Gas-turbine engines that are normally used in jets throughout the world have a maximum speed of 2.5 Mach or 2.5 times the speed of sound. The speed of Mach 1 and above is called supersonic speed, and every fighter jet is capable of achieving it. However, this speed is susceptible to enemy fire as incoming aircraft can be detected and intercepted. To make the plane out of the reach of contemporary anti-aircraft weapons, we need to increase the speed. Speeds above Mach 5 are called hypersonic speeds, and so far, no operational jet aircraft has been able to achieve that speed.
There have been concept designs and concept patents that show planes that will eventually reach speeds of Mach 9 and above, but none of them have had a chance of succeeding since they were based on futuristic ideas like rocket engines or Hydrogen-powered engines. However, Lockheed Martin, the famous weapons manufacturer that has provided the military with F-16, F-22 and F-35 fighters, claims that a new design based on the Scramjet technology is nearing planning stage and might enter the US military service in fifteen years. Scramjets have the same basic principle as jet engines; the air is compressed and then undergoes a rapid expansion that propels the aircraft. In the conventional jet engines, the air is compressed by turbines while in the newer Scramjet technology, the air is compressed by the rapid movement of the aircraft itself. So far, no scramjet has been developed that can be used on an aircraft, but by combining turbines with a scramjet engine; we can get a combined cycle that has raised technical approval in recent years.
Orlando Carvalho of the company’s aeronautics division claims that they are working on the process but admitted that significant design and development work needs to be done to make it happen. To test the engines, the company is partnering with Aerojet Rocketdyne, a rocket manufacturer and engineers are making rapid progress on that front too. The goal is also to make a hypersonic plane that will be affordable to the military and the government. The company is targeting a development cost of 1 billion USD and eventually, the size will be shrunk down to the level of an F-22 fighter which is amazing.
We have heard rumours regarding the testing of infamous Scramjet engine known as Aurora for some time. Conspiracy theorists and speculators believe that the Aurora program has been a work in progress since 1988, and it is the advances in this program that have borne fruit, and now the engine can be used in aircrafts too. The new plane has been named SR-72 or the successor of the famous SR-71 Blackbird that remained a key spying tool for the USAF till 1998 when it was retired. Perhaps SR-71 will also undertake similar roles in the military fabric. But, first, the underlying design issues in a Scramjet Flight need to be addressed and looked at. At this kind of speed, the conventional aerospace material won’t stand a chance, and therefore, new ones have to be developed.