Also in the United Kingdom the Bloodhound SSC team have The Falcon Project led by Daniel Jubb deploying a fully developed hybrid rocket using HTP and HTPB.
The solid rocket propellant used to fuel the Space Shuttle solid rocket booster employs a non-energetic plasticizer/binder/secondary fuel: HTPB.
The first stage is one of the largest solid-fuel rocket boosters in the world and carries 138 tonnes of Hydroxyl-terminated polybutadiene (HTPB) bound propellant with a diameter of 2.8 m.