It's a PNC-60AH nosecone.
The Red Max body tube is actually 8.5 inches, not 9 1/8 inches.
In addition to the above mentioned Mean Machine, the same cone is also used in the Screamin' Mimi kits, which everybody buys on the Hobby Lobby 1/2 price sales to make clone kits...including me before I bought a wood lathe and a lot of balsa and body tubes from BMS.
You can clone a Citation Patriot and the Omega with this nosecone also. The Screamin' Mimi kit has the full 18" length tube needed for the Patriot and the stretched "Der Big Red Max".
BTW, I have an early Citation Red Max kit with the heavy black injection molded nosecone, a later one with blow molded cone, and a couple of clones. I have also built a 4" upscale, and have a BT-80 version ready to paint.