| Plans called for a Marquardt ramjet to power Rigel, whose all-up weight was 19,000 pounds with booster. |
| One type, called a ramjet, slows incoming air to subsonic speeds using a carefully shaped inlet to compress and thereby slow the airstream. |
| Following the boost phase, the missile successfully transitioned to its ramjet operation and accelerated to its operational speed. |
| The ramjet went through a number of experimental stages during the 20th century, but never reached production. |
| An onboard or Earth-based laser could be used to heat the incoming plasma in the ramjet to further increase thrust. |
| The engine, which will be provided by the Air Force, will be a dual-mode scramjet capable of running as a ramjet or scramjet. |
