Easier - add weight sensors to the landing gears. A set of piezo sensors between the mounts and the frames should suffice. Only three sensors to calibrate and maintain, they can give a real-time indication of the actual balance of the aircraft (including fuel), and don't impose on the airline's customers (or staff, other than to move a few people around to correct for a bad CG, something they do today).
I remember thinking this as the obvious answer as well, but then reading a few forum threads discussing that these already exist but were not reliable enough to rely on.
That was some time ago, I wonder if the situation has changed any.
That just shifts the cost to software, which is really complicated and expensive when you're talking about avionics software and airline ticketing systems.
If you do that, you need to synchronize the check-in scale with the aircraft, and the ticket-assigned seat with the weight. You also need to hope they're not gate checking much luggage (which could shift the CG resulting from their weight a lot) or crowding too much and putting two people on the scale.
But yes, the idea to minimize the number of sensors is a good one. I think the ideal place for this would be a pressure sensor within the oleo struts of the landing gear. High-resolution hydraulic pressure sensors are readily available. There would be some static friction errors (I've tried this with hydraulic cylinders, but it's reasonably close. And inducing a little dither in the hydraulics takes out most of the error.) Then you would know while waiting for take-off exactly where the CG was! And all that could be directly wired to and managed by the hard real-time avionics and electronics on the plane, and displayed to the instrument panels where it's actually needed.
...and running a Google search for 'oleo strut pressure sensor center of gravity', it appears there are already multiple patents for similar systems from 30 years ago and older.
> But yes, the idea to minimize the number of sensors is a good one. I think the ideal place for this would be a pressure sensor within the oleo struts of the landing gear.
Yup, this exists.
> In its final report on the Fine Airlines accident, the Safety Board discussed the Sum Total Aft and Nose (STAN) system, which is an electronic system installed on some cargo airplanes that allows flight crews to verify an airplane's weight and balance before departure. According to the report, the STAN system uses pressure transducers to convert main gear and nose gear shock strut air pressure to an electronic signal. The system then provides flight crews with a digital readout in the cockpit (on the flight engineer's instrument panel) of the airplane's gross weight and CG values.