Post
by Oracle427 »
As a teaching tool, I think it might be nifty to show what A2A has computed the W&B moment and inches as so that one can compare their answer to the software. The user would still need to follow their own process to compute and verify the values themselves.
In the C172 POH W&B section, there are two chart that shows if the computed CG and moments are within the fore/aft limits.
This is computed using the information about "stations" as depicted in the POH. The pilot inputs the weight at each station and then multiplies the weight by the distance of the station from the reference point which is at about the firewall on a C172. This will provide a lb-in moment for each weight.
In the POH, the average positions for each station are: front seats 37, rear seats 73, baggage A 95, baggage B 123, fuel 48. Best to download the POH and have a look at the W&B section for details.
Sum all the weights up, sum all the moments up and then divide the total moments by the total weight. The answer is your computed CG position in inches. This is important to determine if the aircraft will perform within the parameters as it was tested for certification.
The second check is to see if the moment vs the total aircraft weight is within range as that will relate to the effectiveness of the controls.
There are two boxes in the graphs as the aircraft is also certified for the utility envelope under tighter CG and moment limits.
It only takes a couple of minutes to do a W&B form. I don't know if we have an actual CG and moment arm for the airplane that the A2A 172 was modeled after. You can slap together a spreadsheet to do this in a couple of minutes and just revise the weights of fuel and px during your preflight preparation.
Flight Simmer since 1983. PP ASEL IR Tailwheel
N28021 1979 Super Viking 17-30A
