newton theories. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">dozens of moons, millions of asteroids, Comets and meteoroids </span><span style="font-family:Verdana;">[<a href="#ref1">1</a>]</span><span></span><span><span></span></span><span style="font-family:Verdana;">. Also, </span><span style="font-family:Verdana;">it </span><span style="font-family:Verdana;">will discuss about The Geocentric model and how scientifically proofed that the Earth is not orbiting the sun as it has a fixed position in the universe with the rotation around its axis and the sun is orbiting the Earth in one solar year. The output of the Geocentric model led to that the gravity is a feature generated by the planet itself to be measured reference to the weight granted to the matter.</span>
