The X-302 was designed following the failure of the X-301 and was intended to be the first manmade craft capable of both aerial combat and interstellar travel. Although many of its systems were retro-engineered from Goa'uld technologies, the X-302 is entirely human-built, unlike its predecessor which was a modified Goa'uld death glider.
The prototype for the experimental craft was built at Area 51 under the direction of Dr. Larry Murphy. The X-302 has four different sets of engines: air-breathing jets, modified aerospikes for high altitudes, a rocket booster, and a naquadria-powered hyperspace window generator. On its maiden flight, the craft, dubbed Abydos One, attempted to reach Abydos, however the energy fluctuations emitted by the naquadria caused the hyperspace window to be unstable, and the mission was auto-aborted.
When Anubis adapted an Ancient weapon to create an uncontrolled power buildup in Earth's stargate, O'Neill piloted the X-302 in Operation Starflight. The stargate was removed from Cheyenne Mountain and attached to the X-302, which was launched in flight from the back of a 747 at an altitude of 10 kilometers. By overriding the safety protocol, the craft was able to engage the hyperdrive generator for only one second and to attain a low altitude hyperspace window just long enough to allow O'Neill to eject safely and to send the X-302 and the stargate over 3 million miles from Earth before detonation. Although the prototype craft was lost, the X-302 program continued, and additional ships were built which became part of the USAF fleet, known officially as the fighter craft, F-302.
Episode Reference: Redemption