Teschler on Topic

Whose bomber is stealthier?

Teschler on Topic

There was a brouhaha a few months ago about a patent granted to Tupolev, a major Russian military aircra maker. The patent covers an aircra engine intake. The intake itself wasn’t all that interesting, but what got a lot of comments among aircra afi cionados was the patent drawing of the aircra carrying the engine intake. Speculation is that the drawing was meant to be a Tupolev subsonic bomber called the PAK DA. The PAK DA is said to be Russia’s answer to the B-21 Raider, a stealth bomber being developed to replace the Air Force’s aging B-1, B-2, and B-52 bomber fl eet. Builder Northrop Grumman says the Raider will be able to penetrate enemy air defenses anywhere, hit targets, and return safely home, something 90% of the USAF’s current bomber fl eet can’t do. Surprisingly, Russia’s plans for the PAK DA have been public for quite a while. It’s development program started in 2007 and has progressed in fi ts and starts apparently because of wide swings in the price of oil, which Russia exports. Russian o cials have said the PAK DA would be a fl ying wing able to fl y 9,300 miles without refueling. They’ve also said some of its weapons would be the same as those on the Tu-160 Blackjack, a Russian bomber in production since 1987. Aircra industry watchers have been trying to divine additional details about the PAK DA om the engine intake patent. The patent itself is available online in the original Russian. It’s only fi ve pages long. Unlike most U.S. patents, it lacks a section that outlines the prior art behind the invention. It’s well known that stealth aircra use complex S-shaped intakes to hide the spinning jet engine blades om enemy radar. Also known is that engine intakes must prevent slow-moving boundary layer air coming off the air ame om entering the jet engine and hampering performance. But there is no mention of any such factors in the Russian patent. So it isn’t clear what’s patentable in the air intake the Russians describe. The ambiguous nature of the patent hasn’t stopped speculation about the bomber that will carry the intake. Some observers suggest the drawings depict an air ame design that’s less stealthy than the B-2, especially when viewed om the rear and below. Time will tell, but absent om the speculation is how any kind of stealth features will fare given the advances in radar technology now on the drawing board. One such development om the Los Alamos National Lab recently won an R&D 100 award and involves launching electromagnetic waves via accelerated polarization currents. The polarization current is generated by applying an electric fi eld to a dielectric so that negative and positive charges in the material move small distances in opposite directions, creating electrical polarization. This polarization can be made to move through a series of dielectrics at faster than the speed of light—the sequentially moving patterns don’t possess mass so they are aren’t bound by the speedof-light limit. When this happens, a special kind of electromagnetic radiation is emitted. It is tightly focused and can contain information that is almost impossible to spoof. Developers say the main application for this technique is likely to be in 5G communications, thanks to the high privacy implications. But it’s not hard to read between the lines of their proposal and realize that they may be outlining a new kind of radar that can’t be defeated or fooled by using conventional methods. If polarization current radar comes to uition, it will be one less arrow in the quiver of stealth designers. DW

Leland Teschler • Executive Editor lteschler@wtwhmedia.com