The Story of the X-51 Waverider: The First Vehicle to Fly at Mach 5 Using a Scramjet Engine

The Boeing X-51 Waverider is not a weapon itself, but a technology demonstrator for a hypersonic cruise missile that could be armed with conventional or nuclear warheads. The Waverider project began in 2004 as a joint effort by the US Air Force, DARPA, NASA, Boeing, and Pratt & Whitney Rocketdyne1 The goal was to test the feasibility and performance of a scramjet engine in a realistic flight environment.

A scramjet, or supersonic combustion ramjet, is a type of air-breathing engine that can operate at speeds above Mach 5, where traditional jet engines fail. Unlike a rocket, which carries its own oxidizer, a scramjet relies on the oxygen in the air to combust its fuel. This reduces the weight and increases the range of the vehicle. However, a scramjet also faces many technical challenges, such as igniting and sustaining the combustion in a supersonic airflow, cooling the engine and the vehicle, and controlling the flight at high speeds and altitudes.

The X-51 Waverider was designed to overcome these challenges and demonstrate the potential of hypersonic flight. The vehicle consisted of a wedge-shaped fuselage, a delta wing, four control fins, and a scramjet engine. The vehicle was about 25 feet (7.6 meters) long and weighed about 4,000 pounds (1,800 kilograms). The vehicle used JP-7 jet fuel, which is also used by the SR-71 Blackbird spy plane.

The X-51 was launched from a B-52 bomber at an altitude of about 50,000 feet (15 kilometers) over the Pacific Ocean. It was then accelerated by a solid rocket booster to about Mach 4.5 (3,000 mph or 4,800 km/h). The booster was then jettisoned and the scramjet engine took over, propelling the vehicle to speeds of up to Mach 5.1 (3,400 mph or 5,400 km/h) and altitudes of up to 70,000 feet (21 kilometers).

The X-51 performed four flight tests between 2010 and 2013, with varying degrees of success. The first flight, on May 26, 2010, lasted for about 200 seconds and reached a speed of Mach 5. The second flight, on June 13, 2011, ended prematurely after a malfunction in the control system. The third flight, on August 14, 2012, also failed due to a faulty inlet design1 The fourth and final flight, on May 1, 2013, was the most successful, lasting for about 370 seconds and reaching a speed of Mach 5.1

The X-51 Waverider program was officially completed in 2013, after achieving most of its objectives and setting several records. It was the first vehicle to fly at hypersonic speeds using a scramjet engine for a sustained period of time. It also demonstrated the ability to control and maneuver the vehicle at high speeds and altitudes. The data and lessons learned from the program are expected to inform and advance the development of future hypersonic weapons and vehicles.

Hypersonic weapons are considered to be a game-changer in modern warfare, as they offer unprecedented speed, range, and accuracy. They could also pose a serious challenge to existing air defense systems, which are not designed to detect or intercept such fast and agile targets. Several countries, including Russia, China, and France, are also developing their own hypersonic weapons, creating a new arms race and a potential threat to global stability.

The US is currently pursuing several hypersonic programs, such as the Air-Launched Rapid Response Weapon (ARRW), the Hypersonic Air-breathing Weapon Concept (HAWC), and the Long Range Hypersonic Weapon (LRHW). These programs aim to develop and deploy hypersonic weapons for various platforms and missions by the mid-2020s. The US is also investing in hypersonic defense research, such as the Glide Breaker program, which seeks to develop a capability to intercept and destroy hypersonic glide vehicles.

The Boeing X-51 Waverider was a pioneering and groundbreaking project that paved the way for the future of hypersonic flight. It demonstrated the feasibility and performance of a scramjet engine, as well as the challenges and complexities of hypersonic flight. It also contributed to the advancement of hypersonic technology and the emergence of hypersonic weapons, which could have a profound impact on the future of warfare and security.