Does anybody understand why Type Certificate gross weights may not match simple scaling rules?
For example a plane is certified in Aerobatic Category, Utility Category and Normal Category as follows:
Normal category: -1.9 g to +3.8 g at 1800 lb max
Utility category: -2.2 g to +4.4 g at 1560 lb max
Acrobatic category: -3.0 g to +6.0 g at 1500 lb max
Why wouldn’t this follow a simple scaling law, for example a limit at 1560 lbs = (1500/1560)*6 = 5.76 g, instead of the Utility Category limit of 4.4 g.
Are the range on CG position and Vne and other speeds the same for all categories?
One reasons could be that utility is limited by the gust envelope rather than the manoeuvring one.
Could also be due to the history of the certification. Maybe aero category was added later with better data, test results or calcs and the manufacturer didn’t go through the hoops of updating the other categories
The forward CG limit is 2 cm further forward when in Normal category (and higher gross weight) relative to Aerobatic category. Utility category is somewhere in the middle. The aft CG limit is unchanged regardless of category. Vne is unchanged. The detail of the limitations strikes me as being ‘over engineered’.
Since I know nothing about gust loading that’s something to learn about… Thanks for the suggestions!
