The US Air Force Research Laboratory (AFRL) has tested its Gray Wolf low-cost turbojet engine.

The TDI-J85 engine, and related low-cost cruise missile, were designed and built in partnership with Northrop Grumman and Technical Directions, says AFRL.

The initial TDI-J85 test campaign involved multiple inflight engine starts and operation at high altitude.

Gray Wolf cruise missile

Source: US Air Force Research Laboratory

Gray Wolf cruise missile

“The engine met performance expectations for thrust and surpassed fuel efficiency expectations,” says AFRL. “The engines tested accumulated sufficient inflight operating time, building confidence in the design durability.”

The laboratory aims to create a cost-effective, easily manufacturable jet engine that can be produced in large numbers and that will power swarms of low-cost cruise missiles. It claims the TDI-J85 is the first in “its class and price point to successfully operate at altitude”.

The USAF wants cruise missiles with ranges more than 250nm (463km) that can be used for a variety of missions.

In 2017, Northrop Grumman was awarded $110 million by AFRL for the Gray Wolf development effort. That contract said the goal of the cruise missile was “defeat of enemy integrated air defense systems”.

The laboratory is also looking at way for the Gray Wolf missiles to work together.

“Additionally, the programme explored using multiple Gray Wolf missiles in a networked swarm to meet an evolving warfighter mission requirement,” says AFRL.

Those abilities fit the description of AFRL’s Golden Horde initiative, a project aiming to create a networked swarm of munitions, including guided bombs and cruise missiles, that would autonomously share targeting information and coordinate attacks.

“When each weapon shares measurements of a target’s location, combining this information reduces errors since it creates a more accurate target location for all to reference,” says the AFRL. “Ultimately, this supports the use of lower-cost sub-systems in place of more-expensive systems without sacrificing capability.”

The Golden Horde is to use a team-like autonomy that AFRL describes as “play calling”.

“A ‘play’ is an established collaborative behavior enabled (or disabled) when certain predefined conditions are met by the swarm,” says the laboratory. “Golden Horde uses a collection of plays called a playbook. Loaded prior to the mission, the playbook provides a choice of plays from which the weapons can choose.”

The AFRL is careful to note the Golden Horde technology would not use artificial intelligence or machine learning to decide what targets to strike.

“The system only selects from set plays and cannot violate defined Rules of Engagement,” it says.

The AFRL plans to start demonstrating the Golden Horde concept in late 2020, using a modified Small Diameter Bomb I and a modified Miniature Air-Launched Decoy. It wants those two weapons to work together to attack simulated targets in a demonstration in the fall of 2021.

As part of the Gray Wolf initiative, the laboratory plans next to use test data to integrate the TDI-J85 engine in flight test vehicles.

“As part of the weapon system integration and demonstration phase, the team will modify and verify the interfacing operating software, perform captive flight test and conduct a missile release test to demonstrate the low-cost cruise missile concept,” says AFRL.

A timeline of that next phase of tests was not given.