Why Can’t We Fly a Plane into Space?
The Role of Air in Flight
Airplanes achieve flight through the generation of lift by their wings, which requires air. As altitude increases, air density decreases, making it difficult for planes to generate lift and for jet engines to function due to a lack of oxygen. Recent advancements in aerospace engineering have led to the development of electric propulsion systems and hybrid engines, which are gaining traction due to their reduced emissions and noise pollution. Advancements in lightweight materials like carbon composites contribute to fuel efficiency and enhance overall sustainability.
The Limits of Human Survival
The scarcity of oxygen at high altitudes poses a limit to human survival and aircraft operation. Above 26,000 feet, the “Death Zone” begins, where supplemental oxygen is necessary for survival. High-altitude flight operations also face practical implications related to the total drag curve and the relationship between induced drag and parasitic drag. These factors become increasingly significant as aircraft operate at higher altitudes.
The Stratospheric Achievements
The SR-71 Blackbird reached altitudes where the air density is just 2% of that at sea level. The quest for high-altitude flight continues, with the history of human flight interwoven with our aspiration to explore the skies. The narrative of high-altitude flight began with hot air balloons and has evolved to sophisticated aircraft like the SR-71 Blackbird.
Beyond the Atmosphere
Achieving spaceflight requires overcoming Earth’s gravitational pull by reaching escape velocity, which is about 25,020 miles per hour. The opportunities and challenges of hypersonic flight are being addressed through innovative developments that will support and enhance air travel in the decades to come.
Enter the Rocket Engines
Rocket engines carry their own oxidizers, allowing them to operate in space. For High Altitude Platform Systems (HAPS), key technological challenges include achieving a durable lightweight structure, energy storage and power delivery, thermal management, system reliability, navigation, endurance, and safe operations at lower altitudes.
The Future: Skylon and Beyond
Skylon, with its SABRE engine, represents a promising concept in space travel. A new generation of spaceplanes is taking advantage of the latest in technology, with vehicles like Sierra Space’s Dream Chaser poised to resupply the ISS with cargo and, eventually, crew.
The Competition: Reusable Rockets
Reusable rockets like SpaceX’s Falcon 9 and Blue Origin’s New Shepard are demonstrating cost-effective ways to reach space. The US Defense Advanced Research Projects Agency (DARPA) has commissioned private companies to develop nuclear fission thermal rockets for use in lunar orbit, which could usher in a new era of spaceflight.
A Hypersonic Future?
The quest for hypersonic and hydrogen-fueled air travel is underway, with ambitious projects like the STRATOFLY proposing a Mach 8 airliner — a hypersonic aircraft that could drastically reduce flight times between major cities.
Conclusion
The boundary between air and space travel is blurring, with the latest advancements in aerospace engineering pushing the limits of what’s possible. From electric propulsion systems to hypersonic aircraft, the future of flight is shaping up to be an exciting journey that blends the best of aviation and space exploration into new possibilities. With ongoing research and development, the dream of a plane that can take off from a runway, fly into space, and return safely to Earth is becoming increasingly tangible.
Keep your eyes on the sky and stay tuned for more developments in this thrilling field!
