What is the benefit of closing air intakes?

[katateochi]

I always forget about closing air intakes and basically I never do it. Am I missing something? What does closing them achieve?

Edited May 6, 2015 by katateochi

[Captain Sierra]

I always forget about closing air intakes and basically I never do it. Am I missing something? What does closing them achieve?

Open intakes apparently produce more drag. Honestly I don't really bother closing them either and I don't think it makes *that* much of a difference up at 25+km alt (where I kick in rockets).

[Gaarst]

Intakes have higher drag than other parts due to their function. Closing intake reduces their drag and make it similar to same sized parts.

[Chris_2]

The question is, because of less drag is also less heat generated? The intakes are usually one of the first parts to burn during re-entry, so in that case it could matter...

[Motokid600]

Honestly I don't see a difference. Got a dozen radial intakes on one craft. I shut all but two in the lower altitudes and... Idk if theres is a difference its very small.

[Reddeyfish]

this is a wild shot in the dark, but reducing drag might increase the amount of heat generated overall; heat sems to be from moving at very high speeds through the atmosphere, not from drag itself. more drag = less speed = less heating.

I also find closing intakes to be a really good way to instantly kill all engine thrust in case of asymmetric flameout or landing.

[katateochi]

ah I see, thanks guys!

[NathanKell]

Actually, as of 1.0, the "intake drag" shown in the right-click menu is utterly meaningless. Intakes, like everything else except wings, use cube drag now, so changing part.maximum_drag (as the intake drag does) does absolutely nothing to the drag the part actually crates.

So closing intakes does nothing other than shutting the resource intake off. It doesn't change drag at all.

Convective heating is related to drag only so far as it's related to velocity; the quicker you slow down, the lower your total heat load. This means that if you can find a way to slow down faster without increasing your convective surface area, you'll get less heat. Compare a pod (entering rear first) and a Mk1 cockpit (entering nose-first). Both have the same cross-sectional area, but the cockpit stays faster longer (and even has more surface area) and thus will take on way, way more heat.

[Chris_2]

Also, what I do, is shut down intakes that I consider 'belonging' to an engine together with the engine. To prevent air-hogging; for example if I have a spaceplane with both turbojets and RAPIERS, when shutting down the turbojets the RAPIERS don't have access to the turbojets air-intakes. As in reality you also can't really suddenly reroute air from one engine to another. (I know it gives less performance in the end but it seems only fair).