How 2 air intake?

[VelocityPolaris]

I've had this game since 2014, yet I could never figure this out, and I didn't understand the answers to other relevant topics. How many air intakes do you need to adequately supply a jet engine? Does thrust or efficiency continually increase as you add intakes, or is there a cutoff limit to the benefit to one engine? I don't know which conditions matter, so assume Kerbin surface atmospheric conditions, and "wheesley", "panther" (wet mode), & "whiplash" types, starting stopped. Thanks!

[Foxster]

Someone will be along with some proper numbers, no doubt. 

I throw on one intake per two engines and see how it flies. If the engines start gasping I'll add a bit more air. 

Edited March 22, 2018 by Foxster

[bewing]

11 minutes ago, VelocityPolaris said:

How many air intakes do you need to adequately supply a jet engine?

One.

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Does thrust or efficiency continually increase as you add intakes, or is there a cutoff limit to the benefit to one engine?

The cutoff limit is one.

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I don't know which conditions matter, so assume Kerbin surface atmospheric conditions, and "wheesley", "panther" (wet mode), & "whiplash" types, starting stopped. Thanks!

Spamming intakes used to be a thing a very long time ago, but it no longer does anything. If you have multiple intakes, the game will choose the next one that has the most input in the current flight envelope.

But basically, one intake gets assigned to each engine, and that's it.

If you have fewer intakes than engines, then the intake with the most spare capacity will have that spare capacity assigned to the next engine.

 

 

Edited March 22, 2018 by bewing

[sebi.zzr]

It's not how many air intakes you need,but more of which intake to use for what purpose.

 

[fourfa]

Air intakes have two relevant stats: static (zero forward speed) air supply, and dynamic air supply.  Static is fixed, dynamic changes with air speed (and each different part has a different dynamic curve).  I've found that at speed, you really need very few intakes indeed.  I've been able to feed 5 RAPIERs at full hypersonic tilt with a single shock cone.  However those same shock cones have rather poor static draw, so on that plane I have to start rolling at very low throttle, then ramp up as you start to move.  Otherwise you get asymmetric flame-outs, and takeoff is rather a mess.  But full throttle is possible at only 30m/s or so.

SSTO design is often about getting rid of things, rather than just moar boosters/moar struts etc.  I think you're more interested in planes, which are more forgiving.  But in general - there's no benefit from additional air intakes past the jet engine's base requirement, only extra mass and drag.  For the 3 you mention, the tiny size 0 intake is too small, and a single long radial intake (Adjustable Ramp Intake) may not be enough for the Whiplash in all conditions.  The pre-cooler is notable for having excellent static draw, excellent dynamic draw, and low drag.  You probably don't need any other intake at all with the precooler.

Edited March 22, 2018 by fourfa

[hms_warrior]

The intakes have no influence at the engine performance. They simply generate intakeAir.

As long as you have enough intakeAir to feed your engines, the engines run. If your intakeAir drops below your engines consumption rate, your engine stops working.

intakeAir > engine consumption: engine works at 100%,

intakeAir < engine consumption: complete engine shut down.

The actual engine performance is a function of (only) the speed you move and the altitude you are flying at, the amount of intakeAir has no influence .

Edited March 23, 2018 by hms_warrior

[bewing]

19 minutes ago, hms_warrior said:

intakeAir < engine consumption: complete engine shut down.

Not quite. When an engine starts to starve for air, the thrust drops. When the thrust hits about 10% of max, then it shuts down. But there is a range there where it still runs at some fraction of normal power.