An arguement for a simple intake / jet engine tweak

[Starwaster]

The intake suggestion actually makes quite a lot of sense. I was suggesting it - not quite in this manner, though - for quite some time now.

It makes sense for two reasons, to me. First is subjective, one I think would plug up (to a point) something I consider abuse of the existing model. Giving more of the mass to the intake, in the intake-engine pair, will mean that the fairly ridiculous practice of airhogging will at least be in some way penalized.

Second is objective, and comes in from a realism standpoint. Right now KSP abstracts away one of the four important pieces of a jet engine. We have the intake that lets air in, the exhaust turbine that pushes air out, and maybe the combustion chamber squished away in the too-short engine part somewhere, but no compressor turbine that allows real jets to function.

http://upload.wikimedia.org/wikipedia/commons/5/56/J85_ge_17a_turbojet_engine.jpg

Notice how there's at least as much stuff in the front of a real turbojet, as there is in the back. The intake part in KSP could weigh as much as the engine itself, and it would still be realistic - in mass, if not size. Even if KSP isn't going to recreate the exact usefulness of compressors, giving the intakes a little more bulk and mass to at least pretend they are there would be quite logical.

And what about when the intake is not actually supposed to be part of the engine? Is in fact just an intake? See below for an example. That's a legitimate location for an air intake and is as far from the engine as possible. What do you think your fix would do to that? And again, if there really is a need to shift the engine's mass forward then use CoMOffset to shift the actual engine part's mass forward to the point that an actual engine would take up. Then you can pretend the nozzle is just part of a larger engine that you're not seeing..

Also, stop worrying about if people are 'abusing' the system. Stay in your own sandbox and stop worrying about them in theirs.

[DundraL]

This isn't supposed to be a fix/workaround/improvement for any aero dynamic model. At it's core, it's all about gameplay.

Using the above post above as a prime example, look at how you might recreate that aircraft in ksp. Its center of lift would be far forward of its center of gravity.

THAT PLANE COULD BARELY FLY IN KSP! (if at all)

It would be horribly unstable, because again, (in ksp im talking here) there is a very heavy jet/turbojet at the very rear of the plane, with FUEL and little else to shift that center of gravity back forwards to the wings. And even then, a major source of that balancing weight, the fuel, is temporary, leaving an already unstable configuration even worse later.

If we were to say, remove some of the weight from the jet engine of that (in ksp) aircraft, and transfer that weight into the intake, you would be much closer to a stable aircraft design. Before AND after fuel consumption.

Why air intakes? Because looking at that aircraft, the only other significant, permanent weight is the cockpit, and increasing it's mass would penalize rockets and wouldn't scale with plane size.

Im not trying to police any system, and the reason I wouldn't want to edit file like you suggested is that after I'm done building and flying, I want to be able to easily share that experience with other players here.

EDIT: Almost forgot realism. While yes, intakes are just "intakes," I think this is a misleading name to begin with, based on both the ingame model, and in function. The models depict a much shortened compressor(with the exception of radials). In function they ALL function as a compressor, as even standing still on the runway, they are force-feeding air into the engine. Even the radial air intake.

Edited September 16, 2014 by DundraL

[Nemrav]

Also, stop worrying about if people are 'abusing' the system. Stay in your own sandbox and stop worrying about them in theirs.

I think this kind of destroys the point of giving suggestions to the devs, or even the devs developing the game apart from engine updates... Why don't we just mod everything in !

On the actual part...

You are right in that the intake is mostly well... an intake, but unless we get a dedicated compressor piece I think a slight weight balance is the best we can do...

that or increase fuel tank weight..

[Wanderfound]

The intake suggestion actually makes quite a lot of sense. I was suggesting it - not quite in this manner, though - for quite some time now.

It makes sense for two reasons, to me. First is subjective, one I think would plug up (to a point) something I consider abuse of the existing model. Giving more of the mass to the intake, in the intake-engine pair, will mean that the fairly ridiculous practice of airhogging will at least be in some way penalized.

Second is objective, and comes in from a realism standpoint. Right now KSP abstracts away one of the four important pieces of a jet engine. We have the intake that lets air in, the exhaust turbine that pushes air out, and maybe the combustion chamber squished away in the too-short engine part somewhere, but no compressor turbine that allows real jets to function.

http://upload.wikimedia.org/wikipedia/commons/5/56/J85_ge_17a_turbojet_engine.jpg

Notice how there's at least as much stuff in the front of a real turbojet, as there is in the back. The intake part in KSP could weigh as much as the engine itself, and it would still be realistic - in mass, if not size. Even if KSP isn't going to recreate the exact usefulness of compressors, giving the intakes a little more bulk and mass to at least pretend they are there would be quite logical.

Yup, this.

I don't really care about the effects of this suggestion on stock aero, because the soupmosphere is so bloody awful that I will never fly in it again (praise be to Ferram, rep be upon him). But a jet engine should not consist of a massy point source hanging off the back of a plane; that's just not what they are.

I'd actually like it if they went all the way and required a line of ducting parts between intake and engine, but that's probably asking too much.

[Wanderfound]

This isn't supposed to be a fix/workaround/improvement for any aero dynamic model. At it's core, it's all about gameplay.

Using the above post above as a prime example, look at how you might recreate that aircraft in ksp. Its center of lift would be far forward of its center of gravity.

THAT PLANE COULD BARELY FLY IN KSP! (if at all)

It would be horribly unstable, because again, (in ksp im talking here) there is a very heavy jet/turbojet at the very rear of the plane, with FUEL and little else to shift that center of gravity back forwards to the wings. And even then, a major source of that balancing weight, the fuel, is temporary, leaving an already unstable configuration even worse laterk.

Yes yes yes yes yes.

The big problem with the stock aero and intake issues isn't that they allow players to build and fly silly, unrealistic things. If that's what you're into, cool; have fun. It is a good thing that the game permits that.

The problem is that if you try to build something that isn't silly and unrealistic, then it often just won't work, and even if it does fly it'll usually be massively outperformed by the LOLplanes. This is extremely Not A Good Thing.

[DundraL]

A shameless bump because it's relevant again due to the upcoming aerodynamics changes, and since the great Ted is starting to tweak balancing on engines by interpretation.

But another thing to add here is with the aerodynamics departing from mass=drag based simulation, the change will be even more needed as planes that once flew under stock aero will no longer have the stabilizing effect at the back due to the excessive rearward mass distribution.

Again, let me know if you guys agree or disagree with this idea, as well as whether or not bacon is awesome.

Edited January 9, 2015 by DundraL

[KerrMü]

I think this is a good bump. This is a good discussion on a still relevant subject.

I mostly agree with wanderfound here. The suggested idea sounds like a good workaround, but why not do it properly?

Something like reduce the current jet engines to be nozzles, implement an engine part (the nozzles then can determine the performance (basic or turbo) of the engine), and integrate intake air into the fuel-flow-system. Fuselage parts and radial intakes would allow the flow of intake air, others don't. Or something like that. This is just a half baked idea with losts of room for improvement.

For the aircraft instability problem: I have strong believe in the devs, that this will get a hell of a lot better with the upcoming aero overhaul.

... and bacon is indeed awesome

[chaos_forge]

Thanks for the bump, I actually hadn't seen this idea before! I think it's fantastic, and would go a long way in making spaceplanes easier to build.

[camlost]

In my mod, CoM offset was implemented to deal with this problem about 4 months prior to OP. It's always a good thing to do research on all available mods regarding the topic before suggesting.

[DundraL]

While both the suggested change and your mod have a few elements in common, their purpose and implementation is entirely different.

As said in OP, the goal is to allow more control over the COM, more variety in terms of viable aircraft design, and easier learning curve via tendency to shift COM forward in conventional aircraft designs.

As far as I can tell, your mod does one of those things. While I knew of your mod at the time of posting, I didnt want to use it because of the many other things it does.

Either way, the existence of a mod does not preclude a change in stock behavior, as indicated by the existence of NEAR/FAR and the upcoming change to aerodynamics.

[GoSlash27]

Unfortunately, this fix would cause drag instability issues.

The drag coefficient of the engine is fixed, while the drag coefficient of the intake is not (and also dependent on mass).

At high speeds, the pressure center would shift forward, making the plane highly unstable.

Changing this behavior would mean rewriting how intakes generate drag.

Best,

-Slashy

[Kegereneku]

that drag coefficient is going to change radically with the new aerodynamic model coming. This should not stay an argument, just saying.

[Red Iron Crown]

that drag coefficient is going to change radically with the new aerodynamic model coming. This should not stay an argument, just saying.

I agree with this. It's hard to suggest part tweaks for a system that's getting an overhaul.

[karolus10]

One viable option would be enabling parts to have fraction of the part "added" to the center of mass of entire craft, this would be also a good solution for parts like ladders or parts that have numerous other components hidden "somewhere in the hull".

[DundraL]

Yea, Im resurrecting this thread again after seeing the Squadcast where Maxmaps make a typical jet that fell to the exact problems mentioned in this thread.

Seeing as he himself fell into to the same trap I assume many new players would: making an aircraft loosly based on what you've seen in reality...

That shouldn't be a mistake! Something most new players are going to do especially shouldn't be a design mistake!

Players should be able to make aircraft like the one he did and correctly assume they will be controllable. But as we heard Maxmaps himself say, his perfectly logical looking plane was uncontrollable. Likely due to the heavy engine at the back shifting CoM too far back. I could probably go further into this but there's already enough of that in this thread...

Other players see this as a problem too squad, we just have different ideas for fixing it. http://forum.kerbalspaceprogram.com/threads/115338-A-new-paradigm-for-air-breathing-engines

Edited April 18, 2015 by DundraL