Delta Cryogenic Second Stage


The Delta Cryogenic Second Stage is a family of cryogenic rocket stages used on the Delta III and Delta IV rockets, and which is planned to be used on the Space Launch System Block 1. The stage consists of a cylindrical LH2 tank structurally separated from an oblate spheroid LOX tank. The LH2 tank cylinder carries payload launch loads, while the LOX tank and engine are suspended below within the rocket's inter-stage. The stage is powered by a single Pratt & Whitney RL10B-2 engine, which features an extendable carbon-carbon nozzle to improve specific impulse.

Delta III

The DCSS first flew on 3 Delta IIIs, and failed 2 of 2 times. The booster failed on the third flight, causing the loss of the DCSS before ignitions. An un-flown example is on display outside the Discovery Cube Orange County.

Delta IV

Two different versions are flown, depending on variant. Composite interstages used to mate the first and second stages together accommodate the different configurations.
For the Delta IV-M, a tapering interstage narrows down in diameter from 5-meters to 4-meters is used on the 4-meter DCSS, while a cylindrical interstage is used on the 5-meter DCSS.

Cryogenic Propulsion Stage (ICPS)">Interim Cryogenic Propulsion Stage

The Interim Cryogenic Propulsion Stage, a minimally modified 5–meter DCSS, is expected to fly as the upper stage of the Space Launch System Block 1.