# Modelling a fin and rudder for a plane

**URL:** <https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004>\
**Category:** Modeling Questions\
**Created:** [May 18, 2024, 10:32pm UTC](https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004 "2024-05-18T22:32:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![RTFM](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/rtfm/32/21385_2.png) [@RTFM](https://discourse.shapr3d.com/u/RTFM)\
**Post date:** [May 18, 2024, 10:32pm UTC](https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004/1 "2024-05-18T22:32:25Z")

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Of all the things in S3D, the ones I find most confusing are lofting and subtracting. I just don’t get the logic. I currently have a profile of a fin and rudder for my full-size plane. I also have the airfoil shape (I’m using half the shape, so I can join them later and get a perfect centre line). What I’m trying to do is to somehow intersect the two shapes leaving the fin/rudder with the airfoil shape.  
[Fin and rudder.step](https://discourse.shapr3d.com/uploads/short-url/3f5LBrjZIe6Ny3ATZTVIcXGWINH.step) (170.3 KB)  
[Fin and rudder 2.step](https://discourse.shapr3d.com/uploads/short-url/mFTjDNxxUOasyVeg2VxVT2PCPQw.step) (170.4 KB)

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**Author:** ![Shaun](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/shaun/32/18786_2.png) [@Shaun](https://discourse.shapr3d.com/u/Shaun)\
**Post date:** [May 19, 2024, 12:47am UTC](https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004/2 "2024-05-19T00:47:13Z")

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Hi mate,

Sorry I’m unfamiliar with aircraft lingo. Is this what you’re trying to achieve? If it is then I’d be happy to explain it further for you.

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**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [May 19, 2024, 6:29am UTC](https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004/3 "2024-05-19T06:29:25Z")

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May be help too:

[![](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/2/9/29f93e46fb63a4c191a3e3cdbd56430aefefa507.jpeg "Fin with loft 2 in Shapr3D") ](https://www.youtube.com/watch?v=295MapU279k)

Or:  
[https://www.instagram.com/tv/CkSiZhDtgP9/?utm\_source=ig\_web\_copy\_link&igsh=MzRlODBiNWFlZA==](https://www.instagram.com/tv/CkSiZhDtgP9/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA==)

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**Author:** ![RTFM](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/rtfm/32/21385_2.png) [@RTFM](https://discourse.shapr3d.com/u/RTFM)\
**Post date:** [May 19, 2024, 9:59pm UTC](https://discourse.shapr3d.com/t/modelling-a-fin-and-rudder-for-a-plane/32004/4 "2024-05-19T21:59:41Z")

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Hi. Nope - I did that and one ends up the the inverse of what is required. Basically I need to end up with the two pieces (fin/rudder( not simply square lofted, but with their plans cut out of the smooth airfoil shape.