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KerrMü

Toggleable Lift on Wing Parts

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Hello Rocketeers and Rockets

With the spaceplane section of the game getting some love now, it might be a good time to bring this up.

Let me get straight to the point:

In KSP every wing part produces lift... and that´s a bit problematic sometimes.

On many RL planes the stabilisators/tailfins don´t provide much/any lift. They just keep the aircraft in ballance. Like this:

XdeTikg.png

So the CoL is located between the main wings and not pushed back by the tail.

To demonstrate this issue in the game, I built a plane we all know and love ;)

9CWoSZJ.png

My suggestion would be, to make the lift, which each wing part produces, toggleable or even tweakable. Basically just turning the lift off via dropdown menu would be fine. Or rather a slider?

Advantages:

- Easier plane building. Just build the body, find the CoM, put some wings a bit behind it, there you go.

- Relocating the COL would become less difficult.

- With the current system, if you angle your wings to a positive angle of incidence, but not your tailfins, then the center of lift is pushed further to the front, the faster you fly. Nearer to the CoM. Possibly resulting in unstable flight characteristics. Wouldn´t be the case with only the main wings providing lift. ( I know it´s a bit more complicated like that )

- The ability to use wings as structural elements without messing everything up. You could build whole fuselages out of wings.

- aircraft would behave more intentional.

KSP can be a brilliant tool for understanding how planes work, and why they look like they do. You can build reasonably acurate replicas in KSP, with the correct distribution of wight, the right kind of propulsion (partly with mods), but you almost always have to cheat some controlsurfaces into the nose to get the right behavior.

Personally I got into planes through kind-of-replicas, because my first own designs have been utterly, utterly bad. Then I thought, what works in real life should be good in the game, right? And yeah, it worked... kind of. But most of the time the designs were a bit nose-heavy.

Now that I know the reason for that, I wanted to make my first suggestion ever in this forum.

If you made it this far, thank you very much for reading. Please leave your opinion and thoughts.

And if you have a clue about programming (which I have not), tell me if this would be possible at all.

cu in space, Mü

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I don't think this would be a good idea, since it would make things less realistic. In real life, if something has an aerodynamic shape like a wing, it will produce lift with positive angles of attack. Allowing you to essentially disable physics for certain parts is not something that KSP needs in my opinion. In fact, I think it needs more lift simulation from parts that currently don't have it - the structural parts. Adding NEAR to the stock game would be an excellent decision and would make for much more fun and interesting airplane creation.

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Actually you want your part to produce lift (= force when at an angle of attack), in order to act as a stabilizer. Removing the lift is like removing the tail fin, or putting a fuel tank of equal weight in its place.

For the mechanic you describe, have you tried to angle the tail fin down slightly? This makes sure its angle of attack is always lower than that of the main wing. So you have fewer Lift when going horizontal (CoL in SPH), but still a correcting force when at a high angle of attack (so it still acts as a stabilizer).

For my planes this even makes the plane pitch-stable (so hands-off it always pulls to a certain pitch angle that depends on airspeed). Angling down by 5° works for me, probably less would be better. You'll also see your CoL move forward in the SPH.

PS: I don't see what this has to do with ferram, other than general bashing of stock aerodynamics. Even a flat piece of cardboard produces lift when at an angle of attack.

Edited by pellinor

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Ahem: wings do not work that way. Tail planes do provide an amazing amount of lift, often similar (when scaled for area) as the maing wing at the same angle of attack. What you're arguing for is that they shouldn't make any lift regardless of angle of attack; you're basically asking for a hologram of a wing that doesn't actually do anything.

Besides the fact that it's completely unrealistic, it's completely unintuitive: why should the player be able to change the laws of physics at their whim? This is hack gravity / infinite fuel level changing of physics, but it doesn't even have the decency to be consistent across all parts!

Even the stock aerodynamics are correct in that the tail does shift the CoL back. That's why we add the horizontal tail, to move the CoL back and make the plane more stable.

Even if it didn't betray a complete misunderstanding of how tails work (they shift the CoL back and make the plane more stable; that's their job), this would be a terrible suggestion by giving the player god powers as a standard thing and allowing inconsistencies in physical laws for no apparent reason.

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I can see how this would be useful, but I can also see how it would be really dangerous. Balancing aircraft is an incredibly tricky business. Take, for example, my passenger jet:

Xxxn9Jq.png

All of the engines are on the underside of the main wings. Without the tailplanes providing as much lift as they do, it would be unflyable. Even something as simple as giving the plane a 747-style hump messed up the CoM-CoL-CoT relationship pretty severely, which for a plane as complex as this one makes it impractical to use without pretty significant redesigns. Having tailplanes with less lift could be a good solution to KerrMu's problem, so it might be nice to get more wings parts rather than tweakable wings.

As Ferram4 said, changing physics is not a sensible solution. Oh yes, it would certainly be useful, but it wouldn't make a lot of sense to be able to change the flight characteristics of crafts on a whim.

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Where is Ferram when you need him....

Let's see if I can invoke him.

FERRAM I CHOOSE YOU!

Holy smokes, you're a forum god! You actually summoned him!

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Ahem: wings do not work that way. Tail planes do provide an amazing amount of lift, often similar (when scaled for area) as the maing wing at the same angle of attack. What you're arguing for is that they shouldn't make any lift regardless of angle of attack; you're basically asking for a hologram of a wing that doesn't actually do anything.

Besides the fact that it's completely unrealistic, it's completely unintuitive: why should the player be able to change the laws of physics at their whim? This is hack gravity / infinite fuel level changing of physics, but it doesn't even have the decency to be consistent across all parts!

Even the stock aerodynamics are correct in that the tail does shift the CoL back. That's why we add the horizontal tail, to move the CoL back and make the plane more stable.

Even if it didn't betray a complete misunderstanding of how tails work (they shift the CoL back and make the plane more stable; that's their job), this would be a terrible suggestion by giving the player god powers as a standard thing and allowing inconsistencies in physical laws for no apparent reason.

Mr. Ferram,

I think what OP meant to say is that the stabilizers do not produce lift (and negligible drag) at 0 AoA i.e. the cross section of the wing is symmetric in the horizontal plane (and thin). However, what OP failed to understand is that any wing/flat plate will produce lift (and drag) for non-zero AoA, which in turn, causes the corrective/stabilizing torque if the CoM is in front of the CoL. Thus, the CoL calculations must still include a horizontal flat plate since for non-zero AoA it will come into the equation.

AmIRight?

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I don't think this would be a good idea, since it would make things less realistic. In real life, if something has an aerodynamic shape like a wing, it will produce lift with positive angles of attack. Allowing you to essentially disable physics for certain parts is not something that KSP needs in my opinion. In fact, I think it needs more lift simulation from parts that currently don't have it - the structural parts. Adding NEAR to the stock game would be an excellent decision and would make for much more fun and interesting airplane creation.

I agree completely. Turning off wing lift would be stupid.

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cu in space, Mü

I insist you not call yourself Mü, as Mu (Pronounced the same way!) is the name of a developer of KSP. KerrMü is pushing it, but acceptable.

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...have you tried turning the angle of attack of the tail plane? has a pretty profound effect on the center of lift..

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On many RL planes the stabilisators/tailfins don´t provide much/any lift. They just keep the aircraft in ballance.

Erm... They keep aircraft in balance by providing a lift. When you have positive AoA, tailfin provides lift, forcing tail to go up and the whole aircraft to pitch down. When you have negative AoA, tailfin provides downforce, forcing tail to go down and the whole aircraft to pitch up. I don't think KSP simulates that because you have a single center of lift, but I think tailfins provide drag, which gives similar effect, forcing aircraft to stick to velocity vector.

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