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#31
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"Greg Esres" wrote in message
news Then you haven't read Part 23. Yes, I have. Let me point out the sections to you: Those sections stipulate, given an existing Va, how the control surfaces must be designed. They do not in any way define Va. The point is that at Part 23 doesn't require this. And not all aircraft publish such variations. You are still hung up thinking that Part 23 is what makes airplanes fly. Again, you didn't read what I wrote. I said it doesn't scale UP. Flying over max gross may increase maneuvering speed, but it doesn't increase VA, because the increased weight won't protect control surfaces from failure. In this context "maneuvering speed" is synonymous with "Va". Yes, you're right, there is only ONE Va. But in the world of piloting, we commonly understand the shorthand "Va" to mean "maneuvering speed at a given aircraft weight" where the weight is changeable. Tangent? It's the essence of what Va is. Not in this context it's not. I seriously doubt Todd has told you that Va remains the same regardless of aircraft weight. You obviously misunderstood him. Ok, you read what he wrote and tell me: If you think that he was explaining the aerodynamics of maneuvering speed, you misunderstood him. If you don't think that he was explaining the aerodynamics of maneuvering speed, then your comments based on that quote are irrelevant to this thread. Pete |
#32
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"Tony Cox" wrote in message
hlink.net... Greg is right. They really ought to have invented another term for it. That's not what Greg said. I don't see why a whole thread that is really about aerodynamics needs to be co-opted by the terminology police. The original question was clear enough in its intent. The OP isn't asking about how to meet FAA certification standards. He's asking about over-gross operations and their effect on airplane performance. Pete |
#33
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"Peter Duniho" wrote in message
... "Tony Cox" wrote in message hlink.net... Greg is right. They really ought to have invented another term for it. That's not what Greg said. I don't see why a whole thread that is really about aerodynamics needs to be co-opted by the terminology police. The original question was clear enough in its intent. The OP isn't asking about how to meet FAA certification standards. He's asking about over-gross operations and their effect on airplane performance. Pete Well, I'm certainly not the terminology police, and I'm awfully reluctant to get confrontational, especially with the holidays about to start. But there is an important point here, and one that I'd not appreciated before this discussion. The fact is that under pt 23, the often-quoted Va speed isn't in fact the speed at which you can apply full control deflection without risk of structural failure. Va is determined by control constraints, and by the requirement that it must be = Vs*sqrt(n). This means that it is quite possible (although, I'd proffer, unlikely) for the POH value of Va to be above the value where you'd risk exceeding the load factor. I think this is an important safety point, unappreciated by many (and until just recently, by me too). Cheers & happy holidays. -- Dr. Tony Cox Citrus Controls Inc. e-mail: http://CitrusControls.com/ |
#34
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we commonly understand the shorthand "Va" to mean "maneuvering speed
at a given aircraft weight" where the weight is changeable. Then what is commonly understood is not correct, because that's not how Va is *necessarily* determined. Not in this context it's not. PARTICULARLY in this context. The control surfaces were designed with withstand full movements at PUBLISHED Va, not his new, derived, HIGHER Va. |
#35
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TC: Greg is right. They really ought to have invented another term
for it. PD: That's not what Greg said. GE: Greg said exactly that. He said "They really should have called it something else, IMO." co-opted by the terminology police. No communication takes place without an agreed-upon vocabulary, which is why technical disciplines define terms very precisely. Equating "Va" to "maneuvering speed" is commonly done, but it's sloppy. You can scale both speeds down with weight, but you can't scale Va up. |
#36
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Michael,
In Alaska, Part 135 operators can get the max gross raised by up to 15%, depending on the airplane. Do you have a reference for this? I've chased it a couple of times but can't find it (I'm assuming I'm looking in the wrong places); all I've found is for an increase for a few very old Dept of Commerce or CAA certified airplanes such as Stinson Trimotors and so forth, nothing modern. If you've got a reference, I'd appreciate it. All the best, Rick |
#37
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I began wondering
about the effects of an overweight takeoff within C.G. limits. This is impossible. As soon as you go over gross you are out of CofG by definition. Paul |
#38
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"Greg Esres" wrote in message
... PARTICULARLY in this context. The control surfaces were designed with withstand full movements at PUBLISHED Va, not his new, derived, HIGHER Va. There are any number of structural issues raised by overgross flight. It was clear to me which one he was asking about, and the control surfaces ain't it. |
#39
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"Paul Cook" wrote in message
... I began wondering about the effects of an overweight takeoff within C.G. limits. This is impossible. As soon as you go over gross you are out of CofG by definition. I guess that depends on how you define "out of CofG". I define it as not within the fore and aft limits for the position of the center of gravity. Under that definition, you certainly can still be within those limits while being above the maximum gross weight. I prefer to use the term "out of weight & balance limits" as the general term for being overweight or out of the CG limits or both. Though, if only overweight or out of CG limits, I'd actually prefer to just use the term that actually describes the condition. Pete |
#40
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"Paul Cook" wrote:
This is impossible. As soon as you go over gross you are out of CofG by definition. Paul Actually not by definition. CofG (Centre of Gravity) is the balance part of weight and balance. It is measured in distance from a datum. There are no weight units in CG. |
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