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bobdina
07-16-2010, 11:53 AM
Protecting rotorcraft

Technology only goes so far in stopping small-arms, RPG fire
By Joe Gould - Staff writer
Posted : Friday Jul 16, 2010 10:41:38 EDT

Four American soldiers were killed when a NATO helicopter was shot down using two rocket-propelled grenades in a midday attack in Afghanistan’s southern Helmand province. The Black Hawk, attempting to pick up a British casualty, crashed in the Sangin district bazaar.

The June 9 attack was the latest in a string of RPG helicopter shoot-downs. In fact, the RPG is responsible for felling scores of military rotorcraft of all types, according to news accounts. As the Army prepares nearly triple the number of air assets in Afghanistan, the cheap, easy RPG used in the famous ‘Black Hawk Down’ crash in Mogadishu, Somalia, remains the weapon of choice for militants, Army officials say.

There have been 375 rotorcraft losses, with 496 fatalities through September. Of those, 19 percent are attributable to hostile action and the rest to mishaps in and out of combat, Mark Couch, of the Institute for Defense Analyses, and Dennis Lindell, program manager for the Joint Aircraft Survivability Program Office, stated in a May report to Congress.

Precise numbers are unavailable due to their sensitivity; however, Couch and Lindell said in a subsequent report for the rotorcraft community that the majority of hostile-fire losses are attributable to RPGs and Man-Portable Air Defense Systems, or MANPADS, which are infrared-guided, shoulder-launched surface-to-air missiles.

“We have had aircraft shot down either by a combination of small-arms fire and RPGs or massed RPGs, of which one or two or more might hit an aircraft,” said retired Maj. Gen. Jeffrey Schloesser, the former director of Army aviation in the Office of the Deputy Chief of Staff, G-3/5/7. “They’re a poor man’s weapon, and they’re available throughout the world.”

Schloesser recalled during his time commanding the 101st Airborne Division in eastern Afghanistan, a Chinook that was felled when an RPG struck its aft pylon. The pilot crash-landed on top of an abandoned farm building in the high mountains, escaping serious injury.

“There are other shoot-downs where that wasn’t the case, so it has always been a significant factor,” he said of the RPG threat.

With the battlefield in mind, the Army has accelerated its aircraft survivability efforts to focus on the ubiquitous “dumb” threats of small-arms fire and RPG’s.

“RPGs are as plentiful as heavy machine guns; they’re cheap, they’re easy and they’re all over the battlefield, so you don’t get away from them,” said Chief Warrant Officer 4 Jon Larue, one of the officials spearheading the Army’s technology effort. Larue is an action officer with the Aviation Division of the Deputy the Chief of Staff G-3/5/7, the division responsible for managing and integrating the modernization process for Army aviation.

“There’s no warning, there’s no defense that you can put up to stop a guy from shooting at you, or detect it until he’s fired the first round.”
‘Cost, ease of use, and lethality’

Common to conflicts since the Vietnam War, the Soviet-made RPG-7 was once a mainstay of the Iraqi army and is now a favorite of insurgents, according to report by George J. Mordica II, an analyst for the Center for Army Lessons Learned.

“The real advantage of this weapon is the cost, ease of use, and lethality,” Mordica writes. “The disadvantage of conducting a close combat attack is the danger of immediate retribution from a superior force. In Iraq, that disadvantage is diminished because the attacker is often willing to give up his life in an effort to create casualties and political unrest.”

A shoulder-fired, muzzle-loaded anti-tank and anti-personnel grenade launcher, the RPG-7 fires grenades with a an effective range of 300 meters against moving targets and a maximum reach of about 1,000 meters. The grenades travel at 200 meters per second and detonate with a bursting radius of 4 meters. One variety self-destructs after flying for 4.5 seconds.

“The most effective use of the RPG-7 against helicopters has been to use the self-destructing round to being down a platform with shrapnel,” Mordica writes. “Engaging from 800 meters away will allow for the 920 meters self-destruct to activate and kill the aircraft.

“Obviously, this technique takes a lot of practice to be effective, but the results of RPG-7 attacks against Soviet helicopters in the mountains of Afghanistan prove that it can be effectively trained.”

Writing in a 1998 issue of Infantry magazine, Lester W. Grau, of the Foreign Military Studies Office at Fort Leavenworth, Kan., described how the mujahedeen in Afghanistan would use RPGs to attack Soviet transport helicopters loaded with troops.

“In Afghanistan, the Mujahideen found that the best anti-helicopter tactics were anti-helicopter ambushes,” Grau writes. “The first variant was to identify likely landing zones and mine them. Then the Mujahideen would position machine guns and RPGs around the landing zone. As the helicopter landed, massed RPG and machine gun fire would tear into the aircraft.”

Grau pegged the RPG as the perfect weapon in an asymmetrical fight: “The chances are, whenever a U.S. soldier is deployed to a trouble spot, the RPG-7 will be part of the local landscape.”

“It’s very comparable to IEDs,” said Schloesser, “in that our sophistication sometimes does not lend itself to an easy solution in the case of a poor man’s weapon that’s commonly available, that’s relatively unsophisticated, and yet devastating en masse and for a relatively well-trained operator.”
Infrared countermeasures

Technology to combat the threat of sophisticated infrared-guided surface-to-air missiles has come further than efforts to counter “dumb” bullets and RPGs.

Many U.S. military aircraft are equipped with these systems: the Common Missile Warning System, which uses ultraviolet sensors to detect missile launches, track them and launch flares that confuse the missile’s infrared seeker, and Advanced Threat Infrared Countermeasures, which uses jamming lasers to misdirect infrared-guided missiles.

Matt Schroeder, manager of the Arms Sales Monitoring Project at the Federation of American Scientists, said funding of these systems has been “money well spent,” as MANPADS have appeared in arms caches in Iraq and, to a lesser extent, in Afghanistan.
Supersonic, subsonic rounds

Meanwhile, Defense and Army officials are taking aim at RPG and small-arms fire attacks against helicopters. Until recently, the Army’s main investment against this has been aircraft survivability equipment like adding additional armor, redundant critical systems and more crash-worthy fuel tanks.

“All of the aircraft survival equipment systems on board to date that we’ve put a lot of money into, both for Iraq and Afghanistan, have been oriented toward the surface-to-air missile threat, IR-guided [missiles], and those systems have done yeoman’s work preventing that from happening,” Schloesser said.

Because there is no system yet that can divert “dumb” bullets or RPGs, the focus has been to determine the origin of the fire and alert pilots.

“Now we’re taking a different focus in recent years, to try to give the pilot that situational awareness to let him know he’s being fired at,” said Ray Gentzyel, chief of Army G-3/5/7’s aviation systems division. “Now we’re trying to give him an indication in the cockpit so that he can use his maneuvers for survivability.”

The DARPA and BBN Technologies have been developing a device that detects such attacks and locates the shooter, and it was installed on a UH-60L Blackhawk for testing in February. In March congressional testimony, DARPA director Regina E. Dugan said several more systems would be deployed Afghanistan for operational testing.

Called the Helicopter Alert and Threat Termination system, or HALTT-A, the system uses 16 sensors mounted on the helicopter’s fuselage to detect the supersonic shock wave caused by firing bullet.

BBN also makes the similar Boomerang ground acoustic shot detection system, which also hones in on the sounds of bullets being fired. That system indicates the “o’clock” azimuth of incoming small-arms fire, announces that direction using a recorded voice and indicates the range and elevation on an LED screen display.

Larue said situational awareness is crucial so that pilots can take evasive action to protect themselves, their passengers and the airframe. Often, aviators are unaware they have been shot at until they inspect the airframe after landing.

“We don’t want a pilot to walk around the aircraft and say, ‘Holy smokes, I was fired at because I have three or four bullet holes in his tail boom,’” Larue said. “We want him to know exactly when that took place so he can react, so he doesn’t have to come home and find out an hour after the mission.”

Because the RPG-7 fires with smoke and a flash, but no supersonic bang, it is tough to detect with acoustic sensors alone. Army officials said detecting the ballistic threat presents the nascent technology with a complex problem probably best met by a combination of ultraviolet, infrared and acoustic sensors.

http://www.armytimes.com/news/2010/07/army_joe_aviation_071610w/