SINGAPORE: Imagine being late for work on a Monday morning and skipping the traffic jam in a pilotless passenger drone taxi, flying overcrowded highways to reach the office in time.
While such a scenario currently only exists in science-fiction, the technology to ferry humans in unmanned drone aircraft could be perfected in the not-too-distant future.
The development of unmanned aircraft systems (UAS) was mentioned in Parliament on Wednesday (Mar 8) by Second Minister for Transport Ng Chee Meng.
“There is huge potential for UAS to spur new and innovative applications across industries," he said. “In time to come, UAS can potentially even ferry people through the air, adding a new dimension to urban mobility."
Two tertiary institutions in Singapore have been pushing the boundaries of what is possible with passenger drones. One of them is Singapore Polytechnic (SP), which had a project group successfully create a battery-operated one-seater drone - called “DATUM” - late last year, which could lift off the ground and hover for about five minutes.
It featured in SP's Engineering Show 2018 in January, where it flew with a seated, 60kg mannequin.
“It’s a fully functional transportation-class aircraft that has the capability of carrying a human being,” said Aeronautical Engineering student Ang Jing Hao. “With a total of 18 motors, we’re looking at carrying a payload of a human being and be classed as a transportation method that can hopefully be used here.”
He added: “It has vertical takeoff and landing function, which is suitable for our urban environment in Singapore.
“We’re not looking to replace cars, but we’re hoping it can be developed further into a form of an air taxi in the future.”
CURRENT INDUSTRIAL PROTOTYPES
Successfully conducting manned test flights of its prototype passenger drone last month, Chinese drone maker Ehang is arguably the closest to achieving the reality of air taxis.
Its drone consists a two-seater pod that is lifted into the air, thanks 16 exposed electric rotors attached to eight arms at its base.
According to China’s Xinhua News, Ehang’s team of 150 technical engineers have conducted thousands of test flights. Its performance allows 230kg to be carried and a vertical climb of up to 300m. There has been a successful routed test flight covering 15km and a high-speed cruising test that reached 130km/h.
“This makes you feel like you have travelled into the future like you’re in a sci-fi movie. But this is real,” Ehang’s founder and chief executive Hu Huazhi said in a company video that showed footage of the flight tests.
“It’s so easy and stable, and its operation is very simple. I’ve flown so many helicopters, but nothing feels like this.”
Another company, German drone-maker Volocopter, is also racing to be the first to perfect unmanned passenger drones.
“While we are far advanced with the aircraft, it takes more to become a mode of transport,” said the company, in response to queries by Channel NewsAsia. “We already have designs for the ecosystem and Volocopter infrastructure.”
Its drone, though, is not for sale for now.
“While we have a long list of individuals interested to buy the Volocopter, we are currently not looking to sell them individually. Rather, we offer a public transport system – our customers will be cities implementing these systems for their inhabitants.”
The current limitation of passenger drone prototypes is battery technology, as modern Lithium-based ones are unable to provide enough power for sustained flight. “For now, the biggest limitation is the duration of the flight,” said Singapore Polytechnic’s Aeronautical Engineering lecturer Reagan Chionh.
“Current passenger drones that purely run on batteries would fly for an average of 10 minutes before they completely run out power,” said Mr Chionh. “That’s due to the amount of energy needed to sustain thrust in order to lift the weight of a person in addition to the frame of the craft.”
He added: “I would think that it would take 15 to 20 years for drone technology to advance to a good stage.”
Mr Chionh’s student Ang Jing Hao is looking to solve this issue in SP’s DATUM drone. “We have an integrated a hybrid engine fuel management system,” he said. “What we have is an onboard battery charging and battery swapping system – which we can say it’s the first of its kind (for drones) in Singapore.”
He explained: “When the first set of batteries has been depleted, the second set will kick in, while the first one is automatically swapped out electronically and charged onboard using a petrol generator.
“That way, we have extended the craft’s theoretical range and flight time to last for 30 minutes in total. Without this hybrid engine system, we’d have a flight time of eight minutes,” said the 21-year-old.
As for Volocopter’s latest industrial prototype, its redundancy systems allow for battery failure. “We have nine batteries, each of which powers two adjacent rotors,” said the German company. “While each individual battery is already very reliable and heavily tested, nothing would happen if one of the nine batteries is lost.”
It added: “A bigger challenge is the battery power to this day. It limits our flight range, which is why we have designed the Volocopter 2X with exchangeable battery packs, which can be changed within minutes.”
NOT SUITABLE FOR SINGAPORE’S URBAN SKYLINE?
Singapore’s densely populated environment, however, may not be suitable for passenger drones. “The area for usage is very limited for Singapore … but there could be certain uses for it, such as for emergency transportation,” said Nanyang Technological University (NTU) transport researcher Prof Gopinath Menon.
He added: “The other issue is high-rise buildings, as there could be security risks involved in flying them close to buildings.”
“To have passenger drones in Singapore… if the numbers are small, then maybe it’s alright,” said the NTU lecturer. “But if the sky is full of them, then it could be an issue due to the limited airspace that we have.”
A drone mishap could have disastrous consequences, according to Prof Menon. “If there were to be a drone accident, it would affect a wider area compared to road accidents which tend to be more localised in a sense,” he said.
It is expected that such passenger drones - if they ever become a transportation reality - would likely be classed the same as helicopters in accordance with Civil Aviation Authority of Singapore (CAAS) laws.
“One of the challenges I foresee would be (drones) meeting all aviation safety standards, criteria and infrastructure,” said Nanyang Polytechnic (NYP) Engineering lecturer Albert Sng.
Mr Sng, however, is hopeful that both law and technology will catch up with each other in about two decades. “While Singapore does not have the luxury of vast land spaces to operate autonomous drones as a mode of transport, there is still a possibility of drones replacing land vehicles in the next 20 or 30 years,” he said.
“This may happen when the cost of building and sustaining the drones eventually decreases over the years.”