>>12089343>TradeoffsSo far it seems like they have lower overall TWR, but almost all of the notable aerospikes used turbomachinery from other already existing rockets. I'm not sure it's fair to say an aerospike must by necessity have worse TWR because none have been built to purpose with their own specialized turbomachinery and plumbing.
In return, you can create a virtual gimbal without needing to move the whole engine by simply increasing or decreasing propellant flow to the individual combustion chambers surrounding the spike, creating differential thrust. They also adapt better to the pressure of the environment, meaning you could make one single aerospike instead of having to create two variants one for SL and one for VAC. Each individual small combustion chamber doesn't have to be pushed to the same extremes as the single large combustion chamber of a conventional rocket.
>Are they massive?Due to the spike technically being a de-laval bell turned inside out they do tend to be slightly wider compared to an equivalent converging/diverging bell rocket, but not by an enormous amount.
>Could we build one with 400+ISPSure, use LOX/LH2. They don't have inherently superior ISP to conventional rocket engines, they just don't lose as much of it to over/under-expansion.
>Reentry shield.Yes, if it sufficiently covers the ass of the rocket then it can be used for reentry, even extremely steep reentry, assuming the rest of the ship is shaped so it doesn't get melted by IR reflection from the plasma wake. If it can survive the heat of it's own firing, it can survive reentry, at least for any safe angle on Earth. If it's actively cooled it can also easily survive a Jupiter or Saturn aerosbrake as well.
