1. Try to not block any rockets, instead use the jump pads to move N around and through them.
2. No reason for that many rockets. Its better to have 20 rockets that are used throughout the level than to have 80 with most of them blocked off. The reason why i chose 34 rockets in my ddas is because of how they are evenly spaced and surrounding N, but there any many other possible combinations. The problem with the 83 rocket arrangment you currently have is that each rocket launcher is spaced too close, causing the gaps between each rocket to be too close together, basically at first creating a wall of rockets and soon after merging into 1 rocket. What i reccommend is for you to take out 75% of the rockets so that they are each spaced out alot more(4times), allowing N to go between individual rockets.
3. Do not constantly retreat from the rockets. Instead, always have N close to a rocket (or group of rockets). Whenever you can, go between rockets(cool close calls)
4. Never add normal doors (the ones that open and close) into a dda. They only really have the purpose of being an easy way out of a situation, and in general it just makes the dda look bad. Also, adding doors in can mess up earlier parts of the dda(block off enemies and change thier timing, for example.
5. It may be helpful to learn other types of propulsion also, as to teach you how to do more with less control over N. If you learn a new type of propulsion, you will be amazed at how easy launchpads and how useful they are in all situations.

If you follow all of these steps you may be able to create a truly great launch-pad only dda.

It doesn't work every time tho, it lags differently and sometimes kills him..

i like this one a whole lot more then your others. Great job on it 4/5