That doesn't solve the problem if you can't get enough flow through those channels. Cooling channels doesn't solve cooling, it just helps it. From my non-Aerosp

That doesn't solve the problem if you can't get enough flow through those channels. Cooling channels doesn't solve cooling, it just helps it. From my non-Aerospace (though I took a couple of Aerospace undergrad classes) perspective, the hardest points to cool in an aerospike engine is the spike itself because it tends to be thin and narrow with no internal room for cooling pathways compared to the intense heat of sitting in the center of the flame.