i just please ask you to think about it with an open mind:
you shoot the cannonbal 100 m underneath you with 90º direction you apply 1 kg tension what puts the ball at 89º direction
now lets say you get down 100 m but the ball is at your horizontal going at 89º direction
you aply another 1 kg or even 10 kg of tension making the ball go 88º or less, now you brake so you dont go down any more and you are at ground level
now you aply another 1kg tension and wait now you are going up and the more you wait without aplying tension the more up you go and you have the ball going at 87º
now you are in your initial position with the ball going at 87º so you keep the 1 kg tension what pulls you UPWARDS for as long as necesary(if you dont aply tension you keep going up) untill the ball is going at 0º when you hold the cable tight and pulls you still more upwards
isnt this reactionless? and of course momentum has been kept it only has been transformed in direction 90º