Lee Coll Posted July 13, 2019 Share Posted July 13, 2019 I am trying to create an aerodynamic "ring" that will represent the forward inlet of a jet engine nacelle. The nacelle itself is circular in cross section and proved easy to model. The inlet ring however is deeper at the top than the bottom. I have attached an image showing the thick and thin profiles in their position above the rest of the nacelle. How can I create a ring (or half ring) with the lower (right) profile and the upper (left) profile as shown? I have tried taking a semicircle and changing it to a NURBS curve, to use as a path and using the small profile Extrude Along Path with an increase in scale of 1.5X as it sweeps 180°. The problem is, the base for both profiles are identical in dimension. Scaling it all, widens the extrusion inaccurately. Have also tried lofting, but no luck there, again using a NURBS semi-circle as a rail. Have also tried subtracting cylinders then loping a wedge out of the top to provide a tapered ring, which when filleted, does not come close to the profiles required. Any ideas? Quote Link to comment
Popular Post Benson Shaw Posted July 13, 2019 Popular Post Share Posted July 13, 2019 (edited) You can get really close with a Loft No Rail Make croquette hoops for the various profiles around the inlet. I made a 2d poly, then, duplicate, raise the top edge with Select Tool My lift was in even increments between initial and max height, but you would know more about what is needed. Convert them to NURBS and array them around the circle or other shape. Loft -No Rail. It misses the circle just a bit between the hoops. More hoops will get closer to the circle. Other than that, maybe try Sub Division. Others will have to show that one. -B Jetv2019.vwx Edited July 13, 2019 by Benson Shaw Loft instruction 7 Quote Link to comment
Lee Coll Posted July 13, 2019 Author Share Posted July 13, 2019 Thank you Benson - will try that now. Quote Link to comment
Benson Shaw Posted July 13, 2019 Share Posted July 13, 2019 @Lee Coll Welcome. I love lofting. I explored a bit more. I think the Loft - One Rail mode is even better. Convert the outer circle to NURBS for the rail. Outer boundary stays circular. Inner boundary more circular if more hoops. The intermediate hoop heights also can control a varying shape to the top "edge". I exaggerated the hoop heights for more drama. (front view, use Select tool handles. Mirror as needed) If the desired shape is known, use that data to draw the profiles. My hoops all have same width aiming at circular inner boundary, but that's not necessary for the loft to succeed. Also tried Model menu> 3d Power Pack>Create Surface from Curves. But couldn't make it work. Post back with your results, or if more help needed. Good luck! -B The loft conforms exactly to the outer rail. The inner rail appears to be circular. 3 Quote Link to comment
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