F15's Tilting Air Intakes Showcased In Awesome Video
A recent video of Japan's F-15J Eagle brilliantly shows the fighter's maneuverable air intakes bouncing up and down during flight. While this certainly seems surprising in the spirit of an engineering miracle, there is an important reason for it, and it is the fundamental reason why the plane works.
The following video, courtesy of @rikizomisono , shows a Japan Self-Defense Force (JASDF) F-15J with serial number 12-9828. Photographed during rehearsals for the JASDF air displays in Gifu this year. The event will take place on November 12 at Gifu Airport, located in the city of Kakamegahara, Gifu Prefecture, southern Japan. Gifu Airport is home to the JASDF's flight development and test division, the Air Test and Development Command, which flies the F-15J and F-2 fighter jets, among other aircraft types.
https://twitter.com/rikizomisono/status/1720357317412327729
The movement of the fighter's variable geometry air inlets is essential to maintaining smooth, optimal airflow to the two notoriously slow Pratt & Whitney F100-PW(IHI)-220E turbofan engines. The F-15 previously suffered from compressor stall, even with manageable air intakes.
The F-15's air intakes move forward from top to bottom. The air intakes "nod" up and down under the control of the aerodynamic data computer so that the opening faces directly into the airflow, allowing a large amount of air to enter through the intakes. engine air. Drag is caused by the plane's angle of attack (the angle at which the relative wind hits the wing) as well as speed. This is particularly useful when the F-15 performs difficult maneuvers at low speeds. Another set of ramps inside the intake helps slow the airflow so it is less turbulent and subsonic when it reaches the surface of the engine.
We reached out to Sari ( @sariinthesky ), a former US Air Force F-15 pilot, to get his take on the video, as well as the F-15's air intake design.
"[The F-15's adjustable external air intakes] maintain subsonic airflow to the engine," he said. "The air inlets move depending on the angle of attack. The person doing it [in the video] plays and moves at the right speed to move the air inlets a little. You can hear the air inlets "drop" when In flight mode they move decently but generally slowly unless significantly deflated.
https://www.youtube.com/watch?v=nQXTn6iZy-Y
Air inlet design remains one of the most difficult aspects of high-performance aircraft design (the toughness makes it even more difficult), and you can read more about its details in previous war articles .
The F-15J and its curved external air intakes will remain common in Japan for the foreseeable future. According to the World Air Force Factbook 2023 , the JASDF has 155 F-15J single-seat fighters, McDonnell Douglas F-15C/D Eagle unit aircraft and 44 F-15DJ two-seat trainer aircraft. Already in 2021, the Japanese government signed an agreement with the United States to upgrade several F-15J fighter jets to the F-15JSI, the " Japanese super interceptor ". It was later reported that 68 F-15Js would receive upgrades built on the same avionics foundation as the F-15EX .
This is the amazing design of the F-15's external air intakes, demonstrated in a fantastic video.
Thomas Newdick contributed to this article.
Contact the author: oliver@thewarzone.com
