United States of America
Dr. Ashish Bagai, Program Manager, Tactical Technology Office, Defense Advanced Research Projects Agency (DARPA)
The DARPA Tactical Technology Office (TTO) cultivates high-risk, high-payoff tactical technologies. Aerodynamicist Ashish Bagai came to the TTO in March 2012 from Sikorsky Aircraft, where he led the aerodynamic design of the rotor blades for the company-funded X2 high-speed helicopter that in 2010 achieved a top cruise speed of 253 kt in level flight. His TTO portfolio today calls on the technical community to make other Vertical Takeoff and Landing (VTOL) concepts faster and more efficient with equally innovative engineering.
Reflecting on the X2 success, Dr. Bagai observes, “Initially, there were a lot of self-imposed constraints we suffered because of what we’d learned previously. Breaking those bonds meant even though I had been taught how helicopters are built and blades are designed, I was going to have to try something different and more radical because the data presented a different story. The ability to crawl out of the box and have the courage to do it with a team behind you was a huge step forward towards arriving at a successful design.”
DARPA, the U.S. Department of Defense agency charged with forming and executing R&D projects to expand scientific and technological frontiers far beyond immediate military requirements, uses Broad Agency Announcements (BAAs) to spark similar out-of-the-box thinking. Dr. Bagai notes, “Regardless of what we say about how exacting a science engineering is, there’s still a lot of visceral feel to it. There’s a lot that’s experience-based. There’s a lot depending on understanding the numbers that you get. I don’t think we’re at the stage in our computational capabilities where you can punch in a number and know the answer returned is accurate or even correct. I know it takes a lot of engineering experience, thought, and instinct to come out the other end with a good solution. I think there are many astute scientists and engineers out there who understand this and can do this. It’s good to see them be given the opportunity.”
Ashish Bagai grew up in India, first in Bombay and later in New Delhi, with an automobile engineer father, an artist mother and an enduring interest in aviation. “It must have been genetic,” he says. “A photograph I’ve seen in the family album shows me when I was two or four with airplanes in my hand. It was a passion that just grew and continued to develop over the years, fueled in part by the passion my sister exhibited in pursuing her own goals.” The aircraft enthusiast came to the U.S. at 20 to study aerospace engineering. “I first attended Northrop University in Los Angeles, but I had concurrent applications at the University of Maryland and Embry-Riddle. During the summer following my first term at Northrop, I got my admission letters for the fall from both. Maryland obviously had good potential for graduate school. That was something that was always on my mind, so I elected to go there.”
The UMD aerospace engineering curriculum at the time offered space and aeronautics tracks with more specialized departments. Dr. Bagai recalls, “Since I was working on campus, I got involved with the composites lab, and that gave me an inroad into what was going on in the rotorcraft department.” His junior and senior years opened opportunities for internships and apprenticeships under small university research grants. “I was taking my aerodynamics classes at the time, and because I was primarily interested in aerodynamics I applied for some of these grants along with Gordon Leishman, who was teaching one of the classes I was taking. That was really my first introduction into the rotorcraft world in more technical terms.”
Studies of rotor blade pressure distributions, blade tip sweep and related explorations refined the undergraduate’s rotorcraft direction. “I started to develop an interest in low-speed aerodynamics, not that all rotorcraft dynamics is low-speed, but that was essentially the hook that got me into it.” Dr. Bagai spent 10 years at the University of Maryland earning bachelor’s, master’s, and doctoral degrees in aerospace engineering and working as a faculty research assistant. Last fall, he was inducted into the university’s A. James Clark School of Engineering Innovation Hall of Fame for his work on the X2. [Editor’s note: see www.vtol.org/videos.]
Dr. Bagai joined AHS International as an undergraduate in 1989. "As the premier organization involved in the exchange of technical information related to rotorcraft, AHS offered me an opportunity to interact with the most prominent researchers in the field worldwide. AHS has always been generous – permitting students to serve as volunteers in exchange for [free] Forum attendance,” and other benefits, says Dr. Bagai, who has served in several official capacities, including as chair of the Aerodynamics Committee and a member of the History Committee.
As a technical reviewer and later Associate Editor for the AHS Journal, he has been an active member of the Society. "The opportunities were like a parallel career path," says Dr. Bagai, “offering an opportunity to serve and excel, while contributing to the technical community." He also served as the Forum 66 Technical Chair, when the Forum was last held in Phoenix in 2010.
Academia to Industry
His university research launched Ashish Bagai into a rotorcraft career. “My first job was at Boeing in Philadelphia,” he explains. “That was a privilege…. At Boeing, I was with the noise technology group. A lot of the work I had done at Maryland during my graduate years was developing free-wake methods and Boeing had an interest in evaluating the work.”
After a year in Philadelphia, he accepted an opportunity to move to Connecticut, where he started work at Sikorsky in late 1998. “The very first job I worked on at Sikorsky was related to DARPA – the variable-diameter tiltrotor project. Sikorsky wanted someone to work on the aerodynamic analysis of the blades, so I got involved with that.” There, Dr. Bagai advanced to become technical lead for rotor systems, overseeing planning and development of methodologies and blade manufacturing technologies. In late 2004, he took on a unique challenge. “When it was decided that the X2 was to be pursued, I was asked to design the rotor blade.”
Like the XH-59A that tested the Advancing Blade Concept in the 1970s, the new high-speed demonstrator stacked coaxial rigid rotors to overcome retreating blade stall. “It’s still an edge-wise flying rotor,” notes Dr. Bagai. “When Sikorsky set out to do the X2, they set some very firm key performance parameters that were going to address the shortcomings of the original concept. These included improving the aerodynamic efficiency of the rotor system, and that was the challenge I was faced with – specifically the design of the rotor blades.” The X2 blades ultimately combined a non-uniform planform with positive and negative twist and a complex distribution of modern airfoils and thicknesses to derive their aerodynamic properties.
The X2 also benefitted from a rapid prototyping environment. “First and foremost, it was a very small core team,” observes Dr. Bagai. “It was a combination of very wise people who had a lot of experience behind them, as well as some of the mid-generation folks like myself, and some of the younger-generation folks who were very bright and who wanted an exercise of this caliber to learn and grow from it.” The people also worked under streamlined rules. “This was an internally funded program and it was unencumbered by excessive process. Everybody was answerable, but you didn’t get wrapped up in day-to-day bureaucracy as opposed to actually doing real work.”
With a tight budget and a focused team, the X2 ultimately demonstrated the key performance parameters. It earned the 2010 Collier Trophy for the outstanding achievement in aeronautics or astronautics in America and AHS International’s 2011 Howard Hughes Award for the preceding year’s outstanding improvement in fundamental helicopter technology. It also gave Sikorsky technologies for the S-97 Raider now in development. “I think credit is really due to some of the management who ran the team – they were critical to remaining focused on the success of the program,” offers Dr. Bagai. “They were dealing directly with the pressures of a high-profile program, yet not letting that filter down through the system.” He adds, “When you have a setup like that, you bring out the best in people. They give it their best. They really enjoy it.”
Industry to Government
After 13 years with Sikorsky, Ashish Bagai was offered broader VTOL challenges by DARPA as a TTO program manager. “It’s superbly intense. It’s superbly rewarding. It’s extremely intellectual, so who could say no in the end?” He explains, “My current portfolio has two parts to it. One is related to traditional large, open rotor systems – looking at technologies to increase the speed of helicopters by delaying or reducing retreating blade stall. Other technology studies look at high-altitude performance, increases in proprotor efficiency if possible. I’ve also got design studies that are ongoing and some key technologies in the aerodynamics of lifting fans – an expansion into some less common VTOL concepts.”
An upcoming BAA likely will focus on VTOL X-plane technologies that increase speeds dramatically, improve hover efficiency and hike the efficiency of helicopters or some other VTOL aircraft, all without giving up the useful load of the aircraft. “The design space I intend to look for – in the VTOL X-Plane program specifically – is you have these performance objectives, and they dictate some form or configuration of aircraft. It may be a tiltrotor, a tiltwing, some combination of lifting fans. Whatever it is, I don’t think that’s where the design stops. The next step is recognizing what are the subsystems that go into this to enable it to be successful, above and beyond what we’ve done in the past.
“We’re all familiar with all the numerous previous attempts that have looked at various configurations. It’s important to understand why they haven’t succeeded, what their shortcomings have been, what’s changed and how to make them happen now. But I want to get beyond that. Are we looking at another hybridized wing with a propeller that can be used for vertical flight, or are we asking what is the true cross-pollination across the fixed wing and rotary wing worlds? It’s the confluence of that engineering design paradigm that really needs to take place right now.”
Not all of Dr. Bagai’s TTO programs focus on aerodynamics. “I’ve also got a study being performed on robotic articulated landing gear. The intent here is to look at alternatives to the traditional ski and wheel landing gear for aircraft. That’s interesting because it talks about merging robotics with lightweight, vertical flight concepts. It may ultimately permit operations from unprepared surfaces, extremely sloped landings and moving surfaces like small ship decks. That’s got a collection of technologies that includes design of robotic landing gear, energy attenuation, adapting variable stiffness joints, touch sensors and associated control laws – things that expand upon my typical area of expertise but are applicable to vertical takeoff aircraft.”
TTO program managers aim to transition their technologies to real-world applications. “I think one of the motivations for what we do at DARPA is to create transformational technologies that may be applicable to a product sometime in the future. What we don’t do is develop requirements or specifically answer any service’s requirement. We’re very particular about creating an objective challenge. You create a challenge because you recognize there’s a potential need for something. You don’t necessarily define that need a priori or say, ‘This is how I intend to use it.’” Technical Innovation also comes with a caution. “I’ve seen in the past attempts to develop enabling technologies that turn out to add more complexity to an already complex system. I think what I would underscore is elegance in design.”
Dr. Bagai expects VTOL designs to take different paths in the coming decades. “I think it will depend a lot on the weight class of rotorcraft. I think if we have the current system of propulsion or power systems, then the large open rotor is difficult to dispense with because it is the most efficient means of hovering. If you have a large hover-duty cycle, I’m not sure there’s much of a way around that. But on the other end of the spectrum or closer to the middle in the weight class categories, I think we’re likely to see quite a dramatic change in concepts.
“I think unmanned systems will become much more popular. I think they’ll be combined with advancements in rotor design that I’m trying to push, and also with autonomy, flight controls and systems and with new propulsion systems – a larger mix of organic fuels and electric systems, perhaps things we haven’t thought of yet. I think the combination of distributed propulsion and multi-purpose systems will become more important.” Dr. Bagai offers, “Rather than have systems that are singular in purpose, you’ll end up with designs to do multiple things, and those will be supported by advancements in controls laws to fly and control the aircraft. I see a dichotomy – with the large open rotor system retaining its place, and yet a huge, brand-new design space opening up that’s enabled by some of these advancements that we’ve talked about.”
Leadership Profile: Vertiflite March/April 2013