Definitely fixed wing since it had wings but they didn’t rotate, but I guess you’d have to classify the X-15 as a “motor glider”.
Another “motor glider”:
“The F-4 established 16 speed, altitude and time-to-climb records. In 1959, its prototype set the world altitude record at 98,556 feet (30,000 meters).”
http://www.boeing.com/history/products/f-4-phantom-ii.page
(Of course, the Phantom basically ‘firewalled’ the throttle, got to max speed, then pointed the nose at the moon and coasted to the record altitude.Then it ‘motor glided’ [like a brick] back down to a low enough altitude to restart the engines. Somewhere along the way, the flight control surfaces had enough airflow mass to become effective again..... “Wheeeeee!!!)