Shop Mobile More Submit  Join Login
Convair Nexus SSTO by William-Black Convair Nexus SSTO by William-Black
Become my patron on Patreon

In 1962 the NASA Future Projects Office called for a post-Saturn launch vehicle for the 1975-2000 time frame. One concept put forward by Convair was the one million pound payload, reusable NEXUS SSTO.

At the time NASA's forward looking plans for the 1970’s and 1980’s called for lunar bases with permanent crews of 100 or more and an ambitious plan for manned exploration of the solar system. This vision helped drive the economics and scale of NEXUS—without a large number of launches its cost would be unsustainable. Large manned interplanetary spacecraft need large liquid hydrogen tanks, nuclear engines were also foreseen … not just solid-core nuclear thermal engines like NERVA, but gas-core nuclear rocket engines and nuclear-pulse engines. These are massive systems and require massive boosters.

The baseline NEXUS could lift 1 million lbs to LEO, or low Earth orbit, this could be extended to 2 million lbs. The booster was a flexible design and could be configured for different payload sizes and weights.

The baseline NEXUS was powered by a system known as a plug cluster engine, which consists of a number of high pressure liquid hydrogen liquid oxygen rocket engines arranged around a centerbody, or plug.  In the diagram, the image top right shows the base of the NEXUS booster and the plug cluster rocket engine.

Plug cluster engines belong to a class of altitude compensating nozzles much like the aerospike. The NEXUS booster design was flexible, the number and type of engines could be varied to fit different payload lofting needs, regardless of number of individual rocket engines the entire engine configuration is referred to as a plug cluster engine.

Beside the plug cluster system there were a number of different engine arrangements for the NEXUS including a single 54-foot diameter, ablative nozzle, 24 million pound thrust Rocketdyne L-24 AH engine, which is, as far as I am aware, the largest single chemical rocket engine ever designed.

For control during ascent four clusters of control rockets were to be employed. Each cluster contained six hydrogen/oxygen rockets. Throttling the engines up and down provided pitch and yaw control due to the long distance from the vehicle centerline.

After deploying its payload NEXUS would reenter Earth’s atmosphere nose-first, relying on the large blunt shape of the booster's forward face for drag to slow the vehicle during descent. Since the booster is base-heavy and would tend to tumble end-for-end, 4 flaps, arranged around the flanks of the booster and hinged at the top, would fold out from the sides, these would stabilize the vehicle aerodynamically. The free-falling vehicle had characteristics akin to a badminton shuttlecock as it plummeted toward the ocean.

Landing rockets (not shown here) mounted in the vehicles nose would fire to apply terminal braking immediately before splash-down. The solid rockets reduced velocity by 200 feet per second via a brief burst of 9,000,000 pounds of thrust, completely canceling free-fall velocity just above the surface of the water. The vehicle would float upside down on the ocean’s surface, probably stabilized by an inflatable air-bag flotation system, until recovery, thus keeping the engines safely out of the corrosive salt-water.

The curved top of the booster is an ablative material which would take the brunt of re entry heat. Below this lay a thick Styrofoam crushable-structure designed to absorb the force of ocean impact and protect the booster’s internal structure and large propellant tanks. Thermal protection and crushable-structure would be replaced between every launch. 

This artwork is available for sale. Full Resolution Digital Print: $10.00
Orders can be placed at

I also do custom artwork. Click on my name above or on the right-hand sidebar to go to my profile page for details.

Convair Nexus Reference Links, courtesy of Scott Lowether’s Unwanted Blog:

Convair Nexus SSTO
Convair Nexus 1million Lb Payload/2 million Lb Payload Comparison
Nexus + Gas Core Nuclear Second Stage
Nexus Gas Core Nuclear SSTO

Related Images

Nexus Booster Comparison
Uprated Nexus + Gas Core Nuclear Second Stage

Convair's two million pound reusable SSTO is the basis for the Martian Nexus designed for my Orion's Arm future history setting, which differs only in the significant detail that it makes a powered tail-landing, image here: First Flight.


Scott Lowther of Aerospace Projects Review put in the hours to dig up the information on Nexus, and the data in this post is credited to his hard work. What I've included here is just the barest essential detail, for the full story on Nexus, along with diagrams and facts covering area's of the program not available elsewhere, I highly recommend  Scott Lowther's complete article on Nexus, available here V3N1 of Aerospace Projects Review.

Photo credit: Atlas scale reference image courtesy of NASA via library, NASA History.
Add a Comment:
LordOmegaZ Featured By Owner Oct 9, 2015  Hobbyist Digital Artist
super nexus o_o...;


wait so it could go to the moon then BACK?!
Add a Comment:


Submitted on
February 23, 2014
Image Size
2.3 MB


9,721 (9 today)
74 (who?)