Old 30th May 2020, 01:47
  #30 (permalink)  
djpil
 
Join Date: May 2002
Location: Melbourne, Australia
Posts: 1,111
Originally Posted by AC103 View Post
What they were actually providing for is later clarified in AC 23-19A - Airframe Guide for Certification of Part 23 Airplanes p.26-27
Much later, after the fact. That AC wasn't written until after myself and others had gotten out of the game.

Originally Posted by AC103 View Post
If the regs were written as follows there would be no question on the interpretation
Interpretation of the rule by that AC means that text itself is only guidance so why is it in the regulation? If just guidance it should only ever be in guidance material.

Originally Posted by AC103 View Post
This begs the question what are they 'providing' for.
After calculating Vcmin by that formula read the next line "(2) For values of W/S more than 20, the multiplying factors may be decreased linearly with W/S to a value of 28.6 where W/S =100." So, if applicable, we can redo the calculation of Vcmin using a lower multiplier, despite (1) stating "Vc(in knots) may not be less than" the number we had first calculated. So move onto the next line (3) as another rule that allows us to change the number first calculated.

I distinctly recall my old Uni lecturer, Henry Millicer, telling me about FAR 23 flight envelopes as above. He was fresh from being Chief Designer of the Aircruiser back in the '60s. The CT/4 was developed from the Aircruiser and the current model, the CT/4E (aerobatic, higher weight than earlier variants and 50% more power), has a Vc of 147 kts (same as previous variants) per the NZ TCDS but my calculated Vcmin is 162 kts.
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