Any of you guys use the RA4 profile instead of the G1?(Posted the following in the other thread last night but it is equally applicable to this thread so...)
You’re right. I misunderstood when I watched it the first time. I thought he was extrapolating between two different states of tune. My apologies for adding to the confusion already swirling, and thank you for the polite correction.
Looking back at Ted's video again just now, I notice in his Chairgun screenshots that he is using a custom drag profile...which means there is a very simple but not so satisfying answer: the drag profile is wrong. If it were correct, the BC would not vary with velocity. That's the whole point of a drag profile.
Elsewhere Bob Sterne pointed out that ballistician Miles Morris found the commonly used G1 profile is wildly off in the transonic region for typical slugs, so if Ted used it as the starting point for his custom profile, that would represent a significant source of the discrepancy.
The good news here is that drag doesn't mount up nearly as quickly as we approach the speed of sound as we might have expected based on the "best we got right now" G1 profile.
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