The AH-64 is powered by two General Electric T700 turboshaft engines with high-mounted exhausts on either side of the rotor shaft. The Apache has a four-blade main rotor and four-blade tail rotor. The crew sits in tandem, with the pilot sitting behind and above the copilot-gunner in an armored crew compartment. The crew compartment and fuel tanks are armored against 23 mm gunfire. The main rotor blade is designed to remain intact after sustaining hits by 23 mm rounds.
The Apache was first used in combat during the 1989 invasion of Panama, Operation Just Cause. The AH-64A Apache and the AH-64D Apache Longbow have played important roles in several Middle Eastern wars, including the Gulf War, Operation Enduring Freedom in Afghanistan, and Operation Iraqi Freedom in Iraq. The Apaches were proven to be excellent tank hunters and also destroyed hundreds of armored vehicles (mainly of the Iraqi army).
The advanced model, the AH-64D Apache Longbow, is equipped with an improved sensor suite and weapon systems. The key improvement over the A-variant is the AN/APG-78 Longbow dome installed over the main rotor which houses a millimeter-wave Fire Control Radar (FCR) target acquisition system as well as the Radar Frequency Interferometer (RFI). The elevated position of the radome allows detection and (arcing) missile engagement of targets even when the helicopter itself is concealed by an obstacle (e.g. terrain, trees or buildings). Further, a radio modem integrated with the sensor suite allows a D-variant Apache to share targeting data with other AH-64Ds that do not have a line-of-sight to the target. In this manner a group of Apaches can engage multiple targets but only reveal the radome of one D-variant Apache. Apaches that include all of the improvements of the Longbow Apache, with the exception of the Fire Control Radar are still designated as “AH-64D Apache Longbows”, as the radome is removable and interchangeable between aircraft.
The aircraft was updated with more powerful T700-GE-701C engines, and a fully-integrated cockpit. The forward fuselage of the aircraft was expanded to accommodate new systems. In addition, the aircraft receives improved survivability, communications, and navigation capabilities. Block III improvements, slated for 2008 onwards, include increasing digitization, the joint tactical radio system, enhanced engines and drive systems, capability to control UAVs, new composite rotor blade and landing gear upgrades. The new blades, which successfully completed flight testing in May 2004, increase the Apache’s cruise speed, climb rate and payload capability. The Block III System Development and Demonstration (SDD) contract was awarded to Boeing in July 2006.