Manufacturer Name: Senior. Other Designations: Aerojet Sr. Designer: Aerojet. Used on stages: Algol 1. Used on launch vehicles: Blue Scout 1, Blue Scout 2, Scout X-1, Scout X-2. Gross Mass: 10,705 kg. Empty Mass: 1,900 kg. Propellants: Solid Thrust(vac): 48,022 kgf. Thrust(vac): 470.90 kN. Isp: 236 sec. Isp (sea level): 214 sec. Burn time: 40 sec. Diameter: 1.0 m. Length: 9.1 m. Chambers: 1. Country: USA. Status: Out of Production. First Flight: 1960. Last Flight: 1963. Flown: 21. This rocket started as a Polaris test motor with a 40 inch diameter, which at the time was the largest solid motor ever tested. It had a nominal performance rating of 45 seconds duration and 45,000 kgf thrust. Variations included Algol I, I-D, II, II-A, II-B and possibly others. Another popular rating was 40KS-115,000 (52,000 kgf for 40 seconds), also known as Senior.