SUMMER PROJECT

AEROMODELLING CLUB

RC ORNITHOPTER

BY: ANKIT CHOUDHARY, VARSHA YADAV, MRIGANK SINGH AND

PARIDHI KABRA

Content:

What is RC Ornithopter

History of the ornithopter

Aerodynamics of RC Ornithopter

Main parts:

Gear Box

Main Body

Wing

Tail Part

How does it fly?

Dimensions we used for our Ornithopter

Difficulties we faced during its construction

Improvements we can make

Applications of RC Ornithopter

What is RC Ornithopter

An ornithopter (from Greek ornithos "bird" and pteron "wing") is an aircraft that flies by flapping its

wings. Those machines are driven by rotating airfoils. In an ornithopter, the driving airfoils have an

oscillating motion instead. This imitates nature, because no animals have any rotating parts.

The ornithopter works on the same principle as the airplane. The forward motion through the air allows

the wings to deflect air downward, producing lift. The flapping motion of the wings takes the place of a

rotating propeller. The wing design is designed with the spar as far forward of the airfoil but still having

acceptable dimensions of strength. Engineers and researchers have experimented with wings that

require carbon fiber, plywood, fabric, ribs, and the trailing edge to be stiff, strong, and for the mass to

be as low as possible. Any mass located to the aft or empennage, reduce the wings performance and

hinder the design of the ornithopter. In order to calculate the performance of the ornithopter, the wings

lift is determined by the lift of the wing versus weight, drag and thrust. A smooth aerodynamic surface

with a double-surface airfoil is more efficient then a single-surface airfoil to produce more lift.

How is it different from an airplane or helicopter?

Unlike airplanes and helicopters, the driving airfoils of the ornithopter have a flapping or oscillating

motion, instead of rotary. As with helicopters, the wings usually have a combined function of providing

both lift and thrust. Theoretically, the flapping wing can be set to zero angle of attack on the upstroke,

so it passes easily through the air. Since typically the flapping airfoils produce both lift and thrust,

drag-inducing structures are minimized. These two advantages potentially allow a high degree of

efficiency.

In propeller- or jet-driven aircraft, the propeller creates a relatively narrow stream of relatively fast

moving air. The energy carried by the air is lost. The same amount of force can be produced by

accelerating a larger mass of air to a smaller velocity, for example by using a larger propeller or adding a

bypass fan to a jet engine. Use of flapping wings offers even larger displaced air mass, moved at lower

velocity, thus improving efficiency. In order to create an effective ornithopter, it had to be able to flap

its wings to generate enough power to get off the ground and travel through the air. Efficient flapping of

the wing is characterized by pitching angles, lagging plunging displacements by approximately 90

degrees.[23] Flapping wings increase drag and are not as efficient as propeller-powered aircraft. To

increase efficiency of the ornithopter, more power is required on the down stroke than on the

upstroke.[24] If the wing on the ornithopter was not flexible and flapped at the same angle while

moving up and down, it would act like a huge board moving in two dimensions, not producing lift or

thrust. The flexibility and move-ability of the wing let it twist and bend to the reactions of the

ornithopter while in flight.

History of the ornithopter

Birds inspired Leonardo da Vinci when he designed his ornithopter in 1490. Leonardo da Vinci was

interested in flying during 1488–1514. He never saw his dream of flight take place because his

ornithopter was too heavy and required too much energy to produce lift or thrust. In 1929, the

human-powered ornithopter constructed by Alexander Lippisch was towed into the air and glided

around. In 1959, in England, another ornithopter was towed into the air and demonstrated the

ornithopter being a birdlike machine.[22] By the 1960s, there were powered unmanned ornithopter

flights of various sizes demonstrating how ornithopters flew. In 1991 Harris and DeLaurier flew the first

successful engine-powered remotely piloted ornithopter in Toronto, Canada. By 1999, there was an

ornithopter design that was designed to take off from a level pavement.

Aerodynamics

Lift is the force that utilises the fluid continuity and Newton's laws to create a force perpendicular to the

fluid flow. It is opposed by weight, which is the force that pulls things towards the ground. Thrust is the

force that moves things through the air while drag is the force of flight that is an aerodynamic force that

reduces speed.

The ornithopter wing is attached to the body at sight angle,which is called the angle of attack, The

downward stroke of the wing deflects air downward and backward generating lift and thrust. Also the

wing surface is flexible, this causes the wing to flex to the correct angle of attack we need in order to

produce the forces that we want to achieve flight.

The mechanics of flapping flight are far more complicated than that of fixed -wing flight.For an aircraft

with fixed wings. Only forward motion is necessary to induce aerodynamic lift. But for flapping flight

wing not only has to have a forward motion, but also must travel up and down. This additional

dimension means the wing constantly changes shape during flight.

Main Parts:

Gear Box

A gear or more correctly a "gear wheel" is a rotating machine part having cut teeth, or cogs, which mesh

with another toothed part in order to transmit torque. Two or more gears working in tandem are called

a transmission and can produce a mechanical advantage through a gear ratio and thus may be

considered a simple machine. Geared devices can change the speed, magnitude, and direction of a

power source. The most common situation is for a gear to mesh with another gear, however a gear can

also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.

Main Body

Body Frame It is made of balsa wood and a carbon rod of 3 mm diameter in the form of a triangular

shape. In order to minimize the weight of our aircraft Styrofoam has been used and appropriate sized

gaps have been made for placing the battery, ESC and receiver and then stuck in the gap of body frame

and we also made the seperate compartment for fitting servos which are used to assign the directions to

the ornithopter. A proper mount is attached in front of the body frame for the motor and gear box.

Wing

In order to create an effective ornithopter, it had to be able to flap its wings to generate enough power

to get off the ground and travel through the air. Efficient flapping of the wing is characterized by

pitching angles, lagging plunging displacements by approximately 90 degrees. Flapping wings increase

drag and are not as efficient as propeller-powered aircraft. To increase efficiency of the ornithopter,

more power is required on the down stroke than on the upstroke. If the wing on the ornithopter was

not flexible and flapped at the same angle while moving up and down, it would act like a huge board

moving in two dimensions, not producing lift or thrust. The flexibility and move-ability of the wing let it

twist and bend to the reactions of the ornithopter while in flight.

Tail Part

The tail is a V shaped tail with an angle of 120 degrees. It is made of balsa . Plastic has been used to

cover it and tightened by a blower. Two servos are mounted on the body frame to move the rudders

attached to the tail which are used to change the direction and pitch of the ornithopter.We keep

rudders in different ways to change the direction-

If both the rudders are in upward direction then Ornithopter deflects

downward.

If both the rudders are in downward direction then Ornithopter deflects

upward.

If rightward is in upward direction and leftward is in downward direction then

Ornithopter deflects leftward.

If rightward is in downward direction and leftward is in upward direction then

Ornithopter deflects rightward.

How does it fly?

Most important thing to notice about the ornithopter is that it cannot land or take-off to the groung

directly, so support must be provided during this crucial times.

Now to fly an Ornithopter we trigger the motion of it by providing it support through our hands. For

initiating the motion we switch on the power supply for motor and servos by simulator (transmitter) and

then the whole dynamics of the aircraft is controlled by simulator. Directions or throttle should be

controlled appropriately for smooth and stable flight.

Dimensions we used for our Ornithopter

We made the ornithopter plan first on paper after referring to various websites and seeing some

videos on youtube.

The main task was to keep the body light as well as make a strong body design along with

obtaining appropriate lift. We have planned the ornithopter to make 4 -5 flaps per second

(flapping rate is adjustable according to situation)

Dimensions

The body is 30 cm long

Wingspan-- 1 meter

Tail-- 15 cm

Motor: 1700 kV hextronix brushless outrunner ( 25 g)

Battery: 7.4 V LiPo

Body Frame It is made of balsa wood and a carbon rod of 3 mm diameter in the form of a

triangular shape. Styrofoam has been cut and stuck in the gap and appropriate sized gaps have

been made for placing the battery, ESC and receiver. A proper mount is attached in front of the

body frame for the motor.

The Tail The tail is a V shaped tail with an angle of 120 degrees. It is made of balsa. Plastic has

been used to cover it and tightened by a blower. Two servos are mounted on the body frame to

move the rudders attached to the tail which are used to change the direction and pitch of the

ornithopter.

Gear Box I want to elaborate more on Gear box because it was most difficult task we felt during the

making of gear box. We had to get a gear ratio of 50:1. And the most difficult task was to find the gears.

We couldn’t find any … at last we fabricated the gears from the 4i lab. The gears are of three types … 2

gears of 40 teeth, 3 of 8 teeth and one of 16 teeth. These have been arranged suitably in series to get

the desired gear ratio. At first we used foam tape for the gear box, but it was destroyed as it was weak

(could not bear the load) … then we remade the gearbox using wood.

The spars are attached to the driving gear mechanism using a V shaped arrangement made of strong

wood. The motor drives the driving gear, and the Output gear drives the V attachment which flaps the

wings . The wing flaps are made symmetric by proper adjustment of the wing attachments to the

gearbox.

Difficulties we faced during its construction

The main difficulty we faced during the construction of the ornithopter was in the construction of its

gear box to make gear box according to proper ratio and also of good strength. We all the time kept care

about the weight of the ornithopter also.

Improvements we can make

Our Ornithopter would be better if we had constructed a strong gear box and also of large or

appropriate size so that wings can flap to their max they can. Also you must be careful about the design

of the wing. You should search properly, see professional’s ornithopter to make wings more effective.

These are the main drawbacks of our Ornithopter which we personally feel.

Applications of RC Ornithopter

The main applications of RC Ornithopter are as they can be made to resemble birds or insects, they

could be used for military applications, such as espionage|spying without alerting the enemies that they

are under surveillance. Several ornithopters have been flown with video cameras on board, some of

which can hover and maneuver in small spaces. In 2011, AeroVironment, Inc. announced a remotely

piloted ornithopter resembling a large hummingbird for possible spy missions.

A SPECIAL THANKS TO ALL OUR CLUB COORDINATORS………..