Asymetric Flameout?

[arkie87]

Anyone still experiencing asymmetric flameout on aircraft?

It still seems to be happening to me...

[Jarin]

I had two widely-spaced turbojets and had them flickering off and on as I bounced in and out of the upper atmosphere to test... no asymmetric flameout at all; they stayed perfectly in sync. I didn't do any fancy intake balancing, either. Can you describe what's happening to you in more detail?

[arkie87]

I had two widely-spaced turbojets and had them flickering off and on as I bounced in and out of the upper atmosphere to test... no asymmetric flameout at all; they stayed perfectly in sync. I didn't do any fancy intake balancing, either. Can you describe what's happening to you in more detail?

perhaps i should remove all mods and do a clean download and install, and see if it still happens.

stay posted...

[ShadowZone]

Yes I had that, even at lower altitudes but supersonic speeds. Seems like the structural air intakes were not enough to provide air fast enough for the hungra Turbojets.

[NathanKell]

Add more intakes. The only time you'll get asymmetric flameout is if you don't have enough intakes.

[arkie87]

Add more intakes. The only time you'll get asymmetric flameout is if you don't have enough intakes.

Isn't/wasn't that always the case? I thought for KSP 1.0 they redid air flow logic to always split air evenly and prevent this from happening?

[Jarin]

Add more intakes. The only time you'll get asymmetric flameout is if you don't have enough intakes.

What is "enough" in this case? No matter how many intakes you add, you're going to be air-starved eventually. What's the break-over point between asymmetric and symmetric? I've not yet seen the former (my engines always flame out perfectly in sync), but I also haven't run at less than 3:1 intakes/turbojets.

[Archgeek]

The spaceplane version of the Stearwing goes pretty asymmetric. It also pulls weirdly to the right for some reason.

[NathanKell]

Jarin: except that's not true in 1.0. In 1.0, you can "flame out" in two ways. One is if the air doesn't have enough density to support combustion; in that case all engines will flame out in sync (same density across the vessel). The other is if you don't have enough intakes; then engines will flame out asymmetrically due to how resource flow works. If you have enough intakes that the latter never happens...the latter never happens.

[Jarin]

I'm just asking how many is required. Is this something that only happens when you have less intakes than engines? I know that resource flow for intake air was completely overhauled for 1.0, but haven't actually seen a proper analysis of it yet.

[Redshift OTF]

Jarin: except that's not true in 1.0. In 1.0, you can "flame out" in two ways. One is if the air doesn't have enough density to support combustion; in that case all engines will flame out in sync (same density across the vessel). The other is if you don't have enough intakes; then engines will flame out asymmetrically due to how resource flow works. If you have enough intakes that the latter never happens...the latter never happens.

Thanks for this tip! I have a plane that flames out in the mid atmosphere but works fine in the high atmosphere. Does the angle of attack not being in line with your prograde direction reduce the amount of air going in intakes?

[Tarheel1999]

I'm just asking how many is required. Is this something that only happens when you have less intakes than engines? I know that resource flow for intake air was completely overhauled for 1.0, but haven't actually seen a proper analysis of it yet.

4 small intakes (long skinny ones) for two rapiers will produce an asymmetric flameout when attempting to reach orbit. At least it did for my vessel.

[arkie87]

The other is if you don't have enough intakes; then engines will flame out asymmetrically due to how resource flow works. If you have enough intakes that the latter never happens...the latter never happens.

I still dont understand what you are saying...

I thought they fixed how resource flow works so that this doesnt happen in 1.0

As Jarin mentioned, there will never be enough intakes once you get high enough...

[blowfish]

Thanks for this tip! I have a plane that flames out in the mid atmosphere but works fine in the high atmosphere. Does the angle of attack not being in line with your prograde direction reduce the amount of air going in intakes?

It appears to, yes. I've gotten engines to flame out near sea level with a high AoA.

[NathanKell]

arkie87: Where did you hear that? I didn't hear that.

Redshift OTF: Yes, ModuleResourceIntake does (and always has) scaled by the dot of the intake vector and the velocity vector (i.e. sin(AoA) ).

Tarheel1999: the long intakes really don't have much area...

[Tarheel1999]

arkie87: Where did you hear that? I didn't hear that.

Redshift OTF: Yes, ModuleResourceIntake does (and always has) scaled by the dot of the intake vector and the velocity vector (i.e. sin(AoA) ).

Tarheel1999: the long intakes really don't have much area...

Yup. Figured that out the hard way. I was using B9 radial intakes in .90 and 1-2 per engine were typically enough for SSTOs using FAR.

- - - Updated - - -

I still dont understand what you are saying...

I thought they fixed how resource flow works so that this doesnt happen in 1.0

As Jarin mentioned, there will never be enough intakes once you get high enough...

The flameout no longer appears to cause flat spins. This may be what you are thinking of.

[basic.syntax]

I knew I'd seen words implying changes to eliminate asymmetric flameout, could not remember where: found it in this Squadcast summary:

Asymmetric flameout is fixed because it shouldn't really exist, Squad are "reworking how fuel and resource flow works while in the air", so that should help reduce or ameliorate asymmetric flameouts for air-breathers.

The linked video is no longer available, so I wasn't able to review the quote.

[Jarin]

Either I've suddenly been miraculously granted the ability to balance all my intakes, when I never could before, or something got fixed.

[NathanKell]

basic.syntax: given that AFAICT no resource flow changed very much, I think that might have been one of the deferred features.

[Alshain]

basic.syntax: given that AFAICT no resource flow changed very much, I think that might have been one of the deferred features.

I've definitely confirmed that jet engines draw from all fuel tanks evenly. That much did change. I thought the air intakes were supposed to be part of that logic.

[Temeter]

I had a bunch of flameout, most of them weren't asymmetric, and the only problem cases were just one engine burning a tiny bit longer than the other.