Am I choking my jet engines for air?

[JoeSchmuckatelli]

Just unlocked the Panther turbofans.  I see that they want 7/sec air intake.  But my radial / circular intakes are only pulling in 2.  Looks to me like a problem.  My best solution thus far is a pair of radial intakes per engine, but (if they stack) I'm only giving the engine 4/sec air.

 

I see that when I unlock the hypersonic flight advancement I get the option to use an engine precooler - but that one only gets 5 under intake air.

 

Question is; do they stack?  A radial + precooler for the full benefit of the system... or do I misunderstand how the engines / intakes work.

 

 

[bewing]

I'm afraid you misunderstand a little. The panthers want 7 units/sec max. Which is flying along at mach 2.5 at 1000m altitude or something. The radial/circular intakes provide 2 units when stationary on the runway. They provide a hell of a lot more when they are rolling down the runway at 35m/s. And a lot more than that when flying along at 350m/s.

So really, those numbers are almost worthless. They can give you some idea about whether you will be able to go to full throttle while sitting still at the very end of the runway, but that's about it.

Even the tiny circular intake can provide enough air not to completely choke a panther.

It's been proven to me that intakes do stack a bit, but not much. The small amount of extra air is not worth the extra drag or mass, though. One intake per engine is more than sufficient. And you can usually get away with two or three engines per intake.

 

 

[Fraktal]

One intake per engine is more than enough, most of the time. Two Engine Nacelles are perfectly capable of running three Wheesleys all the way up to Mach 2.1 without any flameouts. However, keep in mind that an intake's performance on the runway is not indicative of its performance mid-flight. If the engines keep flaming out on the runway, it's not an indication that you don't have enough intakes; almost none of the intakes operate at anywhere near peak efficiency at taxiing speed. Once you take off and get some speed under your wing, the amount of air supplied by each intake increases, which increases engine performance, which increases speed, which increases intake performance even further, which makes you go even faster, and so on in a positive feedback loop.

If you find your Panthers keep flaming out on the runway, start the takeoff roll at low throttle, then gradually increase the gas as your intakes start catching the airstream and spinning up to optimal performance. That or add an Engine Nacelle or Engine Precooler somewhere in the middle (these intakes are special in that you can attach other parts to both ends and they still work, so you can hide them in the middle of your plane for a very low-drag air supply) to increase how much air you have available on the runway.

Intake spam was a thing back in the very early versions of the game, but not anymore.

[JoeSchmuckatelli]

6 minutes ago, bewing said:

...good stuff

It's been proven to me that intakes do stack a bit, but not much. The small amount of extra air is not worth the extra drag or mass, though. ...

 

 

 

5 minutes ago, Fraktal said:

...more good stuff

Intake spam was a thing back in the very early versions of the game, but not anymore.

 

 

Thanks for the fast answers, fellers!

 

About the quotes above:

…after posting the question, I did build a version of my plane with 4 intakes (2 engines) that did get hypersonic (guessing  -- I got the 'flame' animations) - so intake spam does overcome drag still to this day!

[UncleManuel]

15 hours ago, JoeSchmuckatelli said:

About the quotes above:

…after posting the question, I did build a version of my plane with 4 intakes (2 engines) that did get hypersonic (guessing  -- I got the 'flame' animations) - so intake spam does overcome drag still to this day!

Well, even one cone intake can provide enough air for two Rapier. More important with supersonic jets is to get above 450 m/s for the ram air effect to kick in. Click in flight on the tab on the bottom left so that the card for the engines pop out - there you'll see the actual thrust number. More thrust --> more speed... 

Actually going supersonic or hypersonic depends on the altitude. The "shock cone animation" indicates supersonic speed. The "flame animation" is just an indication of friction heating which differs according to altitude. And the Mach number also depends on air density (=altitude). But the ground speed indication in 'meters per second' in KSP is more an indicator on how fast you're actually going since it's not really an accurate simulator for planes. But you can multiply that m/s times 3.6 to get km/h to get an idea. But again: Mach 3.2 at 25000 meters is actually 3367 km/h fast... 

Btw: "hypersonic" per definition are speeds above Mach 5 (6174 km/h or 1715 m/s).

Edited May 13, 2020 by UncleManuel

[JoeSchmuckatelli]

1 hour ago, UncleManuel said:

Well, even one cone intake can provide enough air for two Rapier. More important with supersonic jets is to get above 450 m/s for the ram air effect to kick in. Click in flight on the tab on the bottom left so that the card for the engines pop out - there you'll see the actual thrust number. More thrust --> more speed... 

Actually going supersonic or hypersonic depends on the altitude. The "shock cone animation" indicates supersonic speed. The "flame animation" is just an indication of friction heating which differs according to altitude. And the Mach number also depends on air density (=altitude). But the ground speed indication in 'meters per second' in KSP is more an indicator on how fast you're actually going since it's not really an accurate simulator for planes. But you can multiply that m/s times 3.6 to get km/h to get an idea. But again: Mach 3.2 at 25000 meters is actually 3367 km/h fast... 

Btw: "hypersonic" per definition are speeds above Mach 5 (6174 km/h or 1715 m/s).

Grin - I learn so much just from being wrong!

This community is awesome; thanks for the info