Wright Design Abstract-principal11

8/14/2019 Wright Design Abstract-principal11

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-Development and Application of a RCglider For IITShaastra 2009 Wright Design

ranav N Raichur .Sanketh Adiga R hubhadeep Chowdhury umanth Aramadi HR


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Outline Presentation

About the eventIntroductionProblem Statement

ApproachDesignInnovation


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Introduction

"A soul in tension thats learning to flyCondition grounded but determined to tryCant keep my eyes from the circling skiesTongue-tied and twisted just an earth-bound misfit. "

We at Team AUK firmly believe in letting our imagination take wings, quite literally too. Theintricacy of flight, the rush of wind, from gentle zephyrs to howling headwinds, thechallenges of aero modelling fueled our quest to take up this project. And what better placeto showcase our flyer than at Shaastra 2009.Competing against the best will help usevaluate our position and gain invaluable experience in developing our glider.A lot of work that went into the glider taught us so much, right from mundane and arcanethings like how quickly Feviquick glues your hand, to the techincal aspects like theprinciples that govern flight. It has been an exciting journey so far, and even more excitingis the fact that we are just starting out on our journey.


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Problem statement

Design an RC electric glider with the following constraints that could have maximumtime of flight after 30 sconds of powered flight carrying a payload of 100grams.Hand launch of the glider is allowed.The whole glider should completely fit inside a box of dimensions 110cm x 110cm x35cmIt should carry a payload of 100grams,which will be provided by us during the eventIt should have its static thrust to weight ratio (including the payload) less than 3:4. Incase the ratio is higher than specified, then additional payload will be added by us until itmeets the above mentioned ratio. Details on the simple experimental setup, which will beused to test your glider during the event, will be put up on web soonDuring the run, it should have powered flight duration of 30 seconds after which themotor has to be stopped. The non-powered time of flight, measured after that, is thewinning criterion.


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Approach

The glider configuration chosen for this project is a polyhedral wing with a traditionaltapering fuselage configuration. This configuration was based on the configuration ofcommon sailplanes. The design was created using several assumptions to provide areference base if the design and configuration were to be altered. An initial model wasconstructed and substantial flight testing was performed to determine the mostefficient configuration for the glider regarding wing location, incidence angles, andadded weight. As this configuration was chosen, a second model is being constructedin balsa wood, exactly replicating the prototype made of coroplast.

On the basis of the Problem Statement provided above we have come up with TheAuk-1 a RC glider with wingspan of 48.


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The picture below illustrates the *prototype of the glider made of coroplast

The Glider when placed along the body diagonal of the given dimensions of110cm x 110cm x 35cm


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DESIGN

The devil isnt in the details , its the details thatmake the design

The design parameters of the glider can be broadlyclassified and studied under the head as follows :

FuselageWingManeuverabilityElectronics


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FuselageThe fuselage is the main body of the RC glider. It serves as a housing of theinternal components and holds together the outer parts.The side view and topview of the fuselage is depicted in the following design as follows:

The fuselage specifications are as follows:The fuselage has a length of 38 inches made of balsa wood with the widest part at the wingplatform being 2.5inches supported underneath with formers to hold the wings on the platform.The tail platform is supported by a former of 1.5inches to take the weight of the tail and ruddercombine which has been fixed through the slit mechanism to avoid any relative motion betweenthe two and the fuselage to avoid any bending during the flight and hence to make it stableThe Engine bearer houses the brushless motor with the propeller for the Thrust and poweredflight for duration of 30 seconds


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Wing

Lift is one of the four primary forces acting upon an airplane/glider .The others areweight, thrust, and drag. Weight is the force that offsets lift, because it acts in theopposite direction. The weight of the airplane must be overcome by the liftproduced by the wings. If an airplane weighs X units then the lift produced by itswings must be greater than X units in order for the airplane to leave the ground.Designing a wing that is powerful enough to lift an airplane off the ground, and yetefficient enough to fly over extremely long distances, was the challenge and we

have tried to achieve the same using a 48 inch wing span with a polyhedral wingconfiguration.


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The aerofoil (cross-section of the wing) used in the wing is of NACAflat bottom type .The choice of this aerofoil was made due to itsinherent stability. The flat bottom design is stable on the longitudinalaxis and self-correcting tendency.The highest point on the aerofoil is

0.75 inches.


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The Dihedral is added to the wings for roll stability; a wing with somedihedral will naturally return to its original position if it encounters a slight rolldisplacement.

The polyhedral wingconfiguration was chosen as our design, allows the Glider to hangfrom their center of lift, and are therefore more stable and self correcting during normal flightconditions. A turn is initiated via use of the rudder, and once the rudder is returned to center, aproperly trimmed glider will return to level flight on its own.They are also typically moredrag inducing, and suitable more for slower flight envelopes than a straight wing design.

As the basic requirement of the glider is to stay air borne for a longer period of time andachieve a greater range the polyhderal wing design was chosen and applied to auk -1


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The wing span was chosen to be 48 inches long as measured tip to tip of thepolyhedral wing, as to achieve the longest possible wing span on loading the wing 1/3rd of the fuselage length located right at the centre of gravity position and placing theglider in a diagonal position of the given box as specified in the rules.The wing chord length is 6inches and it was achieved to achieve a high aspect

ratio of 8 in order to minimize the induced drag so which is a effect related to threedimension wings

With the above diagram as reference Aspect ratio (AR) is calculated as follows :Aspect ratio =s/c where s is the span of the wing and c is the chord lengthIn our case s=48 inches and c =6inches therefore AR=48/6=8 inches


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One half of the wing is illustrated in the design explaining the polyhedral andthe dihedral


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ManeuverabilityTo control and maneuver the glider , smaller wings are located at the tail of the plane.The tail usually has a fixed horizontal piece (called the horizontal stabilizer) and a fixedvertical piece (called the vertical stabilizer).The horizontal stabilizer prevents an up-and-down motion of the nose or pitchingmotion of the nose . With the tail wing span of 20inches and wing chord length of8.5 inches .The elevator is attached to the horizontal stabilizerin hinged manner it is used tocontrol the position of the nose of the glider and the angle of attack of the wing.

Changing the inclination of the wing to the local flight path changes the amount of liftwhich the wing generates. This, in turn, causes the glider to climb or dive depending onthe need.The vertical stabilizers, orfins, of glider , are typically found on the end of thefuselage or body, and are intended to reduce aerodynamic side slip.The rudder is used to control the position of the nose of the glider or the yaw motionof the glider . The rudder and the fin stands 7.3 tall and the rudder is attached to

the fin in a hinged reinforced configuartion for easy movement and hence bettermaneuverability of the glider .


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desgin illustrating the horizontal stabilizer of the glider


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ElectronicsThe aircraft powerplant consists of all the accessories needed by the aircraft toproduce thrust,the accessories used to gain thrust during the first 30 seconds ofthe glider flight make use of electronics and can be described as follows :

The Electric motoris used to turn the propellers and inturn which provide thrustto the glider . We are using brushless motor is called "outrunner".These motors

have the rotor "outside" as part of a rotating outer case while the stator is locatedinside the rotor.This arrangement gives much higher torque than the conventionalbrushless motors, which means that the "outrunners" are able to drivelarger andmore efficient propellers without the need of gearboxes.We are using the 2212-13outrunner brushless motor

Battery combination of electrochemical cells which discharge high voltage or current is used asthe power source to run the motor .We for auk -1 are using Lithium polymer rechargable battery asthey achieve higher voltage and power output, with more capacity, in a lighter weight package.We

are going to use 3cell 1amp Li-Polymer to form a battery with potential difference of 11.4 v(less ascompared to maximum allowable 12 v )


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Electronic speed control is used to vary the speed of a brushless motor. Controlled bythe throttle signal from an RC receiver, the brushless ESC provides variable power tothe motor allowing proportional speed adjustments.We are using a ESC with a cellrating ranging from 2-4 as we are using 3 celled Li-Polymer battery set up with a lowvoltage cut-off so as this will limit how deeply the battery is allowed to discharge, and

preventing it from being damaged.

Radio transmitting and reciever We are going to use a 6 channel radio setand theoperations of the different channels are being listed below :The first channel is to control the ESC (electronic speed control) hence the motor andthe thrust produced

The second channel is used to control the elevator so as to control the nose position ofthe wing and the angle of attack of the wing for lift or descentThe third channel is to control the rudder of the plane so as to control the yaw motion ofthe plane and hence maneuver it in the direction requiredThe fourth channel is used to control the hatch movement in the fuselage so as to dropthe relief package from the glider


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radio control illustration

Basic Electric powerplant components 1


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Innovation Slider wing extension

Traditional gliders have a solid wing thats made of a single compositematerial.In a radically new concept we at team auk are trying to incorporate theSlider wing extension . As the name suggests ,this mechanism will extend the wing span duringthe course of the flight and there by giving extra lift to the glider ,and as aconsequence of the same greater flight time can be achieved .

The mechanism works with the help of a bell-crank,and is activated by aservo motor.A small rotation of the servo arm is magnified by the bell-crank,which causes wing extension via the push rod, as illustrated in the diagram

We are in the Testing phase of the innovation ,and the feasibility of thesame is being analysed.


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Note:-*The prototype of the glider as depicted in the pictures is made of coroplastand the original glider for the event will be made of Balsa woodAll dimensions in inches if not mentioned

Wright Design Abstract-principal11

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