The starter is connected to the N2, not N1.
This thread might be the appropriate time to ask.
What about the 20% N2 limitation for starter engagement? After having heard the terrible sound of engaging the starter on a car when the engine is running, one has a tendency to avoid ever wanting to do it again.
Obviously this is a much different design than a car but an explanation of why it is OK up to 20% but not above would be interesting.
As for tailwind on start issues on the JT9D, I have seen 50 knots on a CF-6. Better design?