I just discovered a website that has a treasure trove of information about nearly all commercial rockets. It has the "User's Guide" for each rocket that is published by each company. These user guides are primarily focused on explaining all the capabilities and requirements for the payloads from a user's perspective. However, they also typically contain a whole lot of background information about each rocket including motor information, staging capabilities, performance data, structures, avionics, available orbits, mission profiles, mechanical and electrical payload interfaces, etc. They also show a lot of detail on operating conditions such as acceleration, vibration, temperature, acoustics, and RF transmissions. Many include internal photos and engineering drawings as well as details about the launch facilities, right down to showing pictures and floor plans of the VAB. I found them fascinating to read. The site has a very long list of rockets. Even the JAXA Epsilon that has three stages with all solid motors is there.
Here is the link: https://www.mach5lowdown.com/payload-user-guides/
Here is the link: https://www.mach5lowdown.com/payload-user-guides/