Model rocket motors.  As for what impulse model rocket motor that depends on wind direction.  With favorable winds I would fly just about anything, though drift from a high altitude is always a problem.  Dual deployment or a chute release makes it a walk in the park.  

I flew an Estes Fat Boy (short BT80 size kit from 20 years ago) with an E20-7 and got it back no problem.  I plan on flying it with an F24 reload out there, but only if the wind is favorable.