Describing an experience that few people on Earth will ever have the opportunity to undergo, Lonh Vannsith admits he was nervous when he strapped into the first-ever Cambodia-designed and built aircraft in the Kingdom’s history, despite the extensive testing it had already been through prior to reaching that moment.

“At first . . . Yes, I was scared out of my wits. But then after flying on it several times my nerves settled and my anxiety was replaced by the sheer excitement of it,” Vannsith tells The Post.

Vannsith may have felt nervous about the flight, but his actions were undeniably brave in serving as the test pilot for the small drone-like helicopter aircraft that he and a partner developed and built here in Cambodia, marking a first-ever aviation achievement for the Kingdom.

Born of the cooperative efforts between fourth-year electronics engineering student Vannsith and third- year mechanical engineering student Chroay Sotheara at the National Polytechnic Institute of Cambodia (NPIC), their invention – called the Human Carrier Drone – is intended as a possible solution to Phnom Penh’s traffic jams as well as being a potentially useful skyward conveyance for emergency responders such as firefighters when trying to access the upper-floors of a burning building, for example.

“The Human Carrier Drone was purpose-developed as an air-taxi that can carry two people. One person can act as the pilot and the other can ride along as a passenger,” said Sotheara.

However, before this over-sized drone-copter or under-sized helicopter (take your pick) took flight with anyone on-board it was flight-tested with sandbags perched in its seats around 50 times to ensure that Vannsith’s first trip on it wasn’t likely to be his last.

“When the final prototype is complete, we want it to be an air-taxi for human transportation that will provide a new means of easing traffic problems and also be of potential use for specialized purposes such as emergency response. For instance, we’d like to test it out as a hose carrier that can extend the range of fire-trucks to upper floors that hoses on the ground can’t reach,” Sotheara says.

“To do that we’d need the drone to be able to lift more weight and somehow remain stable in flight by compensating for the kick-back pressure from the hose’s water-flow,” explains the aspiring mechanical engineer from Kandal province.

From the very first modeling done on paper and computer screens to the body suspension design process to the first unmanned flights with sandbags for cargo and then onto Vannsith’s manned test flights, it took over a year of hard work for the pair of NPIC students and their team of five assistants to reach this point.

“The development phase was pretty long since it was started in mid-2020 and it just finished recently for the first phase. The unmanned sandbag flights were important for safety testing the overall stability.

“The flight trials took place in two steps and after 46 flights we were pretty certain that the aircraft could lift-off carrying someone who weighed less than 60 kg. We’ve now conducted about 70 trials total,” he says.

They built the Human Carrier Drone by welding together an aluminum frame with a square suspension that provides a place for someone to sit and pilot the flight. They then attached double-propellers to each aluminum arm with one on top and another placed upside down below.

With an airframe weighing 125 kg and a length of roughly two-and-a-half metres, this functioning flight-capable prototype air-taxi was developed chiefly by Sotheara and Vannsith along with the help of five other student assistants as an original project sponsored in full by the NPIC.

Vannsith, who hails originally from Banteay Meanchey province, says that all of the budgetary expenses and funding was provided by their school, which also helped with recruiting the other student volunteers who provided countless hours of assistance working on this incredibly ambitious project.

“We decided to join up because we saw it was an opportunity to gain really in-depth technical knowledge in this field even if we failed, and any successes meant having the honor of being pioneers in drone-engineering and aviation here in the Kingdom in some small way,” Vannsith says.

The Human Carrier Drone in its current design incarnation is equipped with four double-propellers powered by an electric battery and the costs for everything including materials for the first phase came to $27,000 in total.

The drone can presently take flight with cargo – whether sandbag or human being – weighing 60 kg or less to a height of 5-6m and a range of around 100m with around 10 minutes of battery life.

It’s still a work-in-progress, in other words, and you won’t be seeing them in the skies of Phnom Penh or on sale at Aeon Mall anytime soon, but the team continues to tweak their designs and tinker with the prototype with some very ambitious goals in mind, but they say they won’t settle for anything less before considering the project completed – no matter who it is that ultimately reaches the finish line.

“We aim to fly 100m above the ground with a 15 km range from home carrying a load of two people, of course,” Sotheara says – quite nonchalantly – when asked what he thought success for the project might look like when all is said and done.

Many people would say that a lot has already been achieved by the duo. At the very least they have become something akin to the Cambodian version of the “Wright Brothers” – at least for the Kingdom’s small but growing drone aviation sector.

Perhaps it is a bit more obscure of an achievement than that of the first-ever humans to take flight, but a group of Cambodian engineering students designed, built and flight-tested a drone-copter aircraft capable of carrying a human pilot, and that should rightly be celebrated rather than cynically dismissed.

Their success has been recognized by the masses in the form of test flight videos that have gone viral on social media and the team says they are thankful to everyone for being so supportive of the project both in Cambodia and abroad.

“For future plans, we want to develop better drones that can load more weight onto a lighter body. Moreover, we also need to improve the intelligence of the control system as well,” Vannsith says.

However, the process of developing the first passenger-capable drone aircraft in Cambodia was not an easy one and they often faced what seemed like insurmountable obstacles. The success they’ve achieved took a great deal of time and effort and they also had to order materials from abroad with the usual interminable shipping times.

“While we were building this drone it was actually coincident with the Covid epidemic. So things took more time once the schools closed and the tools and materials took longer to import and came with higher prices and some design choices were based on available materials rather than ideal ones, which meant doing more research and needing much greater flexibility,” Sotheara says.

To achieve their ambition to build a passenger drone aircraft or fly firefighters around flaming skyscrapers the Human Carrier Drone has to pass through two more development phases, both of which demand lengthier periods of time to navigate through.

Sotheara estimates that based on their progress in the first phase it may take four or five years to complete phase two and three, depending on resources and manpower.

“In phase two, they will further develop its appearance and make a shift from aluminum to carbon fibre frames that are strong but lightweight to free up more weight for passengers and keep it in the air longer,” he says.

Though the deployment of a fleet of air-taxi drone helicopters to the bright-blue sunny skies over Phnom Penh is still many years away from being a reality, Vannsith and Sotheara are confident that the project will take on a life of its own and continue at the school long after they graduate and begin their careers because NPIC is already planning for the long-term with student successors taking the reins of the project to learn new lessons from it over time.

“As the first team leaders for the project we have a duty to be mentors and share our knowledge and experiences with the younger students to help them continue to move things forward. Therefore, when we have our successors in place and up to speed and ready to use what we did as the foundation for what they will achieve, that’s when we’ve reached personal success and achieved our individual goals … though not the project’s ultimate goals … yet,” Sothearas says, adding that he has faith that some future class of NPIC students will complete the project with the goals he set out for it and then surpass them and that he hopes to be there to see the Human Carrier Drone take flight when they do.