The Saturn V-3,^[1] also known as the Saturn MLV 5-3,^[2][3] was a conceptual heavy-lift launch vehicle that would have utilized new engines and new stages that were never used on the original Saturn V. The Saturn V-3 was studied by the NASA Marshall Space Flight Center in 1965.^[2]

Saturn MLV 5-3

Function	orbital launch vehicle
Country of origin	United States
Size
Height	121 m (397 ft)
Diameter	10 m (33 ft)
Mass	3,664,570 kg (8,078,990 lb)
Stages	3
Capacity
Payload to LEO
Mass	160,400 kg (353,600 lb)
Launch history
Status	Proposal
First stage – MS-IC-1
Powered by	5 F-1A
Maximum thrust	45.95 MN (10,330,000 lbf)
Burn time	158 seconds
Propellant	RP-1 / LOX
Second stage – MS-II-2
Powered by	5 HG-3
Maximum thrust	7 MN (1,600,000 lbf)
Burn time	324 seconds
Propellant	LH2 / LOX
Third stage – MS-IVB-2
Powered by	1 HG-3
Maximum thrust	1.4 MN (310,000 lbf)
Burn time	489 seconds
Propellant	LH2 / LOX
[edit on Wikidata]

The first stage, called MS-IC-1, was to have used new F-1 engines designated F-1A which utilized a pump-fed design, an anticipated 20% additional thrust, and a six-second improvement in specific impulse on an F-1, with the first stage stretched 20 feet.^[2]

The second and third stages, MS-II-2 and MS-IVB-2, were proposed to use new HG-3 engines in place of the J-2 engines,^[2] but were never used, although the HG-3 led to the development of the Space Shuttle Main Engine.^{[citation needed]}

The V-3 booster was one of six Saturn MLV designs that never flew, but if these vehicles had been manufactured, they could possibly have been used for the Apollo Applications Program, Manned Orbiting Research Laboratory, Mars fly-by and Mars landing missions in the 1970s and 1980s.^[3]