10 Very Strange Propulsion Systems You’ve Never Heard Of

Throughout history, human ingenuity has continuously pushed the boundaries of what’s possible in transportation technology. From the earliest steam engines to today’s electric and hybrid vehicles, we have always sought more efficient, powerful, and innovative ways to move people and goods. But some propulsion systems are so outlandish and unconventional that they seem to belong in science fiction rather than reality. These bizarre technologies challenge our understanding of physics and engineering, offering unique solutions to age-old problems.

In this list, we explore ten of the most unbelievable propulsion systems you’ve probably never heard of. Join us as we delve into these unique propulsion systems that redefine the limits of what transportation technology can achieve. Whether it’s a human-powered ornithopter that mimics bird flight or a nuclear thermal rocket capable of deep space travel, these innovations highlight the fascinating possibilities that emerge when we dare to dream big. Prepare to be amazed by the ingenuity and audacity of these groundbreaking propulsion systems.

Related: 10 Ancient Technologies We Cannot Recreate Today

10 Liquid Air Powered Vehicles

Imagine a vehicle that runs on the cold power of liquid air. Liquid air-powered cars utilize the principles of cryogenics, where air is cooled to extremely low temperatures and stored as a liquid. When it’s time to drive, the liquid air is warmed and expands rapidly into a gas, creating high pressure that drives the engine’s pistons or turbines. This technology offers a unique approach to zero-emission transportation, harnessing the energy stored in cryogenic liquids.

One of the most compelling advantages of liquid air-powered cars is their environmental impact. These vehicles produce no exhaust emissions, as the only byproduct is the air we breathe. Additionally, liquid air can be produced during off-peak electricity hours, potentially making it a cost-effective and efficient energy storage solution.

This method can also integrate well with renewable energy sources, capturing surplus electricity from wind and solar power to liquefy air. Companies like Dearman Engine Company (DEC) have been at the forefront of developing this technology, creating engines that can be integrated into vehicles for practical use. The concept of liquid air-powered cars isn’t just theoretical. Dearman has developed prototype engines that demonstrate the viability of this technology.

These engines use liquid nitrogen, a component of liquid air, to power refrigerated delivery trucks, providing both cooling and power. The engine operates by vaporizing and expanding cryogenic fluids, using ambient or low-grade waste heat as an energy source. This approach not only offers zero-emission cooling but also reduces diesel consumption in hybrid applications by harnessing waste heat from internal combustion engines.

However, challenges remain. The infrastructure for producing, storing, and distributing liquid air needs significant development. Additionally, the energy required to liquefy air must be considered, as it impacts the overall efficiency and environmental benefits. Despite these obstacles, liquid air-powered cars offer an innovative and exciting glimpse into the future of sustainable transportation.^[1]

9 Mando Footloose Chainless E-Bike

The Mando Footloose chainless e-bike is a revolutionary concept in personal transportation, combining cutting-edge technology with sleek design. Unlike traditional bicycles, the Footloose eliminates chains and gears entirely, using an innovative system that converts the rider’s pedaling into electrical energy. This energy is stored in a battery and used to power an electric motor, providing a smooth and effortless ride.

One of the standout features of the Footloose is its electronic control system. This system monitors the rider’s pedaling and automatically adjusts the level of motor assistance for optimal performance and comfort. The absence of a chain reduces maintenance and allows for a more compact and lightweight frame design. The bike can even be folded, making it convenient for urban commuters who need to carry their bike on public transport or store it in small spaces.

In addition to its practical benefits, the Footloose offers an impressive array of technological advancements. It is equipped with a digital dashboard displaying real-time information on speed, battery level, and distance traveled. Riders can customize their riding experience through various settings and modes, enhancing both efficiency and enjoyment. The Mando Footloose sets a new standard for electric bicycles, offering a seamless blend of innovation, convenience, and style.^[2]

8 UTIAS Snowbird: World’s First Human-Powered Ornithopter

The UTIAS Snowbird is a marvel of aeronautical engineering, being the first successful human-powered ornithopter. Developed by the University of Toronto Institute for Aerospace Studies, this innovative aircraft mimics the flapping wing motion of birds. In 2010, the Snowbird achieved a historic flight, sustaining both altitude and velocity for 19.3 seconds while covering a distance of 475 feet (145 meters). This achievement marked a significant milestone in the field of aviation, demonstrating the potential of human-powered flight.

Constructed from lightweight materials such as carbon fiber, balsa wood, and foam, the Snowbird weighs only about 93 pounds (42 kilograms). The wingspan extends to an impressive 105 feet (32 meters), larger than that of a Boeing 737, to provide the necessary lift. The pilot powers the aircraft by pedaling, which drives a complex mechanism that flaps the wings. This design minimizes the energy required from the pilot while maximizing the efficiency of the wing movements.

The success of the UTIAS Snowbird showcases the incredible potential of biomimetic design in aviation. It also highlights the perseverance and ingenuity of its creators, who spent countless hours in design, testing, and refinement. This pioneering project has opened the door to further exploration in human-powered flight, inspiring future generations of engineers and aviation enthusiasts.^[3]

7 Biomimetic “Fish-Like” Propulsion System

In the quest for more efficient underwater propulsion, engineers have turned to nature for inspiration. The biomimetic “fish-like” propulsion system mimics the movement of fish, using flexible, oscillating fins instead of traditional propellers. This method of propulsion is not only quieter but also more efficient, reducing the drag and turbulence typically associated with conventional marine propulsion.

One of the most advanced examples of this technology is found in robotic fish developed for research and exploration. These robotic fish use a combination of flexible materials and advanced control systems to replicate the swimming motions of real fish. By undulating their bodies and moving their fins in a coordinated manner, these robots can navigate complex underwater environments with ease and agility. This makes them ideal for tasks such as underwater inspection, environmental monitoring, and even search and rescue operations.

The advantages of biomimetic propulsion extend beyond efficiency and maneuverability. The reduced noise signature of these systems makes them ideal for stealth applications, such as military reconnaissance and wildlife observation. Additionally, the absence of rotating parts like propellers reduces the risk of entanglement with underwater debris or harming marine life. As research and development in this field continue, the biomimetic “fish-like” propulsion system holds great promise for transforming underwater transportation and exploration.^[4]

6 The Marsh Screw Amphibian

The Marsh Screw Amphibian is a unique vehicle that uses a screw-drive propulsion system to traverse difficult terrains, including snow, mud, and swamps. Unlike traditional vehicles that rely on wheels or tracks, the Marsh Screw Amphibian is equipped with two large, rotating screws that propel it forward by digging into the ground. This design allows the vehicle to move seamlessly over surfaces that would be impassable for most other vehicles.

Developed in the 1960s by the Soviet Union, the ZIL-2906 is one of the most famous examples of screw-propelled vehicles. It was designed for rescue missions in the challenging Siberian landscape, where extreme weather and rugged terrain often hinder conventional vehicles. The ZIL-2906 could not only navigate deep snow and marshy areas but also float and move through water, making it an incredibly versatile machine.

The screw-drive system offers several advantages, including high flotation and the ability to move through loose or soft terrain without getting stuck. However, it also comes with drawbacks, such as lower speeds and higher fuel consumption compared to wheeled or tracked vehicles. Despite these challenges, the Marsh Screw Amphibian remains a fascinating example of innovative engineering, demonstrating how unconventional solutions can effectively address specific transportation needs.

Today, screw-propelled vehicles are still used in specialized applications, such as Arctic exploration and amphibious transport. The unique capabilities of the Marsh Screw Amphibian continue to inspire new designs and innovations in the field of extreme terrain vehicles.^[5]

5 Nuclear Thermal Rocket (NTR)

Among the most ambitious and unconventional propulsion systems is the Nuclear Thermal Rocket (NTR). This technology uses a nuclear reactor to heat a propellant, typically hydrogen, which is then expelled through a nozzle to produce thrust. The idea is to harness the immense power of nuclear reactions to achieve much higher efficiencies than traditional chemical rockets, making long-duration space missions more feasible.

The concept of NTR dates back to the 1950s and 1960s, with significant development undertaken by the United States under the NERVA (Nuclear Engine for Rocket Vehicle Application) program. Although the program was eventually canceled, it successfully demonstrated the potential of nuclear thermal propulsion through ground tests. The NTR could provide thrust levels comparable to chemical rockets but with a much higher specific impulse, meaning it could deliver more thrust per unit of propellant.

The primary advantage of NTR is its efficiency, which could reduce travel times for missions to Mars and beyond. By enabling faster trips, it also reduces astronauts’ exposure to space radiation and other hazards. Additionally, the ability to carry larger payloads makes it an attractive option for future deep-space exploration missions.

Despite its promise, the NTR faces significant challenges, including public concerns over safety and the technical complexities of operating a nuclear reactor in space. However, renewed interest in deep space exploration has led to a resurgence of research in this area, with agencies like NASA exploring modern NTR designs as a potential solution for crewed missions to Mars. The Nuclear Thermal Rocket remains a testament to human ingenuity and the quest to push the boundaries of space travel.^[6]

4 Electrohydrodynamic (EHD) Propulsion

Electrohydrodynamic (EHD) propulsion, also known as ionocraft or lifters, uses electrical fields to generate thrust by ionizing air molecules and accelerating them to create airflow. This technology relies on electrostatic force to propel objects without any moving parts, making it an intriguing area of research for silent and efficient propulsion systems.

One of the earliest demonstrations of EHD propulsion was in the form of small, lightweight crafts called ionocrafts. These devices consist of a high-voltage power supply connected to a thin wire (the emitter) and a lightweight foil (the collector). When a high voltage is applied, it ionizes the air around the emitter, creating a flow of ions toward the collector. This ion flow generates a thrust that can lift the craft off the ground. Although ionocrafts are typically small and limited in their lifting capacity, they demonstrate the fundamental principles of EHD propulsion.

The potential applications of EHD propulsion are vast and varied. In addition to providing a silent and efficient means of transportation for small drones and UAVs, EHD technology could be used for precise movement in microgravity environments, such as maneuvering small satellites or space debris management. Despite its promise, EHD propulsion faces challenges, including the need for high voltages and the relatively low thrust-to-weight ratio. Ongoing research and advancements in materials and electronics continue to push the boundaries of what is possible with this unique propulsion method.^[7]

3 Laser Ablation Propulsion

Laser ablation propulsion is a cutting-edge method that could revolutionize space exploration. This technology involves using high-powered lasers to vaporize material from a spacecraft’s surface, generating a thrust through the rapid expansion of the ablated material. By placing the high-power laser off-board, typically on Earth or a satellite, the spacecraft itself does not need to carry heavy propellant or power sources, making it significantly lighter and more efficient.

The history of laser ablation propulsion spans over 40 years, and its potential applications are vast. One of the key advantages is that it eliminates the need for a spacecraft to carry its energy source, as the laser energy is supplied externally. This allows for continuous propulsion without the limitations of onboard fuel. Additionally, the target propellant can be sourced from the nearby environment, reducing the need for storage space on the spacecraft.

Laser ablation propulsion could also be utilized for various tasks beyond moving spacecraft. It holds promise for space debris clearing, as the focused laser can target and vaporize small pieces of debris, preventing collisions with operational satellites. Furthermore, this technology has applications in inertial fusion energy and air-breathing propulsion systems, showcasing its versatility. Despite the challenges in optimizing the propulsion system and understanding thrust generation mechanisms, laser ablation propulsion remains a fascinating area of research with the potential to transform how we explore and utilize space.[8] ^[8]

2 Thermoacoustic Engine Propulsion

Thermoacoustic engine propulsion is an innovative method that harnesses the power of sound and heat to generate thrust. This technology relies on thermoacoustics, where temperature gradients create sound waves that produce mechanical energy. By exploiting these sound waves, thermoacoustic engines convert thermal energy into propulsion, offering a unique approach to moving vehicles and spacecraft.

One of the standout features of thermoacoustic engines is their simplicity and lack of moving parts. The design involves a resonator filled with a working gas and a heat exchanger that creates the necessary temperature gradient. As heat is applied, it induces pressure waves within the gas, generating sound waves that drive a piston or other mechanical component to produce thrust. This process is highly efficient and can be used in various applications, from small-scale devices to larger propulsion systems.

Thermoacoustic engines are particularly attractive for their potential in silent operation, making them suitable for stealth applications where noise reduction is crucial. Additionally, their ability to utilize waste heat from other processes enhances their efficiency and sustainability. Despite being largely experimental, ongoing research aims to optimize their performance and scalability. As advancements continue, thermoacoustic engines could offer a new avenue for efficient and sustainable transportation, showcasing the possibilities of combining sound and heat for mechanical power.^[9]

1 Microwave Thermal Propulsion

Microwave thermal propulsion is a cutting-edge technology that uses microwave energy to heat a propellant, generating thrust. This method involves beaming microwaves from a ground-based or space-based transmitter to a receiver on the spacecraft. The microwaves heat a propellant, typically hydrogen, causing it to expand and be expelled through a nozzle, producing thrust. This system offers a highly efficient and potentially limitless propulsion method for space travel.

One of the primary advantages of microwave thermal propulsion is the elimination of onboard fuel for energy. Instead, the energy is transmitted wirelessly, reducing the spacecraft’s weight and allowing for longer missions. This technology is ideal for deep space exploration, where maintaining thrust over extended periods is crucial. By harnessing external energy sources, spacecraft can achieve higher velocities and more efficient travel.

Despite its promise, microwave thermal propulsion faces challenges, including the need for precise alignment of energy transmitters and receivers and the development of robust systems capable of withstanding the harsh conditions of space. However, the potential benefits of this innovative propulsion method make it a promising avenue for future advancements in space travel.[10] ^[10]