Gerrard Cowan
By Gerrard Cowan

Gerrard Cowan is a freelance journalist who specializes in finance and defense. Follow him on Twitter @gerrardcowan


Q-and-A with U.S. Army’s Dr. Jaret Riddick

The U.S. Combat Capabilities Development Command’s Army Research Laboratory (ARL) is the service’s in-house science and technology epicenter. It sits under the Army Futures Command (AFC), which is driving efforts to meet the Army’s six materiel modernization priorities.

DARPA UAS concept
Future military unmanned aircraft systems could benefit from research into quiet eVTOL rotor technology. DARPA Artist Concept

Dr. Jaret Riddick is director of ARL’s Vehicle Technology Directorate. In an interview with, he discussed ARL’s efforts to learn from pioneers in the eVTOL space, notably through its collaboration with Uber. In May 2018, the two organizations announced a Cooperative Research and Development Agreement (CRADA) to work together on technologies supporting Future Vertical Lift, one of the modernization priorities. This has a particular focus on the creation of stacked, co-rotating rotors, which would be significantly quieter than traditional paired rotor approaches, an advantage with benefits to both the military and Uber, as Riddick explained. What led to ARL’s collaboration with Uber?

Jaret Riddick: ARL has a long history of collaborating with academia and industry to advance science. Over the past decade, we focused more concertedly on tearing down traditional barriers that prevent commercial and academic partners from working alongside military researchers, and through this more open collaboration business model that ARL has adopted, we’ve widened the pathway to partnership with non-traditional companies.

In standing up the Army Futures Command, it’s very clear from senior military leadership that there is a desire to collaborate with the best people in the world to achieve the objectives that we have for the modernization enterprise of the Army. We recognize that we can’t get there alone. So there’s a big interest in engaging with non-traditional partners, industry partners in particular who are leading in areas that can be beneficial to the Army.

Uber is one of those companies, particularly in the air taxi domain through their Uber Air model. They are leading a dialogue in the UAM community on a future where it will be normal to see commercial, commuter eVTOL transportation flying above urban centers to move people around. Are there any specific areas of technology where you see potential in the collaboration?

Jaret Riddick: The key area of collaboration with Uber is what we call quiet rotor technology. Vertical take-off and landing vehicles all have a rotor system of some sort, whether that converts to forward flight when they’re in the air in the case of tilt rotors, or other things that some other configurations can do. Quiet rotor technology is mutually beneficial. Uber wants to fly hundreds of these flights over urban areas, so there will be noise issues for them.

Jaret Riddick Army Research Lab
Dr. Jaret Riddick, Army Research Laboratory

For ARL, when you think about an army on the battlefield of the future, unmanned systems that provide the capability for silent overwatch would enhance the lethality and survivability of soldiers on the ground. This quiet rotor technology is one where there are mutual benefits, so it was a perfect area for us to strike collaboration. Both sides in the relationship are deriving benefit from the research advances that would come out of the partnership. Could you tell me more about the rotor technology you’re working on?

Jaret Riddick: The particular configuration that we’re looking at with Uber Air for quiet rotor is a stacked, co-rotating set of rotors. So instead of one rotor spinning, there are two rotors that are stacked on top of one another. And traditionally when you have these stacks — or coaxial rotors —– they spin in opposite directions to create lift. But in this quiet rotor approach, those stacked rotors are actually spinning in the same direction: we refer to that as co-rotating.

All of this is enabled by the fact that the vehicle is driven electrically, setting the separation distance between the rotors and maintaining that very precisely as those rotors spin around. It’s very hard to do this with mechanical transmission. With electrical transmission, the spacing and the pacing of the rotors is made more feasible. And so the idea of this co-rotating rotor, which will reduce the noise without affecting performance — in fact even improving performance in certain cases — is a very important thing. What does ARL offer for non-traditional partners from domains like eVTOL?

Jaret Riddick: ARL has a unique offer to make to an industry partner. We systematically built up an approach to this type of engagement almost a decade ago when we adopted a new business model we call “Open Campus.” We have great researchers, we’ve got world-class facilities, but a lot of people were not really familiar with what we do because we existed behind a fence. And so Open Campus was a way to open up the fence and say to potential collaborators, “come in, work alongside our research scientists and engineers, let’s share specialized research facilities and let’s create a broader network of collaboration” by bringing to bear knowledge and other teaming relationships to answer scientific questions of mutual interest.

The key thing, though, is our Open Campus model is not a funding model; it’s not transactional. It’s an “in kind” cooperative agreement, like the work we’re doing with Uber. Are there any other focuses of the work with Uber in particular that you would highlight?

Jaret Riddick: We are developing analytical tools for acoustics analysis. In collaboration with Uber, we are doing some very specific and sophisticated analysis to improve and upgrade the design tools that are available to the community to look at acoustics for these particular rotor configurations. The tools that will come out of this collaboration really will have impact for the entire community of folks who are designing platforms for UAM, but will also impact the wider vertical lift community. Do you work with any other companies in the eVTOL space, or do you hope to grow this work in future?

Jaret Riddick: Interestingly, I am going to California this week to attend the GoFly Prize fly-off. At this event, I’ll engage with some of the brightest, most adventurous minds in aerospace; those who are innovators, engineers, designers, pilots, and revolutionary thinkers and planners with an eye toward the future. 

While I’m in California, I’ll have a packed agenda visiting a number of UAM companies seeking collaborations within the UAM horizontal across various business lines, such as military, commercial eVTOL transportation, and first responders, looking at how each UAM company addresses durability, capacity, payload, and affordability, and the S&T implications that enable the right balance of each of these.

When we talk about the Army engaging with non-traditional industry partners that are leading in a wide variety of technical fields, we want to do that aggressively because these industry partners can prototype proofs of concept very rapidly, including for some of the discovery that’s coming out of ARL. It’s a way to move the technology faster from discovery into the hands of the warfighter, so we want to engage as many industry partners as we can, particularly those non-traditional ones who can partner with us while we’re early in the discovery phase. So while I’m in California, I’ll be visiting a whole variety of these UAM companies, and I’m very excited to see the different configurations that these folks are coming out with.

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