Developed with a Cold War mind-set, communications for stealthy aircraft were largely intended to be limited. But that has become a hindrance to operating the F-22 and F-35 on the modern battlefield.

To address the jets' inabilities to link to one another—or to legacy fighters—in air campaigns, their manufacturer, Lockheed Martin, has demonstrated a new data-linking capability it developed for them secretly through “Project Missouri,'” a proprietary program. During the demonstration, Lockheed validated the use of a Link 16 transmit capability from the twin-engine F-22 Raptor and showcased an exotic waveform developed by L-3 Communications and optimized for low-probability of intercept/low-probability of detection transmissions (LPI/LPD), says Ron Bessire, vice president of technology and innovation at the company's Skunk Works.

The demonstration required 8 hr. of flight time and took place Dec. 17 and 19, 2013, Bessire tells Aviation Week. The trials required use of a U.S. Air Force Raptor and the F-35 Cooperative Avionics Testbed (CATbird), a Boeing 737-based flying laboratory that was used as a Joint Strike Fighter surrogate to test F-35 software. The F-22 also was able to transmit to a Link 16 terminal on the ground.

The F-22 was originally designed to communicate only with other Raptors, in an effort to reduce emissions from the aircraft and maintain signal stealth in the event of a peer-to-peer engagement. However, because of a dramatic cutback in the number of Raptors purchased—187 bought for operations, compared to the 648 planned in 1996 to be procured—the aircraft must now communicate with F-35s expected to enter service next year as well as legacy “fourth-generation” fighters such as the F-15, F-16 and F-18 families.

This so-called fifth-to-fourth capability was highlighted as a need last week by Air Force Chief of Staff Gen. Mark Welsh at the annual Air Force Association Air Warfare Symposium in Orlando, Fla., but a firm requirement and funding are lacking. Describing the technology as “nothing cosmic,” Welsh said such a link would extend the range and improve the effectiveness of each platform. Ultimately, handoff of weapons-quality data is needed, meaning data from one aircraft can be used by another to accurately fire a weapon.

“We demonstrated the data was being transmitted at a high [enough] rate to support rapid update of the air tracks to whomever was on Link 16,” Bessire says.

Should such a capability be fielded, the F-22 could be used to enhance the effectiveness of F-15s and F-16s in an air battle, because most of the older fighters lack the use of an active, electronically scanned array (AESA) radar. The Northrop Grumman radars on the F-22 and F-35 are able to detect and target airborne threats at ranges far exceeding those of radars on the older fighters.

Bessire says the “LPI/LPD waveform still needs some additional maturation,” but he declined to discuss whether it is in use in another platform. Such a waveform would be useful for the B-2, new unmanned aircraft such as the Northrop Grumman RQ-180 and any system hoping to reduce radio-frequency emissions to conduct stealthy operations.

Equipment and the aperture for delivering the signal are at a technology readiness level of 9, he said, indicating more work needs to be done before it can be proven in a relevant environment and garner full programmatic status at the Pentagon. The F-22, however, is able to use its existing apertures to operate the waveform, he says.

Installation of a so-called “open system architecture” (OSA) rack and the radio took place within a year of starting the effort to add Link 16 to the Raptor, according to Bessire. The OSA racks also can enable other operations, such as distributed electronic attack, although this was not demonstrated.

“What we learned out of this demonstration is that there is tremendous power in the Air Force open-mission architecture standard,” Bessire says. The equipment was installed in the F-22's avionics bay.

Through Project Missouri, Lockheed Martin is trying to package a capability similar to that offered by the Northrop Grumman Joint Strike Fighter Enterprise Terminal (JETpack) Joint Capability Technology Demonstration within a stealthy aircraft. JETpack was a podded solution; incorporating it on the stealthy F-22 and F-35 would compromise their low radar cross sections.

Lockheed Martin is briefing Air Force leadership on the demonstration results and hoping to see an official requirement for such a capability. Suppliers, such as L-3, shared in the cost of the demonstration. But the team would like to see a sign from the Air Force to continue work. If funding were not an issue, the Link 16 system could be fielded by the end of this year, Bessire says. “One of the goals of the demonstration was to create a reusable design, whether that was software or hardware,” he says.

The program was dubbed “Project Missouri” as a response to a demand from Air Combat Command chief Gen. Michael Hostage, who told the company to “show me” it was possible when Lockheed briefed plans for the demonstration to him before it took place. Bessire notes that Missouri is nicknamed the “Show Me State.”