Ist der Text so grammatisch richtig ? für ein Referat..

Letter from a parachute teacher:
Hello,
I have made up to now more than 500 parachute jumps (it makes addicted) and it is not to be described easily the feeling(emotion).
After the jump you have approx. 10 seconds an acceleration phase which you can feel of course physically. After these 10 seconds you do not accelerate any more (if the free case position is not changed) and has afterwards a feeling(emotion) of the weightlessness (nobody "case feeling ") more - one can also float it than call.
For the perception: This is very different, because every person differently(else) reacts. Because I hang around very often on the jump places of this world, I can say you that 90% of the tandem company with a smile land (what stops(continues) as a rule longer). So the smiling guests(company) also get something with in the air - maybe not the first 10 sec - but afterwards. I hope - I could help(assist) you something.