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Yet another airship control thread

#1
Hey, all!
I'm trying to build a fairly simple airship that will use jets to keep its altitude, then make strafing runs with a small advanced cannons, but I'm constantly running into control issues.
I've tried a number of combinations of PID blocks and AI mainframes, but none come even close to working, and I'm out of ideas.

With Pitch, Roll, and Altitude PID blocks and an Aerial AI, the ship will lose all pitch authority in an attempt to maintain its altitude, flip over, and use the forward thrusters to fly straight up. It will also constantly overcorrect for Yaw, making it only possible to aim for a brief moment.
With Pitch and Roll PID blocks and an Aerial AI, the ship will stay level and make strafing runs, but will fly upwards without limit.
With Pitch, Roll, and Altitude PID blocks and an Naval or Land AI, the ship will stay level, but not interact with the target in any way.

I've reversed the rear pitch thrusters, set maximum roll angle to 0, and done everything else I could find online to no avail. Can anyone shed some light on the issue?
The last thing is that I recognize the ship's inefficient, but in general I'd prefer to learn by doing. I appreciate that you'll likely find unrelated flaws in the design and want to help fix them, but please don't; one of my favourite things to do in this game is figure out why a particular ship sucks and remake it to be better!

Note: I posted this question a few minutes ago but now I can't find it. I'm assuming it wasn't posted correctly, but I apologize if this is a repeat.
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#2
can u upload ur craft?
ill have a look and see what i acn do
like's strange music Tongue
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#3
Thought I did, but apparently not; there you go!


Attached Files
.blueprint   Strafer.blueprint (Size: 67.79 KB / Downloads: 9)
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#4
i fixed it i think its now doing what u want

i switch to an arial AI(is better for strafer's i think the water AI want to cicle its target)
and added an yaw pid for better gun aim
(if using Arial Ais on ship u have to set the rool to turn angle to 180°)

and ur center of drag was to high i added a bit lead to counter for that


Attached Files
.blueprint   Strafer fixed.blueprint (Size: 83.4 KB / Downloads: 7)
like's strange music Tongue
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#5
That's definitely much better, thanks!
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#6
Looking at the blueprint, you had some upwards thrusters set to "main" which is incorrect and may have been responsible for some of the strange behavior you mentioned. When I tried putting an Aerial AI card on it, the thing just wanted to do loop-de-loops forever. Solving that was as easy as adding a few small downward thrusters to the nose to give the craft some way of counteracting the upward pitch.

General purpose altitude and pitch PIDs can be used together with an Aerial AI, but to prevent your AI from fighting against your GP PIDs you can add an AI pitch PID with its gain settings at zero / max / zero so that AI pitch commands are effectively ignored. Useful for making a hovercraft / airship which always faces the target, especially when combined with control blocks that send "reverse" complex commands if an enemy is too close to cause forward-thrust jets to shut down (have to give them a red input that the ACB triggers) and reverse-thrust jets to fire. Or dediblades instead of thrusters, etc. Adding an AI PID set to Yaw can also be helpful, especially with 2+ additional sideways turn thrusters added at the nose to give it better control.
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#7
A tip that will save you some trouble in these types of builds: always make sure that roll/pitch controls are redundant at both ends/sides of the craft and that each cluster can respond to positive and negative inputs.   By this I mean, always pair pitch up/down and roll left/right this will prevent small imbalances (such as slightly off-set center of pressure/center of gravity/main thrust, etc) from completely destroying the craft's stability, it also means that in the event of battle damage the ship won't become a total loss.  arranging thrusters in this manner also lets you take advantage of counter thrust, which greatly increases the responsiveness of a given craft.
-Do not bring forth an argument as fact that can be disproven with a 10 minute Google search.
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