Manned version of Dragon spacecraft successfully finished propulsion tests

NASA announced that crewed Dragon spacecraft ended tests of propulsion with positive results.

SpaceX Dragon is still developing into manned version. Being part of NASA's Commercial Crew Development (CCDev) along with Boeing CST-100 reached next milestone. Designed as automatic spacecraft, combined with Falcon-9 rocket, is designated mainly as vehicle for lifting men to ISS. Propulsion of Dragon is designed as part of rescue system during aborting mission, even after rocket is launched. Engines should give Dragon enough speed to fly away from rocket and save crew members. To provide such capability engines should be powerful, reliable and able to give full thrust in short time. Tests taken place in SpaceX facility in McGregor, Texas.

Engines utilized in Dragon are named by SpaceX "SuperDraco", are combined in four pairs around spacecraft. They are able to provide around 533 kN of thrust which should allow Dragon to reach speed at 160km/h in 1.2 second. Achieving such speed in such a short time is possible due the propellant used. SuperDracos engines are fueled with hypergolic propellant to short time of ignition. Engines are designed to start for around five seconds stop and be ejected with trunk module to give possibility of ejecting parachutes in safe distance at around 1,524 meters.

Last Dragon abort test was positively completed on 6th May 2015 at Cape Canaveral Air Force Station in Florida. Its main advantage and difference from previous versions, is utilizing fixed engines, instead additional jettisoned tower containing propulsion attached over the spacecraft. It provides capability of using rescue system in any moment of flight. Engines could be also utilized during maneuvers in outer space (for example during docking) and are able for multiple starts and stops. Tests were consisted 27 tries of starting and stopping with no signs of malfunction.

Sources:
http://www.spacex.com/news/2015/05/06/crew-dragon-completes-pad-abort-test
https://en.wikipedia.org/wiki/Dragon_(spacecraft)#Crewed_development_program
http://www.orlandosentinel.com/news/space/go-for-launch/os-spacex-blasts-dragon-capsule-in-abort-test-20150506-post.html
https://blogs.nasa.gov/commercialcrew/2015/11/10/crew-dragon-propulsion-system-completes-development-testing/
https://en.wikipedia.org/wiki/Launch_escape_system