1 | Page BANSILAL RAMNATH AGARWAL CHARITABLE TRUST`S VISHWAKARMA INSTITUTE OF TECHNOLOGY PUNE- 411 037 (An Autonomous Institute Affiliated to University of Pune) Mini Project On “Flying Wing Mechanism” Submitted By Harshal Patil TE T-31 Pooja Patil TE T-33 Vijay Patil TE T-34 Priyanka Salve TE T-43 Under The Guidance of Prof. G. N. Kotwal Department of Mechanical Engineering 2013-2014
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BANSILAL RAMNATH AGARWAL CHARITABLE TRUST`S
VISHWAKARMA INSTITUTE OF TECHNOLOGY
PUNE- 411 037
(An Autonomous Institute Affiliated to University of Pune)
Mini Project
On
“Flying Wing Mechanism”
Submitted By
Harshal Patil TE T-31
Pooja Patil TE T-33
Vijay Patil TE T-34
Priyanka Salve TE T-43
Under The Guidance of
Prof. G. N. Kotwal
Department of Mechanical Engineering
2013-2014
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VISHWAKARMA INSTITUTE OF TECHNOLOGY
PUNE-411 037
(An Autonomous Institute Affiliated to University of Pune.)
CERTIFICATE
This is to certify that the Mini Project titled “Flying Wing Mechanism” has been completed in the
academic year 2013 – 2014, by Harshal Patil (Gr. No. 111675), Pooja Patil (Gr. No. 111229), Vijay
Patil (Gr. No. 111355) and Priyanka Salve (Gr. No. 111291) in partial fulfillment of Bachelors Degree
in Mechanical Engineering as prescribed by University of Pune.
Prof. G. N. Kotwal
(Guide)
Vishwakarma Institute of Technology, Pune
Prof. H. G. Phakatkar
(H.O.D. Mechanical Dept.)
Vishwakarma Institute of Technology, Pune
Place: Pune Date: 22/04/2014
________________
Examiner
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ACKNOWLEDGEMENT
Words are inadequate and out of place at times particularly in the context of
expressing sincere feelings in the contribution of this work, is no more than a mere
ritual. It is our privilege to acknowledge with respect & gratitude, the keen valuable
and ever-available guidance rendered to us by Prof. G. N. Kotwal without the wise
counsel and able guidance, it would have been impossible to complete the mini
project in this manner.
We express gratitude to other faculty members of Mechanical Engineering
Department for their intellectual support throughout the course of this work.
Finally, we are indebted to our family and friends and for their ever available
help in accomplishing this task successfully. We will be forever grateful to our friend
Mayuresh Marhadkar for his precious advice and for letting us do our project in The
Robocon Arena.
Above all we are thankful to the almighty god for giving strength to carry out
the present work.
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ABSTRACT
It is no surprise that humanity’s first attempts at flight were in the form of birdlike,
human-powered ornithopters. The great artist and engineer Leonardo da Vinci is
often credited as the first to propose a reasonable flying machine in 1490: a giant
bat-shaped craft that uses both the pilot’s arms and legs to power the wings. Though
the aircraft was never built, and we now know that it would not have flown, it was a
remarkable achievement considering the knowledge of the day. At the turn of the
20th century, focus shifted both in the method of thrust production, from flapping
wings to the propeller, and the method of power generation, from the human body to
the internal combustion engine. With the aerodynamic problem greatly simplified, the
impossibility of human flight was disproved by the Wright brothers’ flight in 1903 and
the stage was set for the boom of aircraft developments in the decades to come.
Though work on human-powered aircraft was still carried on from time to time by
several groups in various countries, it would be three-quarters of a century before
anyone mastered the art of human-powered flight.
The problem of flapping-wing flight has been tackled by countless engineers and
craftsmen, but until recently only moderate success had been achieved. The
Subsonic Aerodynamics laboratory under Professor James de Laurier at the
University of Toronto has been a prolific contemporary contributor to the body of
knowledge concerning flapping-wing flight, with successes in remote-controlled
ornithopters, flapping-wing micro air vehicles, and even a full-scale human-piloted
engine powered ornithopter. In 1991 the Professor De Laurier and UTIAS were
awarded the “Diplôme d’Honneur” by the FAI for having flown the world’s first
engine-powered remotely-piloted ornithopter. Theoretical and experimental research
intensified in subsequent years, culminating in the successful flight of a full-scale
piloted ornithopter on July 8th, 2006. A patented wing-twisting mechanism and
extensive research in aero elastic tailoring has kept the University of Toronto at the
forefront of ornithopter innovation for the last 20 years.
An ornithopter (from Greek ornithos "bird" and pteron "wing") is an aircraft that flies by flapping its wings. Designers seek to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in form, they are usually built on the same scale as these flying creatures. Manned ornithopters have also been built, and some have been successful. The machines are of two general types: those with engines and those powered by the muscles of the pilot. The research on Micro Aerial Vehicles (MAV) is comparably young, which has
emerged over the past few years. The ongoing miniaturization of electric
components such as electric motors and the improvements in microelectronics made
it possible to build miniature planes and helicopters at relatively low costs. This
development also made it possible to start imitating insect and bird flight, which
needs a sophisticated miniaturized actuation chain for their flapping wing motion.
The goal of this research is to come up with small aerial vehicles that can operate
independently from ground stations, performing certain operations such as
surveillance or measurement, especially in environments that are hardly accessible
or even dangerous for people.
Wing Design
Ornithopters flapping wings and their motion through the air are designed to maximize the amount of lift generated within limits of weight, material strength, and mechanical complexity. A flexible wing material can increase efficiency while keeping the driving mechanism simple. In wing designs with the spar sufficiently forward of the airfoil that the aerodynamic center is aft of the elastic axis of the wing, aero elastic deformation causes the wing to move in a manner close to its ideal efficiency (in which pitching angles lag plunging displacements by approximately 90 degrees). Flapping wings increase drag and are not as efficient as propeller-powered aircraft. Some designs achieve increased efficiency by applying more power on the down stroke than on the upstroke. In order to achieve the desired flexibility and minimum weight, engineers and researchers have experimented with wings that require carbon fiber, plywood, fabric and ribs with a stiff strong trailing edge. Any mass located to the aft of the empennage reduces the wing's performance, so lightweight materials and empty spaces are used where possible. In order to minimize drag and maintain the desired shape, choice of a material for the wing surface is also important. In De Laurier's experiments, a smooth aerodynamic surface with a double-surface airfoil is more efficient at producing lift than a single-surface airfoil.
camera onboard that sends images to a ground computer from where the vehicle is
controlled.
Figure 1: DelFly.
Robotic Insect
Another interesting project is the so called Robotic Insect, being developed at the
Harvard Micro robotics Laboratory. The underlying concept is the applying motion of
small insects such as flies. For the actuation of the wings of this very small scale
MAV a piezoelectric cantilever is used, inducing an oscillation of the wings at their
resonance frequency, in order to produce high amplitude. The joints are integrated in
the structure as exible parts. The power supply however is not included in this
vehicle, which means that despite of already producing remarkably high lift it is not
yet able to actually y.
Figure 2: Robotic Insect.
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Flapping Wings at ETH
The ASL at ETH also aims to develop a MAV of bird size that is based on the
aerodynamic principles used in insect flight and by small birds. Unlike other
developments in this area, the intended MAV at ETH shall be able to hover like
insects or Humming birds, and so it is supposed to become an interesting alternative
to Flapping Wings at ETH helicopters as currently being developed at ASL.
Furthermore, such an aerial vehicle should be large enough to carry some payload
such as a camera, but still small enough to have high agility. Hovering is closely
connected to unsteady aerodynamic effects at small Reynolds numbers used in
nature by insects and small birds. With a wingspan of 280mm and a weight of about
20g the Giant Hummingbird is one of the largest species in nature that can hover,
and therefore had been selected as natural ante type [2]. The goal, however, is not
to copy nature but to adopt the basic principles.
Figure 3: Female black-chinned Hummingbird in hover. (fromhttp://en.wikipedia.org)
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Aerodynamics of Flapping Wings
When flapping the wings, the airflow is highly turbulent and producing more lift
compared to wing flight. These are a consequence of the permanently changing
wing position during flapping, and are connected to the Reynolds number. In this
section the most important aerodynamic are described, however only as a short
introduction because this has already been subject to previous work by S. Gisler and
O. Breitenstein, where fairly detailed explanations can be found.
Lift
The lift that is produced by applying the wings is characterized by highly un-stationary aerodynamic effects which make it difficult to predict the resulting lift force for a given wing. In order to get a rough idea about what could be expected as lift, and therefore have a boundary for the total weight of the MAV, some simplifications are necessary, which allow applying the 2-dimensional airfoil theory with the formula for lift (L) L = (CL.ρ.v2.A)/2 With the air density ρ Airspeed v Platform area A And, The lift coefficient CL, for a specific angle of attack. The lift coefficient (CL, Ca or Cz) is a dimensionless coefficient that relates the lift generated by a lifting body to the density of the fluid around the body, its velocity and an associated reference area. A lifting body is a foil or a complete foil-bearing body such as a fixed-wing aircraft. CL is a function of the angle of the body to the flow, its Reynolds number and it’s Mach number. The lift coefficient CL is refers to the dynamic lift characteristics of a two-dimensional foil section, with the reference area replaced by the foil chord. The lift coefficient CL is defined by
, where is the lift force, is fluid density, is true airspeed, is platform area and is the fluid dynamic pressure. Applying equation for the Flapping wings requires the following assumptions:
1. Non stationary lifts that occur only when the wings are flapping are neglected, with the result that the resulting lift will likely be higher in reality.
2. The lift coefficient CL is independent of time and location on the wing. 3. Induced inflow is disregarded.