Reusable Falcon 9 Second Stage

SpaceX and Elon Musk have multiple times expressed interest in developing a **reusable second stage for the Falcon 9** (**RF9SS**), however no test articles or detailed plans have been released and it seems likely they have abandoned the endeavor to spend time and resources on Starship development, which will make the entire Falcon 9 outdated upon operation, reusable or not. There have been several basic designs, neither of which was specifically design or endorsed by SpaceX but by fans (as far as I know), correct me if I'm wrong (click "EDIT" in the upper right-hand corner).

## Designs

### Dragon-inspired Second Stage Vehicle

This one completely redesigns the second stage to use a cluster of SuperDraco engines and ablative heat shield similar to the dragon spacecraft. This version would also have incorporated fairings. It has no landing legs to save weight and instead would make "a precision landing on a special platform that can safely catch the vehicle" (Original design concept source below). This is very similar to the Mechazilla Starship-catching tower in Starbase, TX in construction by SpaceX. This version of an RF9SS would require immense infrastructure changes to support the new shape of the engines, fairings and stage in general. Since SpaceX plans to replace the Falcon 9 with Starship, which is slated for its first operational flights in the mid-2020s, it is unlikely SpaceX would go to such trouble for something that be used only a few years. It was designed by Anej Kostrevc who first posted it on his blog here, where is gained attention. The link is also in the sources.

It was created in the game SimpleRockets 2 by user VILLTAREYA. The craft file and original images can be found here and at the bottom of the page under Sources.

### Simple Reusable Second Stage

This design coats the second stage as is with an ablative heat shield and adds landing legs and a smaller bell/engine. This is the most feasible design as it would be much easier to integrate into the current Falcon 9 system as the payload fairings would not be needed to change, and minimal changes to the second stage. The other proposals while impressive would require massive changes to the second stage and in ground infrastructure. Perhaps this design will be used on another rocket in the future.

### Fairing Rider Second Stage

This version would use fairings to shield the second stage during reentry. This is (in my opinion) the most kerbal of these designs. From the image to the left, it seems that this proposal would use arms on the second stage to open the fairings to release the payload while still keeping them attached. It would then rotate the fairings to protect the stage during reentry and hold it in place. Iy also deploys parachutes during reentry to maintain stability and increase drag (in the game, this works, but in real life no explanation for how this would be done) after which it would use parachutes to recover. It was created by Anubis space on YouTube.

## Gallery

The second reusable Falcon 9 second stage design landing.The SimpleRockets 2 design during stage separation.
## Sources

* Seradata.com: Speculation on ZUMA launch (Simple Design)
* Anej Kostrevc's Blog: Original Dragon-inspired design concept
* SimpleRockets 2: User creates rendition of Dragon-inspired design
* YouTube (Anubis space): User creates a "fairing rider" RF9SS in SimpleRockets2