Thread: Discussion fuselages
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Old Jul 17, 2012, 08:51 AM
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G_T
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People would have thought at one time that the drag of control surface linkages would also be lost in the total noise... The lower drag the plane has from other sources, most notably at high speeds, the greater any single drag source stands out. Drag gives you sink rate and costs L/D.

The flow past the widest point of the nose of the fuselages is going to be turbulent. On a poorly designed fuselage, or one that is rough, it will likely be turbulent even in front of that. That turbulent wake has drag, and it has width. It hurts the performance of the wing and tails downstream as it guarantees they cannot have any region of laminar flow. Think of it as the equivalent of having very dirty surfaces. On the Supergee-II the wing was located above the turbulent wake from the fuselage. There are costs associated with such an approach, but it has that benefit.

Even just from a surface area perspective, one is adding a fair bit when one goes fatter.

During a turn, and particularly during a launch, the fuselage does not present a perfectly point forward perspective to the airflow. On launch, there is the fishtail. During a turn, the relative airflow is curved. Bigger does not have to be draggier for arbitrary shapes but smaller of the same shape will be less draggy.

Gerald
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Last edited by G_T; Jul 17, 2012 at 08:54 AM. Reason: clarity
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