Airplane design assistance

[stoicboss101]

Hi I posted a week or so ago about subs and got amazing tips and results, but now I'm taking to the skies and would like some pointers.

When I build a plane it has a tendency to either drop to the sea or fly up to space.
Second, when I try to use PIDs for pitch control (to keep it from becoming a sky dolphin) it also tends to head to the sea floor.

What can I do to make a good airplane? Should pids be used?
Thanks for the help guys

[luxon001]

try to avoid PIDs... at least for now.
make sure that your thrusters are at the same height as the center of mass, and use at least 1 thruster for pitching up and down...
Also set the max rotation angle on the AI to 90 degrees.

[stoicboss101]

I guess pids are unreliable? I've heard using them is really useful

[Mortus Eclipse]

For planes you want to pay close attention to your center of mass. Your main forward engines and center of drag should always be along the same plane as your center of mass. The center of drag is less important and can often be compensated by thrusters but keeping it as tight with your center of mass as possible till help eliminate more pitch wobble. Also you want your center of lift in line with your center of mass if not slightly above the center of mass, too much lift in the front or back could also cause what you described.

If you want speed you will want to use as many 4 meter slopes and corners as possible length-wise and never place anything longer than a 2 meter slope or corner width-wise toward the direction of travel. For really fast but effective aircraft (110m/s+) you are going to either want to build big (Heavy/Dedicated Bomber sized.) and use Custom Jet engines or if you want a small fighter like craft you are likely going to want to use spin block tricks to compress multiple structures into one space.

[stoicboss101]

This is the confusing thing. You want the center of drag to be behind the center of mass considerable when building in the real world, and the center of lift should be behind the center of mass as well.

I get that this is a game, but if it's so important I think it ought to be correct.

[An Ning]

actualy, in the real world you try to get the center of lift to be in line with the center of mass (for high speed aircraft, you want it in line with the center of mass at your desired airspeed, since the CoL moves back as you increase speed)...but anyways..

For aircraft in FtD, you need a few things more than just aligning thrust.

1) Ensure your roll thrusters on top have roughly equal thrust to your roll thrusters on the bottom -and that they are likewise equal to the front and back. Otherwise, when you roll, you will increase or decrease altitude (if you have more on the bottom or top respectively), or you will pitch up or down (if you have more on the front or back, respectively).
This means that an aircraft that is unstable and rolls left/right a lot (like many fighters do), can end up in space or in the water just from rolling left/right in an attempt to stay level


2) Ensure the same for pitch thrusters for the same reason


3) Have more picth thrust available than roll thrust -sometimes the AI just can't use all the thrusters efficiently,and an aircraft that you can keep level without much work,ends up at a 45 degree picth at 400 meters in a near-stall doing 20 m/s when you have a max of 70.

[stoicboss101]

The center of lift on supersonic craft is very near or even in front of the COM. Only extremely fast craft dare to place their mass and lift accordingly.
Lift force does not move as a craft flies as lift as it is a perpendicular force and independent of mass. I've never heard of that. It would make every craft unstable unless they shifted fuel around at inconvenient rates.
Combined with drag, the center of pressure moves backwards during flight but only slightly unless the craft has enough drag.

Unless you were talking about center of pressure, I'm not sure what you're talking about.

But thank you for the in-game tips

[Nobsniper]

soon the game will ahve dedicated rudders and elevators so it will be easier to make planes

[stoicboss101]

^ that sounds fantastic. the devs will have to rewrite the arial ai a bit