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X-59: The New X-PLANE

In 2016, Lockheed Martin was awarded a contract to develop a new X-plane, with the goal of researching low-boom supersonic flight. The result – an aircraft now referred to as the X-59 – has now been completed, and will soon begin testing. But what is the X-59, and how will it impact the aerospace world?

HISTORY

From the introduction of the Concorde in the late 1960s, international interest in supersonic flight has increased. From air travel to transport, the utility of supersonic travel is attractive, but there has always been one consistent problem, and that is noise. One of the many failings of the Concorde program was the complications of flight paths. The loud sonic boom caused problems for those on the ground, so these aircraft were slowly but surely limited in their ability to fly over populated areas,  resulting in inefficient flight paths and limiting the number of possible destinations. Thus, a focus on lessening the sound produced by supersonic aircraft has been on the table for some time. This particular area of research precedes the Concorde, but with very limited success. Ultimately, supersonic flights, with their noise and potentially damaging effects on the ground, were banned over the United States in 1973, and this impacted not only commercial travel but also military activity.

To create quiet supersonic activity over populated areas has been a challenge NASA took up, once again, about a decade ago.  In 2016, Lockheed Martin was given a preliminary design contract for a research aircraft capable of dampening sonic boom, and in 2018 was awarded a $247 million contract to design and build such an aircraft, with delivery estimated for 2021. During this two year period, wind tunnel tests had been done on various potential designs. The first predictions were put forward in 2017. It stated that the aircraft may be capable of dampening a sonic boom to less than 1/1000th of the loudness of a regular aircraft. This was a bold claim, resting on the theory that if an airframe is sufficiently long and narrow, with canards, it will prevent the coalescing of shockwaves.

In 2018, the design was further refined. Wind tunnel tests continued on miniatures, and by the end of the year, the first full scale parts were ready to be machined. From 2019 onwards, the design of the full scale aircraft would be underway.

This new aircraft would be designated “X-59 Quest” by the Air Force, or “Quiet Supersonic Technology”. With a length of 99.7 feet and a wingspan of 29.5 feet, this long aircraft would seek to maximise efficiency and reduced drag to the extreme. In fact, the cockpit itself would sit flush with the fuselage, an obvious problem, given the impaired forward visibility. However, with sufficient faith in the tech, NASA announced that this challenge would be overcome using two external vision systems; the NASA XVS for forward view, which would give the pilot a 4k image with a field of view 33 degrees horizontally and 19 degrees vertically, and the Collins Aerospace EVS-3600 multispectral imaging system for landing.

In 2022, the development program accelerated to produce a flying prototype within a few years. The pilot of this large aircraft sits in a cockpit, ejection seat, and canopy taken from a T-38 training jet. Meanwhile, the landing gear system comes from the F-16. A life support system would be integrated from the F-15.  Powering the X-59 would be the General Electric F414-GE-100 – a modified version of the engine found in the Super Hornet –  producing 22000 pounds force of thrust, with an intake mounted above to further reduce the sound of the boom. With this setup, the aircraft will supposedly be able to reach a maximum speed of Mach 1.5, or cruise at Mach 1.42 at 55000 feet.

On January 12th 2024, the first fully completed X-59 was rolled out in front of an eagerly awaiting audience.

Despite many delays, the current plan is to commence the first flight of the aircraft before the end of 2024. This will be an interesting event, with NASA and their partners speculating on several possibilities. Firstly, it is predicted that the ground noise will be higher than originally envisioned in 2017, but nevertheless still quite low, sitting at 75 effective perceived noise in decibels, roughly as loud as you would perceive closing your car door, and just over half as loud as a Concorde. Another point of interest for researchers will be the engines intake, which has been tested in high speed wind tunnel conditions at various high angles of attack, but may yet prove to be in need of further upgrades. This concern comes from a prediction that oscillations from vertices may cause inlet flow distortion, which would obviously effect engine performance and health.

Before any of this happens, the now completed aircraft will first undergo integrated systems tests, engine runs, and taxiing tests. This will happen at NASAs Plant 42, before the aircraft heads to the Armstrong Research Centre.

The second stage of this testing will involve – after the first flights – reevaluating whether the initial core design needs improvement. A third stage will then see supersonic tests occur over different locations in the US, known as Community Response Study. This will assess the public impact of the tests, hopefully to prove that these far more quiet sonic booms do not damage or disturb citizens.

NASA says they will share their findings with others in the industry and regulators, in a bid to prove that supersonic flight is not only beneficial but a great new market to reopen in America.