Recent disasters make the case for heavy unmanned helos

Aviation International News » May 2011
April 29, 2011, 5:40 AM

A heavy unmanned helicopter would be invaluable for operations at highly dangerous sites, such as the crippled Fukushima Daiichi nuclear power plant, providing another avenue to address the problem with a greater measure of safety. Technology for pilotless rotorcraft is already in place but so far has been applied only to micro drones and relatively light rotorcraft.

The escape of the nuclear genie at Fukushima has demonstrated the value of unmanned heavy helicopters, which could have dropped water from lower altitudes than the piloted Boeing CH-47 Chinooks Japanese authorities sent to the site. The Japanese authorities applied lessons learned from Chernobyl in 1986, when helicopter pilots flying Mi-26s over the breached nuclear plant took great risks and dozens of them died, and required pilots to stay relatively high (reportedly slightly below 300 feet) to limit their exposure to radiation at Fukushima. As a result, much of the water intended to cool a reactor and refill a spent fuel rod pool failed to reach its targets. An unmanned aircraft, hovering closer to its objective, would have provided pinpoint precision.

Meanwhile, small unmanned helicopters are available, and on April 10 Japanese electric power company Tepco, operator of the compromised plant, started using a helicopter drone–a Honeywell T-Hawk–outfitted with a camera to assess the damage in some areas of the plant.

Crewless Payload

What about combining a heavy payload with the absence of a crew? Jean-Michel Billig, Eurocopter’s executive v-p for research and development, told AIN an unmanned helicopter is “the outcome of an ongoing task–alleviating pilot workload.” Both autonomous and remotely controlled flight are possible, Billig explained, pointing out that an EC155 flew autonomously, from takeoff to landing, in 2008. The safety pilot riding inside the helicopter did not use the controls.

Helicopters that already have sophisticated avionics and digital engine control (mostly medium and heavy helicopters so far) are easier to convert for unmanned operations, and Eurocopter deems retrofits doable. “You could envision software upgrades and even adding sensors and actuators, depending on the complexity of the mission,” said Billig.

What about protecting on-board systems against nuclear radiation damage? To a certain extent, Eurocopter’s NH90 and Tiger military models “are already fitted with protection against nuclear radiation,” Billig said, by heavy metal screening around critical systems such as computers, Fadecs and actuators. This technology could be applied to other helicopters such as the Dauphin and Super Puma.

However, protection has its limits. After a certain amount of time in a hostile environment, even a “hardened” computer will reach its maximum exposure to nuclear radiation. Moreover, a helicopter flying to and from a hazardous nuclear site to spray water or drop sand or concrete would be contaminated, suggesting the need for automated refueling.

One European source in the military helicopter industry said it would be quite easy to turn a latest-generation military transport with fly-by-wire controls into a radiation-zone drone. He estimated development would cost dozens of millions of euros, rather than hundreds of millions, and that the process could produce a usable helicopter in three years.

The fact that such a helicopter would not require civil certification could simplify the task. “These unmanned helicopters would be assigned missions in dangerous areas such as battlefields or nuclear accidents, for example, so they would not have to be integrated into civil traffic,” the source explained.

Confident, too, that such an aircraft is within arm’s reach is retired engineer Claude Frantzen, who has extensive experience in both the aerospace and nuclear industries. He used to be head of Sfact, a branch of the French civil aviation authority, in charge of pilot training and technical inspections. He was inspector-general for nuclear safety with French electric power provider EDF.

Frantzen sees little technical difficulty in developing unmanned helicopters fit for nuclear accident operations. “If the helicopter flies in a contaminated environment, contaminated particles [dust] will settle in many nooks and crannies,” he explained. But he anticipates no problem in ridding the machine of these particles. “They are easy to detect and you can certainly eliminate them with water showers,” he said.

Such de-contamination processes are familiar in nuclear power plants. A helicopter’s exterior surface and engines can be washed. To limit the penetration of contaminated particles into the airframe, “one could envision modest pressurization, along with filters,” Frantzen said.

Radiation

He was equally confident about protecting avionics from radiation, arguing that the electric screening required “is relatively easy, albeit heavy.” He added, “It is well known technology, and we may end up just replacing a 160-pound pilot with 160 pounds of screening.”

Is it possible that radiation would damage the airframe? No, Frantzen answered. He acknowledged that permanent exposure over a number of years has proved that metal in nuclear power plants can suffer creeping but, unlike a contaminated particle, a piece of irradiated material is not a radiation source and therefore cannot harm technicians.

An active EDF nuclear safety specialist gave AIN more understanding of radiation. There are three types of nuclear radiation–alpha, beta and gamma. They can be found in various proportions on a nuclear accident site, depending on the power plant’s technology and the damage it has undergone.

Gamma radiation–the most difficult to contain–will always be found over a serious nuclear accident site. In practice, it “travels” farther than alpha and beta radiation. “To protect against gamma, you can use screens made of lead, a dense metal, but it will not stop 100 percent of gamma radiation,” the engineer said.

U.S. Expertise

In North America, experts such as Piasecki Aircraft president John Piasecki think unmanned helicopter technology can be applied to helicopters even larger than medium twins. Conceivably, such helicopters potentially would include the Erickson Air Crane, the Sikorsky CH-53 and the Boeing CH-47.

Most of the experience with unmanned helicopters can be found in the U.S., where OEMs have been working on pilotless helicopters since 1953 when Kaman first fielded its HTK-1K. That helicopter could be controlled from the ground or from piloted “teaming” aircraft. Basic commands included altitudes and headings. The Pentagon-funded program fizzled due to lack of interest, but company founder the recently departed Charles Kaman called it “a concept before its time.”

Almost 60 years later, a confluence of factors including vastly improved sensors, computers and navigation controls, government agency budget cuts, anti-terrorism campaigns, and military actions in increasingly hostile and challenging environments, have made remotely piloted helicopters relevant. Almost all of the expected contenders for the U.S. Army’s anticipated Armed Aerial Scout (AAS) program are offering helicopters that can be “optionally piloted” and several have already flown technology demonstrators incorporating these systems.

Boeing first flew its Unmanned Little Bird autonomously in 2004 and two years later demonstrated the ability to control it from an AH-64 Apache via datalink. Last year, working with Piasecki Aircraft and Carnegie Mellon University, Boeing demonstrated the ability of the aircraft to autonomously avoid dynamic, low-altitude obstacles, select suitable unmapped landing sites, and successfully land after self-generating approach paths. The system can guide the helicopter to avoid obstacles such as power lines and safely land in brownouts. At its heart is a forward- and down-looking inertial sensor and laser scanner that can build 3-D maps of the ground while locating obstacles in the helicopter’s path. Piasecki said the system could be applied to large helicopters. “Enabling a helicopter to have self-awareness in a near-earth environment unleashes a whole bunch of different mission capabilities that are currently done by manned platforms at great risk or that are not possible,” he said.

Unmanned Helo Developments Abound

Other OEMs are also working on unmanned helicopters. Bell developed an unmanned tiltrotor prototype called Eagle Eye and is currently working with Northrop Grumman on the Fire-X, an unmanned helicopter based on the Bell 407. The Fire-X first flew last December. The helicopter relies on the same flight control software and hardware used in Northrop Grumman’s unmanned MQ-8B Firescout, a platform based on the Sikorsky 333.

When Sikorsky unveiled its X-97 Raider program last year, it said it plans to develop the aircraft so that it can be flown by one, two or no pilots. The company also plans to offer the Army an optionally piloted version of its MH-60 Black Hawk for the AAS program. Sikorsky declined to be interviewed for this article.

At this year’s Heli-Expo, AgustaWestland announced that it would use the Swidnik SW-4 light single-turbine helicopter as the platform for its optionally piloted offering, with a first unmanned flight scheduled for next year. Israel Aerospace Industries has developed a pilotless Bell 206.

Numerous smaller companies have developed purely unmanned rotorcraft that can be scaled up from the miniature for use for everything from law enforcement to agricultural spraying. In the U.S., Utah-based Leptron Industrial Helicopters has developed a line of all-weather machines that can fly at altitudes up to 12,000 feet at 45 mph in a control radius of 21 miles. Several law enforcement agencies are already flying Leptrons, which cost between $17,000 and $72,000 each.

And Kaman is back in the game with an unmanned version of its K-Max heavy-lift “aerial truck.” Working with Lockheed Martin, Kaman has been flying an unmanned K-Max since 2007. Earlier this year, it made successful, pilotless guided airdrops from 10,000 feet, carried and dropped 4,400-pound sling loads, and precision-dropped 1,100-pound containers from 2,000 feet. Two unmanned K-Maxs are scheduled to become operational with the U.S. Marine Corps this summer in Afghanistan, where they will fly exigent re-supply missions in combat areas. A K-Max can carry sling loads up to 6,000 pounds and has a combat radius of 150 miles with a one-ton load. Equipped with an SEI “Bambi Bucket,” a K-Max can drop 640 to 680 gallons of water per load.

Russian Helicopters, a company highly experienced in heavy helicopter design, did not answer AIN’s requests for comment.

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