public void updateCamera() {
        rootNode.updateGeometricState();

        Vector3f pos = spaceCraft.getWorldTranslation().clone();
        Quaternion rot = spaceCraft.getWorldRotation();
        Vector3f dir = rot.getRotationColumn(2);

        // make it XZ only
        Vector3f camPos = new Vector3f(dir);
        camPos.setY(0);
        camPos.normalizeLocal();

        // negate and multiply by distance from object
        camPos.negateLocal();
        camPos.multLocal(15);

        // add Y distance
        camPos.setY(2);
        camPos.addLocal(pos);
        cam.setLocation(camPos);

        Vector3f lookAt = new Vector3f(dir);
        lookAt.multLocal(7); // look at dist
        lookAt.addLocal(pos);
        cam.lookAt(lookAt, Vector3f.UNIT_Y);
    }
initial orientation of the tank (in world/physics-space coordinates)
jme3-examples/src/main/java/jme3test/bullet/TestHoveringTank.java