World Trade Center

Complex formerly consisting of seven buildings around a central plaza, near the southern tip of Manhattan. Its huge twin towers (completed 1970–72) were designed by Minoru Yamasaki (1912–86). At 1,368 ft (417 m) and 1,362 ft (415 m) tall, they were the world's tallest buildings until surpassed in 1973 by the Sears Tower in Chicago. The towers were notable for the relationship of their simple, light embellishment to their underlying structure. In 1993 a bomb planted by terrorists exploded in the underground garage, killing several people and injuring some 1,000. A much more massive attack occurred on Sept. 11, 2001, when first One World Trade Center and then Two World Trade Center were struck by hijacked commercial airliners that were deliberately flown into them. Shortly thereafter both of the heavily damaged towers, as well as adjacent buildings, collapsed into enormous piles of debris. The attacks claimed the lives of some 2,750 people. Thousands more were injured. See September 11 attacks.

Learn more about World Trade Center with a free trial on

California ground squirrel (Spermophilus beecheyi) .

Any of numerous relatively short-legged, terrestrial rodents of the squirrel family (Sciuridae), found in North America, Mexico, Africa, Europe, and Asia. The name is often applied to chipmunks. Ground squirrels belong to the genera Ammospermophilus, Xerus, Atlantoxerus, and Spermophilus. They live in burrows, sometimes in colonies. Though primarily herbivores, some feed on insects and other small animals and on carrion. Many species collect food, carrying it in their cheek pouches, and store it in their burrows. Those in cold areas may hibernate in winter; those in dry areas may become dormant in summer. Species range from about 7 to 20 in. (17–52 cm) in length, including the tail.

Learn more about ground squirrel with a free trial on

Name that originally referred to a species of southern European spider (Lycosa tarentula) but now refers to more than 175 spider species (family Lycosidae) found in North America, Europe, and north of the Arctic Circle. The body of L. tarentula, the largest species, is about 1 in. (2.5 cm) long. Most species have a long, broad, hairy brown body; stout, long legs; and strong, prominent jaws. Wolf spiders chase and pounce upon their prey, hunting mostly at night. Most species build a silk-lined, tubular nest in the ground, which they dig with their heavy front legs. A few species spin webs. The bite of L. tarentula produces no ill effects in humans.

Learn more about wolf spider with a free trial on

Any of about 200 species of primitive vascular plants that constitute the genus Lycopodium (order Lycopodiales), mainly native to tropical mountains but also common in northern forests of both hemispheres. They are evergreen plants with needlelike leaves and, often, conelike clusters of small leaves (strobili; see cone), each with a kidney-shaped spore capsule at its base. Representative species include running pine, or stag's horn moss (L. clavatum), ground cedar (L. complanatum ‘flabelliforme'), shining club moss (L. lucidulum), fir club moss (L. selago), ground pine (L. obscurum), and alpine club moss (L. alpinum).

Learn more about club moss with a free trial on

or mayflower

Trailing evergreen plant (Epigaea repens) of the heath family, native to sandy or boggy, acidic woodlands of eastern North America. Its leaves are oblong and hairy, and its white, pink, or rosy flowers grow in dense clusters. It is grown in shady wildflower gardens and as ground cover in terraria.

Learn more about trailing arbutus with a free trial on

or blue ground

Dark, heavy, often fragmented igneous rock that may contain diamonds in the rock matrix. Kimberlite is a mica peridotite, an ultrabasic rock type with a complex and often highly altered mineral composition. It occurs in the Kimberley district of South Africa and the Kimberley and Lake Argyle regions of Australia, as well as near Ithaca, N.Y.

Learn more about kimberlite with a free trial on

Ground-attack aircraft are military aircraft designed to attack targets on the ground and are often deployed as close air support for, and in proximity to, their own ground forces. The proximity to friendly forces require precision strikes from these aircraft that are not possible with typical bomber aircraft. The resultant proximity to enemy targets also require aircraft that are more robust than other types of military aircraft. Examples include the US Fairchild A-10 Thunderbolt II and Soviet Sukhoi Su-25 Frogfoot.

Because they are typically deployed as close air support to ground forces, their role is tactical rather than strategic, operating at the front of the battle rather than against targets deeper in the enemy's rear. As such, they are often attached to and in the direct command and control structures of army units as opposed to air force units, though tactical air forces attached to army formations are still an organic part of the air force and ultimately under air-force command. A number of names have or are used for ground-attack aircraft: attack aircraft, fighter-bomber, tactical fighter, tank-buster, tactical bomber, strafer, strike aircraft etc. A light strike aircraft is another category, based on adapted trainers or other light aircraft.


Like most combat aircraft classifications, the definition of ground attack is somewhat vague. A key difference between it and otherwise similar designs like attack aircraft is the expectation that they will receive small arms fire and are generally armored to protect the pilot against this threat. In general a ground-attack aircraft will also be smaller and more "fighter like" than designs like strike fighters, attack aircraft or interdictors.

In US service ground-attack aircraft have been identified by the prefix A- as in "A-6". British designations have included FB for fighter-bomber and more recently "G" for Ground as in "Harrier GR1".

The NATO reporting names for Soviet/Russian ground attack aircraft classified them as "fighters" instead of "bombers" possibly, because they were often only variants of fighter aircraft, but always similar in size, range and weapons to fighters.


In the First World War Germany was the first country to produce dedicated ground attack aircraft such as the Junkers J.I. The Allies experimented with attack planes such as the Sopwith Salamander and the Boeing GA-1 but the war ended before they could used in combat.

Between the World Wars, as the United States embraced the role of global power with the United States Marine Corps as its preferred force for military intervention, marine aviation pioneered ground attack and close air support tactics in the Banana Wars. Marine Aviators pioneered the technique of dive bombing during interventions in Haiti and Nicaragua.

At the start of World War II engine power was scarce and aircraft had to be tailored to individual roles. Ground attack aircraft during this era were generally created for the role, one that was considered largely unimportant and therefore saw little development. Perhaps the only early-war aircraft in this niche was the Henschel Hs 123, a biplane. The Germans worked on a suitable replacement and eventually delivered the Henschel Hs 129, which featured a steel-armored cockpit and windows made of bulletproof glass. Only small numbers were built, however, as the Germans widely used the more flexible Junkers Ju 87 Stuka dive-bomber in the ground attack role. A more famous example is the Soviet Ilyushin Il-2 Shturmovik, a light bomber that was adapted into the ground attack role with it armoured fuselage, powerful artillery and possibility of using air-to-ground missiles. More than 43,000 Ilyushin Il-2 were built through World War II. Stalin credited the Il-2 with winning the war.

As engine power improved, roughly doubling over the course of the war, even the average day fighter was more than capable enough to carry out the ground attack role, and some of the most successful designs were slight modifications of existing designs. One of the most successful of these was the RAF's Hawker Typhoons, although they deployed a variety of other aircraft due to changing availability. The Germans made a series of adapted versions of the Focke-Wulf Fw 190, the F and G series, serving roughly the same purpose. The same was true of the USAAF, who moved former front-line fighters into the ground attack role during the war, notably the P-38 Lightning and P-47 Thunderbolt, as newer aircraft took up the air superiority role.

While machine guns and cannon were sufficient against infantry and light vehicles, and one or two small bombs could be easily fitted to most fighters, for operations against tanks heavier weapons such as the 40 mm Vickers S gun or high explosive rockets (such as the RP-3 60 lb rocket) were needed. The former equipped the Hawker Hurricane to good effect in North Africa Campaign, the latter was used by many RAF aircraft among them the Typhoon. Both the US and Soviets also used a variety of rockets in this role. The Germans also deployed rockets, as well as the first cluster bombs.

Post World War II

In the immediate post war era the piston engined ground attack aircraft remained useful - Royal Navy Hawker Sea Fury fighters and the US Vought F4U Corsair and Douglas A-1 Skyraider operated in the Korea with the latter plane effective into the Vietnam conflict. The long loiter times of the piston powered planes gave an advantage over thirsty jet planes.

In most of the post-World War II era air forces have been increasingly reluctant to develop combat aircraft specifically for ground attack. Although close air support and interdiction remain crucial to the modern battlefield, attack aircraft are less glamorous than fighters, and both pilots and military planners have a certain well-cultivated contempt for 'mud-movers.' More practically, the extra cost of a dedicated ground attack aircraft is harder to justify as opposed to having multi-role aircraft.

In the late 1960s the US Air Force requested a dedicated air support plane that became the Republic A-10 Thunderbolt II. It eventually became a primarily anti-armor weapon with limited capability in the interdiction and tactical bombing role, and even in the anti-tank role it was met with mixed feelings. However, the A-10's performance during Operation Desert Storm negated these criticisms. Current US doctrine increasingly emphasizes the use of US Army helicopters for close air support and anti-tank missions. The Soviets' similar Sukhoi Su-25 (Frogfoot) found greater success in the flying artillery role, although it, too, shifted to anti-armor use in later versions and has largely been phased out in favor of 'fast mover' fighter-bomber versions of the MiG-29 and Su-27.

Examples of modern ground attack aircraft include the A-10 Thunderbolt II, Sukhoi Su-7, Sukhoi Su-17, Sukhoi Su-25 (Frogfoot), Nanchang Q-5. Ground attack has otherwise become the domain of converted trainers like the BAC Strikemaster, BAE Hawk, and Cessna A-37.

Recent History

U.S. experience in the Gulf War, Kosovo, Afghanistan, and Iraq War has resulted in renewed interest in fixed-wing ground-attack aircraft.

Under the Key West Agreement which governs the allocation of aircraft between the U.S. Army and the U.S. Air Force, fixed-wing ground-attack aircraft were generally allocated to the Air Force, while attack helicopters were generally allocated to the Army. The Army, wishing to have its own resources to support its troops in combat and faced with a lack of Air Force enthusiasm for the ground-attack role, developed the AH-64 Apache attack helicopter for ground-attack roles such as destroying enemy tanks and supporting troops in combat.

One concern involving the Apache arose when a unit of these helicopters was very slow to deploy during U.S. military involvement in Kosovo. The Apache, which is the main alternative for the same airborne anti-tank role in the U.S. military as the A-10, ended up performing more poorly than anticipated, while the A-10 performed well in anti-tank roles in the Gulf War and in Iraq. Indeed, in the 2003 Invasion of Iraq, a unit of AH-64 Apaches was severely mauled by the Republican Guard division, Hammurabi.

According to the Army Times, the Army is shifting its doctrine to favor ground-attack aircraft over attack helicopters for this role because ground-attack helicopters have proved to be highly vulnerable to small-arms fire. The U.S. Marines have noted similar problems.

Officially, the U.S. Air Force planned to replace the only dedicated ground-attack aircraft currently in U.S. service, the A-10, with its new "Joint Strike Fighter", the F-35 Lightning II. But, facing political concerns that the new fighters were not designed for the ground-attack role that had proven particularly useful in Iraq and Afghanistan, a plan to decommission the A-10 has been replaced with a plan to upgrade the existing aircraft with improved electronics extending the service life of the planes until as late as 2028. The U.S. Air Force has not commissioned any new designs for this role (in part, out of concern for the F-35 program).

The UK is replacing its current ground attack aircraft with the F-35 (replacing the Harriers), and the Eurofighter Typhoon (Jaguars and Tornado GRs)

The other major complication to planes of military forces to purchase new ground-attack aircraft is uncertainty over the degree to which manned fixed wing aircraft may be replaced by unmanned combat drones in this role, a possibility illustrated by the armed Predator drone which has been used in this capacity.

See also




Search another word or see groundon Dictionary | Thesaurus |Spanish
Copyright © 2015, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature