While a number of large hybrid engines have been made in the N, O, and P classes, none have ever been made for certification. A P motor wouldn't ever be cert'd since it is beyond the certified limits of HPR. But that shouldn't stop you from making one
One area of interest i have had is the reverse hybrid, with solid oxidizer and liquid fuel. While it may not have any real advantages, i like a challenge, just for my own knowledge and the fun of experimentation.
Another facet of hybrids i would like to explore is a FAST hybrid, and i am talking Kosdon fast! Using large injector orfices and metallized fuels.
you might want to check out the RRS site <www.rrs.org
> they have some very impressive liquids and hybrids that they have built, many of them using LOX. Also, if you can find out a way to contact him, you might try Rick Loehr <never sure if I spell that last name right
>, he builds some VERY large LOX hybrids, after having done large solids for years. He still builds the massive composite engines fro Ky's spaceshots though