How do you make a Large Plane turn, and pitch smoothly?

[MeepTicoMeep]

So I recently decided to make a larger plane than I normally do. But whenever I make turns or pitch it goes forcefully then goes back down. I've noticed it happens around 100 m/s. I's Guessing it is drag because I learned that with my rockets. Please excuse this horrible question I have very basic knowledge on aerodynamics let alone in KSP. 

[Xd the great]

Shift + controls? Reduce control surfaces?

[MeepTicoMeep]

I didn't think of that.

Also do you know why the wings keep flopping when rolling and pitching?

[Pascovian]

hmm... maybe its the plane's mass or it's your controls? other than that, there are reaction wheels in the editor, so it's probably that

[Mad Rocket Scientist]

Are your wings properly strutted? Large planes suffer badly from wobble. Consider using autostruts to strut all wing pieces.

[MeepTicoMeep]

2 minutes ago, Mad Rocket Scientist said:

Are your wings properly strutted? Large planes suffer badly from wobble. Consider using autostruts to strut all wing pieces.

I will try that next time. 

I'll give an update tomorrow.

Edited August 23, 2018 by MeepTicoMeep

[Adsixnine]

thank

[KerbolExplorer]

If it still doesnt work can you give us the craft file?

[Vanamonde]

Your small planes probably are trying to do the same thing but the reaction wheels are strong enough to stop it on craft their size. Pictures of the plane in question would help diagnose the problem. 

[MeepTicoMeep]

So I tried Autostrut. The left wing broke off...

Craft File: https://drive.google.com/open?id=1Wq7tuzlTourZRyLYfusalGDx5UcjjVoJ

 

Here are the Screenshots:

Uh when I exited the game the Start Menu text was just blocks...

Sorry didn't get a screenshot.

Edited August 24, 2018 by MeepTicoMeep

[Pascovian]

if the text was just blocks then the problem should be in the "Squad" folder i think, but other than that, is that you have a little bit of control sensibillity or it's reaction wheels missing from the plane. 

[MeepTicoMeep]

26 minutes ago, Pascovian said:

if the text was just blocks then the problem should be in the "Squad" folder i think, but other than that, is that you have a little bit of control sensibillity or it's reaction wheels missing from the plane. 

How would you put reaction wheels on it though?

Here is it missing a wind and plummeting to death.

[Mad Rocket Scientist]

1 hour ago, MeepTicoMeep said:

So I tried Autostrut. The left wing broke off...

Sorry. 

I'm taking a look at the craft file. You may not need all that much fuel, are you making this super long distance plane?

[bewing]

OK, so the basic deal is that your wings are at your CoM. And most of your control surfaces are attached to your wings. So they are all at your CoM. And when they are at your CoM, they accomplish nothing because they have no leverage.

So your control surfaces are applying immense forces to your wings, but those forces are in the wrong place to actually turn your plane. If you only apply forces in places where they have leverage, then your plane turns nicely.

Also, wings are delicate things -- so if you apply large forces directly to them, they usually break one way or another.

Also also, with your engines so very far below your CoM, they constantly try to pitch your nose up when they are at full thrust. It's not unmanageable, but your steering does change a lot depending on the thrust levels of your engines.

So, in general:

You should not attach your engines directly to the wings -- attach them to the fuselage and use the move tool to offset them to the proper location. Same for wheels.

If you attach elevons to the wings, then autostrut each of those elevons to the fuselage -- to prevent the elevons from bending the wings.

So here's a quickly edited copy of your craft file: https://pastebin.com/raw/q2ZJsfr9

Edited August 24, 2018 by bewing

[Mad Rocket Scientist]

By the way, the problem you were having with pitch control was to do with the way KSP handles control surfaces just a little bit in front of the center of mass.

Basically, it makes them angle down, rather than up when they are in front of the CoM. This is fine when they are way in front of the CoM, and there aren't very many of them, but when lots of them are right near the CoM, bad things happen. In this case, they were making the CoL shift in weird and unpredictable ways.

The solution is to simply set the control surfaces to not control pitch right near the CoM. I changed that, and also removed a bunch of fuel from it. That makes it so it will remain stable when the fuel runs low, and also allows you to remove an entire set of engines. It still has something like 2 hours of flight time at 10km.

Here's a craft file with all those modifications, and action groups set to reverse thrust and flaps.

https://kerbalx.com/Mad_Rocket_Scientist/Kersion-K500-for-MeepTicoMeep

EDIT: Ninja'd.

Edited August 24, 2018 by Mad Rocket Scientist

[MeepTicoMeep]

17 hours ago, Mad Rocket Scientist said:

Sorry. 

I'm taking a look at the craft file. You may not need all that much fuel, are you making this super long distance plane?

I was making it long distance.

17 hours ago, bewing said:

OK, so the basic deal is that your wings are at your CoM. And most of your control surfaces are attached to your wings. So they are all at your CoM. And when they are at your CoM, they accomplish nothing because they have no leverage.

So your control surfaces are applying immense forces to your wings, but those forces are in the wrong place to actually turn your plane. If you only apply forces in places where they have leverage, then your plane turns nicely.

Also, wings are delicate things -- so if you apply large forces directly to them, they usually break one way or another.

Also also, with your engines so very far below your CoM, they constantly try to pitch your nose up when they are at full thrust. It's not unmanageable, but your steering does change a lot depending on the thrust levels of your engines.

So, in general:

You should not attach your engines directly to the wings -- attach them to the fuselage and use the move tool to offset them to the proper location. Same for wheels.

If you attach elevons to the wings, then autostrut each of those elevons to the fuselage -- to prevent the elevons from bending the wings.

So here's a quickly edited copy of your craft file: https://pastebin.com/raw/q2ZJsfr9

I was taught to make planes that the CoL is slightly behind the CoM but then when I moved the wings forwards the plane would flip and loop making it tail heavy. oof. So now I need to autostrut more.

17 hours ago, Mad Rocket Scientist said:

By the way, the problem you were having with pitch control was to do with the way KSP handles control surfaces just a little bit in front of the center of mass.

Basically, it makes them angle down, rather than up when they are in front of the CoM. This is fine when they are way in front of the CoM, and there aren't very many of them, but when lots of them are right near the CoM, bad things happen. In this case, they were making the CoL shift in weird and unpredictable ways.

The solution is to simply set the control surfaces to not control pitch right near the CoM. I changed that, and also removed a bunch of fuel from it. That makes it so it will remain stable when the fuel runs low, and also allows you to remove an entire set of engines. It still has something like 2 hours of flight time at 10km.

Here's a craft file with all those modifications, and action groups set to reverse thrust and flaps.

https://kerbalx.com/Mad_Rocket_Scientist/Kersion-K500-for-MeepTicoMeep

EDIT: Ninja'd.

Thank you both I made a quick 50 min flight to the Desert Airfield. Sort of crashed because I forgot about reverse thrust.