I'm still confused... What exactly do engine precoolers do????

[Levelord]

I still find no difference in engine performance when using these things. They weigh as much as bricks, don't provide as much intake, take up space, doesn't provide much fuel and doesn't radiate heat as effectively as dedicated smaller radiators. I've been scouring threads and googling them up to see what the community has said in the past about them, but never got a straight answer... What exactly, are the uses for engine precoolers???

[Alshain]

I don't think they do anything.

[G'th]

Ideally, they'd be the best option for keeping engines cool during flight, especially for spaceplanes.

Whether or not they actually do anything towards that, as of yet, is up in the air.

[Frank_G]

Put them in front of R.A.P.I.E.R.s and speeds above 1.5 km/s is no magic anymore. And yes, they dont provide much intake air... But they store a LOT of it, keeping your engines alive at high altitudes for much longer. In numbers... 100 - 150 m/s more acceleration in atmosphere and 2 - 3000 m more altitude before you need to switch to the closed cycle.

[Rune]

Put them in front of R.A.P.I.E.R.s and speeds above 1.5 km/s is no magic anymore. And yes, they dont provide much intake air... But they store a LOT of it, keeping your engines alive at high altitudes for much longer. In numbers... 100 - 150 m/s more acceleration in atmosphere and 2 - 3000 m more altitude before you need to switch to the closed cycle.

That has more to do with the TWR of the design, since the RAPIER thrust curve is dependent on speed (I think).

I still find no difference in engine performance when using these things. They weigh as much as bricks, don't provide as much intake, take up space, doesn't provide much fuel and doesn't radiate heat as effectively as dedicated smaller radiators. I've been scouring threads and googling them up to see what the community has said in the past about them, but never got a straight answer... What exactly, are the uses for engine precoolers???

Basically, they are front-less intakes. Which means they may be heavy (cutting into mass fraction), but they are very low drag, so they help with maximum speed. You can make a SSTO with 1.25m of pointy frontal area feeding a couple engines!

Rune. I think that's all the gameplay use they have, but it's not nothing.

[Red Iron Crown]

AFAICT it's just a combo fuel tank/intake, with better radiative properties than most parts. Unfortunately, radiating heat can't keep up with the output of any non-tiny engine, so they don't help a huge amount with preventing overheats.

I think Rune has it with pointing out that the inline form factor is the main useful property of them. For designs where you need more intake but don't want to add frontal area they work very well.

[selfish_meme]

In a real Sabre/Rapier design they should be necessary to cool incoming air to make it denser for high altitude operation. Maybe they just have not managed to implement that yet.