PPRuNe Forums - View Single Post - PA-28-181 Vno below Vc minimum design speed?
Old 4th Dec 2018, 01:06
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AC103
 
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Haaaaang on.. I know it doesn't strictly apply to 3.184 but from AC 23-19A - Airframe Guide for Certification of Part 23 Airplanes p.26-27

46. Why would I want to define VC as equal to 0.9 VH? Use this definition if you are designing an airplane that is capable of a sustained speed (VC) higher than that obtained by using the wing loading (W/S) formula.
So The PA-28-181 Archer III does not seem to be compliant with Vc min regs, it looks be 7MPH short. Other PA-28s Cessnas etc. appear OK but not the Archer III:
Vc min for 15lbs/sq.ft wing loading = 147mph CAS
PA-28-181 Vno = 140mph CAS

§ 3.740 Maximum structural cruising speed
(Vno). This operating limitation shall be:
(a) Not greater than Vc chosen in accordance with § 3.184.
(b) Not greater than 0.89 times Vne established under § 3.739.
(c) Not less than the minimum Vc permitted in § 3.184
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