From Gagarin to Jet Suits

On April 12, 1961, Soviet cosmonaut Yuri Gagarin accomplished a groundbreaking feat by piloting a 2,400-kilogram spacecraft in humanity's inaugural manned space flight. Just a week later, Bell Aerosystems introduced another advancement in aviation: the gas-powered rocket pack. Spectators marveled as the rocket pack soared 35 meters in a mere 13 seconds. However, the engineers behind the device were less impressed. Despite years of cutting-edge work, they knew that this short flight was the extent of what the rocket pack could achieve. Why was it easier to propel a massive spacecraft than a single pilot?

According to Newton's laws of motion, the principles underlying flight are deceptively simple. All that is required is a force powerful enough to counteract the downward pull of gravity. Since objects with less mass experience weaker gravitational forces, lighter objects should theoretically be easier to lift off the ground. However, when it comes to modern jet engines, our primary means of propulsion, their efficiency actually improves with size. Jet engines operate by ingesting large volumes of air and expelling it as rapidly as possible. Although a significant portion of the air bypasses the inner workings of the engine, it still contributes to a substantial portion of the thrust.

The compressed air that enters the engine's core passes through tightly packed blades, which increases its pressure. This compressed air then enters the combustion chamber, where it combines with jet fuel and ignites. The resulting heat causes the compressed air to rapidly expand, blasting out of the exhaust and propelling the engine forward. As the air exits the engine, it drives a turbine embedded in the exhaust nozzle, which powers the fan and compressor blades, creating a continuous cycle that sustains thrust as long as there is fuel to burn.

The more air an engine can take in and expel, the greater thrust it can generate. In modern jets, the frontal fan's diameter exceeds that of a truck. Even at relatively low speeds, these engines produce more than enough thrust to maintain the necessary velocity for passenger aircraft flight. However, smaller engines simply cannot ingest such vast quantities of air. Throughout most of the 20th century, engineers struggled to develop an engine that was compact and light enough for an individual to wear while possessing sufficient power to lift both itself, the pilot, and the necessary fuel.

Previous designs could only carry enough fuel for a mere 30 seconds of flight, and once airborne, the powerful thrust in a single direction made jetpacks challenging and perilous to control. Nonetheless, the advent of the new millennium brought remarkable advancements in materials, manufacturing techniques, and computing technology. These breakthroughs included systems capable of precise fuel injection management, significantly enhancing fuel efficiency and the power-to-weight ratio of jet engines. By 2016, micro-engines the size of a coffee can and weighing less than 2kg could generate a force of 220 Newtons.

It was during this period that Richard Browning, an English engineer, recognized the potential to create a novel type of lightweight jetpack. Dubbed the Jet Suit, it featured a single engine strapped to the back, along with a pair of micro-engines on each arm to split and balance the thrust. Working in conjunction with the back engine, these arm engines provided three points of stability, creating a sensation akin to comfortably leaning on crutches while a friend supports your back. Although managing multiple engines simultaneously may seem complex, pilots quickly master the technique, often within a day, leveraging their highly advanced computer system—their brain.

Through the seamless coordination of various brain regions and multiple sensory systems, pilots can precisely calibrate their sense of balance and spatial orientation, enabling them to maneuver their flights with fluidity. Slight arm movements allow operators to adjust lift, execute mid-air turns, or glide forward for up to five minutes. While this technology is still relatively nascent, significant advancements in fuel efficiency and engine technology are necessary before jetpacks become widely accessible. However, considering the tremendous progress we have made in reaching for the skies, who knows where our future flights will take us?

Henrik Leandro