Dolphin

American sea-launched test vehicle. The Dolphin hybrid rocket (solid fuel and liquid oxygen oxidizer) was built by Starstruck (formerly ARC Technology), a predecessor to AMROC. The Dolphin included not only innovative propulsion technology but was also launched from a floating launch canister at sea. One test article of the hybrid was successfully launched in the summer of 1984. But the project was backed entirely with private funds and when backing for further development was not forthcoming, the project folded.

The Dolphin featured a hybrid motor using liquid oxygen oxidizer. A sea launch arrangement was used for lift-off - the booster floated in the ocean separately from the launch support ship. The Dolphin was designed to be a commercial sounding rocket and a stepping-stone to a much larger booster for commercial orbital launches called the Constellation. Constellation was to have been a 4-stage vehicle that could deliver a payload of 1450 kg to a geosynchronous transfer orbit.

The hybrid rocket engine for the Dolphin was developed and tested under the leadership of Douglas Ordahl in Carson City, Nevada. Ordahl had previously been head of hybrid propulsion at United Technologies' Chemical System Division.

Water launch was selected to reduce cost by eliminating the need for a launch pad, increase payload to low inclination orbits by allowing the tender ship to deposit the rocket for launch near the equator, and to avoid strict government regulation of land-based launch sites. In order to launch the rocket, the Dolphin was first loaded with liquid oxygen, then moved off the boat and floated horizontally in the ocean. A counterweight, attached to the aft end of rocket, was then dropped into the water and this pulled the rocket vertical. The nitrogen tanks were pressurized in the water and the vehicle was ready for launch.