Shuttle-Derived Heavy Lift Launch Vehicle

The Shuttle-Derived Heavy Lift Launch Vehicle, also known as the High Confidence Heavy Lift Launch Vehicle (or even variations of the "Side Mount Launch Vehicle" or "HLV" or "Not Shuttle-C") was an alternate Super heavy-lift launch vehicle proposal for the NASA Constellation program. It was first presented on June 17, 2009 by John Shannon, NASA's Shuttle Program manager, to the Augustine Commission which is tasked to review NASA's human spaceflight program.

It was based on the Shuttle-C concept which has been the subject of various studies since the 1980s. Derived from then currently used Space Shuttle hardware, i.e. an Shuttle-Derived Launch Vehicle (SDLV), it was proposed to replace the winged Orbiter from the Space Shuttle stack with a simple non-winged side-mounted payload carrier. The designs of the Space Shuttle's External Tank (ET) and the four-segment Shuttle Solid Rocket Boosters (SRBs) would have been reused.

According to NASA's John Shannon the HLV could have be developed within 4 ¹⁄₂ years until the first manned flight occurs. The development program should have costed about US$6.6 billion, which was only about 20% of the costs estimated for the Ares I and Ares V vehicle development.

Following President Obama 2010 space policy speech at Kennedy Space Center and the NASA Authorization Act of 2010 another HLV program, the Space Launch System, which is also Shuttle-derived, has been selected to replace the Constellation launch vehicles, with the development commencing thereafter.

An unmanned side-mounted concept of the Space Shuttle named Shuttle-C was the subject of various concepts that were investigated between 1984 and 1995. After the Space Shuttle Columbia accident a two-year industry study was prepared in 2004 and 2005 to further investigate the concept in order to replace the Space Shuttle. The Exploration Systems Architecture Study (ESAS) in 2005 also investigated a Shuttle-C option for Project Constellation, however again only in an unmanned version. All these concepts included the side-mounted carrier to be an autonomous spacecraft which would detach from the External Tank after main engine cut-off similarly to the Space Shuttle. Some of the studies included the reuseability of the Space Shuttle Main Engines on this side-mounted carrier. None of the concepts involved in-ascent fairing separation.

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