15.09.2018

The F-35 Helmet (K2 Communications Inc.)

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One of the F-35 Lightning II’s most impressive and controversial components is the $400,000 helmet produced by a joint venture between Rockwell Collins and Elbit Systems of America.

Plagued by issues — and criticism — throughout its development, the Gen III Helmet-Mounted Display System (HMDS) is finally in use and the companies behind it say pilots are effusive about its performance. Rockwell is even looking at ways to leverage the base technology for other uses, outside the F-35 or the military altogether, according to Business Development Manager Joe Ray.

The price tag is high, but “helmet” doesn’t really do the HMDS justice. The system consists of a number of components, such as a virtual HUD, beyond just the helmet to help save weight by replacing analogous systems on other jets. It also provides some unique and groundbreaking functionality — Rockwell Collins fellow and mastermind behind the HMDS Bob Foote said it is the first aircraft primary flight display that is worn by the pilot.

Each carbon-fiber helmet is 3D-milled to custom fit each pilot. Fit data is stored so replacements can be crafted to order.  The custom fit ensures that alignment of the pilots' eyes and helmet displays is precise, which allows pilots greater ability to see the display during high-G maneuvers, Foote said.

That alignment is particularly important in the F-35 because so much crucial data is provided to the pilot on the helmet’s display. Not least of which is the technology that lets pilots “see through the plane,” in the words of Elbit America Senior Director of Communications Rod Gibbons.

The helmet uses a tracker to tell where the pilot is looking at any given time, then, working with the Distributed Aperture System (DAS)’s 360-degree real-time video, augments the vision in both eyes (as opposed to just one, thanks to pilot feedback) with additional information, even if the pilot isn’t looking out the cockpit’s windshield.

Using the same tracker, pilots can essentially aim their weapons just by looking at a target. A built-in, visor-projected night vision system without the need for separate goggles. And continuous iteration and stripping out weight, combined with the balance provided by custom-fitting, means the helmet is light and balanced enough to help combat fatigue, which is important for long cockpit sessions that will involve high-G flying.

This didn’t all come painlessly, though. “We certainly were meeting the requirements, but that doesn't mean we necessarily met the expectations,” Foote said.

Beyond trying to generally drive down weight and price, there were a handful of specific issues that Rockwell, Elbit and Lockheed had to work out before the helmet would be ready for operational use.

One involved a blooming effect during night-time usage that was especially problematic for F-35Cs trying to land on aircraft carriers.

A pilot's-eye view of from the F-35 HMDS. (K2 Communications Inc.)

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“The thing that they discovered with our previous display technology, which was active-matrix LCD (liquid-crystal display) — AM-LCD, was that there was a certain amount of bleed-through of our back-lighting technology,” Foote said. “So they would sort of see this green haze in front of them from the backlight, and it was making it difficult for them to find the aircraft carrier which obviously creates an unacceptable situation.”

Greg Lemons, Lockheed Martin’s missions systems expert for the F-35, compared the glow to a TV that’s on with nothing on the screen in a dark room. It’s not bright, but there’s still a noticeable glow, and it was plenty to impair the pilots’ ability to operate in dark conditions, he said.

The solution the companies found centered on a technology change from AM-LCD to organic light-emitting diode (OLED) displays, which shut off much more quickly and completely, eliminating the offending green glow.

Another issue involved latency in the tracker. Eliminating as much latency as possible is always a concern for something that is going to be ever-present in pilots’ vision so they can receive visual data and react. Air-to-surface gun strafing performance, in particular, was not meeting requirements thanks to latency with the helmet tracker, according to Lemons.

“We started out with a purely magnetic based tracker that just didn't have the performance we needed to meet our requirements on helmet line-of-sight accuracy for strafing,” Lemons said. “The change that was made was to put an optical-magnetic hybrid tracker into the aircraft, sort of blending those two together along with getting some changes into the helmet itself by actually applying an inertial measurement unit on the helmets to improve the data we had on position and rates of the helmets so we can get a predicted line of sight faster with more accuracy.”

With those issues ironed out, Rockwell’s Ray said pilots are “ready to make it a little bit more customizable when they get on the aircraft; they want to move symbology here and there.” Nothing is imminent on that front, but a few years down the line, in future-generation helmets, he said Rockwell and Elbit are definitely considering ways to allow additional customization as one of the improvements.

Beyond that, both Lockheed and the military are always focused on keeping weight down, cutting costs and more processing power. Combining and presenting all the data an F-35 generates to a pilot in a timely manner takes a powerful processor, and Foote said that task is only going to get more demanding.

Rockwell Collins is also considering other applications. The Joint Program Office isn’t the only group interested in an advanced piece of helmet technology.

“We're looking at special mission aircraft,” Ray said. “The JSOC (Joint Special Operations Command) guys are very interested—and not just airborne applications but also maritime and ground applications. We actually received some information, believe it or not, from the Department of Interior where they're looking at an application of using something like this to fight fires on the west coast.”

The trick there is just to make sure to find the balance between the important capabilities — the wide field of view, the situational awareness, the comfort — and the price. The DOD can pay $400,000 for what Ray calls “the Ferrari,” but firefighters can’t.

Quelle: Avionics