High flying IO-3 passenger solar plane !

I made amazing discovery...I counted that in 16 kilometre altitude the air is only 10% thick of what it is on the sea level...this would men that IO-3 with 305 m2 wing at 81 m span could actually soar at amazing 700 km/h at 52 000 ft. Not fully loaded but with 4 man crew using oxygene masks. It means that the trip from New York to Paris would take ( 3600 mi ) 9-12 hours..last 4 hour gliding down at 50:1 glide ratio. I have no idea how costly it would be. I hope Chip would succeed in his attempt; http://www.gizmag.com/fotc-electric-aircraft-lindbergh-flight/22765/