The Saturn INT-20 was a proposed intermediate-payload follow-on from the ApolloSaturn V launch vehicle. A conical-form interstage would be fitted on top of the S-IC stage to support the S-IVB stage, so it could be considered either a retrofitted Saturn IB with a more powerful first stage, or a stubby, cut-down Saturn V without the S-II second stage.[1]
Three variants were studied, one with three F-1 engines in the first stage, one with four, and one with five.[2]
Performanceedit
Without the S-II stage, which made up a large fraction of the mass of the Saturn V, a version of the INT-20 using an unmodified five-engine version of the S-IC booster would be greatly overpowered and accelerate substantially faster than the Saturn V. This would create excessive aerodynamic stress in the low atmosphere. Several solutions to this problem were considered.
Using the original five-engine S-IC would require three engines to be shut down 88 seconds after launch, with the remainder of the first-stage flight flown on only two engines. This meant that a considerable amount of the firing time would be carrying three engines of "dead weight". As a consequence the extra payload over a four-engine variant would only have been about one thousand pounds, and the extra cost and complexity of the fifth engine was unjustified.
A four-engine variant would launch with four engines firing and shut down two engines 146 seconds after launch. The remaining two engines would burn until first-stage shutdown 212 seconds after launch. This variant could put approximately 132,000 pounds (60,000 kg) into a 100 nautical mile (185 km or 115 statute mile) orbit, versus around 250,000 pounds (110,000 kg) for the three-stage Saturn V.[3]
The three-engine variant would burn all three engines up to first-stage shutdown at 146 seconds after launch. This variant could put approximately 78,000 pounds (35,000 kg) of payload into a 100 nautical mile (185 km) orbit, around 2.5 times the useful payload of the Saturn IB.[3]
Both three- and four-engine variants would therefore have provided useful payload capacities (Saturn C-3) intermediate between the Saturn IB and Saturn V, and re-using Saturn V components would reduce costs and simplify ground operations compared to building an entirely new launcher in that payload range.
^ ab(PDF). Boeing Space Division. October 7, 1966. Archived from the original (PDF) on June 14, 2006.
January 01, 1970
saturn, proposed, intermediate, payload, follow, from, apollo, saturn, launch, vehicle, conical, form, interstage, would, fitted, stage, support, stage, could, considered, either, retrofitted, saturn, with, more, powerful, first, stage, stubby, down, saturn, w. The Saturn INT 20 was a proposed intermediate payload follow on from the Apollo Saturn V launch vehicle A conical form interstage would be fitted on top of the S IC stage to support the S IVB stage so it could be considered either a retrofitted Saturn IB with a more powerful first stage or a stubby cut down Saturn V without the S II second stage 1 Saturn INT 20FunctionManned LEO launch vehicleManufacturerBoeing S IC Douglas S IVB Country of originUnited StatesSizeHeight85 m 279 ft Diameter10 m 33 ft Mass2 304 000 kg 5 079 000 lb Stages2CapacityPayload to LEOMass60 500 kg 133 400 lb Launch historyStatusProposalLaunch sitesLC 39 Kennedy Space CenterFirst stage S ICEngines3 5 Rocketdyne F 1Thrust34 02 MN 7 650 000 lbf Burn time212 secondsPropellantRP 1 LOXSecond stage S IVBEngines1 Rocketdyne J 2Thrust1 MN 220 000 lbf Burn time 475 secondsPropellantLH2 LOX edit on Wikidata Three variants were studied one with three F 1 engines in the first stage one with four and one with five 2 Performance editWithout the S II stage which made up a large fraction of the mass of the Saturn V a version of the INT 20 using an unmodified five engine version of the S IC booster would be greatly overpowered and accelerate substantially faster than the Saturn V This would create excessive aerodynamic stress in the low atmosphere Several solutions to this problem were considered Using the original five engine S IC would require three engines to be shut down 88 seconds after launch with the remainder of the first stage flight flown on only two engines This meant that a considerable amount of the firing time would be carrying three engines of dead weight As a consequence the extra payload over a four engine variant would only have been about one thousand pounds and the extra cost and complexity of the fifth engine was unjustified A four engine variant would launch with four engines firing and shut down two engines 146 seconds after launch The remaining two engines would burn until first stage shutdown 212 seconds after launch This variant could put approximately 132 000 pounds 60 000 kg into a 100 nautical mile 185 km or 115 statute mile orbit versus around 250 000 pounds 110 000 kg for the three stage Saturn V 3 The three engine variant would burn all three engines up to first stage shutdown at 146 seconds after launch This variant could put approximately 78 000 pounds 35 000 kg of payload into a 100 nautical mile 185 km orbit around 2 5 times the useful payload of the Saturn IB 3 Both three and four engine variants would therefore have provided useful payload capacities Saturn C 3 intermediate between the Saturn IB and Saturn V and re using Saturn V components would reduce costs and simplify ground operations compared to building an entirely new launcher in that payload range See also editApollo program Saturn I Saturn IB Saturn V Apollo Applications Program S IC S IIReferences edit Final Report Studies of Improved Saturn V Vehicles and Intermediate Payload Vehicles P 115 PDF Boeing Space Division October 1966 Archived from the original PDF on 2006 06 14 Saturn INT 20 www astronautix com Retrieved 2024 01 18 a b Final Report Studies of Improved Saturn V Vehicles and Intermediate Payload Vehicles PDF Boeing Space Division October 7 1966 Archived from the original PDF on June 14 2006 Retrieved from https en wikipedia org w index php title Saturn INT 20 amp oldid 1218023023, wikipedia, wiki, book, books, library,
