Mohsen Bahmani is an Iranian-born mechanical engineer and a man with a dream. When he was just 17 years old, he made a pair of floating shoes that allow you to walk on water, which he sold for millions a few years later. Now he has invented a revolutionary propulsion system that can lift a drone or taxi into the air that doesn’t use propellers or jets but is based simply on Newton’s third law of physics: for every action there is an equal and opposite reaction.

“I am a mechanical engineer and have been working as an inventor for over a decade. My passion is developing new technologies that challenge existing limits of mobility and energy generation,” he told bne IntelliNews. “Our team wants to develop technologies that not only work today – but actively shape the future. Our goal is to redefine movement: quiet, sustainable, autonomous.”

The idea is very simple but could create a whole new class of flying machines. The “reaction propulsion system”, as Bahmani dubs it, drives blocks around a track, accelerating them upward before they turn and fall back down again. At the top of the curve the energy of the blocks is transferred to the track through centrifugal force and can lift it off the ground. No need for propellers or jets, making it quiet, clean and efficient – ideal for driving flying cars or drones working in urban environments.

Mohsen Bahmani has been inventing things since he was 17 years old and became a millionaire at 19 thanks to his floating shoes. 

Floating shoes

Born in Iran where he studied mechanical engineering at the Karaj Azad University in Tehran, Bahmani’s adventure started when he invented shoes that allow you to walk on water, based on the principles that hovercrafts use.

Bahmani showcased the shoes at several fairs around Europe and bagged the silver medal at the Archimedes Invention Competition in Moscow and another prize in Romania. But at the Geneva Inventions Fair in Switzerland in April 2008 he not only won second prize in a field of over 1,200 other inventors but was also awarded a scholarship to continue his studies in Geneva while he was still only 17 years old.

Back in Iran, the authorities were very pleased with him and exempted him from national service and allowed him to continue his studies aboard. Two years later Bahmani sold the rights to his shoes to an Italian company for several million euros and started to shop around for a place to continue his studies. After Geneva, Bahmani received dozens of offers to study for a masters but eventually settled on the Karlsruhe Institute of Technology, one of Germany’s very best schools, where he began work on his reaction propulsion system.

“At first, I asked the university to help develop the propulsion system, but they said if we give you the money, we get 80% of the ownership. So, I thought about it for a while and decided I would pay for it myself,” recounts Bahmani who was at this point a fairly wealthy man. “But the professor was very strict. He said I had to produce a working prototype in nine months or they would throw me out of the university.”

Bahmani rolled up his sleeves and got to work. At the time he was actually living in Berlin, a more fun town, and drove his Porsche down to Karlsruhe, a six-hour drive, when he had to attend lectures, seminars or do some lab time, occasionally staying in a hotel or sleeping in the library if he had to overnight there. But sure enough, Bahmani completed the prototype on time in 2018 and it was formally patented by the European Patent Office in 2023.

A drone version of the system is already working, but Bahmani has much bigger ambitions. He wants to scale his reaction propulsion system up and make it big enough to fly an air taxi and is currently hunting for an investor and applying to the EU for grants to raise the necessary investment capital to get the work done.

“It’s a revolutionary technology and we already have a working prototype. All we need now is some more money to continue the development to get to the scale of a working flying car. Then the possibilities become multiple,” Bahmani says with the enthusiasm of a man on a mission.

Bahmani has already tired up with German firm, Mansory, famous for putting power into engines and creating distinctive looks for luxury cars, to develop a radical flying car concept, the Empower, that look like a futuristic flying Lamborghini, but is unlikely to go into production any time soon.

Reaction propulsion

At the core of the idea is a novel, energy-efficient thrust system that extends the flight time of drones and reduces their physical size for use in urban areas. The radical departure from convention is to abandon using gas (air) to provide the lift, which almost all aircraft use in one form or another.

The propulsion system is based on Newton's third law, converting the kinetic energy of a moving block (the action) directly into thrust by making the blocks change direction (the reaction). In more simple terms: you make some blocks travel around a closed track and the fact that they have to go around a curve at one end faster than at the other makes the track fly.

“Our propulsion system consists of several small-scale reaction motors (comparable to electric impellers) driven by highly efficient BLDC [brushless direct-current] motors. These units move along a closed path, generating directed reaction or centrifugal forces. The result is a compact, energy- and fuel-efficient propulsion system that can be modularly integrated into a wide variety of vehicles and devices,” Bahmani describes the system on his website.

The swarm of tiny "thrust generators" blocks of about 200g working in synchronization are forced to run around a vertical looped track. Magnetic fields could be used to accelerate them upwards on the same principle as a maglev train until at the top of the loop the curve forces them to turn. The centrifugal force of the turn transfers the blocks’ kinetic energy to the track and is enough to lift it off the ground. Then the blocks fall back to the bottom of the loop under the force of gravity.

Bahmani was actually cagey about the details of how the blocks on the drone prototype are driven and has not released the videos of its test flight, as it would reveal too many technical details that could be stolen by potential competitors or copycats, he said. The footage of an early-stage ground-bound prototype he has released uses small fans to propel the blocks around the track.

“During the phase in which the reaction drives travel through the first curved section, they transfer their previously accumulated kinetic energy to the loop track through centrifugal force,” says Bahmani. “The deactivated drives then move slowly through the second straight and the second curved section until they reach the beginning again—and the cycle begins again. Since several of these drives are simultaneously in different phases on the loop track, a uniform and directed force is generated that acts on the loop track. This, in turn, can be coupled to any vehicle.”

Bahmani claims he has perfected the control system and that each 200g block can generate up to 5kg of upward thrust. Propellers that force gas downwards to create thrust are inherently inefficient compared to a block forced to move on a smooth track so much less energy is wasted, says Bahmani. He claims the reaction drive has an energy efficiency of 50% -- twice as efficient as conventional propeller or jet systems, although the gas-based systems are capable of generating far more powerful thrusts and so much higher speeds needed for commercial or military jet planes.

The other advantage is that without gushing torrents of gas, the system is almost silent. In the world of physics, fast moving gas striking your eardrum is sound.

As the loops can be oriented in any direction their thrust can be altered to drive the drone upwards or forwards making it highly manoeuvrable and ideal for flying at low speeds in built up urban landscapes.

“Billions have been invested in propeller-based drone technologies in recent years. Yet, urban applications often fail due to installation space, noise, safety issues with open rotors, and limited flight time,” says Bahmani. “Our propulsion technology addresses precisely these bottlenecks: compact, energy-efficient, and encapsulable making it highly suitable for urban applications where conventional systems reach their limits.”

As bne IntelliNews reported, the world is on the cusp of building a “low-altitude economy” where groceries are delivered to your door by drone and workers can avoid the crowds by taking an inexpensive air taxi across town to the office. It may sound like science fiction, but Chinese planners are preparing the groundwork and projecting the sector could generate up to CNY2 trillion ($280bn) in annual output as soon as 2030.