Tim,
I'm not entirely sure what the default is but for me it was "Rocket Speed"! Scared the crap out of me the first couple of flights. What I do know is that the performance settings in the Solo app have no impact on the speed of a Tower Mission. I have used multiple Change Speed Waypoints on missions. Another thing I noticed is that setting the change speed waypoint to the first waypoint does not appear to work. I usually put my bird in the air manually, above and forward of me, make the first waypoint at the default height just in front of my Home Point. The second waypoint is always my change speed waypoint (15 is tolerable for me on most flights).
Jerry
Right-- "Rocket Speed" here too! Didn't know whether to laugh or cry...
Good tip about using the 2nd waypoint to set speed-- makes sense actually.