Star Wars in Real Life Published April 27, 2020 By Cadet Alexander E. Brun Wild Blue Yonder / Maxwell AFB, AL -- Introduction What is considered fast? Well, that is all relative. In a car, fast might mean 100 or 200 miles per hour (mph). In a boat, that might mean 200+ mph. But, in a plane, well, that is just a whole new story. For small planes, like a Cessna, fast is close to 190 mph, and a jet airliner could go around 600 mph. However, that does not even come close to the speeds that some military jets can go; some jets can go faster than the speed of sound, which is called supersonic. This means that they are traveling faster than 700 mph. However, supersonic does not even come close to the speeds that some missiles can go. Some missiles have the capability to go hypersonic, more than five times the speed of sound. This sounds like something from science fiction, but it is not. China’s hypersonic glide vehicle (HGV), the Xingkong 2 (Waverider 2), has the capability to reach speeds faster than Mach 5 (3,806 mph). As if going faster than five times the speed of sound was not impressive enough, this missile can also be maneuvered and flown. The consequences of this claim by China could spark a new Cold War among three of the world’s most powerful militaries. This prompts the questions: How can a missile go hypersonic? What exactly is the Xingkong 2? How much fuel does it need to reach those speeds? What are ways to defend against this weapon? And, what does this mean for the world’s militaries? Basics of Flight Before getting into the techniques of flight for this missile, a brief explanation of the forces of flight is necessary. Thrust, drag, lift, and weight are the forces that act on a vehicle when flying. Thrust is the propulsion of the object, in this case, the rocket engine on the back of a missile. Drag is the opposite of thrust—a force that acts in the opposite direction. It is affected by the shape of the aircraft or missile. Lift is the upward motion of an aircraft. Currently, Bernoulli’s Principle of Flight is the leading method of lift. What affects lift is the airfoil of an aircraft, the “wings” in simpler terms. The top of the wing is curved, the bottom is flat, and the air is split into going over the top and the bottom. Because the air must meet back at the end of the wing at the same time, the air molecules on the top move faster. Faster air on top and slower air on the bottom creates a pressure differential. More pressure on the bottom and less pressure on the top causes lift. Weight is the opposite of lift, and it is how much the aircraft weighs. Photo Details / Download Hi-Res Figure 1. Forces of flight Photo Details / Download Hi-Res Figure 2. Bernoulli’s Principle The Design Another description that is necessary to understand the principles of the Xingkong 2’s flight is its wing design. Conventional airfoils are designed to go along with Bernoulli’s Principle of Flight, creating a pressure difference on the top and bottom of the airfoil, creating lift. However, with the Xingkong 2, the wing design is nothing like that. The design is a sort of conical shape with a concaved bottom to capture the air. The Caret Wing, designed by Terrence Nonweiler in the 1950s, was so named because of its similarity to the caret symbol on a keyboard “^.” With its negative dihedral and concaved inside structure, the Caret Wing was able to fly remarkably stable at extremely low and extremely high speeds (fig. 3).1 Hence, the use for this design on Xingkong 2. Photo Details / Download Hi-Res Figure 3. Caret Wing Negative dihedral is what is considered when the wingtips are lower than the body of the wing, or the wing root.2 Negative dihedral creates a big pocket of air underneath the body, this pocket of air allows the airflow to sit there and create that high pressure where the air wants to escape, which in turn causes positive lift—and a lot of it. How Does It Work? The Xingkong 2 uses a unique way of flying and a particular wing shape to obtain speeds of greater of Mach5. The Xingkong 2 uses the technique of flying called wave riding. As John Pike describes this technique, “wave riding is a flight vehicle that flies in the atmosphere and uses shockwaves generated by its own hypersonic flight with the air to glide at high speed. An aircraft traveling at Mach 1 or higher produces a shock wave in air.”3 What this means is that the missile uses its own shockwave to propel itself faster and faster. For example, the missile is first launched into the atmosphere using conventional methods, on top of a rocket or an intercontinental ballistic missile (ICBM). Once the ICBM gets to the desired height of about 18 miles above the surface,4 the Xingkong 2 detaches from the main body and starts its gliding decent. As the missile hits Mach 1, the sonic boom is captured inside of its Caret Wing design and creates a positive lift and pressure difference. The positive lift makes the missile sink slower and keeps the missile from slowing down. Then, suddenly, that first push from the Mach 1 sonic boom causes the second sonic boom at Mach 2, generating the same situation as the first. This chain reaction of sonic boom goes on and on until the missile reaches the ground, cruising at an astounding Mach 6. Due to the ICBM doing most of the work with getting Xingkong 2 into the atmosphere, the cost for fuel is decreased significantly. This is because with each sonic boom, the Xingkong 2 is propelled forward using its own force, effectively moving itself without the use of fuel or any other means of propulsion. On top of this HGV being able to move faster than five times the speed of sound, it may also have the capability to be maneuvered while in flight. While this ability is unconfirmed, if true, it would mean that this HGV would be able to move toward targets along with being able to dodge defense systems. With these drastic improvements in performance, maneuverability, and stability, the Xingkong 2 can go farther and faster for less. Photo Details / Download Hi-Res Figure 4. Sonic boom diagram What Exactly Is It? The Xingkong 2 is a wave rider HGV that is able to reach speeds exceeding Mach 5. This HGV was built due to the threat of increasingly more sophisticated US military technology. US intelligence analysts have stated that this HGV has the possibility to reach distances up to 1,500 miles, meaning it could be used as a regional weapon targeting China’s neighboring countries.5 Other sources have stated that it could reach distances around 8,000 miles, meaning the potentional of intercontinental strikes against the United States.6 A recent report from the US Congressional Research Service indicated the Xingkong 2 has the capability to carry either conventional or nuclear payloads. How Can We Defend against Them? Currently, the United States does not have the means nor the research to defend against such a weapon. For the 2021 Fiscal Year, the Department of Defense requested $3.2 billion for all hypersonic-related research and development, $206.8 million of which was requested for the defense program alone.7 According to Richard Stone, the United States’ current defense against regular missiles, like ICBMs and cruise missiles, uses satellites to look for flashes from their launches and track them. Once the missile reaches the peak of its trajectory, it is shot down in the upper atmosphere to avoid harm to the people and assets below. Thomas Karako, the director of the Missile Defense Project at the Center for Strategic & International Studies, says that there is a need to continually track the missile throughout its course to avoid shooting at it blindly. The problem with the HGVs is that they move so fast and can change course so quickly, which makes it nearly impossible to track them or shoot them down. Currently, an assortment of satellites is planned to go into orbit to search for the heat sources made from the launch, not the physical flash itself. Once able to track this hypersonic missile, another challenge is posed: shooting down the missile or disabling it before it reaches its intended target. The Missile Defense Agency (MDA) is researching ways to destroy these HGVs while they are still en route. Proposed methods include lasers, neutral particle beams, and micro/radio waves. Much like Pres. Ronald Reagan’s “Star Wars Initiative,” direct-energy waves could be used to destroy these HGVs. By 2025, the MDA intends to develop a space-based neutral particle beam and a 500-kilowatt airborne laser.8 Photo Details / Download Hi-Res (Source: Stephen Carlson, “A Look at President Reagan's Star Wars Program, 33 Years Later,” We Are the Mighty, 23 March 2016, https://www.wearethemighty.com/articles/look-president-reagans-star-wars-program-33-years-later) Figure 5. Reagan's Star Wars Program A hypothetical defense strategy that has been thought of by many is to combat the HGVs with projectiles, such as bullets. Once the HGV is airborne and tracked, a “bullet” would be sent up into the atmosphere to intercept and disable it. This could also be possible with the use of warheads being shot at the HGVs and detonated near them. The major challenge facing such a method is that it is like hitting a hypersonic bullet with another bullet—nearly impossible. Making it even more improbable, the attacking bullet can also move out of the way and maneuver through the sky. What Is the Effect on the Worlds Militaries? Photo Details / Download Hi-Res (Image courtesy of DARPA) Figure 6. A new arms race? Like China, the United States is developing its own hypersonic capabilities. This illustration depicts the Defense Advanced Research Products Agency’s (DARPA) Falcon Hypersonic Test Vehicle as it emerges from its rocket nose cone and prepares to re-enter the Earth’s atmosphere. DARPA has conducted test flights of the vehicle; in the second, in 2011, the HTV reached a speed of Mach 20 before losing control. The effect that this missile capability has on the world’s most powerful militaries is interesting. No one knows what will happen, and no one knows what to do about it. One theory is that this will spark another Cold War, with an arms race for hypersonic missiles, which is dangerous. This theory is very likely, and some believe that the United States should mitigate its risks and expand the New START nuclear arms reduction treaty to include hypersonics. Russia and the United States signed the New START in 2010, focusing on the limitation of strategic offensive arms. To expand this treaty would be to negotiate with Russia again and to include China in the deal. To effectively mitigate the US risk against HGVs, an addition to the New START treaty would have to be made, since HGVs are not included in the treaty. According to the treaty, if one party feels as if strategic offensive arms are emerging from the other party, then the first party can question if said offensive arms should be added to the treaty. Instead of just adding to the New START treaty, some analysts say there should be an entirely new treaty focused on a moratorium for HGVs. As of now, the most democratic and peaceful way to deter this missile threat is transparency. Transparency will allow all involved countries to exchange weapons data and conduct joint tests with these weapons. Is this likely to work? Only time will tell. Cadet Alexander E. Brun Cadet Brun is in his AS200 year at West Virginia University’s Air Force ROTC Detachment 915. He is studying civil engineering and wants to become a pilot once he commissions into the Air Force. His hobbies include running, hiking, and music. Notes 1 Rick Newlands, “The Caret Wing,” Aspirespace Rocket Engineering Society (website), 15 January 2020, http://aspirespace.org.uk/caret_wing.html. 2 Ibid. 3 John Pike “Weapons of Mass Destruction (WMD),” GlobalSecurity, September 2019, https://www.globalsecurity.org/wmd/world/china/xingkong-2.htm. 4 Ibid. 5 Kelly Sayler, Hypersonic Weapons: Background and Issues for Congress, CRS Report R45811 (Washington, DC: Congressional Research Service, 17 March, 2020), https://fas.org/sgp/crs/weapons/R45811.pdf. 6 Pike “Weapons of Mass Destruction.” 7 Sayler, Hypersonic Weapons. 8 Richard Stone, “‘National Pride Is at Stake’: Russia, China, United States Race to Build Hypersonic Weapons,” Science, 9 January, 2020, https://www.sciencemag.org/news/2020/01/national-pride-stake-russia-china-united-states-race-build-hypersonic-weapons#.