Gamma Centaur aka Centaur Junior

[Michel Van]

Found on SDASM archive on Flickr Album

Convair had Study in 1960 a Three Stage Atlas Centaur with smaller Centaur as Third Stage

 

[blackstar]

I'm no rocket engineer, but I can imagine that the performance on this vehicle was not that great. You get your best bang for the buck from your high energy upper stage, so it doesn't make much sense to give it a small propellant tank and burn it only a short duration.

 

[Michel Van]

I'm no rocket engineer, but I can imagine that the performance on this vehicle was not that great. You get your best bang for the buck from your high energy upper stage, so it doesn't make much sense to give it a small propellant tank and burn it only a short duration.

That's main reason this was never build,
i believe this is idea for Small Deep Space probes on high energy trajectories like into inner Solar system or outwards to Jupiter.
With payload of 200 kg, Like Mariner 1 to 3 they fit under Payload shroud depicted on illustration.

 

[Michel Van]

have additional Information from http://forum.nasaspaceflight.com
thx to Blackstar and Ed Kyle

Centaur Jr was proposal for singel engine Version launch of Atlas F/Centaur
This F version is not the Atlas "F" but a 1960 proposed Stretch Atlas with Engines from Saturn IB and lift of mass of 169 tons
https://forum.nasaspaceflight.com/index.php?topic=26915.msg1431549#msg1431549

although this Gamma version let to some confusion special it use of Vega Hardware and standard Atlas D instead the 1960 F proposal.

more here
http://forum.nasaspaceflight.com/index.php?topic=42255.0

 

[blackstar]

Also, what you are basically looking at is an Atlas, with a Centaur second stage, and then that Gamma Centaur at the top. So think of it as Centaur and Smaller Centaur.

Also, according to Ed Kyle, the company pitched that proposal a number of times during the 1960s, to no avail.