How Stealth is Born: Engineering & Building a Radar-Evading F-35
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By Kris Osborn - Warrior Maven
(Washington D.C.) Stealth, or Low-Observability operations hinge entirely upon a specific set of specialized construction techniques, according to engineers familiar with the process. While many if not most of these techniques are, understandably, not available for public reports for security reasons, there are many public elements of the technology written about for public consumption by engineers and many of the industry developers involved in F-35 construction offer detailed profiles of their contributions to the airplane.
A seamless-looking exterior -- devoid or sharp contours, external structures and protruding “edges” more recognizable to enemy radar -- contains a secret blend of composite materials designed to engineer a radar-absorbent airplane. Weapons can be carried internally so as not to expose shapes vulnerable to enemy radar. One commonly discussed element of stealth coating includes the use of “carbon fibers” to - among other things - reflect electromagnetic energy from the surface of the material.
Carbon materials are long-known to have contributed to stealth configurations. Interestingly, a 2016 essay from the Smithsonian Air and Space Museum cites a 2008 expert assessment in which Northrop Grumman engineers sought to determine if a 1943-built German Horten 229 prototype aircraft contained elements of stealth technology - decades ahead of its time. The Nazi aircraft was beset with technical problems and failed a few test flights. It never saw combat, but some of the adhesives, wood and other materials - coupled with its horizontal “all-wing” like configuration, have inspired many to view the aircraft as an early iteration of what became stealth technology. Carbon-like materials were found in the investigation; the engineers Dobrenz and Spadoni write "during our inspection of the Horten 229 at the Smithsonian museum, it appeared that a material similar to carbon black or charcoal was mixed in with the glue between the thin layers of the leading edge shape.”
Whatever the particular composition of material, the stealthy exterior of the F-35 represents an effort to achieve low-observability, survivabilty and lighter weight to enable speed and maneuverability. The seamless F-35 structure is, by design, a result of a particular engineering technique.
“Every hinge, every bolt, every fastener and every panel is closed back up when we are done with work on the airplane, so every time we take off we are in that stealth, non-detectable configuration,” Billie Flynn, F-35 Pilot, Lockheed Martin, told Warrior Maven in an interview.
Electronic pings generated by enemy radar, need specific structures against which to bounce off - sending a return signal. If a fuselage is configured such that it does not offer those structures and edges against which an electromagnetic ping can collide, shapes and contours defining an aircraft are more difficult to detect. In essence, it blinds or removes the return signal, and radar is unable to produce a “rendering” of the fighter jet. As an electronic signal, radar emissions travel at the speed of light - a known entity. If the speed of light, which is fixed, is known and the amount of travel time is also able to be determined, then algorithms can calculate the exact distance, shape and even speed of an object.
“We hide the radar, antenna and fuel -- they are all protrusions which reduce hope that you would ever reduce vulnerability,” Flynn said.
Flynn explained that the stealth engineering contributing to the F-35 has some origins as far back as the Gulf War-era F-117 NightHawk. “With the F-117, we learned how to embed antennas in the leading edge of the airplane. This concept went right into the F-22,” Flynn added.
Lockheed Martin F-117 Night Hawk
Flynn also explained that every F-35 sensor was “flush-mounted,” or built into the skin of the aircraft, making the plane less detectable to enemy radar.
Reducing the heat emissions, or thermal signature, is also known to be of vital importance to preserving stealth. There are a variety of ways this can be accomplished, such as burying engines inside an airplane to lessen the release of heat. The F-35 is built with small coolant tubes running under the wings into the body of the aircraft, designed to dissipate the heat generated by the airplane’s avionics and electrical systems. This avoids overheating and controls overall airplane temperatures. Controlling temperature also enhances the stealth properties of the aircraft. Fuel traveling through pipes underneath the airplane also brings a cooling effect, engineers say.
“We can take full advantage of our stealth signature to penetrate enemy defenses, whereas a 4th Gen fighter will have to operate outside of those areas. We can go inside there and fill that close-in air support role,” Flynn said. “We can stay outside of small arms fire because of the sensor suite.”
Overall, Lockheed has delivered more than 360 airframes to 16 bases worldwide and plans a production rev up to meet growing international and US military demand, Edward “Stevie” Smith, Lockheed’s Domestic Director of Development for the F-35, told Warrior Maven in an interview.
Smith explained that all eight original partners, and new ones such a Japan, South Korea, Belgium and Israel, are advancing plans to produce and develop the aircraft.
“We are on target now for the A-models to be at or less than 80-million per copy,” Smith said.
Kris Osborn is the defense editor for the National Interest*.* Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.