They are affected by air pressure, but it doesn’t actually hurt, it actually helps! because of the way an aerospike engine works it actually relies on that pres

They are affected by air pressure, but it doesn’t actually hurt, it actually helps! because of the way an aerospike engine works it actually relies on that pressure change behaviour on the “outside” edge. The expansion of the exhaust on the atmospheric side of the aerospike is actually part of how it obtains its efficiency…. That expansion pushes the expanding exhaust plume back towards the nozzle wall in proportion to the normal expansion with outside pressure and that drives the physics that make aerospike nozzles work at all altitudes. It’s a clever feedback loop if you want a computer analogy, but it’s really just a clever arrangement that maximises system efficiency in that lovely “continuous” way that mechanical/physical systems work.