Future E-VTOL Illustration
Major airspace and aircraft changes are underway. But how could they impact the development of future aircraft design? Ken Elliott considers…
Extrapolating an aircraft design of the future is like predicting the weather. There are many factors in play. An aircraft’s design is more than just its aerodynamics and system engineering. It includes economics, geopolitics and international regulations, all of which can shape the development of each emerging technology.
Taking a holistic approach, an aircraft may be designed within the context of the total airspace in which it intends to operate, including how that will appear several years hence. Consider how the aircraft, as a platform, either navigates an optimum route between two points, carrying passengers or cargo; or equipped with sensors and tools, flies out and back from a single location, fulfilling enterprise missions.
Once you know the aircraft is either intended for transit or for enterprise, the operational considerations can be bound within very specific constraints, defined by the airspace required and the regional environment.
This thought process includes all types of aircraft and envisions a much greater use of the ‘airspace in between’. Typically, this implies lower altitudes within uncontrolled Class G airspace. So, in some cases, the design requirements can serve the need of low altitude urban transit, where unconventional scenarios of very short range and higher density altitude operations will exist.
Airports are expensive to build, operate and maintain (as China is now discovering). The desire to create efficient aircraft that do not require runways is significant. Runways also eat up real estate and the closer they need to be to urban areas, the harder the decision to build. Heathrow’s third runway is a great example.
One other driving factor is the expectation of convenience spurred on by a bourgeoning global middle-class. They may be wealthy enough to move via air transport, but not quite able to own the aircraft in which they fly. This same educated group is likely to prefer flying in something quiet, safe and tamper-proof. If an aircraft also happens to be hybrid electric and by default, light on ‘fuel’, even better.
These assumptions take us to a very different place than today’s aircraft. They are real but also idealistic - so, a more accurate expectation would be the design of an aircraft to operate somewhere in between our familiar current environment and what we think is possible.
For example, moving from piloted to autonomous will be a phased, deliberative approach (see Figure 2b). Today, for people and cargo movers, we are edging toward operations using a single pilot. We are planning for remote pilot and envisaging the day of no pilot. As with piloting, emerging technologies will also be iterative. Their introduction will be paced in line with that of regulations and guidance.
Emerging and mature technologies, needed to meet the changing airspace requirements, are not new. However, they will be approached differently. This, in part, is because future users will be a much broader group. There will also be more acceptance for the use of open-source, as opposed to proprietary software platforms.
Remotely piloted and autonomous flight will naturally incur greater scrutiny. Technologies will need to be tamper-proof and become more integrated. Live monitoring and safe recovery from a flight failure is to be essential. Concern for people on the ground will increase exponentially when users operate within urban areas (the future turf of Electric Vertical Take-Off and Landing (e-VTOL) aircraft).
Emerging Airspace Crucial to Aircraft Design
The space we need to design for cannot be viewed as isolated segments. Today, we carve up our airspace into oceanic, continental, enroute, approach and terminal. Operations are centered on metroplexes, hubs, spokes, airports and heliports.
Future airspace must also accommodate the needs of urban transit, enterprise ‘out and back’ operations, high altitude endurance, supersonic and low-earth-orbit space traffic. Given the projected complexity, holistic integration will be essential.
High volumes of transit air traffic can be anticipated in dense urban areas, slowly easing as the terrain becomes more rural. On the other hand, enterprise drone traffic can be expected to gravitate around industrial locations and along associated physical infrastructure.
Other future traffic, such as space transport, should be easier to accommodate as there will be less short-term demand for those services than for others.
As aircraft evolve there will be less need for runways. For example, aircraft platforms designed for VTOL do not require runways. Their (air)ports could be parking lots and rooftops. Because both drones and e-VTOL are designed to operate with maneuverability and agility, they require limited real estate for take-off and landing.
Low-Altitude Authorization and Notification Capability
Recently, the FAA finalized the implementation of its new Low-Altitude Authorization and Notification Capability (LAANC) digital airspace program. Currently this is set up for Part 107 unmanned aircraft operators.
It involves 470 airports and 288 ATC facilities, all having LAANC capability. This positions the US to successfully integrate small unmanned aircraft into its existing infrastructure, below 400ft.
Under LAANC, drone operators request approval via one of several service providers. The providers will either indicate an automatic approval or in cases where the intended operation falls outside of specific limits, seek FAA approval. In the case of automatic approval, the request turns into a notification with the service provider advising air traffic and other interested parties.
The notification provides route and flight details, like filing a flight plan. Service providers also inform users of flight advisories and alerts, show restricted areas and show other aircraft, by type and intent, as display information.
The service provider uses FAA LAANC maps. These show pre-approved, one square-mile, altitude blocks around and within commercial and military airports and other sensitive sites. Typically, blocks at airports show zero-altitude approval and a progressively higher altitude approval, of up to 400ft, as you move further away.
Areas not covered by these blocks may be considered OK to operate in. However, all existing Part 107 rules will still apply. Of course, not all airports and regions are participating in the LAANC program, so it is crucial to check that first.
Applying LAANC to Urban Areas
Taking this concept to the next level, LAANC may be applied (with some variation) to urban areas in general. This will include obstacles, such as towers and buildings and just as existing Terrain Awareness Warning Systems rely on high density data bases, these new maps may provide the same service but with even greater complexity.
A significant take-away is that an individual operator may only concern themselves with an approval to operate in the area in which they intend to fly. Equally, this allows for a more localized approach to airspace approvals, somewhat in line with the White House and Department of Transport approach to involve local and regional authorities in a current drone integration effort.
This effort has commenced with the FAA UAS Integration Pilot Program (FAA-IPP) where only City, State and Regional Authorities can apply for limited operation programs. They must work with industry partners and maintain a continuous FAA involvement. The idea is for the FAA to learn from these local, low altitude ‘experiments’ by gaining experience, in preparation for long-term unmanned aircraft guidance.
By natural progression, this implies a similar approach to e-VTOL transit aircraft programs and later a totally integrated national airspace.
So, looking at the traditional airspace, plus the ‘spaces in between’, we can expect to see a gradual in-filling of Class G via ‘managed’ fixed altitude airspace blocks. These blocks will protect non-towered airports that have no instrument approaches. They may be reduced in size to a half-square-mile within dense urban environments.
Today, notification of air activity is required within 5 miles of any airport, irrespective of the airspace classification in which it is located. This hints at how the future airspace may be ‘sliced and diced’. In turn, aircraft will be designed with their technologies best suited to accommodate developing airspace requirements.
The complexity of the design requirement, to accommodate a dramatic increase in convenience and efficiency, will demand adaptive air vehicles with technologies that can rapidly process large-scale data.
Major highways and rail lines already determine routes with acceptable noise limits between centers of urban activity. It is therefore likely that e-VTOL and other modes of future air transport will use these same corridors.
Not only will these expand in 3D, but they will function in 4D, using time and Performance-Based Navigation (PBN).
Another consideration for an overall integration is the role of ATC, automatically processing traffic flow via datacom. Further, the use of direct traffic to traffic situational awareness, will allow a more seemless (potentially unmanned) air traffic integration. Controller to Controller (C2C), Controller to Vehicle (C2V) and Vehicle to Vehicle (V2V) are projected features of a future airspace, providing for efficient, reliable and expedited direct traffic management.
In SummaryMajor airspace and aircraft design changes are underway. The common denominator will be greater access, achieved by greater vehicle agility, increased awareness and an ability for all users to handle large volumes of data, among other considerations.
These factors drive the enhancement of existing technology and will introduce the new. So be assured, that today’s ADS-B, VDL clearance, FANS and WAAS-LPV will evolve. Existing TCAS and TAWS will also look very different.
New technologies, being integrated into drones, will expand into other aircraft platforms. Connectivity, using Ka-band for international and 5G for domestic flights, will serve to advance high-speed solutions at lower cost.
Regular smartphones will become even smarter and, in some form or fashion, control a lot more than you might think possible or allowable at present. Relying on a constant internet signal, these personal devices will connect to high altitude, terrain following, fixed-position drones.
Because civil aviation authorities are moving over to performance based (instead of prescriptive) requirements, there is a lot more room for the development and acceptance of technology. Already in use with drones, smart devices controlling aircraft, while using open source software is a possibility that may not be as far away as you think.