The Smaller, Faster, Cheaper thread had revived an idea I have had for a long time for a rationalisation of US ballistic missile development from the late 1940s to the early 1960s. That is:
one IRBM instead of Jupiter and Thor
and
one ICBM instead of Atlas, Titan I and Titan II
That should save money by reducing the R&D and production costs.
At first glance Delta should be the IRBM because it was used as a space launcher after it was retired as missile. However:
-AFAIK Jupiter was the better missile because it was mobile.
-Did Jupiter have any features that would have made it a better satellite launcher than Thor? I haven't checked but as far as I can remember the dozen or so Jupiter missiles that were used as satellite launchers under the name Juno II weren't very reliable, even by the standards of the day.
-AFAIK Saturn I was an development of the Jupiter (and was originally called Juno V) so there might be some possibilities for economies of scale in R&D and production in a family of Jupiter based space launchers.
For the ICBM the most obvious candidate is Atlas as it came first. IOTL the redundant Titan I missiles weren't reused as satellite launchers so the USAF has 54 extra Atlas missiles plus their backing rounds to be used as satellite launches.
On the other hand Titan II had a much longer service life. That might mean that the USAF would want a larger force of Minutemen or a Super Minuteman to complement it.
Furthermore no Titan II means no launcher for Gemini an nothing to develop Titan III from. That could be a good thing as it means the USAF would have to use Saturn I by default.
Could Titan II have been started early enough for a force of 240 to be deployed in place of the 132 Atlas, 54 Titan I and 54 Titan II of OTL?. Because:
-It would have been a better investment for the USAF and American taxpayer because they would have longer service lives as ICBMS;
-It might give America a more powerful launcher than Atlas in the early years of the space programme. Though it might also mean no Agena or Centaur as there was no Atlas to develop an upper stage for and the basic Titan II might satisfy current requirements.
So should it be?
Thor and Atlas. Or:
Jupiter and Atlas. Or:
Thor and Titan. Or:
Jupiter and Titan.