A 2010 document describes an idea for an ultra-fast aircraft: draw energy from the airflow, then put it back farther along. The system would use electricity and magnets to influence the air around the aircraft.
But the document set a clear limit. It said the method has little effect below a certain speed. Instead, it proposed a different approach: creating a kind of air wall, as if part of the aircraft’s structure were made of air.
Energy Out, Then Back In
The first idea is called AJAX. That’s not the name of an aircraft or an engine, but of a method: a system extracts energy from the air near the front of the aircraft and returns it farther along. This is supposed to help propel air along the aircraft.
According to the document, the method has little effect below Mach 12, more than ten times the speed of sound. In colder air, it is harder to generate enough electrically charged particles. Without them, electricity and magnets have less ability to affect the airflow.
A Wall Made of Air
The document also presented another idea, called a “virtual cowl.” Imagine an invisible wall that directs air around the aircraft. Electricity creates electrically charged gas in the air, and the system then uses it to influence the airflow. The air is supposed to behave as if an additional part of the aircraft’s structure were there.
The wall was intended to help control airflow around a high-speed aircraft, as well as around a vehicle returning to the atmosphere. The document saw this approach as a more promising option for specialized applications. But it comes at a cost: the systems require a great deal of electricity and add weight and complexity.
What Remains Unknown
The document reviewed concepts; it did not show that any of the systems had operated on a real aircraft. Nor did it solve the challenge of supplying them with abundant electricity without adding weight and complicated systems.
Between the aircraft’s body and the surrounding air, the document imagined a wall made of no material at all. Could such a wall ever actually be created?
