C - 5 Galaxy The C - 5 Galaxy is a plane freighter produced by the company US . Lockheed Martin and used by U . S . Air Force ( USAF ) . In size the Lockheed C - 5 Galaxy only not exceeds the An - 124 Ruslan and the An - 225 Myria . The development began in the early Galaxy 1960 to meet the requirement CX - 4 ( after CX - HLS ) USAF . Origin . Starting in 1960 , with the appearance of reactors more powerful , it became possible to create a military transport plane to giant size . The aim was to Lockheed transport in the hold a weight of 115 tonnes over 6000 km , or 65 tonnes over 12000 km and can use a runway 1200 meters . The first C - 5A flew in 1968 , followed by 76 versions . The Galaxy were used in South Vietnam for delivery of military equipment . To this end , the front end raised and lowered to the landing gear to reduce the slope of the ramp , which also could make the rear . To distribute the weight on land , the plane was equipped with twenty - eight wheels . But however the C - 5 Galaxy were the focus of economic and political polemics , having exceeded the original budget . Until the appearance of An - 124 , C - 5 was the largest cargo aircraft in the world . It will be modernized until 2040 with the USAF . Design . The plane left the factory at Lockheed in early 1968 had some similarities with the C - 141 : The four Engines were under the wings , the tail was in T the back fuselage was raised , adding that cargo doors could be opened during flight . However , the front section of the fuselage is quite different from C - 141 , especially with respect to flight deck located on the front of the cargo hold . That provision , unusual at the time , allowed the installation of a front that opens up , allowing loading or unloading volumes from both ends of the aircraft simultaneously . Just behind the cabin of the pilots there is a small cabin to fifteen passengers , a second , larger , was installed on the upper fuselage and rear wings , accommodating up to 75 passengers . Operational history . Tests of the new plane had relatively good results . The costs , estimated at the beginning of 20 million U . S . dollars per unit came to $ 60 million , bringing the USAF to reduce its order from 115 to 81 devices , which began to enter service in May 1969 . By 1971 , the C - 5 was already hard at work and there was no doubt that his arrival had increased significantly the ability of MAC transporting any type of cargo around the world quickly and efficiently . At that time , the United States was completely drowned in Vietnam War and urgently needed the services of an aircraft like the C - 5 . However , it was only in August that year that the C - 5A made his debut in the conflict . Once in the war zone , the Galaxy took the growing demands of replenishment , carrying large amounts of cargo at once . By then , however , the question of fatigue the material of wings came up with attempts to strengthen the main box of the wings just minimizing flight restrictions imposed since the C - 5 entered service . In 1977 , the USAF decided to solve the problem . Work began in 1978 with Lockheed designing and manufacturing new sets of wings , using the maximum of common parts . The use of a league of aluminum more resistant reinforced wing structure and gave it a high degree of resistance corrosion . After 178 million dollars , 77 of the original C - 5 had been elevated to the standard C - 5B and followed up for 50 new C - 5B . In December 1984 the Galaxy justified his costly retirement , setting a new record for the carriage of payload and national records of gross weight takeoff and landing , showing finally be able to establish itself as a safe device and very efficient transport heavy load . References . N1 Dial Thrust Director for the Re - Engined C - 5 Galaxy Cargo Aircraft , IEEE Paper , Digital Avionics Systems Conference , 2007 .