It follows every advance in aviation, from the boom in early airliners to the frenzy over very light jets in the 1990s: a gradual retrenchment as the best-prepared companies pull ahead of the pack. Now there are signs it’s beginning to happen in the white-hot competition over urban air mobility aircraft, too.

With more than 150 companies worldwide racing to field UAM prototypes, the smartest are quietly preparing for the next phase: partnering with major aerospace suppliers that have the technology, global reach and certification expertise to make aircraft not just flyable, but viable.

We’ve seen this change up close because of Honeywell Aerospace’s close relationship with the top UAM aircraft developers, regulators, industry groups and consulting firms worldwide. And because we’ve also got decades of experience helping aircraft get certified, we’ve got a pretty good idea of what’s coming next.

Here’s our view of the six areas where UAM companies will need to excel in the next few years:

Foundations for Autonomous Flight

Every trade study of urban air mobility is clear on one thing: to succeed in the long-term, companies must prepare for a future without pilots in the aircraft. Removing pilots dramatically increases payload and reduces labor costs.

The public is still skeptical: a survey by Booz Allen Hamilton for NASA found that only 21 percent of people would feel comfortable flying alone in an automated aircraft – though that number increased to 40 percent if they were accompanied by other passengers that they knew.

Two factors should increase public acceptance: the advent of self-driving cars and trucks, and the introduction of rugged, accurate flight systems.

Honeywell, for example, is developing an integrated flight system that will grow to support autonomous operations. It combines a vehicle management computer, compact fly-by-wire computers, the new IntuVue RDR-84K radar and an array of sensors and navigators. Inertial measurement units provide location information even when radio or GPS signals are blocked, such as in “urban canyons” between buildings.

Fly-by-wire

Companies that built their first UAM prototypes using controllers designed for small UAVs are discovering those systems simply are not robust enough for passenger flights.

A Porsche Consulting study noted that the generally accepted risk models for hobby drones, when applied to 23,000 passenger drones clocking close to 50 million flight hours per year, would translate into one critical incident every other day – “which is clearly not acceptable.”

To bring air transport-level safety and reliability, the leading UAM companies are now looking to install true fly-by-wire computers.

Honeywell’s fly-by-wire computers for UAM aircraft are derived from its systems for airliners, but are only about the size of a hardcover book. They are intended to work in threes, a design known as a triplex architecture.

The three computers continuously consolidate mode states, meaning they “vote” on actions, while equalizing commands across channels to isolate failures and prevent control upsets.

Each computer uses lockstep processing, meaning two computing paths run in parallel and constantly check each other’s work.

Collision avoidance technology

Most UAM companies are flying their prototypes at small airports or over remote test ranges. But as designers begin to put the “urban” in urban air mobility, collision avoidance technologies will become critically important.

Honeywell pioneered the traffic collision avoidance system and enhanced ground proximity warning system used to keep passenger aircraft safe. This year it is debuting the new IntuVue RDR-84K for UAM and Part 23 aircraft.

The RDR-84K is a compact, software-based collision avoidance radar that “steers” multiple beams electronically using a small phased array. It has no moving parts and can mount flush against an aircraft’s skin.

Electric and hybrid-electric propulsion

Advances in distributed propulsion – the use of multiple electric motors located around the aircraft – have helped fuel this boom in new aircraft designs.

Multirotor designs – including that of Volocopter, a Honeywell partner – distribute rotors around the edges of the aircraft. Pipistrel, another Honeywell partner, uses a “lift-and-cruise” design combining rotors and fixed wings. Lilium and other companies use “tilt-x” designs that can tilt wings, rotors or ducts.

Honeywell is developing an integrated propulsion system that includes motors, controllers, power conversion, distribution, propellers and fans. For longer-range VTOL aircraft, such as air ambulances that must venture into rural areas, the company has also introduced a hybrid-electric turbogenerator that combines the rugged HTS900 turbine engine with two 200kw generators.

The system burns conventional or bio-derived jet fuel and can feed motors or high-capacity batteries.

Actuation

Electromechanical actuators don’t get as much attention in the press, but they are key to the design of urban air mobility vehicles.

UAM aircraft will fly low, through thermals and the unusual winds caused by buildings. They must make pinpoint landings dozens of times a day, requiring dramatic power changes and fly-by-wire computers that make hundreds of tiny adjustments every second.

The aircraft’s actuators must perform millions of these movements, withstand the unusual vibrations caused by multiple rotors, and be impervious to bad weather, all while maintaining the highest degrees of precision and reliability.

That’s why Honeywell is introducing a line of electromechanical actuators especially for these aircraft, based on our extensive pedigree in commercial and military applications.

Certification expertise

Finally, the winners in the UAM race will be able to navigate the regulations of multiple countries. Consultants can help, but savvy companies will pick partners with certified, ready-to-fly systems and decades of experience getting new aircraft in the air.

Out of flight testing, into your neighborhood

There’s no doubt that urban air mobility is here to stay. The excitement is building with every test-flight video that appears online. Now smart companies are partnering up for the next phase: getting passengers, not just hopes, aloft.

At Honeywell, our dedicated UAM team is actively looking for new partners. Learn more about our technology, sign up for updates or tell us about your project at our Urban Air Mobility systems page.