Saturn V-4X(U)

American orbital launch vehicle. Boeing study, 1968. Four core vehicles from Saturn V-25(S) study lashed together to obtain million-pound payload using existing hardware. First stage consisted of 4 Saturn IC's stretched 498 inches with 6.64 million pounds propellant and 5 F-1 engines; second stage 4 Saturn II standard length stages with 5 J-2 engines
Status: Study 1968. Payload: 527,600 kg (1,163,100 lb). Thrust: 160,135.00 kN (35,999,780 lbf). Gross mass: 15,504,720 kg (34,182,050 lb). Height: 95.00 m (311.00 ft). Diameter: 10.06 m (33.00 ft). Apogee: 486 km (301 mi).

LEO Payload: 527,600 kg (1,163,100 lb) to a 486 km orbit at 28.00 degrees.

Stage Data - Saturn V-4X(U)

Stage 1. 4 x Saturn MS-IC-25(S). Gross Mass: 3,223,800 kg (7,107,200 lb). Empty Mass: 211,900 kg (467,100 lb). Thrust (vac): 45,925.500 kN (10,324,463 lbf). Isp: 304 sec. Burn time: 192 sec. Isp(sl): 265 sec. Diameter: 10.06 m (33.00 ft). Span: 19.00 m (62.00 ft). Length: 54.70 m (179.40 ft). Propellants: Lox/Kerosene. No Engines: 5. Engine: F-1A. Status: Study Boeing 1967. Comments: S-IC with 41.5 foot stretch, 6,640,0000 lbs propellant, uprated F-1 engines.
Stage 2. 4 x Saturn MS-II-4(S)B. Gross Mass: 494,100 kg (1,089,300 lb). Empty Mass: 42,300 kg (93,200 lb). Thrust (vac): 5,169.000 kN (1,162,037 lbf). Isp: 421 sec. Burn time: 355 sec. Isp(sl): 200 sec. Diameter: 10.06 m (33.00 ft). Span: 10.06 m (33.00 ft). Length: 24.84 m (81.49 ft). Propellants: Lox/LH2. No Engines: 5. Engine: J-2. Status: Study Boeing 1967. Comments: Standard S-II but with structural strength increased from 86% to 502% depending on station, resulting in 8.6% increase in empty weight.
Stage 3. 1 x Saturn MS-II-4(S)B. Gross Mass: 494,100 kg (1,089,300 lb). Empty Mass: 42,300 kg (93,200 lb). Thrust (vac): 5,169.000 kN (1,162,037 lbf). Isp: 421 sec. Burn time: 355 sec. Isp(sl): 200 sec. Diameter: 10.06 m (33.00 ft). Span: 10.06 m (33.00 ft). Length: 24.84 m (81.49 ft). Propellants: Lox/LH2. No Engines: 5. Engine: J-2. Status: Study Boeing 1967. Comments: Standard S-II but with structural strength increased from 86% to 502% depending on station, resulting in 8.6% increase in empty weight.

From : astronautix