On 21st November 2020, the students of class XI and class XII of Mushtifund Aryaan Higher Secondary School(MAHSS) had the opportunity to interact with and gain invaluable knowledge on ongoing research in the field of drones and helicopters from Dr. Rajneesh Singh. On behalf of the students of MAHSS I would like to thank our Director, Mr Vyankatesh Prabhudesai, for providing us with this opportunity to interact with such an imminent personality.
Dr.Rajneesh Singh started off by telling us about himself. He was born in an area close to the border between UP and Uttarakhand called Dhampur. He studied from 7th to 10th grade in Lucknow. He then moved to IIT Kanpur for his BS and then went to IISC, Bangalore for his MS where he met our Professor, Sir Vyankatesh Prabhudesai. He fondly talked about the beautiful memories from IISC. He then moved to USA to obtain his Doctorate in Aerospace Engineering from the University of Maryland at College Park which included research on helicopters, how they made noise and how to predict what noise they made.He then moved to Michigan and worked for about 10 years in the Aerodynamics group at General Motors.He then joined Army Research Laboratory (ARL) in 2009 where he is still working.
Dr. Rajneesh Singh leads a team in the Vehicle Technology Directorate (VTD) of the Army Research Laboratory at Aberdeen Proving Ground, MD. The ARL is Army’s Corporate Research Laboratory providing foundational research in support of U.S. Army modernization. His group conducts research to enable highly-manoeuvrable, high-speed, energy-efficient air vehicle platforms ranging from small Unmanned Aerial System (UAS) to heavy lift rotary wing aircraft.
Dr. Singh then asked us to recognize four helicopters. The students accurately recognised the first three as Apache, Chinook, and Osprey.The fourth one, Sikorsky X2, is an experimental helicopter designed to demonstrate high speed capabilities and only one of it has ever been built.While the first three have speeds on the scale of 250-300 kmph the Sikorsky X2 has a speed of nearly 500 kmph. All four of the helicopters had drastically different designs as different designs are different ways by scientists to approach high speeds.He said that the specialty of the Osprey is that it is a combination of helicopter and fixed wing aircraft.
He then said that first helicopters flew in the 1940s which means that helicopters have been around for nearly 80 years but in the last 10 years drones have made quite the revolution. He said that as technology is advancing these drones are becoming more important and relevant. We then learnt about different applications of drones and saw a few drones of different designs all of which had been built less than six years ago. Dr.Singh pointed out that while most helicopters had one or two rotors the drones had four or more rotors. He also mentioned that helicopters had a turbo-shaft engine along with drive shafts and gears which are used to spin the rotors but the drones have electric motors which are either running on battery or engine powered generators. He also mentioned electric motors available are unable to spin the rotors of helicopters which have a large radius(Apache’s rotor has a radius of 38 m) while most drones have a rotor of radius of only 4 feet.
Dr. Singh then mentioned that due to advancements in electric motors, new control technology, and new materials, a new class of drones are coming into play which is the focus of his research. A lot of math and physics is involved in deciding what design should be used,how many rotors should be used and how they should be arranged.
He said that although helicopters and drones are different vehicles there are certain attributes which are required from both such as performance, ability to fly longer and faster,agility and manoeuvrability. From a military point of view, they need to create less noise and should be able to continue flying even if a certain part fails.
He then explained to us why this was so difficult to create a design that can fly fast and also hover a vertical take-off and landing (VTOL) at the same time. He said that this would also help us to know the difference between a helicopter and a fixed wing aeroplane. There are two main parameters to understand this- hover inefficiency and disk loading.
Hover efficiency measures how efficient the design is in doing a vertical take-off.
Hover efficiency=Vehicle Weight/Power req. to hover
Disk loading=Vehicle weight/ Rotor disk area
The graph between these two (Hover Efficiency as y – axis and Disk Loading as x-axis) was a rectangular hyperbola which means that with increase in disk loading, hover efficiency decreases and vice versa. In other words, as rotor disk area increases for given weight power required to hover given weight decreases.
We were then showed a video shot in Maryland in which a student sitting inside a helicopter with huge rotors is able to lift it simply by cycling. He was able to lift the helicopter with such less power as the helicopter had a very high rotor disk area. However, the trouble is that it would be difficult to move such a design forward and hence it would move slowly compared to a more compact design with a small disk area. So, a design with large rotor disk area would do a vertical take off easily while a design with small rotor disk area would move forward more easily.
Dr. Singh then explained three different designs which are used to overcome this difficulty. In the first one there are “edgewise rotors”.As helicopters/drones take off they move sideways which means the spinning rotor is moving sideways but rotors do no prefer to move sideways. As a result, it requires more energy and hence, is an inefficient method. The second design is called lift and cruise design wherein helicopters have one rotor for vertical take-off and another for forward movement. In this method there is no edgewise flight but the flaw is that the helicopter has to carry dead-weight in either mode. The third design is called tilt-X (eg. Osprey) in which the wing or rotor is tilted. In this case there is no dead weight and the rotors are not moving in an unpreferred direction. However, the downside is that the design becomes complex and lowers reliability and increases maintenance (X indicates that either the wing or rotor or both may be tilted for eg. in Osprey both are tilted).The design is chosen based on priority and requirement.
Dr. Rajneesh went on to explain how different aspects of math and physics are involved in the designs such as aerodynamics and fluid mechanics. He went on to say that the shape and structure should be decided and the materials can’t be too heavy or too weak and hence need to be chosen carefully. Parameters such as air density and temperature must also be taken into consideration. Guidance and control designing is a crucial aspect.Dr. Rajneesh then said that there were a few other areas of research such as autonomy. Power and propulsion is also another area of research which focuses on providing energy to move the rotors. Battery technology is a new upcoming technology which is critical to how new designs can be created. Fuel cells in which hydrogen is used are also being researched.
Dr. Rajneesh then showed us the history of aviation including helicopters. He said that the next big thing could be flying cars and that our generation would probably sit in one. Uber apparently has claimed that the cost for flying cars would be similar to their luxury cars.
Dr. Rajneesh ended off by giving us advice that first of all we need to be curios and always ask questions. Secondly, teamwork and cooperation is extremely important. Finally, Dr. Singh gave us an invaluable advice which can never be given or received too many times-“Work hard”.
After this, Dr. Rajneesh Singh answered the questions posed by the students of MAHSS.
The first person asked how students can inculcate the habit of looking at things scientifically and whether research is something that comes after graduation.
Dr. Rajneesh said regarding the first part that it comes down to curiosity and asking questions.
Regarding research Sir that the most crucial part regarding research is defining the problem. He said that we need to know what other researchers have done in the past and we also need to know the current level of research and identify what it is lacking. Dr. Singh said research may not necessarily come after graduation. He said that as we have easy access to internet, we can easily do research on our own.
The next question was asked by Mrugank Pednekar of class 12th.He asked how autonomous drones were better than manually controlled ones.
Dr.Singh said that autonomous drones can be used in areas which had the three D’s-dull,dirty,dangerous.
The next question was asked by Vignesh Gaonkar from the coaching batch. He asked what crazy ideas are used to design drones?
Dr. Singh replied by saying that 3D printing is being widely used now and research is ongoing into 3D printing with regard to drones.
A few other questions were asked which were beautifully and brilliantly answered by Dr. Rajneesh Sardesai.
After this Ronit Kuncolienkar, a student of class 11th summarised the lecture and proposed vote of thanks on behalf of the Institution.
I would like to thank Dr. Rajneesh Singh for taking time out of his busy schedule to impart his invaluable knowledge to us. I would also like to thank our Director Sir Vyankatesh Prabhudesai for organizing the guest lectures which give us the opportunity to interact with such eminent personalities from time to time and allow us to learn new and exciting things.
Aariz Shaikh XI Regular, MAHSS