[cubefox]

Regarding the first point, I'm not sure whether aerospike engines can still be considered heat limited. Even in the 90s with the X-33 aerospike spacecraft, heat was not cited as the reason for cancellation. And nowadays material science as progressed by a lot, which resulted in more heat resistant materials, e.g. this one: https://www.nasa.gov/feature/glenn/2022/nasa-s-new-material-...

[panick21_]

Maybe I wrote it wrong. Closed expander cycles are heat limited.

Areospike require more cooling then traditional bell designs.

So an areospike epxnader cycle could produce more thurst.

See here for some research:

https://www.phoenix-int.com/wp-content/uploads/2017/05/Param...

[cubefox]

Now I understand, thanks.