Delta IV is comprises of RS-68 engine which is designed and manufactured by Pratt & Whitney Rocketdyne. The throttleable RS-68 engine is the largest existing hydrogen-burning engine.
Delta IV vehicles can launch payloads weighing from 4,300 kg (9,480 lb) to 12,980 kg (28,620 lb) to GTO, and can lift over 23,000 kg (50,000 lbs.) to LEO.
