The Navy and Raytheon [RTN] last month simulated a submarine launch of an unmanned aerial vehicle (UAV), not from a torpedo or vertical launch tube, but from the boat’s trash disposal system, a company official said.
The program, Submarine Over the Horizon Organic Capabilities (SOTHOC), is a method of taking an unmanned aerial system (UAS) that’s required to be maintained dry, and transitioning from the water environment to the air, Jeffrey Zerbe, SOTHOC program director, told sister publication Defense Daily earlier this week.
Currently, Raytheon and the Navy are using what Zerbe called a “mass model representative” of a UAV for testing. The launcher was developed by Ultra Electronics Maritime Systems.
“They worked on some communications at speed and depth. That was the precursor to this effort,” he said. “We use some of that technology to develop this launch mechanism for the aircraft.”
The launcher was designed within the dimensional flexibility of the trash disposal unit to be as large as possible, Zerbe added.
“[The trash disposal unit has a] relatively large diameter orifice that can not only be used for shooting trash but other things can be placed in it, and through the ball valve, released into the ocean,” he explained. “That was an existing method to get something out.”
The challenge became once the launcher holding the UAV is outside the submarine how does it get safely clear of the boat and then back to the surface in such a manner that it would be ale to launch an aircraft given the right parameters, Zerbe said.
“It’s initially negatively buoyant. We put some weights on it. Once it leaves the submarine’s trash disposal unit and gets into the flow stream, and based on its center buoyancy and gravity it rights itself at a preset depth,” he said. “At a preset depth, we start pulsing the inflation collar, and it starts going up.”
Once on the surface…it has an inertial measurement unit (IMU) onboard and some electronics that sense it is in the right place in respect to the wind and angle for launch, Zerbe said. “Then it goes ahead and cocks the launch position, opening the pressure vessel and the aircraft flies away.”
The UAV is preloaded with the mission profile, and for the most part it is an autonomously controlled vehicle, he said. The submarine, which will be at periscope depth, can transmit updates to that mission profile, Zerbe added.
Raytheon has some growth opportunities in regards to the vehicle it is using, and the system is adaptable to different vehicles, within reason, Zerbe noted.
“In the realm of the smaller [UAVs] there are even a few that would withstand this scenario, and have the robustness in a maritime environment to deal with the winds and all that go with that,” he said. “So there is probably a short list of vehicles and manufacturers that would fit the bill here.
“But another important point to make here, this launcher concept is scalable. So even though we might be launching a smaller tiered-type vehicle now, if it is desired at some point to expand the capability–longer endurance, greater payload, we can essentially scale up this submarine launch vehicle to house larger vehicles,” Zerbe said.
But the size of the launcher does limit the size of the vehicle, he noted.
Within the launcher there is a pressure vessel that houses the aircraft, Zerbe said. That is going to impact the size of the vehicle to be carried by the launcher.
“We designed it, both from a cost perspective and capability perspective, to be a one-way,” Zerbe said. “Part of the system architecture here allows you, in different scenarios depending on where it’s launched from, to fly it into the beach and have it recovered on land and potentially returned to service. That’s within the CONOPS (concept of operations) of this capability.”
And the launcher itself is not limited to transporting a UAV to the surface, Zerbe said.
“Many concepts are coming out…you’ve got a dry interface, you can house something, you can store something, potentially for a lengthy period of time and then activate it to launch whether it be submerged or on the surface,” he said. “Obviously, there are other applications, both military and civilian, that would apply here, especially as you start talking about the scalability of it.”
Demonstrating the capability of releasing the launcher and getting it to the surface, was the culmination of Phase I of the program, Zerbe said
“Phase II is where we then take the developed launcher, the highest risk portion of the project, and fully integrate a proven vehicle into it,” he said.
Early next year, after successful completion of testing at Naval Air Station Pt. Mugu, Calif., Raytheon will go onboard a submarine and do exactly the same test only this time, instead of dropping the launcher over the side of a submarine, it will be deployed out of the trash disposal unit, Zerbe said.
“We anticipate getting out to Pt. Mugu this year, and then out to PMRF (the Pacific Missile Range Facility) and complete submarine testing early next year,” he said. “Upon successful completion of the Pt. Mugu testing, we will identify an aircraft manufacturer.