enderw88
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- Feb 24, 2014
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I'll post this here since there is not an Aero section. Over in the techniques section we were discussing whether or not it was worthwhile to put fillets on the interior fin-BT joint. The general consensus was that it is worthwhile. There was some disagreement over my claim that external fillets reduce drag overall by reducing interference drag at the fin-BT junction. Rather than moving off topic on that thread the question here is NOT whether external fillets are necessary from a structural point of view, that is undisputed. But whether or not they increase the amount of drag over not having them at all.
Like any hard question there appears to be little published data on this. Using Fluid Dynamic Drag by Hoerner and some high school algebra and physics I explain my claim. The math is difficult to read with the formatting available on this forum (no WebMath or MathML, yuck)
Let me know if you think I erred somewhere or made an assumption you think is cheesy. It's happened before.
View attachment InterferenceDrag.pdf
Like any hard question there appears to be little published data on this. Using Fluid Dynamic Drag by Hoerner and some high school algebra and physics I explain my claim. The math is difficult to read with the formatting available on this forum (no WebMath or MathML, yuck)
Let me know if you think I erred somewhere or made an assumption you think is cheesy. It's happened before.
View attachment InterferenceDrag.pdf