This book provides awesome discussions of motors, delay modification, and electronics:
Mike Westerfield Make: High-Power Rockets: Construction and Certification for Thousands of Feet and Beyond
https://www.amazon.com/Make-High-Power-Construction-Certification-Thousands-ebook/dp/B0775K67RF
Np. This book provides a good discussion, btw.
Mike Westerfield Make: High-Power Rockets: Construction and Certification for Thousands of Feet and Beyond
https://www.amazon.com/Make-High-Power-Construction-Certification-Thousands-ebook/dp/B0775K67RF
Bought this one book:
Amazon.com https://www.amazon.com/dp/B0775K67RF?psc=1&ref_=cm_sw_r_apin_ts_MPT7YGTJPXAS8XG0PH84
And I guided me through everything I needed to know and answered all my beginner and even some expert questions.