Per-resource crossfeed

[damerell]

I would find it useful if different resources could have different crossfeed settings on parts. Specifically, this came from a discussion on IRC about intake air, which presently flows everwhere like electricity or monoprop. It struck me that most of the problems with asymmetrical flameout could be fixed if it was possible to disable crossfeed across the centreline of a plane.

A further refinement would be to permit crossfeed only if demand is satisfied on a given side of the part. This could be used to allow intake air to flow outwards only when the innermost engines on a 4-engined plane are sated.

I have no idea if fiddling with fuel flow logic is a viable thing to do in a mod and would be interested in comments on the subject.

[Red Iron Crown]

Intake air is kind of a special case in that it's not a carried resource, IMO some special rules for it would not be unreasonable. Personally, I would make it so intake air cannot move from one stack/fuselage to another, this would both increase realism and simplify intake/engine balancing. I'm not sure such a change would be popular though, I'd imagine some would complain about it limiting creative freedom.

[sal_vager]

Also, available intake air is now determined by intake area, air speed and air density, it's not simply "intake air" from 0.90.0 anymore.

If you have enough intake area your engines will run, unless there is insufficient pressure and speed.

If you are flaming out on the ground or hovering it's because intakes have different static air flows now, so make sure you have enough static flow from your combined intakes to meet your engines needs.

Flaming out in the air is due to their not being enough air to begin with, going faster can help but there's a limit, so resource crossfeed on air doesn't really apply anymore.

[steve_v]

11 minutes ago, Red Iron Crown said:

Personally, I would make it so intake air cannot move from one stack/fuselage to another, this would both increase realism and simplify intake/engine balancing.

This would get much approval over here, I like realism. But yeah, some would most certainly complain.

[panzer1b]

3 hours ago, Red Iron Crown said:

I'm not sure such a change would be popular though, I'd imagine some would complain about it limiting creative freedom

Im not for it as yes, it heavily limits freedom, and is actually unrealistic.  It actually would not affect any of my own designs per say (everything i have now uses shock cones on the front of every stack since its the lowest drag option available), but there are enough options that would be ruined by this.  That and the whole realism discussion makes no sense to me, its actually less realistic to limit the ability to feed air throughout the plane imo.

For example placing engines on nose cones that are attached to wings.  While extremely unpractical, who says that it is impossible to bleed air from the fuselage and feed it through the wing (air ducts in there) to the engines.  While it may not be practical (and there is a reason virtually all planes have intake in front of the engine), who says it is impossible to rout air through wings, or structural parts?  If you really think about it, it would be less realistic to impose this limitation since there is no physical law that states you cannot feed air throughout the vessel with air ducts.

Look at planes such as the harrier, they have what are essentially ducts that feed the air from the fuselage mounted turbine to the swiveling nozzles.  There is absolutely no physical reason you could not extend the ducts in length and perhaps feed them through the wing to the wingtip.  Im not claiming this is practical on any level whatsoever, but it is perfectly possible to both feed thrust to other parts of the plane, as well as feed intake from any part to any other part of the plane via ducting.

 

Now as for adding penalties for not stack placed i think i would agree with (provided it doesnt waste any dev time since bugs are way more important then some minor mechanic like this), such ducting would considerably increase the drag and resistance to airflow, limiting the air moreso then a classic stack mounted intake, but it should still be possible to have air move from stack to stack as desired.

Edited December 11, 2015 by panzer1b

[damerell]

3 hours ago, sal_vager said:

Flaming out in the air is due to their not being enough air to begin with, going faster can help but there's a limit, so resource crossfeed on air doesn't really apply anymore.

If there's not enough air to run all my engines, surely wanting a way to stop the engines flaming out asymmetrically is entirely reasonable?

On a two-engined aircraft, I'd rather both flame out than one.

[sal_vager]

My 1.0.5 planes are flaming out symmetrically, yours are still flaming out on one side ?

[Stone Blue]

3 hours ago, Red Iron Crown said:

I'm not sure such a change would be popular though, I'd imagine some would complain about it limiting creative freedom.

Maybe an option to enable/disable it in right-click?.... Simple enough to satisfy BOTH sides of the argument?

[Red Iron Crown]

39 minutes ago, sal_vager said:

My 1.0.5 planes are flaming out symmetrically, yours are still flaming out on one side ?

I've talked to NathanKell about this, as I understand it if you have enough intake to keep up with demand until the thrust curve starts killing it from altitude the engines will gradually reduce thrust evenly. It is still possible to have an under-intaked plane flameout asymmetrically (this seems more prevalent with subs than planes IME).

34 minutes ago, Stone Blue said:

Maybe an option to enable/disable it in right-click?.... Simple enough to satisfy BOTH sides of the argument?

Honestly I'd rather have it be one way or the other, makes it easier to help people diagnose issues with craft.

[damerell]

1 hour ago, sal_vager said:

My 1.0.5 planes are flaming out symmetrically, yours are still flaming out on one side ?

The offending plane wasn't mine, I just produced the suggestion as a result of IRC discussion. As I now understand it from Red's comments below, the plane was simply mis-designed. That said, it would be nice if even mis-designed planes didn't suffer, but this suggestion might be overkill.