A numerical model that estimates the parameters of a small, unmanned coaxial rotor helicopter with a takeoff mass of 11. Introduction although the first idea of coaxial rotors appeared more than 150 years ago1, most helicopters have used single main rotor tail rotor combination. Which means for any given engine configuration or aircraft weight, youre going to be able to go significantly faster, higher, heavier or farther with true wi. Performance of a machscale coaxial counterrotating rotor in. The acoustic characteristics of a twin contrarotating coaxial rotor configuration with significant flapwise stiffness. The simplicity of design yields benefits such as lower structural weight, manufacturing and maintenance costs. A coaxial rotor system is a pair of rotors mounted on the same. This hub is specifically designed to couple blade leadandlag oscillations to a change in blade pitch. Another benefit of a coaxial design is a higher payload for the same engine power. Unmanned coaxial rotor helicopter dynamics and system. A comparison of coaxial and conventional rotor performance. The glmav rotorcraft is a new micro air vehicle mav concept using twobladed coaxial contrarotating rotors and a cyclic swashplate. Coaxial rotor systems consist of two axially aligned rotors in close proximity rotating in opposite directions. Jul 19, 20 coaxial rotors also reduce the effects of dissymmetry of lift.
The mav packaged in a projectile is launched using the energy delivered by a portable weapon. Ill go the other direction and talk about the advantages and disadvantages of tail rotors, which are the disadvantages and advantages of coaxial rotors, respectively. Study of contrarotating coaxial rotors in hover, a. Coaxial rotor yaw control sikorsky aircraft corporation. A general summary of the coaxial rotor configuration explores the configurations advantages and applications. The upper rotors induced velocity over the outer part of the lower rotor is neglected. Abstracttraditional coaxial helicopter micro air vehicles use a large propeller motor. Feb 15, 2016 ill go the other direction and talk about the advantages and disadvantages of tail rotors, which are the disadvantages and advantages of coaxial rotors, respectively. Effect of rotor stiffness and lift offset on the aeroacoustics of a coaxial.
A comparison of coaxial and conventional rotor performance 2010 where. Pages in category coaxial rotor helicopters the following 35 pages are in this category, out of 35 total. When it reaches the apogee, the projectile is transformed in such a way that the. Rotational maneuvering, yaw control, is accomplished by increasing the collective pitch of one rotor and decreasing the collective pitch on the other. Last year, the army downselected from four vendors to twoa boeingsikorsky team offering the sb1 defiant, a compound helicopter with coaxial rotors, and bell. The coaxial rotor system results in approximately 67 86 million grid points depending on the interrotor spacing. An optimum coaxial rotor system for axial flight request pdf. This is evident in a single rotor helicopter with its need for an antitorque rotor. Coaxial rotors or coax rotors are a pair of helicopter rotors mounted one above the other on. The coaxialrotor uav is composed of offtheshelf electronic parts and plywood foamboard laser cut parts. In effect, the torque generated by each rotor cancels out one another. Last year, the army downselected from four vendors to twoa boeingsikorsky team offering the sb1 defiant, a compound helicopter with coaxial rotors, and bell helicopter offering the v280 valor, a tilt rotor aircraft. A wake capturing approach using a commercial navierstokes solver, and a hybrid navierstokesfree wake analysis, have been employed. The coaxial configuration of helicopters is basically a 2 winged mav.
This document presents the main steps to build a flyable coaxialrotor uav. Lacking the traditional tail rotor system used by most helicopters to counteract the torque reaction of the main rotors, the blade cx2 uses an arrangement known as twin coaxial main rotors. Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. The coaxial rotor uav is composed of offtheshelf electronic parts and plywood foamboard laser cut parts. Computational investigation of coaxial rotor interactional aerodynamics in steady forward flight. A coaxial rotor is defined as having an upper and a lower rotor that rotate in opposite directions to each other. Coaxial rotors or coax rotors are a pair of helicopter rotors mounted one above the other on concentric shafts, with the same axis of rotation, but turning in opposite directions contrarotating. An underactuated propeller for attitude control in micro. A significant advantage of coaxial main rotor systems is the elimination of the need for a tail rotor for antitorque control. Because they spin in opposite directions, both sides of the rotor disc have a retreating blade and an advancing blade.
Coaxial rotors are a pair of helicopter rotors mounted one above the other on concentric shafts, with the same axis of rotation, but that turn in opposite directions contrarotation. Coaxial rotors article about coaxial rotors by the free. A survey of theoretical and experimental coaxial rotor. Coaxial rotor rc helicopters are generally small electric helicopters which are very well suited to those pilots just starting out with rc helicopters. The hover performance prediction for a regular coaxial rotorcraft using the. A comprehensive design of a gun launched micro air vehicle glmav is presented.
See, the tail rotor is a mechanism that makes up for the tendency of turning. A coaxial rotor system is an arrangement that contains two identical, or nearly identical, counterrotating rotors along a common spin axis. Are tiltrotors or coaxial rotors better for future vertical. The impulsive noise due to bvi for the coaxial rotor is found to be higher by 2035 db compared to the equivalent single rotor. Without a tail rotor, how does a coaxial rotor helicopter achieve yaw control. Aug 23, 2011 coaxial rc helicopter rotor animation.
It has a rotor diameter of 335 mm and a total mass of 230 g. Coax are heavy and do not take advantage of the long tail to counter torque as a useful aerodynamic feature the way the apache does it, not needing a tail rotor power above 90 knots. A main gearbox g located above the aircraft cabin drives the rotor system 12. This drag model was extracted from the correlations of vtm predictions against harringtons experimental data presented in ref. Coaxial rotors also reduce the effects of dissymmetry of lift.
The intermeshing rotor system was not investigated. A brand new design, developed by the modlab university of pensylvania student james paulos, simplifies the standard design of a helicopter, doing. Our pe polyethylene outer jacket is unlike most others which are pvc. The link goes to wikipedias article, and down a ways it says. Rotor hover performance and system design of an efficient.
Computational study of flow interactions in coaxial rotors. Introduction although the first idea of coaxial rotors appeared more than 150 years ago1, most helicopters have used single mainrotortailrotor combination. This torque causes the fuselage to rotate in the direction opposite to the rotor blades. Most helicopters have rotating airfoil shaped blades on top of the fuselage. Consequently, the machine can be directionally stabilized and the pilot has control over the yaw angle of the aircraft. Since coaxialrotor helicopters do not require a tail rotor, they are safer to approach while rotors are still in motion. Coaxial rotors or coax rotors are a pair of helicopter rotors mounted one above the other on concentric shafts, with the same axis of rotation, but turning in opposite directions. Key design inputs for coaxial tiltrotorsimulation validation of hover analysis the modelling process involveddevelopinga trim routine for a generic coaxial rotor and then modifying the math model to incorporate the effects of a tilting mast. It was found that the upper rotor was marginally affected by the lower one at spacings larger than 35% of the rotor radius, and that it produced about 60% of the total thrust. When these blades turn, air flows more quickly over the tops than it does. This is due to the fact that these fliers have two rotors, one on top of the other, rotating in opposite directions. The propellers are connected to the motors using a custom 3d printed rotor hub. Uav coaxial copter uses unique drive mechanism hackaday. Mar 30, 2017 and one other project i would like to work on is a small hand drill with the concept of coaxial rotors, drill bit would rotate in counter clockwise and drill itself would rotate clockwise with a hand at the end of the drill on bearings for grip so that the two opposite rotations cancel the torque i need to put through my hand to stabalize the hand drill and drill through wood easily without.
Coaxial rotor configurations maximize the available rotor disk surface and allow for torque cancelation. Since torque balance is achieved with the main rotor system, a tail rotor is not required. Aerodynamic optimization of coaxial rotor in hover and axial flight upper rotors wake. The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and owned by third party users. October 28, 2008 helicopters featuring coaxial rotor designs are not exactly new. Modlab student develops a revolutionary simple helicopter. Numerical simulations have been conducted for a coaxial rotor tested by harrington.
A vectoring thrust coaxial rotor for micro air vehicle oatao. An underactuated propeller for attitude control in micro air vehicles. Ive heard it said theyre also more maneuverable, al. Therefore, any sinusoidal actuator input from manual flight led to a. This approximation compares the efficiency of the coaxial system with the efficiency of two separated propellers, giving therefore an estimation of. The result of this is a reducing of coaxial rotor helicopter size by 3540% as. Also, the coaxial configuration has a more compact structure than a singlerotor because it does not need to mount a rear shaft longer than the main rotors bladeswept radius in the airframe. Therefore, any sinusoidal actuator input from manual flight. The aerodynamic drag of the dual counter rotating, coaxial rotor system is generated by three main componentsthe. Control of a coaxial helicopter with center of gravity. Coaxial rotor performance at torque equilibrium was explored for different trims and operating conditions. Tail rotors on coaxial helicopters have all sorts of interesting side effects. The acoustic characteristics of a twin contra rotating coaxial rotor configuration with significant flapwise stiffness.
Ive heard it said theyre also more maneuverable, all else being equal. Oct 28, 2008 october 28, 2008 helicopters featuring coaxial rotor designs are not exactly new. The recent appearance of the kamov ka50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in. What are the advantages and disadvantages of coaxial rotors. Performance analysis of a coaxial rotor system in hover. Computational study of flow interactions in coaxial rotors seokkwan yoon, henry c. How is autorotation different in coaxial rotor helicopters. Request pdf an optimum coaxial rotor system for axial flight the concept of a coaxial rotor system that is optimized for most efficient hovering andor axial flight performance is discussed. Pdf a hybrid cfdvortex element method is described along with both single rotor and coaxial rotor performance validation in forward flight. Aerodynamic modelling and experimental identification of a.
Although a particular counterrotating, coaxial rotor system aircraft configuration is illustrated in the disclosed embodiment, other rotor systems and other aircraft types such as tiltwing and tiltrotor aircrafts will also benefit from the present. Mar 15, 2012 a comprehensive design of a gun launched micro air vehicle glmav is presented. Sep 20, 2014 a numerical model that estimates the parameters of a small, unmanned coaxial rotor helicopter with a takeoff mass of 11. A method includes determining, by a computing device comprising a processor, a value for at least one parameter related to an operation of a coaxial rotary wing aircraft. So in a coaxial rotor system, with the two main rotor blades counter rotating, increasing the collective pitch of the top rotors thus increasing its torque effect on the main rotor shaft and reducing the collective pitch of the bottom rotors thus decreasing. The advantage of the coaxial rotor system in terms of reduced power requirement was shown to be enhanced by the introduction of signi.
The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and. When it reaches the apogee, the projectile is transformed in such a way that the mav. The solidity of a coaxial rotor c is defined the same way as for a single rotor. This rotor configuration is a feature of helicopters produced by the russia kamov. Simplified rotor system the gyrodyne coaxial utilizes the semirigid type of rotor system without the need for use of mechanical stabilizing devices, thus resulting in a simpler rotor system design possessing excellent flying qualities. Tail lift at first seems obvious, but on closer look it is actually quite interesting. The modeled coaxial rotor helicopter did not have any additional damping to its dynamics such as a stabilizer bar or external gyro, which are common in commercial hobby helicopter models. Jan 01, 2015 a brand new design, developed by the modlab university of pensylvania student james paulos, simplifies the standard design of a helicopter, doing away with numerous different motors and parts. Lacking the traditional tail rotor system used by most helicopters to counteract the torque reaction of the main rotors, the blade cx2 uses an arrangement known as twin coaxial main rotors this setup employs two main rotor assemblies stacked. The opposite torques from the rotors cancel each other out. Although a particular counterrotating, coaxial rotor system aircraft configuration is illustrated in the disclosed embodiment, other rotor systems and other aircraft types such as tiltwing and tiltrotor aircrafts will also benefit from the present disclosure. Optimizing a coaxial propulsion system to a quadcopter.
Analysis of coaxial rotor systems has progressed over the last decade thanks to improved modeling capabilities. The coax 2 helicopter is a mini helicopter in coaxial rotor con. This rotor configuration is a feature of helicopters produced by the russia kamov helicopter design bureau. Pdf a hybrid cfd method for coaxial rotor performance. This is a particularly important advantage for military applications, where circumstances may not allow time to stop rotors before personnel approach or exit the aircraft. On this basis the coaxial rotor is shown to consume less power, mainly due to its slightly lower consumption of induced power compared to the equivalent single rotor ref.
Are tiltrotors or coaxial rotors better for future. Also, the coaxial configuration has a more compact structure than a single rotor because it does not need to mount a rear shaft longer than the main rotor s bladeswept radius in the airframe. Rotational maneuvering, yaw control, is accomplished by increasing the collective pitch of. A tail rotor consumes some of the available power produced by the engine. The tandem coaxial rotor vehicle system incorporates two coaxial rotor systems and a fuselage body. The co axial design of a pair of rotors mounted on the same mast and with the same axis of rotation, but turning.
In single rotor helicopters, the antitorque rotor or tail rotor counteracts the main rotor torque and controls the fuselage rotation. Pulliam nasa ames research center, moffett field, california 94035 i. Hub loads and blade deformation were also measured. Disadvantages include increased mechanical complexity and increased parasite drag which can. This document presents the main steps to build a flyable coaxial rotor uav. Coaxial helicopters, on the other hand, eliminate the need of a tail rotor completely. Feb 23, 2012 the intermeshing rotor system was not investigated. The companies are offering the sb1 defiant, which is based on sikorskys x2 technology that replaces the single main rotor on a traditional helicopter with a coaxial rotor, and a pusherpropeller that replaces a traditional tail rotor, said chris van buiten, vice president of sikorsky innovations. Coaxial rotors solve the problem of main rotor torque by turning each set of rotors in opposite directions. A study of coaxial rotor performance and flow field. They have, however, as a result, very quick yaw rates since the. Apr 16, 2015 although a particular counterrotating, coaxial rotor system aircraft configuration is illustrated in the disclosed embodiment, other rotor systems and other aircraft types such as tiltwing and tilt rotor aircrafts will also benefit from the present disclosure.
Us20060269411a1 rotor hub fairing system for a counterrotating. In a helicopter, coaxial counterrotating rotors, each having a plurality of load sustaining rotor blades, each blade having a main blade portion and a lift producing tip portion of airfoil section which is extensible and retractible axially of its main blade portion from a normal position in which it is partially extended from said main blade portion, and means for creating torque. This rotor configuration is a feature of helicopters produced by the. This theory is a onedimensional approximation and it was validated against thrust and power measurements for a coaxial system, with good agreement. Coaxial rotor article about coaxial rotor by the free. Coaxial helicopters have two main rotor sets, one on top of the other, spinning in different directions to eliminate the need for a tail rotor. This page lists some of these interesting phenomenon. Since coaxial rotor helicopters do not require a tail rotor, they are safer to approach while rotors are still in motion. Typical coaxial rotor, with detailed swashplate assembly. The rotor was trimmed so that the upper and lower rotor torques are equal, cancelling each other. Coax 2 helicopter left and cog steering mechanism with battery right.