I've been thinking about this for a while now, and this in general has been an issue IMO for a long time now. Currently, CJE's have basically zero efficiency, and zero ways to increase it. Here's an example:



You would think that the CJE on the right would be much more efficient, being literally 6x the size. Unfortunately, that isn't really the case. Both engines output 16000 thrust, with the 3 block long one (only using fuel injectors on combusters) takes 588 fuel per minute, and the one on the right takes... 411. Yep. 6x the size for a 30% decrease in fuel usage. At this rate, it just isn't worth it to use anything but just injectors and combusters.

My proposal can change that (hopefully). I propose that we make a new formula for the efficiency and power output of CJE's. It should look something like this:

Thrust output = Fuel per minute * Efficiency * Mode Efficiency * Vectoring Efficiency * 35

Fuel per minute = 25 * # of injectors (could be 6-8 for the small ones)

Efficiency = (1 + # Intakes * 0.07 + # Extra Intakes * 0.03) * (1 + # Compressors * 0.12 + # Extra Compressors * 0.05) * (1 + # Combusters * 0.12 + # Extra Combusters * 0.08)

Top speed = 175 + Mode Modifier + Vectoring Modifier

Please note that the values will need some tweaking, but overall they are supposed to represent how impactful they would be on efficiency. The larger values are supposed to be larger, and the smaller ones smaller. If they really need to be tweaked, that's perfectly fine with me, even if it switches up the order of efficiency.

The overall goal of the new efficiency equation is not only to make everything more efficient, but also make the component efficiencies multiply, so that you shouldn't just spam the largest efficiency one. This encourages a good mix of components and addons for the best efficiency. It also means that adding on extra components that aren't fuel injectors will not actually increase the fuel usage as well (as is the current system)

Notice I also added a variable called "Vectoring efficiency." This is a new feature I would like to propose, where you can vector the thrust (so a portion of the total thrust goes in X direction based on the controls). This is a real life thing, and I would love to see this in the game. It would add a lot of maneuverability to fighters and planes, and possibly remove the need for fuel engines on them in some cases. The efficiency itself could be something like 100%-70% based on the portion of the thrust redirected in another direction (also subject to change if necessary). There could also be another vectoring type efficiency, that simply increases the top speed at the cost of some efficiency. In real life, this would be the exhaust narrowing and/or dilating to increase the output speed of the exhaust. This would be much more efficient than the redirection vectoring, something like 100%-85%. This would also give a use to the currently useless exhaust part, if you could only do this if you attached it.

You might have also noticed the "Mode efficiency" variable on the first equation. This is part of another, more complex feature. In real life, jet engines come in many types, not just the "jet engine." Some of these types include: Turbofan, Turboshaft, Turboprop, RAMjet, and SCRAMjet. These types each have their individual uses and each have different efficiencies. For example, Turboshaft and Turbofan jets typically have much higher efficiencies than normal jets and especially compared to RAMjets and SCRAMjets.

My proposal for implementing this is as follows:

We add several buttons in the CJE customization menu (the "q" menu for the controller) that allow you to select what mode. There could even be tooltips that give the effects and efficiencies of each one, to explain them to newer players. Each mode would have an effect that would reflect the real life counterpart.

Jet Engine mode would be the default; It acts exactly as the CJE's act now, and has a mode efficiency of 100% and a top speed modifier of 0

Turbofan mode would be an efficient but relatively slow option; with a mode efficiency of 120% (subject to change) and a top speed modifier of -50 (also subject to change)

RAMjet mode would be a very fast, but very inefficient option; it would have a mode efficiency of 60% but a top speed modifier of +100 (values... you know the drill)

Finally, the most complex mode: Turboshaft. It would have a mode efficiency of 85%, and a top speed modifier of -10, but it has a much more useful feature. It would generate engine power when active. It could translate X% thrust into engine power at a 2:1 ratio, and the % thrust used could even be modified to your liking. This would add an endgame large ship use for fuel, as large CJE's could provide a lot of power, albeit likely less efficient than normal fuel engines. Again, all values are totally in the air for change, but they should give a pretty good idea of how it will end up.

Another fun feature for prop planes could be that a certain % of the total thrust could be applied to any active dediblades directly in front of the CJE. This could kinda replicate the Turboprop type of engine if implemented. (Could be a feature of the turbofan mode if needed as well)

Final suggestion: This was already hinted at a while ago, but never really came into play (as far as I've noticed at least). Direct air access required for full efficiency of the CJE. I suggest that 4 blocks minimum of clear space must be directly in front of the first intake (mainly so that dediblades can still be directly in front). Another block addon could be a "air injector" addon or new component. The addon could be placed on existing intakes, and the new component directly in front. Each addon could add 20% efficiency back from lost efficiency due to no air access. The component could add 100% as an alternative for low space applications.

As I've said repeatedly, all values suggested are just general guidelines, and will probably need to be changed for balance. I haven't played around too much with them, and it could end up being very overpowered. If possible, there could also be deminishing returns for each component, to limit the maximum possible efficiency from getting unreasonably high.

TL;DR: CJE's need to be able to be more efficient, so I've come up with a few equations mentioned to help fix that. I've also proposed a new feature: Jet Modes. Each mode will have its own use and efficiency, and will even modify the top speed. The modes include: Jet Engine, Turbofan, RAMjet, and Turboshaft. Jet Engine mode will be the current CJE's, Turbofan will be more efficient but slower, RAMjet will be much faster but much less efficient, and Turboshaft generates engine power in return for a percentage of the thrust being lost. Air access could even be implemented and new components called "air injectors" could be added to supplement air access. An optional extra feature is that a percentage of thrust could be added to any dediblade directly in front, to "replicate" real life Turboprop engines. Overall, smaller engines would be only slightly less effective, and larger ones would be much more efficient and useful, even to endgame ships and airships as power generators.