Why is it hard to engage/throttle/reignite rocket engines if it’s easy to do so with jets?

Question

With jet engines, it’s relatively easy to light it up and throttle. I know you can’t shut them down mid-flight and then turn them back on while still in the air, but you can easily throttle them. Now with rocket engines, you can only light most engines 1-3 times, and their throttle ability is minimal. Why is this so?

Thanks in advance.

In: Engineering

Answer 1

Startup is expensive in terms of power because the initial reaction needs to be started. Things like turbopumps that are their own gas turbines need to start before that can happen.

And rocket engines are hot and violent things… the mechanical wear is Huge.