NASA and Booz’s Executive Brief in Detail NASA and consulting firm Booz Allen Hamilton released a joint study on November 12 that outlined future projections of the urban aviation industry. The original executive briefing was presented on October 5th to NASA’s Aeronautics Research Directorate. Before we go into the details of the study, here are some of the key takeaways:...
NASA and Booz’s Executive Brief in Detail
NASA and consulting firm Booz Allen Hamilton released a joint study on November 12 that outlined future projections of the urban aviation industry. The original executive briefing was presented on October 5th to NASA’s Aeronautics Research Directorate. Before we go into the details of the study, here are some of the key takeaways:
- Airport Shuttle and Air Taxi markets have a total addressable market of over $500 Billion
- Air Ambulance services are not practical due to technology constraints – but hybrid aircraft may provide feasible alternatives
- Legal, regulatory, weather, public perception, and infrastructure hurdles exist
- 0.5% of the TAM, or $2.5 Billion, could be captured in the near term
- Constraints may be eased by government partnerships, industry collaboration, industry commitment, and existing legal and regulatory enablers
That’s the Summary. Here are the details.
A Strategic Advisory Group, or SAG, was assembled from prominent figures in the UAM, transportation, government regulations, infrastructures, public policy, and insurance disciplines – the SAG serves as an invaluable resource that enabled the information and advice of experts in their respective disciplines to offer their work and research toward answering some of the most pressing issues in the path towards wide spread UAM application. The study analyzed the following key components, each of which will be detailed below:
- Market Selection
- Legal and Regulatory
- Societal Barriers
- Weather Analysis
- Market Analysis
The study focused on a consortium of 10 cities across the United States to represent the larger industry.
Of potential interest in the selection of these 10 cities (and one city that has not been considered as heavily in the past) was that of Denver. Other cities that were selected, such as Los Angeles and Miami, have already been under consideration by real estate development companies and technology firm UAM development plans. However, the selection of Denver in this study is important – Denver has the potential for the lowest portion of air taxi shuttle trips within the FAA’s National Airspace System (NAS), which balances the perspective of a mostly urban-dominated, completely NAS-immersed UAM operating environment.
Legal and Regulatory
The largest legal and regulatory challenges that have the potential to slow urban aviation are regulations that already exist. In general, the framework for certifying aircraft already exists, but there are numerous legal barriers and gaps in the path to certification for some aircraft that may be classified as rotorcraft/mixed propulsion. Similarly, determining which regulations apply to what component(s) of air taxis is another challenge that has not yet been answered. Finally, system redundancy and failure management are critical safety considerations that will not be amended whatsoever for the sake of introducing a new type of aircraft such as an air taxi.
Fortunately, there are answers on the horizon to these challenges; for instance, ballistic parachute recovery systems are being developed for UAM systems. Additionally, the summary also cited that voluntary self-regulation (or even proposal of standards) may help to advance the regulatory process faster than relying solely on federal and state governments.
The largest concerns from the audience surveyed in this study (both younger persons aged 18-29 and older persons aged over 50) focused on credibility of pilots and the manufacturers of the aircraft. In general, those pilots/companies who were older attained a higher level of perceived experience, but gender and racial bias also played a role in affecting a passenger’s comfort with boarding a given flight. Passengers preferred intra-city hops instead of inter-city trips, and surprisingly, accepted a “hybrid flight deck” configuration where one pilot was onboard and the other “pilot” was automated.
Interestingly, the study also analyzed the position of weather in effecting UAM operations, and how in some locales the weather has enough of an adverse effect on air taxi services that their application could be placed in jeopardy. In general, cities in the Western United States had favorably weather, with the exception of impacts due to potential low visibility, high temperatures, and strong surface winds during summer thunderstorms. Cities like San Francisco suffer during the summer mornings when low-lying fog banks generate IFR conditions.
In the Eastern United States, storms and low visibility are the primary limiting factors, especially during summer afternoons. In areas such as Texas, low level wind shear, high temperatures, and storms have large impact potential to UAM operations, storms in the summer, and low visibility in the winter. While the summary did not expound further, expect more details in the full report – and also an overview of just how much the TAM may be reduced by seasonal weather shifts.
A Monte Carlo analysis was performed under a range of constraints to determine max usabilities – constraints involving customer’s willingness to pay, infrastructure limited, time of day limited, weather limited, and unconstrained scenarios. After performing these analyses, it was determined that only ~0.5% of unconstrained trips were captured after all other constraints were applied. This figure translates the $500 Billion as mentioned originally to the $2.5 Billion TAM. While the UAM market itself provides a lucrative magnitude of TAM, it is not without competitors – such as autonomous cars.
Additionally, analyses were conducted to determine the cost of air ambulance transports. After 10,000 iterations of this analysis, the estimated cost for an average trip was $9,000 for an eVTOL, and $9,800 for a hybrid – compared to $10,000 for that of a conventional helicopter transport. While there is a potential cost savings and practical benefit to eVTOLS as air ambulances (potential lives saved) the operational proficiency for eVTOLs will require time to establish – time that helicopters have had to demonstrate their applicability in situations that require extreme consistency. Another important consideration is the return time for an eVTOL, which is much higher than helicopters. While helicopters can be fueled with Jet-A in a matter of minutes, the charging technology for eVTOL’s is still not completely matured.
The best case scenario for air shuttle and air ambulance services includes a TAM of $500 Billion. In the near term, 5-seat eVTOL’s will cost ~$6.25 per passenger mile to operate. The high cost of infrastructure (and the current availability of infrastructure) are both large hurdles to overcome. Legal and regulatory analysis found that the air taxi, air ambulance, and air shuttle markets all face similar barriers. Additionally, psychological analysis and market surveys have proven that the general public is much more likely to board a piloted aircraft than an autonomous one. Finally, weather is a larger influencer in the applicability of air shuttle services than the industry has previously considered.
Why it’s Important: The joint Executive Summary between NASA and Booz Allen Hamilton has underscored many of the points made by numerous other consulting studies – but it also includes new considerations that will be important for the future development of the UAM industry, including the effects of return time for air ambulance operations and the effects of weather on all three markets. Stay tuned for the release of the full study and increased details on each of the topics addressed in the executive summary. The study emphasizes that a market of $2.5 billion may be reached in the short term (even after all the constraints are applied to market modeling) which is a large enough magnitude to continue to sustain the level of interest and dedication toward making this industry commercially operational in about five years.
They’re Great for Cars, But Not so Much Urban Aviation Over the last 20 years, batteries have been one of the slowest developed hardware components in the world. Solar power, advanced materials, and next generation manufacturing processes have all sparked new business and provided the technological momentum to create new industries. All but the battery. In order for the Urban...
They’re Great for Cars, But Not so Much Urban Aviation
Over the last 20 years, batteries have been one of the slowest developed hardware components in the world. Solar power, advanced materials, and next generation manufacturing processes have all sparked new business and provided the technological momentum to create new industries. All but the battery. In order for the Urban Air Mobility industry to accomplish the major tenet of environmental sustainability, battery tech needs to catch up. So why the lag? And how have companies like Tesla and Faraday Future been able to bring their products to market despite the challenges that battery technology provides?
The Current State of Battery Technology
To understand why the Urban Air Mobility industry is still 10 years from being completely electric, the current state of battery technology should be understood. The key metric for any battery is energy density – the amount of energy that can be stored in a given volume. The higher the density, the smaller the battery required for a certain amount of energy, or the more energy that can be stored in the same amount of space. To “optimize” battery tech, energy density must be maximized. However, unlike Moore’s law (in which processor power, or components per function, increases exponentially with time) battery energy density has seen a meager 3% increase in energy density year over year.
Just 3% in Energy Density Increase Per Year.
There are a couple types of batteries that have widespread application – Lithium Ion and Alkaline. While Alkaline is used in virtually all household batteries, its energy density is much lower than that of the Lithium Ion batteries (by about 200x) – but Alkaline batteries are much safer than Li-Ion batteries, which have a nasty habit of being impossible to extinguish should they combust. Most electric transportation applications require a large amount of energy, and so virtually all use Li-Ion batteries to take advantage of the greater energy density while accepting the safety risk. But, Li-Ion energy density is still too low; the required density for flying transportation modes is much higher than driving applications because weight is at a premium.
Surely the world can do better – so why haven’t we?
Similar Industries: Tesla & Trucks
Tesla (and more recently Faraday Future) have been able to market electric vehicles effectively because they’ve capitalized on Lithium Ion batteries with energy densities reported to be around 900Wh/L, or 250 Wh/kg.  For reference, an Alkaline AA battery holds about 4 Wh of energy  with a corresponding energy density of 700Wh/L. While this comparison illustrates how much higher the energy density of Li-Ion batteries is compared to that of Alkaline batteries, the quantity of energy required for an electric vehicle is still staggering. A Tesla Model S boasts fast acceleration and performance, but what many fail to realize is that the vehicle itself weighs almost 1,000 lbs more than any similar sedan with an internal combustion engine (mostly due to battery weight). 900 Wh/L is “good enough” for road applications because higher weights are acceptable. However, an electric vehicle in flight demands the minimum weight possible. How much farther must energy density be increased for batteries to become a practical source of aerial energy? The answer is simple: a comparable power to a Tesla Model S is required, but at 80% of the current weight of the Tesla battery packs (which is about 1,200lbs) – more on how we arrived at that figure later. For comparison, the Volocopter weighs 996 lbs – less than the total weight of the Tesla battery packs. Fortunately, the Volocopter (and other UAM solutions) require less than 1,200 lbs, or 85kWh, of power, but weight is still at an absolute premium.
Before we address this ultimate goal of the feasibility of battery power in the urban aviation industry, we’ll turn to a different industry that’s familiar to many: consumer drones.
The Drone Industry
One hybrid industry that provides a bridge between aviation and electric transportation is the recreational drone industry. Drones are little more than battery packs with any number of brushless electric motors powering small propellers at each corner of the device; oftentimes four are used to aid in stability. UAM solutions are much larger and more complex – but the physics of the energy required to stay aloft remain the same in both cases. For instance, the DJI Mavic Pro weighs 734g and can stay aloft for 31 minutes using a 46Wh battery, which is a typical capacity for a small drone. To condense these statistics into one comparable unit, like kg/Wh, we get 0.03. This number doesn’t mean much on its own, but if the weight of the aircraft is multiplied by the time aloft desired, a rough estimate of the total energy required may be obtained.
An important note – using different propeller sizes and energy conservation assumptions will yield different quantities of energy required; this is just a simplified first principles approach.
The UAM Industry
So how much power would a vehicle like the Volocopter require to fly for one hour? Using the kg/Wh factor of 0.03 to solve for this figure the Volocopter would conservatively need 14kWh of power. Remember back to the Tesla example – the Model S batteries have a capacity of 85kWh (6 times greater than that of the Volocopter) but at a weight of 1,200lbs. So if the Model S batteries were removed and 1/6th of the cores were installed on a UAM, they would represent a 200lb weight – which is more than 20% of the weight of the entire aircraft.
This 20% figure doesn’t sound high, but when you compare the energy in that 200lbs of weight (14kWh or 50.3 Megajoules) to the energy stored in 200lbs of Jet-A (4126 Megajoules) it quickly becomes apparent that Jet-A has prevailed for so many years because of its extremely high energy content.
But this doesn’t mean that it’s not possible for batteries to be “good enough”. Fortunately, aerodynamic innovations mean that matching the energy density of Jet-A is not required; batteries can do good enough with their own lower energy density, and with the added benefit of zero emissions, which is a huge win over Jet-A fuel. The magical 80% figure mentioned in the first comparison of Tesla batteries’ applicability to the UAM industry is critical because, in general, a 20% weight reduction of the battery pack alone would free up enough weight for additional energy storage, baggage capacity, or avionics and flight hardware. This would reduce the 200lb Volocopter battery to 160lbs (or just 16% of the total weight of the aircraft) and would allow energy density to scale to the third power since the reduction in volume for a reduction of weight is not linearly proportional. The 20% reduction, or 80% capacity rule is a benchmark to chase.
How realistic would it be to achieve this reduction in weight; this increase in energy density? At the current rate of battery technology advancement, about 7 years. Is this soon enough? Many would say yes, but the bigger concern is not being addressed: how long will it take battery technology to achieve 30% and 40% reductions, or progress to the point where the energy capacity of Jet-A is challenged? The next 7 years will be a true barometer of success, and small scale demonstrations of battery technology in people-carrying Urban Air Mobility situations will help increase the general awareness of the advantages of electric aerial transportation. Eventually the time will come for more than 3% per year, but only once a larger audience realizes the potential benefit.