NASA Study Summary- "Modified Saturn Launch Vehicles for AAP Earth Orbit Missions"

[luke strawwalker]

Here's another Bellcomm study relating to SRB and SRM first stage Saturn IB's and the INT 20 and 21 versions of Saturn V. Some good graphics and charts in there, and lots of costing data (which I didn't bother summarizing since it's all in 1966 dollars)

At any rate, it shows the 'front runners' that led the pack among the myriad Saturn Ib and Saturn V variants that were being floated at the time...

Later! OL JR

[luke strawwalker]

Pic one is a graphic showing the various Saturn IB versions with different SRB's attached. The first rocket on the left uses 4 120" Titan IIIC SRBs, the second uses the same Titan IIIC SRBs with a dummy segment installed in each so it will reach the top spider beam on the 20 foot longer S-IB first stage (tank stretched). Third rocket is the same 20 foot stretched S-IB as before, but using the 7 segment SRBs used on Titan IV, the fourth rocket uses a pair of the same 7 segment Titan IV SRBs instead of four, on the same tank-stretched Saturn IB first stage, the last one on the right uses four Minuteman ICBM SRM first stage motors as add-on boosters... I sent it over to paint and added tags to the pic to make it easier to keep the variants and their differences straight...


Pic two is a performance chart for the previously shown variants.


Pic three is a weight summary of all the different Saturn IB/SRB upgrade possibilities, since the weights would have major impacts on the launch infrastructure and therefore on costs.


Pic four is a comparison of the proposals for replacing the S-IB first stage with either a monolithic or cluster of segmented SRMs. I sent this one over to paint and added tags to assist in telling the differences in the performance and mods to the various versions as well.


Pic five is a chart showing the performance of the three top contenders from the studies.


More to come! OL JR

[luke strawwalker]

Pic one is the Saturn V INT 20 and 21 vehicles-- INT 20 lost it's S-II stage, putting the S-IVB directly atop the S-IC which dropped a center F-1 engine, as mentioned in a previous study summary. The INT 21 version was basically what launched Skylab, with only the S-IC and S-II stages operational with the payload on top. I sent this one over to paint as well and added the tags listing the performance to help keep things straight...


The second pic is a performance chart to various orbits and inclinations... rockets launching out of KSC are flying into a 28.5 degree orbital inclination, since that's how far north KSC is from the equator. The further north from the equator the launch site is, the lower the 'assist' from earth's rotation, which is fastest at the equator. So the further north or south you go, the less payload capability the rocket can deliver for the given amount of fuel and ISP it has. Rockets going into polar orbit get essentially zero 'free ride' since they're launching north-south instead of east-west, and have the "lowest" performance. Highly inclined orbits like ISS (51.6 degrees) also inflict a payload hit on the rockets launching into that inclination, even from more southerly launching points, due to the need to fly north instead of due east and therefore sacrificing some of the 'free speed' from earth's rotation. BUT, it DOES make it possible for other nations with launch sites further north than ours (Russia chief among them) to be able to access the ISS from their launch sites without a very costly (in terms of fuel and therefore payload capability) orbital inclination change to match orbits and dock with the ISS. It also means, though, that launchers flying from those northerly launch sites would have less payload capability than if they were launched from sites further south closer to the equator.


Interesting that they were looking at all the different inclinations for space station missions even back then... they even proposed a very similar inclination to the ISS orbit (49.5 degrees IIRC instead of ISSs 51.6 degrees) to overfly the entire US except Alaska. More on space stations later...

Enjoy! OL JR