Sophrodyne has been working for some time with the Helicopter Aerodynamics group at the German Aerospace Centre (DLR) on a joint experimental-numerical project to determine the best way to measure and quantify the effects of the outwash produced by helicopters and other rotorcraft on their surroundings.

The initial findings of this research were presented by Dr Christian Wolf of the DLR during the Aerodynamics Technical Session at the 82nd Vertical Flight Society Annual Forum, held from 5-7 May 2026 in West Palm Beach, Florida. Dr Wolf's presentation showed clearly how sensor fidelity influences very strongly the characterisation of the velocities within the outwash, as well as how numerical methods need to be constructed very accurately if they are to resolve accurately the unsteady nature of the flow.

The tab below will take you to a page from which you can download a copy of the paper.

Flightcrowd is an educational not-for-profit organisation, based in the UK, that aims to inform, engage, and inspire the public on the topic of the Future of Flight. One of their foundational tenets is that the future aviation industry relies for its survival on a steady stream of inspired, motivated and capable young professionals entering the field.

Ensuring the future of aerodynamics as a discipline is a topic that is close to Dr Brown's heart, and he was invited to talk to a group of Flightcrowd's aspiring young trainees as they start out in their careers.

In his seminar, Richard described how he became interested in aerospace as a career, and in the aerodynamics of rotary-winged aircraft specifically. He described the various twists and turns in his journey so far, then rounded off his talk by offering some advice on how best to plan for a long-lasting and fulfilling career in aerospace engineering.

The tab below will take you to a recording of Dr Brown's talk.

Dr Brown recently presented his lecture, titled 'The Aerodynamic Challenges of eVTOL Aircraft Design' to an engaged audience of students from the Glasgow University Engineering Society.

In his talk, he concentrated on the areas where more research is needed to fully understand the aerodynamics of these vehicles, and hence to ensure that this new generation of aircraft will be able to integrate safely into the urban transport system.

With an audience of young students eager to find suitable topics for their Masters research projects, the discussion afterwards centred around the technicalities of the aerodynamics of eVTOL aircraft - and how experiment, numerics and theory might work hand-in-hand to provide fresh insights into their likely behaviour under real-world operational conditions.

The tab below will take you to the GUES LinkedIn page where you can find more details of their recent activities.

With the subtitle "CFD Validation Challenges - Perspectives from Modellers and Measurers", the 2026 RAeS Aerodynamics Workshop set out to bring the aerodynamics community together to discuss how numericists and experimentalists might adopt more exacting methods to ensure the accuracy of their methods and thus the fidelity with which we understand the physical world.

Dr Brown drew from his own experience in the rotorcraft modelling community to present a talk titled "Rotorcraft Safety - Should the Real World wait for the Science?".

He used the example of rotor outwash modelling to explain how the lens through which we view the system can often distort our interpretation of new data, and how this becomes a particular problem in a world in which there is real pressure to deploy technology before its scientific basis has been properly established.

The tab below will take you to a recording of Dr Brown's presentation.

Dr Brown and colleague Dr Mike Pryce from the UK Civil Aviation Authority have been awarded the prestigious Royal Aeronautical Society Team Silver Medal in recognition of "their fundamental contribution to helicopter and eVTOL safety."

The award follows several years of collaboration between Sophrodyne and the CAA in understanding the physics of how helicopters and more complex rotorcraft interact aerodynamically with the ground. This work has given new insights into how humans respond when exposed to the resultant outwash, and has prompted regulators worldwide to revise the way in which outwash is quantified in terms of its effect on the safety of bystanders and nearby infrastructure.

The award was presented to Mike and Richard at a reception held at the Society's headquarters at 4 Hamilton Place, London, on the evening of 26 November 2025.

"Since 1909, the Royal Aeronautical Society has been honouring individuals and teams for their outstanding contributions to aerospace. This recognition encompasses significant technical innovations, outstanding leadership, and efforts that substantially advance the field of aerospace."

The tab below will take you to the RAeS web page containing more details about the award.

On 20 November 2025, Richard reprised his Chadwick lecture, titled 'The Aerodynamic Challenges of eVTOL Aircraft Design' in slightly shortened form to an enthusiastic and engaged audience at the Royal Aeronautical Society's Hamburg branch.

The presentation drew from his original research, as well from as his experience in advising regulators and OEMs working at the leading edge of eVTOL aircraft development, to lend an unique perspective on these new aircraft. In this version of his talk, he concentrated on some of the most important outstanding issues that need to be addressed before these vehicles become a practical and safe component of the urban transport system.

The tab below will take you to a page giving more details about the event.

With its theme "Advanced Air Mobility: Preparing for Integrated Operations," the 2025 Royal Aeronautical Society Rotorcraft Conference set out to bring together a range of diverse perspectives from within the international Advanced Air Mobility community in order to try to establish common ground for future progress.

Speakers representing the manufacturers, operators and infrastructure developers, together with insurers, regulators and air navigation service providers, contributed to a day of lively discussion and real progress towards a common understanding of the challenges that the industry faces in becoming an economic reality.

Besides co-chairing the conference, Dr Brown presented a keynote lecture titled "Rules and Responsibilities - These are the Ties that Bind Us," in which he outlined the complex task of reconciling aspirations within the industry both with physical reality as well as with the need for the new technology to be demonstrably safe. He ended with a plea to the industry to put aside commercial interests where possible and to contribute to global efforts to develop a set of standards to which the community might hold itself.

The tab below will take you to a recording of Dr Brown's presentation.

Dr Brown presented a keynote lecture on helicopter safety to an engaged audience of pilots, operators and regulators attending the British Helicopter Association's annual Safety Day, held on 6 November 2026 at the DARTec Centre on the Cranfield University campus.

In his talk, titled "Understanding the Aerodynamics of Helicopter Outwash," he explained how traditional views of the structure of the flow out across the ground might yield a misleading impression of the risks posed to bystanders and nearby infrastructure. He described how recent research in conjunction with the UK Civil Aviation Authority has exposed, in particular, the importance of the unsteadiness of the flow in determining the human response to being immersed in a helicopter's outwash.

He encouraged pilots and operators alike to rely additionally on their own experience and judgement in ensuring the safety of bystanders from the effects of their vehicles' outwash, and to avoid the temptation to rely solely on currently accepted norms and standards until we have a better understanding of the physics.

The tab below will take you to the BHA homepage giving details about future such events.

The venue proved too small to host everyone who wished to listen to Richard's presentation on the aerodynamics of eVTOL outwash at the 51st European Rotorcraft Forum in Venice in September 2025.

Dr Brown thus hosted an evening online seminar in which he presented his paper again. He also took the opportunity to summarise some of the background to his paper by describing some of the work conducted by Sophrodyne on behalf of the UK Civil Aviation Authority over the last couple of years to improve our understanding of the physics of helicopter and eVTOL outwash.

The tab below will take you to a recording of the seminar.

Dr Brown presented his paper, titled "Understanding the Aerodynamics of eVTOL Outwash" at this year's European Rotorcraft Forum, held from 9 - 12 September 2025 in Venice, Italy.

The flows out across the surface that are produced by eVTOL aircraft when operating close to the ground are very different in character to those produced by the conventional helicopters on which much of our current understanding of rotorcraft outwash is based, yet accurate quantification of the velocities within these flows is seen as an important part of ensuring the safety of this new form of aerial transport.

An analysis of the fundamental fluid mechanics that governs the formation of the flows in the outwash below these aircraft shows the importance of the inherent instability of the vortical structure of the wakes produced by their propulsors in governing both the form and strength of the flow out across the ground below the aircraft. Numerical experiments show the outwash to be particularly susceptible, through the long-term action of this vortical instability, to losing the symmetries that might have been imparted to it by the geometry of the aircraft. This results in flows that in many cases are far more spatially inhomogeneous than might be expected, where the overall characteristics of the flow can vary considerably over time, and, indeed, where the character of the flow might be dependent on the way in which it was formed in the first place.

Dr Brown concluded that we might need to know a great deal more about the physics that governs the aerodynamic behaviour of these systems before we place too much faith in our ability to quantify the risks posed by these aircraft to bystanders and infrastructure that might become exposed to their outwash.

The tab below will take you to our Downwash Resource page from where you can download a copy of Richard's paper.

In the eVTOL world as it presently exists, a real danger is that our appreciation of the issues is formed by exposure to an incessant quick-fire barrage of fireside chats, podcasts, and conference panels, rather than being founded on rigorous physical insights derived through the much less media-friendly process of measured and purposeful cross-validation of theory, numerics and experiment.

In a supreme irony, Dr Brown was given only fifteen minutes during the Vertical Flight Society Special Session on eVTOL Challenges, held as part of the 81st Annual Vertical Fight Society Forum and Technology Display, to reflect via an online presentation on his own experience of how the discourse within the eVTOL community is shaping our understanding of the salient issues.

In a talk titled "Faith and Reason in the Age of Social Media" he argued for a more discerning and fact-based approach to the subject - during which we take the time to distinguish truth from fiction, wishful thinking from reality, and true expertise from mere hubris, lest we waste significant human effort and capital in chasing chimeras and mirages rather than on making true progress in what is undoubtedly a very demanding technical area.

The tab below will take you to a recording of Richard's talk.

In this online seminar, Richard presented some of the most recent findings of his work in understanding the physical mechanisms that govern the behaviour of the flow of air out across the surface that is generated by rotorcraft when operating close to the ground.

In his talk, he emphasized that the flow is dominated by the behaviour of vortical structures that are created by all the rotors of the vehicle, and suggested that very accurate numerical techniques might be needed to resolve the salient features of physics, and particularly the details of the interactions between the vortical structures that are produced by the individual rotors, before we can quantify properly the risks posed by these aircraft to bysteanders and infrastructure that might become exposed to their outwash.

As such, the seminar provided a taster for the more technical presentation that Dr Brown gave in September 2025 at the European Rotorcraft Forum.

The tab below will take you to a recording of the seminar.

Richard was honoured to present this year's Royal Aeronautical Society lecture in memory of Roy Chadwick, Chief Designer at Avro in the 1930s and 1940s, and father of the famous Lancaster bomber, as well as of the Lincoln, Shackleton and Vulcan aircraft.

His talk, titled "The Aerodynamic Challenges of eVTOL Aircraft Design," drew from his original research, as well as from his experience in advising regulators and OEMs working at the leading edge of eVTOL aircraft development, to lend an unique perspective on these new aircraft, and brought the audience up to date with the latest developments in aerodynamic technology.

The tab below will take you to the RAeS web page containing more details about the event.

The leader article in the April edition of the Royal Aeronautical Society Aerospace magazine gives a perspective on some of the work that we've conducted in partnership with the Civil Aviation Authority in trying to understand the properties of rotorcraft outwash.

The aim of our work is to improve the safety of both helicopter and eVTOL operations through an improved understanding of the physics. Our initial technical findings were published as UK Civil Aviation Authority CAP3075 "Protecting the Future: Trials and Simulation of Downwash and Outwash for Helicopters and Powered Lift Aircraft."

The tab below will take you to a page from where you can download a copy of this document.

As part of the Verticon 2025 course 'Introduction to eVTOL Aircraft for Helicopter Pilots,' Richard presented a 90 minute overview, showing how the aerodynamic features and characteristics of eVTOL aircraft compare to those of more conventional rotorcraft and helicopters.

He showed that, despite the very obvious differences between these types of flying machines, they share many common aerodynamic features and problems - and thus that the eVTOL and helicopter communities have much to learn from each other's experiences.

This is particularly the case when considering the aerodynamic problems that will arise when these aircraft start to operate from urban landing sites, and Richard drew on his current research on Vortex Ring State and rotor outwash to explain some of the challenges that will need to overcome in integrating these vehicles into the urban transport infrastructure.

The tab below will take you to the conference web page.

Richard was presented with his award 'for extraordinary work in vertical flight' at the annual meeting of the Vertical Flight Society's UK chapter, held at the RAF Club in London on 23 February 2024.

The award recognises Richard's work in understanding the physics of the Vortex Ring State, a particularly hazardous operating regime that a rotorcraft can enter into during the critical descent and landing phases of flight, and in particular his recent analysis which shows how the safety of eVTOL aircraft might be impacted by this phenomenon.

The tab below will take you to the VFS-UK web page containing more details about the award.

Dr Brown has been awarded the prestigious Royal Aeronautical Society Bronze Medal in recognition of "his contributions over several decades to our understanding of rotorcraft aerodynamics."

The award was presented to Richard at a reception held at the Society's headquarters at 4 Hamilton Place, London, on the evening of 14 December 2023.

"Since 1909, the Royal Aeronautical Society has been honouring individuals and teams for their outstanding contributions to aerospace. This recognition encompasses significant technical innovations, outstanding leadership, and efforts that substantially advance the field of aerospace."

The tab below will take you to the RAeS web page containing more details about the award.

Dr Brown presented a keynote lecture, titled 'Back to the Future: How Helicopter Experience can Contribute to the Safety of New Rotorcraft,' essentially a shortened version of his October RAeS Cierva lecture, at this year's European Rotors conference, held from 27-30 November in Madrid, Spain.

Dr Brown described how helicopter experience, when suitably augmented by new theoretical insights and supported by appropriate numerical analysis and experimental data, is contributing to the safety of eVTOL aircraft by helping us to understand those features of their aerodynamic behaviour that are particular to this new class of aircraft.

In his talk, he focused on how we are starting to understand which aerodynamic phenomena are likely to be most problematic, especially when eVTOL aircraft start to operate from vertiports that are located within densely-populated urban environments.

The tab below will take you to the conference web page.

Dr Brown presented his lecture "A Vision of Future Space Access" to GU Rocketry, a team of enthusiastic young students based in the School of Engineering at Glasgow University.

The talk was based on his experience as Director of the Centre for Future Air-Space Transportation Technology, where his research group was engaged in developing the methodologies that could be used to design the spacecraft of the future.

Dr Brown's lecture concentrated specifically on the problems associated with the design of Single-Stage-to-Orbit spacecraft. These vehicles do not discard any tanks, engines or other components during their ascent, but instead return intact to their launch site. The intent is that these vehicles be refurbished and re-used very simply and quickly for their next mission, allowing very economical access to space compared to expendable launch vehicles.

In his lecture, Dr Brown discussed some of the technological obstacles to achieving this goal, focusing on the hurdles that need to be overcome in developing suitable propulsion and thermal protection systems, and the difficulties involved in integrating the system into a light enough package so that an economical payload can be transported into orbit.

Use the tab below if you would like to schedule Dr Brown to present this lecture to your organisation.

Dr Brown presented a public lecture on rotorcraft aerodynamics at the headquarters of the Royal Aeronautical Society at 4 Hamilton Place, London.

His lecture, titled 'Back to the Future: How Helicopter Experience can inform the Design of Future Rotorcraft' showed how several pernicious aerodynamic problems that have been encountered during the development of historical rotorcraft stand to re-emerge, albeit perhaps in slightly different form, when eVTOL aircraft start to take to the skies.

Dr Brown described in detail how the body of historical knowledge needs to be augmented by new theoretical insights, and supported by appropriate numerical analysis and experimental data, to yield the fundamental aerodynamic understanding that is required to ensure the safety of this new class of aircraft. He payed particular attention to the issues that are likely to arise if and when eVTOL aircraft start to operate from vertiports that are located in densely-populated urban environments.

Rather frustratingly, a technical fault on the evening prevented the lecture from being recorded! Instead, use the tab below if you would like to schedule Dr Brown to present this lecture to your organisation.

The full version of Dr Brown's research into the outwash that might be created by eVTOL aircraft has now been released publicly as part of the UK Civil Aviation Authority's Publication 2576: 'Understanding the downwash/outwash characteristics of eVTOL aircraft'.

When a rotorcraft is operated at low enough height above the ground, the aerodynamic interaction with the surface below causes the flow from its rotors to expand out across the ground as a layer of rapidly-moving airflow, called its outwash. If this outwash is strong enough, it can cause significant upset to bystanders and nearby infrastructure. A recent numerical study by Dr Brown has shown that the shape and strength of the outwash that any multi-rotor eVTOL aircraft will generate is strongly dependent on the layout of its rotors, amongst other factors.

Indeed, several aspects of the behaviour of the outwash that is created by eVTOL aircraft may come as a surprise to the rotorcraft community - where intuition is largely based on experience with conventional helicopters. In his paper, Dr Brown thus discusses the implications of his findings for the prospective operators of this type of aircraft, as well as for the designers of the vertiports from which these aircraft will fly.

The tab below will take you to our Downwash Resource page from where you can download a copy of Richard's report.

Dr Brown presented his paper, titled "Do eVTOL Aircraft create an inherently more problematic Downwash than Conventional Helicopters?" at the European Rotorcraft Forum, held from 5 - 7 September 2023 in Bückeburg, Germany.

When a rotorcraft is operated at low enough height above the ground, the aerodynamic interaction with the surface below causes the flow from its rotors to expand out across the ground as a layer of rapidly-moving airflow, called its outwash. If this outwash is strong enough, it can cause significant upset to bystanders and nearby infrastructure. A recent numerical study by Dr Brown has shown that the shape and strength of the outwash that any multi-rotor eVTOL aircraft will generate is strongly dependent on the layout of its rotors, amongst other factors.

Indeed, several aspects of the behaviour of the outwash that is created by eVTOL aircraft may come as a surprise to the rotorcraft community - where intuition is largely based on experience with conventional helicopters. In his paper, Dr Brown thus discusses the implications of his findings for the prospective operators of this type of aircraft, as well as for the designers of the vertiports from which these aircraft will fly.

The tab below will take you to our Downwash Resource page from where you can download a copy of Richard's paper.

Dr Brown travelled to the USA in May to attend the 79th Annual Vertical Fight Society Forum and Technology Display, where he presented his award-winning paper "Are eVTOL Aircraft Inherently more susceptible to the Vortex Ring State than Conventional Helicopters?" at a special session of the conference.

Richard's paper was awarded 2022's prestigious Ian Cheeseman Prize, given annually to the best technical paper presented at that year's European Rotorcraft Forum.

Richard's work shows how our current understanding of the Vortex Ring State applies to the design of modern eVTOL aircraft. The paper has attracted considerable interest from the community through highlighting a range of effects that designers and operators should be aware of in order to ensure the safety of these vehicles.

The tab below will take you to our VRS Resource page from where you can download a copy of Richard's paper.

Dr Brown was recently a panellist on the final day of the 2023 Helicopter Investor Conference, held from 22-23 March at the Royal Garden Hotel in London.

The topic for discussion was "Is the future electric? Helicopters and electric VTOL aircraft - what is the future and is there room for both?" Richard was joined by Frank Liemandt, European Rotors, Jean-Marc Youkhana, Uplifting Aviation, Nigel Leishman, LCI, and Tim Chun-hing Li, from Ascend by Cirium, for a lively debate on the technical and commercial future of the VTOL community.

The tab below will take you to the website for the conference.

Dr Brown presented his new public lecture "Back to the Future - How can Helicopter Experience inform Future Rotorcraft Design?" to the Prestwick branch of the Royal Aeronautical Society in their first live event of the year, held at the University of the West of Scotland in Ayr on 13 February.

He spoke from his own experience of thirty years as a helicopter aerodynamicist, and showed how dealing with the effects of aerodynamic interactions within the system remains one of the biggest challenges to designing a rotorcraft that has acceptable performance, stability and control.

Dr Brown explained how the challenge is to abstract the historical record into a body of knowledge that can be used to design the next generation of rotorcraft. He showed how specialised modern numerical techniques can be used to contextualise what we know from existing experimental and flight test data. The outcome might be a framework that can be used by the designers of modern eVTOL aircraft to predict and overcome the aerodynamic issues that are presented by this new class of rotorcraft.

Use the tab below if you would like to schedule Dr Brown to present this lecture to your organisation.

Dr Brown presented his lecture "Shock Waves and the Design of Future Spacecraft" to GU Rocketry, a team of enthusiastic young students based in the School of Engineering at Glasgow University.

The talk was based on his experience as Director of the Centre for Future Air-Space Transportation Technology, where his research group was engaged in developing computational methods that could predict the aerodynamic and thermal loads that spacecraft will encounter during their re-entry into the earth's atmosphere.

Dr Brown showed how sensible spacecraft design is constrained by the ability of the engineer's tools to be able to calculate accurately the properties of the flows that are generated by the vehicle during re-entry, and how, from early beginnings with vehicles that had spherical or conical geometry, we can now design our vehicles with shapes that are complex enough for the craft to behave very much more like a high-speed aircraft than a purely ballistic device.

He finished by explaining how the history of NASA's Space Shuttle gives a salutary warning against over-confidence in the predictive capabilities of our tools.

Use the tab below if you would like to schedule Dr Brown to present this lecture to your organisation.

Just before Christmas 2022 we learned that Dr Brown had been awarded the prestigious Ian Cheeseman Prize, given annually to the best technical paper presented at that year's European Rotorcraft Forum.

The prize will allow Dr Brown to travel to the 79th Annual Vertical Fight Society Forum and Technology Display, to be held this May in West Palm Beach, Florida, USA, where he will present his paper "Are eVTOL Aircraft Inherently more susceptible to the Vortex Ring State than Conventional Helicopters?" at a special session of the conference.

The Vortex Ring State is a particularly hazardous operating regime that a rotorcraft can enter into during the critical descent and landing phases of flight. Richard's paper shows how our current understanding of the phenomenon applies to the design of modern eVTOL aircraft, and highlights a range of effects that designers and operators should be aware of in order to ensure the safety of these vehicles.

The tab below will take you to our VRS Resource page from where you can download a copy of his paper.

Dr Brown presented an updated version of his paper, titled "Are eVTOL Aircraft Inherently more susceptible to the Vortex Ring State than Conventional Helicopters?" at this year's EASA Rotorcraft and VTOL Symposium, to be held from 8 - 9 November 2022 in Cologne, Germany.

The paper built on his earlier presentation at the European Rotorcraft Forum by showing some of the real problems that might be induced in the design of eVTOL aircraft if their physical characteristics and limitations are not held firmly in mind when drawing up the regulations governing the vertiports from which they will operate.

The tab below will take you to the online recording of Dr Brown's presentation.

Dr Brown has presented a paper titled "Are eVTOL Aircraft Inherently more susceptible to the Vortex Ring State than Conventional Helicopters?" at this year's European Rotorcraft Forum, held from 6 - 8 September 2022 in Winterthur, Switzerland.

The Vortex Ring State is a particularly hazardous operating regime that a rotorcraft can enter into during the critical descent and landing phases of flight. Richard's paper shows how our current understanding of the phenomenon applies to the design of modern eVTOL aircraft, and highlights a range of effects that designers and operators should be aware of in order to ensure the safety of these vehicles.

The tab below will take you to our VRS Resource page from where you can download a copy of his paper.

During his online lecture to the Bedford branch of the Royal Aeronautical Society, Dr Brown examined our current understanding of the Vortex Ring State - a particularly hazardous operating regime that a rotorcraft can enter into during the critical descent and landing phases of flight.

He first told the story of how data from laboratory and numerical experiments was combined in the mid-'00s to change our understanding of the basic mechanisms at the heart of the phenomenon. As an illustration of how mathematical abstraction can lend deep insights into practical engineering problems, he then showed how a theory was developed that is now used throughout the world to help aircraft designers to understand the susceptibility of their creations to this potentially dangerous aerodynamic phenomenon.

The specific case of the V-22 Osprey tilt-rotor was covered in detail, and Dr Brown then went on to discuss the implications of his research for the next generation of rotorcraft that are on the drawing boards.

The tab below will take you to a recording of the event.