Military Embedded Systems

6G stealth fighter planes: The quarterback of the kill web


January 31, 2020

Ray Alderman

VITA Standards Organization

WARFARE EVOLUTION BLOG: There are 14 countries working on 6th Generation (6G) fighter planes these days: the U.S. (PCA, F/A-XX, NGAD); the United Kingdom, Sweden, Italy, and maybe India (Tempest); France, Germany, and Spain (FCAS); Japan (F-3); Taiwan (ADF); South Korea and Indonesia (KF-X); Russia (MiG-41); and China (J-XX). Before we get into the details, we need to define what a 6G fighter jet is. The F-35 and F-22 are 5G fighter planes. There are six aircraft generation classification charts out there: Hallion, Aerospaceweb, Air Force Magazine, Winchester, Air Power Development Center, and China’s Air Force. All these templates have been overcome by advances in technology and evolving mission requirements. So, we’ll be breaking new ground in this essay, by adding to the common 6G characteristics from the old charts and building an updated definition. Then, we’ll integrate those new aircraft into the kill web.

6G stealth improvements

There are six spectrums that stealthy aircraft must consider: physical shape (radar signature), IR (infrared or heat) signature, acoustic (sound) signature, visual (visible light) signature, EMR (electro-magnetic radiation) signature, and wake turbulence (vortices) signature. What can we do with shape to further reduce the RCS (radar cross section) on 6G fighters?

From the front, the F-35 (RCS of 0.005 square meters) and the F-22 (RCS of 0.0001 square meters) are already very small. Both carry their weapons in internal bays, since we know that carrying missiles, bombs, or fuel tanks on pylons under the wings increase RCS dramatically. We also know that the engine air intakes below the wings, the tail fins, and the exhaust nozzles also raise RCS numbers. Most of the 6G fighter concept drawings show the air intakes integrated into the fuselage or on top of the wings, the tail fins are removed, and there’s a cover plate on the bottom of the exhaust nozzles. In the past, sensors were added to the airframe as bubbles or pods or "warts," that protruded and reflected enemy radar signals. Today, sensors and antennas are now part of the smooth "smart skins" on stealth aircraft. Shapes like flying wings and arrowheads significantly reduce RCS from the sides, bottom, top, and rear.

Our present 5G stealth fighter planes are coated with a ferromagnetic paint containing microscopic iron balls, that absorb the energy in enemy radar signals. Older 4G F-16 fighters were never designed to be stealthy and have an RCS of 3 to 5 square meters. Coating them with the ferromagnetic paint reduces their RCS to about 1.2 square meters. But air friction, rain, and temperature cycles erode the paint requiring continuous maintenance.

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The U.S. Navy has created a “laser shock peening” process that makes the surface of the aircraft uniform with no dimples or flaws that could reflect radar waves. Peening also makes the surface panels stronger and reduces warping and cracking from stresses. In 2006, Dr. David Smith of Duke University created a metamaterial that can conceal small objects from microwave radar signals. In 2019, Prof. Luo Xiangang of the Chinese Academy of Sciences engraved microscopic patterns on a piece of metal, and it absorbed a broad spectrum of radar frequencies better than the iron-ball paints. So, expect 6G stealth airframes to be built with some of these advanced radar-absorbing metamaterials instead of painted aluminum.

We also know that when these stealthy jets fly above the speed of sound (MACH 1), the nose and leading wing edges heat-up from air friction. That makes the plane visible to enemy IR (infrared) sensors. 6G fighters will have a cooling system built into the wings and nose to remove the heat. The new B-21 bomber uses this IR-reduction technology. Additionally, a secondary airstream is brought into the engine exhaust nozzles, decreasing the temperature of the exhaust gases and that further reduces the heat signature. 6G fighters will be much harder to detect with IR sensors than present 5G stealth fighters.

Then there's engine noise. That’s the acoustic signature of the aircraft when flying overhead. If you can hear an airplane, you can see it and shoot missiles at it. Prof. Ajay Agrawal at the University of Alabama has created an “acoustic sponge” made from hafnium carbide and silicon carbide. It’s a heat-resistant and pressure-resistant ring, about the size and shape of a doughnut, that fits inside the combustion chamber of the engine. It absorbs sound waves and reduces the turbulence of the exhaust gases without affecting thrust or fuel consumption. The B-2 bomber engines have already been modified, and they are very quiet.

Being able to see a stealth jet in the visible light spectrum (visual signature) is another liability. There have been numerous achievements in creating "invisibility cloaks" with metamaterials in the past decade. They are coatings or solid materials that bend light waves around an object, or they act like mirrors reflecting the surrounding colors and shapes. Go watch the movie "Predator" to get an idea of how invisibility cloaking works.

There’s also the EMR emitted by systems on the aircraft: radar signals and communication signals. They can tell the enemy ELINT and SIGINT intercept people the plane's location, speed, and course. This vulnerability can be overcome by emitting lower-power signals, sending data by hopping around in the frequency spectrum (including lasers), using different waveforms, and varying the pulse rates. Expect 6G aircraft radio emissions to be very low compared to present fighter planes.

Finally, there’s wake turbulence detection: discovering the vortices that remain after a plane flies through the air. You already know that Doppler weather radar can detect microbursts (downbursts of air near an airport) and hook echoes (formation of tornados in storms). There are some esoteric technical papers on the web showing how radar can recognize man-made air turbulence, and that each type of aircraft leaves a unique vortex signature. Radar detection of wake turbulence will also influence the shape of 6G fighter planes. We can already detect submerged enemy submarines with our satellite radar by looking for the pressure wave created by the nose pushing the water up to the surface (the “Bernoulli Hump”), and the turbulence trail they leave behind in the surface water (the “Kelvin Wake”). Same principles apply to fighter planes. Water and air are both fluids.

New stealth aircraft engines

Most 5G stealth fighters can reach supersonic speeds only by using their afterburners. That mode burns a lot of fuel and reduces the combat radius of the aircraft. The F-35 has a combat radius of 680 miles, and can fly at MACH 1.2 for about 150 miles without using afterburners. With afterburners engaged, it can reach MACH 1.6, but that burns much more fuel. The F-22 has a combat radius of about 680 miles at subsonic speeds. But it is powered by supercruise engines that can fly a combat radius of 530 miles at MACH 1.8. With afterburners engaged, it can fly at MACH 2.25 but not for long.

If you are a fervent reader of this series, you already know about jet engine bypass ratios (BPR). That's the amount of air flowing around the engine core compared to the amount of air flowing into the combustion chamber. A typical fighter plane uses turbojet engines with a BPR of 0.36:1 for maximum thrust. Commercial airliners use turbofan engines, that have BPR's of 10:1 for very high fuel efficiency. The new 6G fighter planes in design will use ADaptive Versatile ENgine Technology (ADVENT). These are variable cycle engines: they combine the turbojet for high thrust, and the turbofan for high fuel efficiency. The pilot can adjust these engines for maximum speed, or for minimum fuel consumption, depending on the mission requirements.

Traditional fighter planes use movable control surfaces, creating drag in specific places to maneuver the aircraft. The rudder turns the plane left or right, the elevator moves the plane’s nose up or down, and the ailerons move the wings tips up and down. However, those control surfaces increase the RCS of the aircraft. 6G fighters have no tail fins so we have already removed the rudder. Next, we will remove the ailerons and the elevator. When the ADVENT engines are refined, 6G aircraft will be steered by thrust-vectoring nozzles that point the exhaust gases in certain directions (left, right, up, down). This concept could also make the aircraft more agile in combat. What kind of engines will fighter planes use after ADVENT? Take a look at U.S. Patent 10144532B2, awarded to the U.S. Navy in 2016. It’s an anti-inertial engine with some anti-gravity properties, something that might power a flying saucer.

New 6G weapons

There are two basic problems with all fighter planes: the combat radius is too short and the ordinance load is too small. There are two ways to solve these problems: make the 6G fighter planes bigger, or have one 6G fighter plane control four or five armed unmanned drones (loyal wingmen) like the XQ-58 Valkyrie. Stealth fighters conceal their ordinance in a weapons bay, inside the fuselage, to keep RCS low. That limits their weapons and fuel loads. The F-35 can carry about 5,700 pounds of bombs and missiles. The F-22 can carry more than twice that weight. Drones can have a combat radius of 1,000 miles, carry more bombs and missiles, they are cheaper to build, and they don’t require training pilots. According to a recent RAND Corporation study, it costs more than $10 Million to train an F-35 or F-22 pilot. Go read about an Air Force program called “Skyborg” and you’ll see how joining multiple armed drones with one 6G fighter plane makes sense. Writing software is much cheaper than training pilots.

What kind of advanced weapons will the 6G fighters (and wingman drones) carry? First will be long-range hypersonic air-to-air missiles, to knock-down enemy fighters from long distance. Traditional radar used on some of our fighter planes can see for nearly 300 miles. The best missile we have today is the AIM-120 AMRAAM (Advanced Medium Range Air to Air Missile). It has a range of about 100 miles, and a speed of MACH 4 (3,045 MPH). The Brits have the Meteor air-to-air missile. It has a range close to 100 miles, and a speed of nearly MACH 5 (3,800 MPH). The U.S. Air Force is working on the AIM-260 missile, but the specifications are top secret at this point. Expect it to fly at MACH 5 or faster, and have a range of more than 100 miles. Hitting an enemy aircraft 100 miles away with a MACH 5 missile only takes 1 minute 34 seconds.

As technology matures, we'll see 6G fighters armed with high-power laser weapons. To hit an enemy fighter plane 100 miles away with a laser, at the speed of light, only takes 0.00054 seconds. Next, the planes will be armed with powerful microwave EMP weapons (Electro-Magnetic Pulse). Those waves can destroy the sensors (radar, IR, SIGINT, ELINT) and the navigation and flight control computers on enemy aircraft and missiles from a distance. 6G fighter planes will also be able to deploy a swarm of microdrones, to attack land targets. In 2016, a U.S. Navy F/A-18 fighter dropped 103 Perdix drones over the desert in China Lake. They autonomously formed into a swarm and attacked a designated ground target. Before we get all these new weapons, 6G fighters will carry our current bombs and missiles when they first go into service.

6G electronic systems

All these new 6G fighter planes will actually be very powerful flying computers. Those systems will be monitoring enemy radar and communication signals to identify threats and find targets in fractions of a second. They will be intercepting enemy radio and radar signals and sending electronic warfare (EW) signals to confuse them. The cyber systems onboard will be sending malware packets to enemy sensor systems to disable them. At the same time, the aircraft will be fusing radar/IR/IMINT/SIGINT data from friendly forces on the ground, in the air, on the sea, and from satellites. The pilot will have complete and instant situational awareness of the entire battlefield. Flight control/navigation computers will assist in flying the plane. There are 2 million lines of code running in the F-22’s onboard computers. The F-35’s computers are executing over 8 million lines of code. Using artificial intelligence (AI) chips, 6G aircraft computers could have fewer lines of code and be many times more powerful. The bigger question to ask here is if any of these new 6G planes really need human pilots in the cockpit.

Integrating 6G fighters with the kill web

At this point, you have a general Idea about what a 6G fighter plane can do. Here is what the U.S. Navy F/A-XX concept looks like <>, and this is an artist’s conception of the Air Force PCA. <> These planes will become both a data processing center in the sky and a deadly weapons platform at the same time. They can assign targets to other weapons systems like the Valkyrie drones, ships at sea, long range bombers (B-2, B-52, B-21), and ground weapons. These new fighter planes will be like the quarterback on the football team, reading the defense and calling the plays. When the airframes, engines, onboard systems, and weapons are perfected and refined, our forces will be able to hit any enemy target on the battlefield in less than 10 minutes just like General John Jumper wanted. Moreover, 6G fighter planes will manipulate space and time on the battlefield, to the degree that enemy commanders will be disoriented, indecisive, and limited in their tactical options.

The Air Force PCA (Penetrating Counter Air) and the Navy F/A-XX are slated to fly in the 2025-2030 time frame. The only way to do that is through the NGAD (Next Generation Air Dominance) program, where both services work together on common elements like airframes, engines, weapons, and electronic systems. It took over 20 years to design and test the F-35. What NGAD proposes to do is build a new fighter aircraft every five years, with whatever level of the technologies mentioned above may exist at that time. Why not use the technologies as they develop instead of waiting 20 years for all of them to mature?

The UK-Sweden-Italy Tempest 6G fighter is planned to fly in 2035. The Germany-France-Spain 6G FCAS (Future Combat Air System) is planned to fly in 2040. Good luck with that. These dates assume that they can actually develop and perfect the technologies mentioned above. It cost more than $55 billion in RDT&E (research, development, testing, and evaluation), and 20 years of engineering effort to make the F-35 fly. It still had a lot of bugs to work out. So far, there’s not much money or brain power going into any of these foreign 6G fighter projects. By the time their 6G planes fly, our 7G fighter planes will be using the anti-inertial anti-gravity engines in the Navy patent, and firing photon torpedoes at the speed of light instead of missiles traveling at MACH 5.

In our next adventure, we’ll delve into the fundamental mechanism that makes the kill web work: time. In a war, history has proven that time can be our master or it can be our slave. If you control time, you also control space. And, that doesn’t leave much for the enemy to control.