Re: Heron flightplanning
Posted: 22 Jan 2014, 21:37
Worth bearing in mind that the datum is a completly arbitrary point, on a lot of aircraft it's in front of the nose which handily means you don't have to bother with positive and negative arms when you're doing your maths. You don't particularly need the datum point marked on the aircraft as you already know the moment arms to all the places you're going to put stuff, it would only really be of use if you wanted to load something in an unusual position and you needed to measure it but even then it wouldn't be vital as you could measure reference a known point.
Regarding units, you can have any combination of weight and distance units as long as you're consistent. For instance if you were in a metric country flying an aircraft designed in imperial units it wouldn't be out of the question to weigh everything in kilos but still use inches for the measurements as long as you had the CoG chart in KG which would be relatively easy to do by just converting the units on the weight axis. This has the advantage of only doing the conversion once rather than for every passenger. Having said that a lot of aircraft have a metric and imperial CoG chart.
Regarding units, you can have any combination of weight and distance units as long as you're consistent. For instance if you were in a metric country flying an aircraft designed in imperial units it wouldn't be out of the question to weigh everything in kilos but still use inches for the measurements as long as you had the CoG chart in KG which would be relatively easy to do by just converting the units on the weight axis. This has the advantage of only doing the conversion once rather than for every passenger. Having said that a lot of aircraft have a metric and imperial CoG chart.