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You can not flight test structural integrity and strength of an airframe and live to tell about it. Therefore Ted's original comment that flight testing is an acceptable substitute for engineering analysis is misinformed and naive. Ted's subsequent comment that "A good test pilot should be able to nibble at that edge of the envelope to identify a flight limitation" is equally absurd in the context of structural integrity. A structural failure, when it happens, is likely to happen without any warning or the opportunity to rectify things. As I wrote earlier, the goal of flight testing is to validate engineering analysis, not as a substitute for it. Regards, Hamid John Hafen wrote: Hamid: Sorry for this ignorant question: How do you flight test the structural integrity and strength of an airframe and survive to do anything about it? You can't bail out of an IVP. And you would lose the plane anyway -- a plane that is unique. What am I missing? John Hafen -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Hamid Wasti Sent: Wednesday, May 09, 2012 10:39 AM To: lml@lancaironline.net Subject: [LML] Re: Necessity of A/C in IV-P? Ted Noel wrote: 3. Flight testing with a competent test pilot. I think #3 is best since it deals with the variabilities of the installation and creates a hard VNE number. Does it? How much margin do you have? Testing is intended to validate engineering analysis, not to substitute it. Also, there are a lot of A/C installations flying. This implies a degree of safety. Does it? How does your installation compare to the flying installations? How much safety margin do they have and how much will you have? How far have they pushed their airframe (intentionally and unintentionally) and how far will you push yours? All that the flying installations indicate is that no one has done anything in their aircraft that has led to the airframe failing due to the modifications. Maybe there is enough margin that it has not compromised safety at all. Maybe it has cut deeply into the safety margin and there have been a lot of very close calls that no one has known about. Without a real engineering analysis taking the big picture in mind, no one really knows. Regards, Hamid -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html