Creative Speculation
In reply to the discussion: Skygate 911 [View all]William Seger
(10,923 posts)You're not going to post that bullshit "no additional FoS" diagram somewhere that real aeronautical engineers might comment on it because you don't believe Rob Balsamo, either. And you should know, I guess.
> All you have to do is post the requirement of a FoS beyond Vd for a maneuvering aircraft.
FAR 25.301 (a) says, "Strength requirements are specified in terms of limit loads (the maximum loads to be expected in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). Unless otherwise provided, prescribed loads are limit loads." FAR 25.303 says, "Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure." FAR 25.305(e) defines one of the "prescribed limit load" cases: "The airplane must be designed to withstand any vibration and buffeting that might occur in any likely operating condition up to VD/MD, including stall and probable inadvertent excursions beyond the boundaries of the buffet onset envelope." Your misreading of that as only meaning g-loads is belied by the fact that those quotes are from the "Structural - General" section, whereas the section after that is called "Flight Loads" which 25.321 defines as, "Flight load factors represent the ratio of the aerodynamic force component (acting normal to the assumed longitudinal axis of the airplane) to the weight of the airplane." That would be those loads shown in a Vg diagram, and that section doesn't specify an FoS because it's already specified in the General section. You irrationally claim the 1.5 FoS only applies to g-loads just because Vg diagrams only show a 50% margin of safety for g-loading and a red line at Vd, but making that assumption just proves that you don't really understand structural engineering or the actual definition of Vd. It's an understood redline on the flight envelope because you really don't know how far over that you can go without structural failure, and you don't want to find out. But Vd is a speed made safe by "over-engineering," your interpretation of Vg diagrams notwithstanding. You're reading something into them that isn't there. Those diagrams don't tell us anything about maximum speed that the Vd number alone doesn't tell us, and you obviously don't understand what that is.
Your claim about "impossible speeds" is nothing but an argument from personal incredulity, and if that weren't bad enough, your incredulity turns out to be based on faulty logic protected by stubborn ignorance. You don't know the true maximum speeds of 757s and 767s because nobody does. Out here in the real world, however, the events of 9/11 gave us some insight into that.
Unless you post your diagram and your argument somewhere you can get some feed back from professional aeronautical engineers, it's game over, and we both know why you're not going to do that. Please don't waste everyone's time by endlessly repeating the same bullshit arguments and pointless diversions over and over.