Sunday, October 11, 2009

ABRAcadabra - AirBorne ReArming

The technology for rearming aircraft with weapons in midair might soon be a reality. This revolutionary technology would enable combat missions, currently requiring dozens of aircraft, to be performed by very few, and to carry out numerous missions by unmanned combat aircraft without returning to base. Airborne rearming might prove to be as significant as the airborne refueling revolution that occurred half a century ago.

KB-29M performing mid-air refuling (Credit: U.S. Air Force Museum)
In 1921, Alexander P. de Seversky, a Russian pilot who immigrated to the U.S., was the first to apply for and receive a patent for midair refueling. Two years later, the U.S. army began operational testing of midair refueling, but although successful, another decade passed before the necessary technology and technique were perfected and midair refueling became routine. World War II witnessed an even greater improvement in the field of midair refueling technology, but the increase in internal aircraft fuel capacities reduced the need for this technology at the time. With the introduction of “fuel-hungry” jet-powered bombers in the post-war years, the requirement for aerial refueling became apparent once again. Since existing refueling methods proved inadequate for refueling jet bombers, the Boeing Company began testing the "Boeing boom" system, in which a wide pipe connected to the rear of a modified B-29 fitted with small wings, was lowered and "flown" to a connector on the receiver aircraft. This new system permitted the transfer of over six-times as much fuel per minute and since the 1950’s, further improvements to the boom system have increased its efficiency and safety. But although computers and a variety of sensors were integrated in recent years, the refueling system remains humanly-operated. Several companies world-wide are developing automatic technologies for aerial refueling, designed to further increase the safety of this complex procedure.

Whereas aerial refueling increases the range of an aircraft almost indefinitely, bombers still must return to base for rearming as they are limited in the amount of weapons they carry. However, when the target is situated hundreds of miles away from a friendly base, precious time and resources are lost on flights to base for rearming. Furthermore, in some cases the political situation precludes the use of friendly military bases near the operating theater.

Bombs inside a rearming plane
To resolve these problems, the Israeli company Far Technologies developed the Airborne Rearming System (ABRA; currently patent pending) in conjunction with the Israel Aircraft Industries (IAI) engineering group that conducted preliminary system design. The ABRA concept is similar in many respects to airborne refueling, with a number of notable modifications. Far Technologies' system comprises a rearming plane (a C-130, C-130c, C-17, or even a C-5) with an internal bomb storage area and loading device consisting of a large aft door with a modified remote-driven robotic arm (boom) equipped with a day-night camera as well as sensors, and, on the attack aircraft, a special smart pylon to receive the arms from the boom. Each C-130c would be able to carry a payload of up to sixteen 2,000 lb (907 kg) bombs (such as an MK-84), while larger aircraft would easily be able to rearm a full squadron of planes. (A C-17 could potentially carry up to seventy MK-84s and a C-5, around 100.)

Rearming mechanism
At present, manned attack missions may take up to several hours, and most of this time is spent flying to and from the target. By employing a refueling and rearming aircraft positioned 50 to 150 miles from the target, the efficiency of an air strike could be doubled with only a slight increase in time and flight distance. While manned aircraft could benefit from airborne rearming in certain scenarios, unmanned combat air vehicles (UCAVs) currently under development could theoretically gain much more from such a technology. Unlike manned aircraft, UCAVs can currently stay aloft for days, and in the future, weeks or even months at a time, performing countless refueling and rearming rounds. Such a capability does not yet exist and would require some level of automatic operation, similar to that currently under development for aerial refueling; if successful, however, it would dramatically increase the flexibility of air power utilization in future conflicts.

A comprehensive study, conducted by Professor Asher Tishler from Tel Aviv University, on the logistical, economic, and operational aspects of ABRA outlined a number of benefits over conventional rearming: (1) the number of bombs delivered in a given time frame could be quadrupled in certain situations, (2) a great cost reduction would be incurred, due to the reduction in the number of aircraft needed to perform each mission, (3) an operational capability could be maintained even while airfields and carriers are under attack, (4) a reduction in aircraft response time whenever a new target is located, and, although not explicitly mentioned in Tishler's report, (5) the potential for aerial conquest, in which an aircraft (typically a UAV or UCAV) occupies a specific area of the enemy's airspace and maintains it for an unlimited period to observe enemy movements and eliminate all relevant targets in that area.

TFOT recently interviewed Nir Padan, CEO of Far Technologies as well as a distinguished Israeli test pilot, who elaborated on ABRA. antike parusto


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