How to simulate aero of deployable canards? [SOLVED]

[Kurld]

I've been working on my Launch Escape System again. It's modeled after the one from the Apollo spacecraft. I have revised the nose-cone part to have animated canards. I created the part and animation in Blender and imported that to Unity. The animation simply rotates the two child objects around their two axes (I don't have any rigging in other words). Then I wrote a simple plugin to listen for the Abort action, and to deploy the canards (activate the animation) after 11 seconds.  Everything so far is working the way I want:  I abort, and 11 seconds later the canards pop out.

What I am still really confused about is how to simulate the actual aerodynamics of the canards.  In real life, when the canards deployed, they shifted the center of pressure of the escaping CM such that it became aft of the center of mass and thus the CM re-oriented so that it was pointed retrograde.

I've tried fooling around with the drag cubes for the nosecone, vastly increasing the area and coefficient of drag of the "deployed" state of the part in the X dimension, hoping it would act like a big lollipop and catch enough of the airstream to cause the CM to flop around the Z axis, but that didn't seem to work.

I've also tried dynamically adding a ModuleLiftingSurface to the part, but that didn't seem to work either. I don't ever see any lift when I turn on the aero overlays.  If I had been smart enough to copy down the code I tried I would paste it here. But I wasn't that smart and now I don't remember where I copy-pasted that code from.

My next guess is having some kind of control surface, which is, of course what a canard is.  I just don't understand what I need to do next, or even if it is possible. Most of what I've seen in these forums is for control surfaces that respond to user input. I don't need that... I need something that either generates no lift, or else, once deployed, is locked into a specific orientation. Which to me is what a wing does. But like I say, I couldn't figure out how to make that work.

Can anybody point me (and my CM...) in the right direction?

Thanks!

Edited June 11, 2016 by Kurld
solved!

[Kurld]

OK, I figured out I had the part oriented wrong to work as a wing.  Once I got the Z-axis pointing the direction I want the lift, things started to gel.  I have a ModuleLiftingSurface on the part with deflectionLiftCoeff = 0.  Then at the point where the deployment occurs, the plugin code sets that value to 1 (arbitrary) and now the part flops around like I want it to.

Part cfg:

	MODULE
	{
		name = ModuleLiftingSurface
		useInternalDragModel = False
		deflectionLiftCoeff = 0
	}

plugin code:

        private void DeployCanards()
        {
            _hasDeployed = true;
            Debug.Log("PEBKAC LES deploying canards");

            // start the animation
            if (_deployAnimation != null)
            {
                _deployAnimation.Toggle();  
            }

            // update the ModuleLiftingSurface
            if (_liftingSurface != null)
            {
                _liftingSurface.deflectionLiftCoeff = 1f;
                _liftingSurface.useInternalDragModel = true;
            }

        }

 

[flywlyx]

Does it works with FAR?

[Kurld]

On June 17, 2016 at 4:39 PM, flywlyx said:

Does it works with FAR?

I don't use FAR, so I have no evidence either way. Assuming it doesn't mess with the implementation of ModuleLiftingSurface, I'd expect it to work.