Project seminarintroducing

R/C WIG Hovercraft a.k.a. Junior

INTRODUCTION

Move anywhere you want to despite of the terrains.

1Move on ground like a car

2Float on water

like a boat

3Fly in air like

an aircraft

What exactly is junior? Junior is a all terrain vehicle that can

R/C WIG hovercraft is a radio controlled wing in ground effect hovercraft. It will use ground effect to fly. It is a new type of ground effect vehicle. Conventional hovercraft can only hover over the surface but it has the capability to fly up like airplanes. The design was selected via an iterative design methodology in which many different designs for the five separate sections; namely, thrust system, lift system, platform & skirt, wing design and RC control/steering, were considered.

Introduction cont.

SR.N1

The idea first presented by Emanuel Swedenborg in 1716.. In 1876 the true design of a modern day hovercraft was given by John B. Ward.. On the 25th of July 1959, Christopher Cockerell's invention, the SR.N1 crossed the English Channel from Calais, France to Dover, England.

Prin

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ratio

nA Hovercraft is a vehicle which travels over any surface on a cushion of air which is trapped in a chamber under the vehicle. This chamber is supplied with air under pressure from an axial 3-blade lift fan. The top and bottom of the chamber is formed by the vehicle bottom and the surface over which the vehicle is traveling respectively. The sides of the chamber are formed by the flexible skirt. The simplest and effective skirt is bag type skirt as shown in Fig. below

Principle of ground effect

When a wing is flown very close to the ground, wingtip vortices are unable to form effectively due to the obstruction of the ground. The result is lower induced drag, which increases the speed and lift of the aircraft.A wing generates lift, in part, due to the difference in air pressure gradients between the upper and lower wing surfaces. During normal flight, the upper wing surface experiences reduced static air pressure and the lower surface comparatively higher static air pressure. These air pressure differences also accelerate the mass of air downwards.

Military services: Assault vehicles and transporting troops Carrying bomb diffusing robot to the place of more height like building’s roof etc. Can be used as a target vehicle by military, air force and navy. Hover over the land mines and can give necessary data by reaching the enemy’s location Exploring the vast number of shallow and narrow waterways that cannot be reached by

boat . Wildlife conservation and research

The purpose of making this project is to give a concept and construct a R/C WIG hovercraft that will fly using ground effect.

Objective and significance

Objective

Significance

The project shall be made in following phases:

METHODOLOGY

Wing constructionHull constructionSkirt constructionLift systemThrust systemSteering systemElectronics assembly

winghull

skirt

Rudder

Lift system Thrust system

Wing construction• This is the additional feature that we are including in the hovercraft. It will provide

the capability of flying to hovercraft. So, we have given more attention to wing design. We have used two software XFLR5 & Nasa’s FOILSIM III Student Version for determining wing specifications and for the analysis of wing.

• Construction Depron is a light weight material like a thermocol but it is much more strong and flexible. It can be simply bent to form a wing of required wingspan and cord. Its top and bottom surface must be covered with tape in order to minimize the skin friction drag. For camber and angle of attack rectangular shaped depron can be inserted in wing as shown in figure above. The wing will be attached to body with carbon rod.

Fig. : Depron Wing

Final specifications determined after analysis on FoilSim III

Leading edge

Trailing edge

OUTPUT OF FOILSIM III

Hull construction

The hull can be considered as the chassis of a hovercraft.it has all the mountings over it. It should be light weighted to make a hovercraft fly.it will be made of depron. The platform of the hovercraft is important as it will house all of the components and must take all of the respective loads. “Depron” was selected due to its light weight and strength properties. The overall size of the hovercraft has been selected as 550 mm in length by 350 mm in width. The final design of the platform can be seen in Fig.

Fig.: Hull or platform.

Skirt construction

Skirt does not allow the pressure created inside the chamber (the top and bottom of the chamber is formed by the vehicle bottom and the surface over which the vehicle is traveling respectively) to escape from it. The sides of the chamber are formed by the flexible skirt. The bottom of the skirt is opened the pressure escapes from there and in reaction to that it provides lift to the hovercraft. Skirt shall be made up of poly urethrine or vinyl coated nylon.

TYPES OF SKIRT:There are three basic kinds of skirts that can go on a hovercraft1. BAG SKIRT2. SEGMENTED SKIRT3. JUPE SKIRT

The bag skirt was chosen from the available options because: Better stability It weighs less It is much cheaper.

Skirt construction contd.This design is readily used in industry as one of the more reliable constructions. In this design the lift air is ducted directly into the skirt which then inflates. The skirt allows the air to exit under the craft using specified holes in the skirt. This air flow under the craft creates the high pressure which lifts the ACV. The skirt is constructed using a Polyurethane-Coated Nylon Fabric which is attached directly to the platform at two separate locations sealed off air tight.

Fig.: Bag skirt

Lift System The air ejected from the propeller is allowed to flow downwards that will make the required cushion of air. The weight distribution on top of the deck is arranged so that the air is distributed throughout the cushion volume in an approximately even fashion to provide the necessary support. A air duct will be made for proper air flow under the body. For producing enough lift a high rpm brushless motor will be attached to a 3-blade propeller of dimension 10 x 4.7(Inches).A separate battery and ESC (Electronic speed controller) will be attached to the motor.

Fig.: Lift system

LIFT SYSTEM

• A 3-blade propeller of 10 x 4.7

(inches) connected directly to a brushless dc motor that is capable of producing 1.2 kg of thrust will be used for the thrust system. A separate battery and ESC will be connected to the motor. The size of the propeller (diameter), pitch of propeller and rpm are the determining parameters for the

thrust force.

Thrust System

Fig.: Thrust system

Motor stand

ESC

• Steering System • The steering will be remote controlled. The leftward and rightward movement of hovercraft will be controlled by the rudder.

• The two rudders will be connected together by a thin plastic connector. The one of the rudder will be governed by a servo motor.

• The servo motor shall be further controlled with an ESC (electronic speed controller) and will take power from battery that will be used for lift.

• A receiver will be mounted on the motor stand of thrust system while the transmitter will be with the operator.

Rudder

3

Electronics assembly

The final stage will be adding of all the electronic components like receiver & transmitter for radio control, assembling the lift motor, thrust motor and servo motor with the rudder.

Fig.: Block diagram of electronics assembly.

Calculations

After calculating the weight of wing, body, skirt and all the electronics components the total weight of project comes out to be 1.12 kg or 10.99 N.

density of depron: 0.03616 g/cm^3

From table the speed at which minimum effective 10.99 N lift generated is 25 kmph (actually 14N). So, by calculation we found that the hovercraft will start to takeoff at a speed of about 25 kmph.

There is no need to calculate effective thrust produced by motor because we will be using a combination of motor and propeller that are capable of producing 1.2 kg thrust with pre- defined configurations.

Formula used: Mass = density x volume

Budget

Time Table

Original images of components

Thank you

Total weight of entire wing span = (91.64+10) g = 101.64 g Total weight of all the electronic components = 562 g Body: Dimensions = (55 x 35 x .5) cm Area = 962.5 cm2

Weight = (962.5 x 0.03616) g = 34.804 gTotal weight of body or hull = 2 x 34.804 = 69.60 g (two layer of depron) Skirt Length = 2(55+35) = 180 cm Area = 180 x 4 cm (height is 10% - 15% of breadth of hull) = 720 cm2

Total Surface area= 35 x 55 + 720 - 15x50 = 1895 cm2

Thickness = 0.2 cm Skirt weight = 379 g Total weight of craft = weight of wing + weight of all components + weight of body + weight of skirt material = (101.64 + 562 + 69.60 + 379) g = 1.12 kg Therefore, total weight to be lifted = 1.12 kg = 10.99 N