I'll tell you how it can be achieved without the use of monster power or some super-duper ptfe coated airframe....build yourself a WIG(Wings In Ground effect) machine such like the Russian Caspian Sea Monster or the many other wild and wonderful creations of all shapes and sizes that exploit this concept !! Then learn how to fly very fast right down around 25% of your wingspan off the hard deck!!

Probably best done over flat calm water with the use of giros for stability. You will get all the speed you need and mach 0.5 would be a walk in the park.

The Caspian Sea Monster needed it's 8 massive forward engines to get up to speed but once there in the hugely reduced drag zone of ground effect.... all 8 engines were shut down and only the 2 small tail mounted engines needed to sustain.

In theory even the best low drag high speed airframe can only achieve half the drag coefficient of a well designed ground effect machine.

Food for thought.

Rob.