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What’s Next in Aviation Technology?

What are the significant developments in the systems guiding aircraft? How does an assumption of safety underline these? Ken Elliott concludes his discussion

Ken Elliott   |   15th December 2017
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Ken Elliott Ken Elliott

Ken Elliott is an avionics veteran of 40 years and more recently has focussed on NextGen. His...
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Advanced and future technology for Business Aviation, Part 2

What are the significant developments in the systems guiding aircraft? How does an assumption of safety underline these? Ken Elliott concludes his discussion of emerging electronic technology for business aircraft… 

In last month’s article on emerging technology for business aircraft, we considered advanced technologies in relation to Big Data; Surveillance; Time-Based Projection; Flight Execution and Redundancy. We continue our analysis with discussion of:

  • Propulsion;
  • Security;
  • Piloting; and
  • Monitoring. 

Together, the above technology fields are rapidly evolving to meet the demands of exponential innovation, throughout all sectors of industry and the society it serves.

Propulsion

Turbine and propeller technologies lead the way in aircraft propulsion today. The forces of environmental concern, market demand and natural technological evolution itself combine to drive different propulsion methods into aircraft platforms.

Incremental improvements of existing technology are regularly advanced. Where such innovation can benefit but not replace existing methods, there is a cautious introduction of totally new power and propulsion methods. 

Because we have been burnt so often, it is human nature to embed a large delay factor into anything introduced and likely to create a dramatic change in our lives. While we gradually begin embracing electric and other propulsion sources, as an alternative to Jet-A (A-1) and Avgas fuel, we will continue to improve traditional engines using existing fuel sources, but only ‘step-by-step’ and likely in a hybrid form.

Factors that drive the change of propellant source, and by default the type of engine, are primarily the environment, hourly operational costs including fuel charges, reduction of risk and a genuine desire for alternatives.

Power and energy required for vehicles

 To be useful for aviation, new propulsion technologies should conform to a combination of requirements. It is not about power or fuel alone. Engine efficiency should be complimented by aircraft size and weight; overall practicality; safety and reliability; cost to operate; and cost to maintain.

Note that the power needed to propel an aircraft increases at greater than the airspeed squared. It takes much more power to fly at higher speeds over longer distances.

One big propulsion factor is the power requirement for an aircraft at take-off. This is where consideration of baseline aircraft weight, fuel on board, payload, runway length, airport elevation, ambient temperature and climb rate play into the formula for deducing engine requirements.

Consider how significant these factor elements play into the powerplant design when contemplating solar power, lithium batteries and electric motors as an alternative energy source and engine type. 

When current aircraft are modified for longer endurance or additional mission capacity, there is a very large penalty incurred by adding fuel tanks to provide for the extra energy source needed. For the military, in-flight refueling has long-been the preferred method of increasing single leg range to meet mission requirements, rather than modify the aircraft with extra tanks.

NASA, GE and many others have attempted various propulsion alternatives. Everyone seems to be settling on hybrid solutions. These are solutions where existing technologies are merged with new concepts to create cleaner propulsion efficiencies. 

Mostly, physical limitations prevent the regular use of non-hydrocarbon liquid or gaseous fuels such as hydrogen or natural gas. An electric or hybrid solution is the primary alternative for a stored energy source. However, when Jet-A fuel hydrocarbons are burnt off during flight, aircraft performance improves as weight is reduced and flight can occur at a higher altitude. The same does not hold true for electric stored energy in the form of fixed batteries, however efficient they become.

The Three Primary Stages of Propulsion

While stored energy and a motor are crucial to propulsion for flight, the method of moving the aircraft through the sky is equally important. From the internal blades in turbine engines and external propellers in fixed-wing aircraft, to the external rotors attached to helicopter engines, there are various means to propel the aircraft in motion.

Incremental efficiencies in aircraft flight include improvements and changes in all three stages of propulsion.

Conversions (or motor types) are predicated on their weight and efficiency. There is a constant effort to tweak efficiencies and find materials that will allow for weight reduction. This effort is expended on the understanding that we are not yet at the point where revolutionary game-changing motors are ready to deploy. The gas turbine, for example, is here to stay for some time. 

However, when we look at aircraft that are not required to carry large or heavy payloads and operate out and back from a fixed base, as opposed to flying between cities, the requirements change.

So, as we enter the unmanned world of autonomous flight, every flavor of propulsion technology is fair game.

Because most drones use lithium batteries, their range and endurance are limited to up to two hours, with infrequent ultra-endurance making headlines almost daily. Using small sensor payloads, their gross weight presents a minimal burden to the energy source. Also, because they tend to operate locally and within line of sight, their endurance requirements are not usually a major performance factor.

For unmanned autonomous aircraft that will need to fly in similar operations to fixed-wing vehicles, there are several key limiting factors. The first three are crucial to operations Beyond Visual Line of Sight (BVLOS):

  • Regulation and Certification (both operational and airworthiness);
  • Ability to identify (for example N-number);
  • Ability to reliably see and avoid;
  • Stored energy, power plant and propulsion method; and
  • Physical capability to consistently fulfill the overall mission (in all-weather conditions). 

Interestingly, we are seeing hybrid stored energy, powerplant and propulsion solutions rapidly emerging in the autonomous vehicle environment. As with manned aircraft, practical solutions are emerging such as fixed-wing platforms with vertical take-off capability. These operate as an airborne ‘Prius’, using a hybrid turbo-electric powerplant, while selecting rechargeable electricity or wet fuel at different phases of flight. An example is to use electricity for taxi and cruise and wet fuel for the other phases of flight.

Moving Slowly: The cautiousness of investors and the interests of shareholders are slowing the pace of change in technology overall. Risk-averse investment and the ‘fastest road to dividends’ may be the order of the day across much of industry. Therefore, we see more of a forward thrust within the defense and commercial ‘dot org’ world, while others get to play in the corporate sandbox within partitioned research and development teams.

An occasional entrepreneur or successful executive will invest and break the tradition, experimenting with game changing propulsion or a complete new aircraft, but that is the exception rather than the rule. A list of game-changing solutions should, however, include sub-orbital aircraft such as Richard Branson’s – Virgin Galactic and Jeff Bezos’s – Blue Origin. 

The US Defense Advanced Research Projects Agency (DARPA) is one place where ideas are flushed out behind the scenes. While traditionally defense-related, they have commercial applications. NASA, Boeing, Airbus and others also line up an impressive array of future versions of propulsion.

With a first flight planned for early 2018, NASA is about to test a redesigned lithium-ion battery module for its first electric propulsion demonstrator, the X-57 Maxwell. The platform’s existing Rotax piston engines are replaced with two 60kW electric motors, and the propellers are mounted on the wingtip to take advantage of the vortices found there. 

So, the future is bright, especially when low earth orbit propulsion is included. Proposed ideas are also hybrid in their use of technology.

One can expect incremental improvements to existing means of propulsion and the introduction of hybrid solutions along the road travelled in the near-term. The long-term, meanwhile, is simmering in a pot of secrecy within the corridors of DARPA, the design shops of Amazon, Google, Tessler and Uber and the well-funded commercial skunk works at Boeing, Airbus and others. 

Security

Even the best laid plans can all come tumbling down if there is just one weak spot in data security. There is no point in advancing technology, both airborne and ground-based, without corresponding embedded security at a level that matches the threat.

FAA Security and System Safety

Recently, a major aircraft service provider—Satcom Direct—announced an increased focus on data security within its popular service programs. It realized the potential risk to business aircraft operators across all areas of aircraft communication and data, particularly where data can be accessed as it travels outside of the aircraft itself.

Satcom Direct, as well as others, realize the significance of adding layers of security because they work with the subject all day long. It is a core tenant of their business, acting as the provider, enabling seamless operation between the operator and the companies that provide satellite and other services. These are locations where vulnerabilities are at their greatest.

For aircraft there are three areas of security concern:

  • Crew & cockpit;
  • Passengers & cabin; and
  • The aircraft systems themselves.

For both crew and passengers, there is a layer of security added when personal devices are connected, even wirelessly, to the aircraft. For all three, there is a grey area between commercial network protocols and the aircraft busses themselves. Aircraft busses are, today, guided by complex ARINC, Ethernet and other data standards. 

A risk, constantly monitored, is the ability of commercial network activity directly connecting to an aircraft bus, where snoopers and hackers may explore their nefarious art in uncharted territory. 

Aircraft routers, for example, typically connect to aircraft busses and at the same time act as routers for cockpit and cabin personal devices. Within, the router should be all the necessary hardware and software to ensure firewalled and physical separation between devices and busses. The desire and need to transfer real-time data to and from the aircraft requires that analogue, and digital information are gathered and converted to Application Programming Interface (API) formatting for communication off the aircraft. 

Companies communicating with their own aircraft have the additional challenge of ensuring their intranets and servers are not exposed at either the corporate end and/or at the office in the sky.

Whenever corporations take on new cabin or cockpit devices as well as the associated service provider programs, their IT department should be involved right from the start. All sorts of issues and risks may be avoided by being proactive in this collaboration. 

Today’s advanced aviation data bus uses packets of data, each of which is integrity-checked before being passed on for processing.

There are significant checks and balances in aviation data busses. The FAA has a 2016 policy order document 1370.121 outlining information security and privacy, helpful to designers, system manufacturers, integrators and users.

Industry and FAA, via RTCA special committee SC216, has issued the following aviation security documents:

  • DO-326A ‘Airworthiness Security Methods and Considerations’
  • DO-355 ‘Information Security Guidance for Continuing Airworthiness’
  • DO-356 ‘Airworthiness Security Process Specification’

(These correspond to EUROCAE - WG72 documents ED-202, 204 and 203, respectively.) 

Security also extends to databases and software updates that are imported into the aircraft and may be corrupted in some way. Databases and software have direct access into on-board systems when updates are loaded, thereby providing an avenue for corrupting critical information.

Unfortunately, the protection of aircraft systems will continue to be an evolving issue as hackers reinvent themselves and their malicious tools.

Also of concern to aviators is the security risk associated with ground equipment. Here FAA and other agencies are providing communication, navigation and surveillance services, all of which must continue to operate consistently and reliably.

As a credit to the FAA, it is smart enough to ensure the continuation and enhancement for DME (Rho-Rho/DME-DME) navigation services. These extremely accurate position sources are being maintained as an assurance against the loss of GPS signals.

The future is likely to consist of additional security layers, each with an increasing granularity in the protection and transfer of data. There will need to be alternative solutions, as a backup, to critical onboard systems that rely on infrastructure, positioned on the ground or in space.

The virtual aircraft of the future will become a cloud-based digital-duplicate of the original. In the instance of degraded data, it will be able to provide specific flight commands, derived from a remote replication of vulnerable aircraft and infrastructure systems. 

Piloting

As we rapidly advance toward the world of autonomous flight, an ability to remain in control of the aircraft becomes more important. While flying vehicles over people gets the attention of the public, any flight needs to be conducted safely and the pilot, whether seated in it or in a remote-control facility, needs to remain in command, from taxi out to taxi in. 

For fixed wing ‘loss of control in flight’ (LOC-I), there is no one weak link in the chain of flight, but there are several common denominators. Either the pilot may have difficulty in controlling the aircraft or the pilot may not be seeing the visual cues, including those associated with terrain and obstacles.

 

LOC-I Accidents by Phase of Flight

 

Jet and Turboprop accidents by phase of flight

 

For unmanned vehicles, the weak links are ‘loss of control’ and ‘loss of lock’. One occurs while still electronically connected to the aircraft and the other occurs because of an inability to maintain control connectivity. 

IATA-LOC-I-1st-Ed-2015 Loss of Control In-Flight Accident Analysis Report covers aircraft over 12,500 lbs (5,700kg). This document is complimented by IATA’s Environmental Factors Affecting Loss of Control In-Flight: Best Practice for Threat Recognition & Management. Together they paint a grim picture, where a staggering 97% of LOC-I accidents, for the period measured, resulted in fatalities. 

The external environment and how pilots deal with it, are key factors in the cause of LOC-I for manned aircraft. Meteorological events and abnormalities such as wake turbulence may cause the initial upset and, in some cases, the pilot then exacerbates the event by improper corrective action.

Manned aircraft, fixed and rotary, are much more responsive these days, resulting in fewer occurrences of LOC-I. There will continue to be an iterative process of continued improvement going forward.

Unmanned aircraft will not be openly allowed to operate as BVLOS until the ability to maintain locked-on and in-control is assured. Long before they fly autonomously, they will be operated by a remote pilot, with redundancy built in at every level. In fact, the more that an unmanned aircraft can be operated and maintained like a manned vehicle, the easier and quicker will be the transition into BVLOS operations, allowing transition through multiple airspace categories.

 

Unmanned Aircraft

 

The first unmanned operational approval is planned for Class G airspace and the last is anticipated to be Classes associated with airports and terminal areas. 

Monitoring

Imagine a world where for every action there is an instant monitoring check. Even today we can monitor airborne aircraft remotely, in all sorts of ways and for many interested parties. We can monitor many activities in virtual real time, and record as we go for later analysis and data memory.

As aircraft operate closer together, within limited airspace, the criticality of monitoring increases. An early example of monitoring is Reduced Vertical Separation Minimums (RVSM). Now with ADS-B, and later worldwide space-based ADS-B, even RVSM may become redundant. Indeed, future aircraft performance monitoring will be a 4D application, combining altitude, lateral navigation and time-at-point, as universal position tracking provides a single Total System Error (TSE) to meet different allowable tolerances throughout phases of flight.

High-capacity cloud-based servers will store and forward constant position status. Because the monitoring is full-time, actual errors should be minimal, unless unplanned. Failures will be broadcast in real time, for both manned and unmanned platforms, simultaneously providing corrective action. Crews may elect to act on correction suggested, just as with flight instrument commands of today, but with added voice ‘commands’ and an automatic display of relevant pilot checklist items on a secondary monitor.

Summary

The time has arrived when flight departments are exploring the supplemental use of unmanned aircraft, where their pilots may be strapped in and airborne for the first flight of the day and operating as remote pilot for the next flight.

Manned fixed-wing flights mostly involve the carriage of people and cargo from city to city, while unmanned vehicles operate locally using sensor payloads to conduct useful industrial activity, out from and back to home base. Together, these operations will satisfy an overall corporate mission. At least in our life-times, unmanned aircraft will not be dismissed as ‘job deniers’. They will instead enhance the capabilities of existing flight departments. 

Including the amazing array of new technologies and advancements covered in the last two articles, flight departments will also benefit, because of improvements gained in safety, efficiency, performance and overall cost reduction.

The surface has just been scratched when it comes to advanced and future technology. Also, keeping up will be tough as changes occur exponentially, despite cautions imposed by necessary regulation and our natural reluctance to adapt to change. 

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Read more about: Business Aviation Engines | Business Aircraft Safety | Business Aircraft Security | Avionics

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