Beat me to it!
...a Wankel rocket?
No. The only thing similar is the name.
Briefly an explosion is a much more efficient release of energy than a continuous stream of fire going out the back of a rocket motor.
The problem is the release of energy is all at once.
So you need to either make it small and balance it with a bunch of little explosions or have some sort of shock absorber. Or both.
Think of a giant spaceship with 100 nozzles in the back in a big round cluster.
They’re all off. The captain says “go” and one single nozzle lights up for just a second. The another lights up for a second on the opposite side.
Boom. Boom.boom. You can see each one. On off. On off. Slow.
Then the pattern starts speeding up and eventually it looks like all the nozzles are lit up at the same time. They’re not. It’s just the pattern of explosions is going fast enough that it looks like they are all on.
It’s probably how we will go between stars.