a sugar rocket requires a launch rod 10 mm or smaller flies about 300m fully packed. also i use a 75 35 ratio of 75 potassium nitrate and 35 sugar

to use:
put rocket fuel in the back BEFORE putting the nose cone on

then pack the rocket fuel repeat 2-3 times till about 2cm and then get the nozzle put super glue ALL over the outside and put it in with the LONG side facing in so the short side is on the outside of the rocket. - if the nozzle is a tight fit tilt it on a 45 degree angle put it in then grab a hammer and hit it till it moves and becomes flat

put the top on

then put the fuse or sparkler in the bottom, slide the rocket down light it and RUN this could explode so go far and watch it woosh.

(by the way it would be nice if you commented that it worked for you and if not i can change the design)