I’ve found that the SpaceX Raptor rocket engine and the BE-4 rocket engine use methalox (Liquid Methane and Liquid Oxygen), is there any other rocket engines that use a methalox.
No orbital class rocket so far has used methalox. But there are multiple orbital class methalox engines / rockets in development right now, in what has (tongue-in-cheek) been called the methalox race:
- LandSpace (蓝箭航天)'s Zhuque-2 (朱雀二号) (using its own TQ-12 (天鹊-12) engines),
- United Launch Alliance's Vulcan Centaur (using Blue Origin's BE-4 engines),
- Relativity Space's Terran 1 (using its own Aeon 1 engines),
- SpaceX's Starship and Super Heavy (using its own Raptor 2 engines),
- Blue Origin's New Glenn (using its own BE-4 engines),
- Rocket Lab's Neutron (using its own Archimedes engines), and
- Relativity Space's Terran R (using its own Aeon R engines).
The predecessor of Firefly Aerospace, Firefly Space Systems planned to power the original 1.0 version of its Alpha (α) rocket's first stage with its own FRE-2 engine, an aerospike engine burning methalox. The second stage engine, FRE-1, was planned to be a methalox engine as well, with a conventional bell nozzle.
If you want to know why methalox has not been used much until now, this question on this site may be of interest to you: When was liquid methane used for the first time in rocket engines?
It is likely that at least one of these will at least attempt an orbital launch in 2022. It is also highly likely (in my opinion) that Vulcan Centaur's first orbital launch attempt will result in a successful orbital insertion. Hence, I would expect at least one attempt in 2022 and at least one success at the latest in 2023.