@nullstack
Here's one I use but it's just a quick one that doesn't collide with the tilemap. Maybe it will help.
var _blood = new FlxEmitter().loadParticles(new FlxSprite().makeGraphic(1, 3, 0xFFFF0000).graphic, 50);
_blood.launchAngle.set(-135, -45);
_blood.speed.set(120, 240);
_blood.acceleration.set(0, 300, 0, 480);
_blood.lifespan.set(1);