“The common question that gets asked in business is “why?”, that’s a good question, but an equally valid question is, “why not?”.” ~Jeff Bezos (CEO of Amazon)
Fig. 1: Image Representing a Typical Amazon Air Drone
Early December of 2013, Amazon CEO Jeff Bezos, revealed to the world a new dimension to fulfill their customer’s online shopping experience on popular news show “60 minutes” of CBN news. It took correspondent Charlie Rose and the 60 minutes crew completely by shock as he walked into a secret R&D unit to find what looked like a flying tarantula. It was in fact a drone. To be more precise, it was a UAV (Unmanned Aerial Vehicle) with eight propellers (commonly known as an “Octocopter”). At first glance, he had no idea what purpose that it would fulfill. Bezos played a demonstration video showing how the drones pick up the packages which are placed in a yellow Amazon bucket and deliver them to the consumer within a period of 30 minutes.
With its new found concept, Amazon promises delivery of consumer goods within a period of 60 minutes. As the commercial use of UAV drones is restricted by the FAA (Federal Aviation Administration, controlling board for civil aviation in the United States of America), amazon has not yet received its clearance to operate drones commercially concerning certain safety regulations. They are yet to come up with redundancies which will protect the drones from rough weather and other causalities (just imagine kids trying to throw stones or dogs chasing low flying drones!). However, Jeff Bezos promises to offer a sight where people would see drones zipping around the sky later in this decade.
The Science Behind the Drones
This technology is not applicable to all amazon products (yet). The load carrying capacity set by Amazon is 2.3Kgs (5 pounds, for the FPS system fans). The package is packed into the yellow Amazon bucket at the Amazon fulfillment centers, where they are carried by the drones to their destinations. During this journey many different mechanical, electronic and computational components of the drone must play a team game to ensure optimum functioning.
The drone used by Amazon Prime Air is an Octocopter, meaning that it has eight rotor blades arranged in an octagonal arrangement. The rotation of the rotor blades create a pressure difference, forcing air to strike the ground which will give it the required thrust. Therefore, eight rotor blades implies that the required thrust power is distributed equally among the rotors reducing dimensional requirements. If the thrust force produced by the rotors is equal to the weight of the drone, the drone will hover in the air, additional thrust will supply lift.
Fig. 2: Diagrammatical Figure Showing Yaw Mechanism in a Quad Copter
The above pic demonstrates the yaw (rotation about the vertical axis) mechanism in a quad copter
The design of the structure supporting the rotor blades must consider the torque forces acting on the rotor beam (arms). The moment of the blade unit caused on the arms will cause bending, therefore the design parameters must consider all possible load failures
Fig. 3: Graphic Showing Inner Electrical Hub of a Quad Copter
The central hub of the drone will contain the brain of the drone i.e., the control unit. The control unit will consist of a battery pack, motor(s), gyroscope, actuator, a receiver, processing unit, a wide array of electronic sensors, GPS etc. This should be as light as possible to provide for greater load carrying capacity. The motor must be governed by an actuator device which will vary the rotor speed (in rpm) as per the thrust required.
The physical model for the Octocopter is developed from the same equations governing the motion of a helicopter.
In a helicopter, the rotor having a diameter of “d” (meters) spins with a rotational speed of N (rpm) pushing down air having a
(Greek letter Rho, Kg/meter3) producing a thrust to lift the whole system having a total mass “m” (kg) against the gravitational pull of the earth “g” (9.8meter2/sec). The power P (Watts) required to run the Octocopter is the rate at which work is done leading to an equation looking something like this
Since there are eight rotors in the Octocopter, the effective area of the blades is given by
(Area of a circle)
Next, we can obtain approximate results by assuming certain values as long as they are not random and are logical.
The density of air at mean sea level is 1.2Kg/m3, the rotor blade diameter being 0.24m (24 cm) considering the dimensions of the yellow bucket, if the payload capacity is 5 pounds and the mass of the copter body itself is considered to be 10 pounds, the total mass of the Octocopter system will be 6.8 Kgs the gravitational acceleration is 9.8m/sec2
Plugging in these values would give the effective area A = 0.362m2 and power required to run the Octocopter in hovering conditions would be P = 550 Watts. Since the thrust upwards initially and then run faster for longer distances (to keep the 30 minute deliveries promise), more power is required. Considering a running time of 30 minutes (1800 seconds), the energy requirements of the battery to be used will be formulated from
A battery is specified by the energy produced per unit mass (Eb, units: MJ/kg). Therefore the mass of the battery required would be E/Eb. Therefore an appropriate battery is selected considering cost and weight. Most of the times, a Lithium-ion battery is utilized in quad copters (Eb = 0.875 MJ/kg).
These results (although not very accurate) provide a basic idea that goes into the physical design of the drone. Further, material selection (light and strong), electronics, programming and design of the mechanism thathelps hold the packages are some of the important considerations that the design crew had to bear in mind.
The odds failure of the prime air are as many as that of success. Amazon prime air has received both positive and negative comments from tech gurus and enthusiasts all around the world. So, is the Amazon Prime Air just a reach for the skies or is it going to be a game changer? Read on.
Predicaments and Impact on the Future
The main hurdle pressing down the amazon prime air project is the limitations of drones for commercial use by the Federal Aviation Administration, who are working on laws to allow drones to operate commercially, which are expected to be issued by 2015. Until then Amazon are working on redundancy tactics to ensure safety to the public. You wouldn’t want a drone landing on your head, would you?
One of the main reason behind the criticality commercialization of drones is the opening of a new danger that is, “Drone Terrorism”. Drones can easily carry dangerous explosives and cause mayhem being after all this, untraceable, or even traffic drugs, even drone surveillance by governments and spies are against democracy. Such are the hurdles to be surpassed.
In spite of the innovative concept by Amazon it has received much criticism from well-known tech websites around the world, Wired.com’s writers stated “Even if the feds let them fly, the Amazon Drones are a complete nonsense,” while some claimed it to be a publicity stunt by CEO Jeff Bezos also affecting the credibility of CBN’s 60 minutes. But are these statements valid or are they just narrow sighted? This would make for a pretty good debate topic. When credit cards and debit cards came out, people questioned the security of their money, but today credit cards are among the most popular modes of payment. Not that there are a few faults (in terms of frauds) here and there, but it never stopped it from being an essential element in every person’s wallet. It will also be wise of us to remember that the success of theAmazon e-kindle reader is threatening to diminish the print publishingbusiness, especially newspapers. Amazon Prime Air does look to do the same to package delivery systems. This has also triggered interest in other firms who are testing out to include drone operations, of which include Domino Pizza, DHL and UPS.
Fig. 4: Dominos Testing Amazon Air For Pizza Delivery
It is highly probable that Amazon Prime Air would come out in the European countries before the United States, since the commercial drone concept is booming in Europe. Nearly 1000 unmanned commercial drones are licensed to fly in over a dozen European countries led by France, England and Germany. One-third of nearly all the drone systems in the world are being produced in Europe out of which 80% are being made specifically for civilian purposes. The introduction of Amazon Prime Air into such a market would almost certainly catalyze a revolution. This concept would give out a chain reaction giving out a dozen more applications, such as transport of medical supplies, monitoring the wildlife, cargo and firefighting to name a few. In the big picture, this boom will cause the revival of a dying aerospace industry which will help the economy and help create jobs across the world. Therefore the race is on as to which country will clutch this global opportunity, not hastily, but delicately, so as to ensure it cannot be used against mankind.