The airspeed sensor you have is probably fine. They're all noisy because they all mostly use the same sensor IC. There's a new IC that Philip is working with for a CAN airspeed sensor that should be much better, well see. Not available yet, but you would be a great candidate for alpha/beta testing when we get there.
Generally, on a good calibration you'll get upwards of 3.5 m/s airspeed while on the ground. Any more than that and you'll want to do another calibration... And that requires a computer.
How about we add a joystick combo to trigger airspeed Cal? Like.. while disarmed and have sticks outward and up, opposite to arming, we could trigger a Cal. Do you have a favorite combo you'd like to propose? Do any other autopilot systems trigger airspeed Cal with RC inputs that we could copy the joystick scheme so we don't fragment from the community's expectation?