By Geoff Fein
The Navy and a Raytheon [RTN]-led team have been exploring the use of a submarine-launched AIM-9X sidewinder air-to-air missile to provide self- defense against enemy aircraft and small fast surface boats, according to a company official.
Submarines today are operating more and more in the shallows, near coastlines, supporting Special Forces and other U.S. and friendly forces, Mike Sharp, director of maritime systems and advanced technology programs group, told Defense Daily in a recent interview.
In the “old days” if an enemy helicopter or some other aircraft came out, the submarine would have to go deep and run out to sea, he added. “There was never a need for a weapon like this.”
“But these days if you are in shallow water and you have to stay there and support somebody else, you’d like to have some way of defending yourself and that’s what the concept of the LWW (Littoral Warfare Weapon) was about,” Sharp said.
The LWW was one of many efforts under the Navy’s “Payloads and Sensors” program, where the submarine force told industry they need to have more capability developed into their submarines, to look beyond torpedoes and Tomahawk missiles, Sharp added.
There were a couple of efforts that grew out of the LWW–one was the concept to develop a capsule, the Stealthy Affordable Capsule Systems (SACS). Northrop Grumman [NOC], one of Raytheon’s teammates, built the LWW risk reduction SACS canister, Sharp noted. Northrop Grumman has previous experience building the canister for Raytheon’s tomahawk cruise missile, he added.
“Northrop Grumman’s demonstrated encapsulation system opens the door to submarine launch of a wide variety of defensive, offensive, communications, and intelligence, surveillance and reconnaissance payloads without needing to adapt such payloads to survive in an undersea environment,” the company said yesterday in a statement.
The second concept was the need for a missile. “We chose the AIM-9X because it’s a well-known reliable and mature missile and we didn’t want to spend this effort on proving the missile would work. We wanted to spend the effort proving we could launch it out of a submarine,” Sharp said.
Raytheon Integrated Defense Systems is the prime contractor and is partnered with both Northrop Grumman and Raytheon missile systems.
Risk reduction efforts for LWW have been ongoing for the past three to four years, Sharp added.
One of the things that makes the fifth generation infrared (IR) AIM-9X a good choice for this transition is that it has its own internal cryocooler, Jeff White, AIM-9X business development manager, told Defense Daily in the same interview.
A missile seeker head needs to be cooled with Argon or Nitrogen gas to get good detection, White explained. “Obviously, it would get very expensive and time consuming to put an AIM 9X in a capsule if you had to put coolant in there and continually do that.”
Additionally, the AIM-9X has Jet Vane Control, White added.
“As long as the rocket motor is burning, it’s a thrust vector control, so it can put some really good bat turns on to try and track targets with high track crossing angles,” he said.
One change that was made to the AIM-9X is that while the missile is typically locked on to a target before it launched, that can’t be done if shooting out of a submarine, Sharp said.
So the first phase was a land launch out of a vertical tube,” he said. “The test was to launch it and see that it locked on to [a drone helicopter] after it was launched, and then knock the helicopter out.”
“That worked,” Sharp added. “It was really the targeting characteristics of the missile that had to be modified to have it do something it hasn’t done before.”
Nothing has been done to harden the missile for an undersea launch, he added.
“The canister basically protects the missile up until it is out of the water and then the end caps come off and then the missile is basically in air,” Sharp said. “Nothing has been done to the missile…for it to survive the environment.”
The ability to use a stock missile was one of the goals of the LWW program, he added.
“That gives us the flexibility, in the future, to put any missile in there. It’s just a matter of what would fit in the tube,” Sharp said.
The AIM-9X being used for the LWW effort is a Block 2 variant, White said.
“As we got into an obsolescence program, we ended up having to redo some parts of the missile, which brought on the advent of Block 2,” he said. “So what started out as AIM-9X, we are moving on and now producing AIM-9X Block 2, and that missile has lock-on after launch and a data link capability. That’s what makes this so appealing to submariners.”
One of the other advents, albeit a small one but an important one, White said, is that the AIM-9X Block 2 no longer has a safe arm handle.
“If you were to arm the missiles, the ordnance man on the fight line has to turn the handle on the rocket motor. We now have an electronic safe and arm device, called ESAD.”
ESAD arms the warhead after launch.
“My understanding is that there are fundamentally three things that had to be done to the missile to make it fly out of a submarine: One is you obviously can’t arm this thing in the tube so they had to develop an electronic arming device that arms the missile after it leaves the submarine–that’s been done. We talked about the ability to launch it and lock-on after it is up and out of the water–we proved that,” Sharp explained. “The third thing which is currently ongoing is to develop the ability to see and target small surface ships.”
The IR capability of the AIM-9X makes it very good at both targeting and taking out aircraft and small surface ships, Sharp added. “That’s why we like it, for that capability.”
LWW Phase A1 focused on the land launch and lock-on after launch. The focus of Phase A2, which has been ongoing for a couple of years, is to prove the AIM-9X could be shot from a submerged vertical tube, Sharp said. “We just completed the last test at Aberdeen Proving Ground. They have a big pond there. We actually put a tube in the water and launched the missile, and a number of canisters, looking at the trajectory, looking at the ends blowing off [the capsule].”
In July, the LWW team was able to prove that a missile could be launched from a submerged tube, go up into the air and fly, he added.
“We are about to start the third phase, which will be the final phase in risk reduction, to do all of that from a moving tube,” Sharp said. “Now you want to know you can do this with water flow across the end of the tube? In this case, we are going to set up a similar situation and move the tube through the water as we launch the missile. It’s all about making sure the trajectory isn’t affected by the forces of the water as the submarine would be moving through the water when it launched.”
The goal of the Navy, Sharp added, is to get funding to turn LWW into a program of record, sometime starting in fiscal year ’12.