Garvey has done abit of Aerospike work with CSULB and have successfully flown a liquid aerospike motor and have tried a multi chamber toroidal aerospike plug arrangement, I was out at Mojave when they tried this, one of the chambers burnt through causing a side thrust making the huge rocket cartwheel and crash not to far from where it was launched. Heart stopping.
http://www.garvspace.com/Nasa has also done some work with Blacksky Corporation and have flown some aerospike rockets
http://www.nasa.gov/missions/research/a ... ocket.htmlAnd back in the day, the Apollo J-2 engine was modified to become a toroidal aerospike plug engine, Engine Model: J-2T-200K and J-2T-250K
http://en.wikipedia.org/wiki/File:Annular-Aerospike.jpgCooling is the biggest issue, Garvey I believe ran a fuel rich mixture in their multi engine design and an ablative chamber with a graphite spike in their other design. If you can overcome this and afew other issues you should be on to a winner!