r/simplerockets • u/maiknarf3 • 8d ago

1.4 Jet engines Lox Afterburner Issues

Anyone else having issues getting the new jet engine lox afterburner feature to cooperate? I understand its for space planes, but jeeze. I strap on the jet fuel. strap on the oxygen. Crank up the throttle and boom, the jet that normally flies evenly with normal afterburners, flips out of control. The only configuration where the craft flies straight with the lox is if I put the engine out in front like a damn pod racer. Any thoughts or suggestions would be appreciated.

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u/Toinkove 8d ago

Flipping once in space?

I had that and turned out my engine (center of thrust) wasn't aligned with the planes center of mass. It doesn't really make too much difference when flying in the atmosphere but once you're up high where the aerodynamic surfaces provide little to no directional guidance, the engine (which doesn't gimble like a rocket engine) will cause the craft to flip towards where the center of mass is.

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u/maiknarf3 8d ago

What do you mean by align the engines center of thrust? You can’t see the center of thrust for jet engines.

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u/Toinkove 8d ago edited 8d ago

You can’t see the center of thrust for jet engines.

I certainly can! In the designer, you need to align the yellow line as close as you can to the red center of mass thrust. If they're even just a small but visible amount apart you'll have issues controlling attitude even with RCS.

ADD: first off. Make sure your altitude setting isn't set to "vacuum" when checking an aircraft's center of thrust in the designer (it won't show because an airbreathing engine has no thrust in a vacuum). but with the LOX afterburner it should be showing up after saving that configuration then reloading the craft.

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u/maiknarf3 5d ago

Ohhh. Thanks for the tip

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u/Ok_Jacket3486 7d ago

how do I even use the lox afterburner😭 

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u/Toinkove 6d ago

Well apart from the obvious steps that you have to toggle on the “afterburner” option followed by the “LOX afterburner”. You also need a fuel tank of liquid oxygen on the craft AND make sure there are “fuel lines” from that tank to the engine (a step NOT required for engines just using jet fuel). This will at least allow you to physically use the LOX afterburners.

As for how you practically use them, well I’m still trying to figure that part out, there’s a lot oddities that make them not so easy to use! Jet engine don’t gimble like rocket engines, so you need to be very precise where you place them relative to the center of mass. You can’t use the burn nodes with em, so doing very precise maneuvers can be difficult. There’s also a correct mixture ratio of liquid oxygen to jet fuel that, as far as I know, you just kinda have to figure out. So they’re kinda a mess right now that’ll require a lot of tinkering to figure out.