Two reports that put in perspective the issue over the helmet development.
Source : Jan 2015 DOT&E
The second iteration of Block 3i software, 3iR4,included capability to test the new Generation III HMDS. The Edwards test center flew four test missions with 3iR4 on AF-3 in September, accomplishing regression test points and some initial test points from the Generation III HMDS test plan. This was the first testing of the new HMDS on F-35 test aircraft. The
test team discovered deficiencies, particularly in the stability of the new display management computer for the helmet, and suspended further testing until software that fixes the deficiencies in the helmet system can be provided to the major contractor and included in an
updated load of mission systems software. The third increment of Block 3i software, version 3iR5, will be used to provide production software for Lot 7 aircraft, the first lot to be delivered with the Generation III HMDS. The program plans for the production software to have the equivalent capabilities as Block 2B and plans to deliver 3iR5 software to flight test in January 2015. However, even if this occurs, since Block 2B development and flight testing were
not completed as planned in October, the completion of Block 3i testing will be delayed if the equivalent capabilities from Block 2B development are to be realized in Block 3i. The program plans to convert four of the five Block 2B mission systems test aircraft at
the Edwards test center to the Block 3i configuration in February 2015. Assuming this transition takes place, Block 3i flight testing could conclude by July 2015, two months later than the planned completion of May 2015. This assumes nominal growth of 66 percent
is experienced during the rest of Block 3i development and flight testing, the program completes testing of the remaining baseline test points without reductions, and the program uses four of the six mission systems test aircraft at the Edwards test center for dedicated
Block 3i testing. Of the two remaining mission systems test aircraft, one other test aircraft could be available for further Block 2B testing and one could be used to start Block 3F testing. Additional time will be needed to address corrections if additional deficiencies are
identified in the Generation III HMDS and will add risk to the schedule.
Source:
Eliminating the head-up display and relying instead on a helmet-mounted display (HMD) was only one of the bolder design decisions for the Lockheed Martin F-35. It has also proved one of the more challenging, but a system meeting the requirements is in the final stages of testing. Aircraft hardware for the third generation of the F-35 HMD is being delivered to Lockheed for production Joint Strike Fighters, with the “Gen-3” helmets expected to arrive at pilot training locations beginning in late spring. The new HMD incorporates fixes to several shortcomings identified in the Gen-2 helmet during F-35 flight testing and pilot training. These included night-vision acuity, symbology jitter, imagery latency, alignment and green glow. Gen-3 helmets will be fielded beginning with low-rate initial production (LRIP) Lot 7 F-35s now in assembly at Lockheed. Improvements to the Gen-2 helmet, meanwhile, have been made to support U.S. Marine Corps’ efforts to declare F-35B initial operational capability (IOC) by year-end. “Latency, jitter, etc. are well behind us with hardware and software improvements incorporated into Gen-2 with LRIP 5. We are now finishing up development of Gen-3 and are in qualification testing,” says Robert McKillip, senior director for HMD programs at Rockwell Collins. “Gen-3 involves a lot of little things that improve performance and producibility,” he says. A major change is to use two new Intevac ISIE-11 night-vision cameras: one on the helmet and one on the aircraft glareshield looking forward. The ISIE-11 has a larger aperture and higher resolution, sensitivity and speed than the ISIE-10 on the Gen-2 helmet. Originally just a simple forward-looking day sensor, the aircraft-mounted camera now performs several key functions in the Gen-3 system: helping to track the pilot’s head, aligning the helmet display and improving visibility while flying at night. Replacing the conventional head-up display, the F-35 HMD projects stabilized flight symbology and sensor imagery onto the pilot’s visor. With Gen-3, imagery from both the forward and helmet ISIE-11 cameras is used to minimize obstruction of the pilot’s night vision by the canopy bow. “We fuse the imagery and eliminate most of the bow frame,” says McKillip. This is critical during hose-and-drogue refueling at night in the F-35B and Navy F-35C variants, as it enables the pilot “to see the probe go into the basket,” he says.Gen-3 adds a light-emitting diode (LED) and camera to the front of the helmet and back of the forward camera. The sensors optically track the LEDs to augment head-tracking and automate the calibration of display alignment. Three methods of tracking head motion are used. The main one is magnetic, using a sensor mounted on top of the ejection seat, but alignment can shift over time so long-term optical- tracking has been added to keep the helmet aligned. An inertial measurement unit (IMU) also is installed in the helmet to mitigate symbology jitter caused by aircraft buffet. “It is a trade between twitchiness and damping. When the IMU senses higher buffet, symbology is more heavily damped. We now use a different trade that errs on the side or readability.” A third function of the forward camera is to enable the pilot to quickly perform an end-to end check of the Gen-3 helmet using the boresight reticle unit. “This gives the pilot visual feedback on alignment. It’s a go/no-go test that the helmet is aligned,” McKillip explains. Because of the design changes, the Gen-3 helmet requires ground-testing to clear the helmet for pilot ejection at speeds up to 550 kt. A component failed on one ejection-seat test and is being redesigned and retested. First flight of the Gen-3 helmet on an F-35 was on aircraft AF-3 in September at Edwards AFB, California. Testing was halted after four flights due to stability problems with the new display-management computer, says the latest report by the Pentagon’s director of operational test and evaluation. “There were integration issues between Elbit’s software and Lockheed’s software. These were fixed in an Oct. 30 software release. We have not seen this issue in our lab, in Lockheed’s lab or on the jet since,” says McKillip. Rockwell Collins leads development of the F-35 HMD under the Rockwell Collins ESA Vision Systems joint venture with Elbit Systems of America. It replaces the original Vision Systems International consortium and has a simplified structure. Deliveries of aircraft equipment for LRIP 7, including the forward camera, began late last year. Helmet deliveries will begin in late spring to the F-35 integrated training center at Eglin AFB in Florida.