{"id":267,"date":"2011-05-14T17:17:02","date_gmt":"2011-05-14T23:17:02","guid":{"rendered":"http:\/\/www.velocity-xl.com\/blog\/?p=267"},"modified":"2011-08-05T06:50:17","modified_gmt":"2011-08-05T12:50:17","slug":"267","status":"publish","type":"post","link":"https:\/\/www.velocity-xl.com\/blog\/2011\/05\/14\/267\/","title":{"rendered":"11.1.5 NACA Duct modification"},"content":{"rendered":"
This entry is part 3 of 17 in the series 11 - Fairings<\/a><\/div><\/div><\/div>

The NACA ducts provide cooling air to the engine. To obtain the maximum airflow (in my opinion) the path must be as smooth as possible. But I noticed a problem with this.<\/p>\n

Here’s a picture looking up at the back of the pilot side NACA duct.
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When the engine cowling is installed, there will be about an 1\/8″ flange on the inside of the top of the duct.<\/p>\n

To illustrate, here’s a couple of drawings<\/p>\n

Here’s the “big picture”. Looking at the right side of the airplane at the top. To the right would be the front of the plane, left is the rear and the vertical line is where the engine cowling meets the aft end of the fuselage. The circle shows the area of interest.<\/p>\n

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This is the enlarged view showing the bottom of the duct (sloped) and the top\/rear of the duct.<\/p>\n

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Here’s the same view but with the cowling installed (Red).<\/p>\n

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Now instead of a smooth surface along the top, there’s a “step”. The other problem is that the factory ducts are missing an important feature which is a large radius along that top lip.<\/p>\n

And now my solution. I’m going to glue a strip (Blue) in front of the engine cowling which will be the same thickness as the flange.<\/p>\n

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This will accomplish 1) smooth surface on the inside 2) a thicker radius and 3) a more rigid surface across the top of the duct.<\/p>\n

Here’s the same view as before with the strip installed.
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Then it’s time for Malcolm to work his magic. Creating a proper, uniform radius is an artistic thing. And I’ve come to learn that when it comes to something like that, it’s best left to Malcolm.<\/p>\n

It was hard to get a picture of the leading edge of the lip. This is the best I could do.
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This entry is part 3 of 17 in the series 11 - Fairings<\/a><\/div><\/div><\/div>

The NACA ducts provide cooling air to the engine. To obtain the maximum airflow (in my opinion) the path must be as smooth as possible. But I noticed a problem with this. Here’s a picture looking up at the back … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[8],"tags":[],"series":[35],"class_list":["post-267","post","type-post","status-publish","format-standard","hentry","category-8","series-11-fairings"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/posts\/267","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/comments?post=267"}],"version-history":[{"count":3,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/posts\/267\/revisions"}],"predecessor-version":[{"id":277,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/posts\/267\/revisions\/277"}],"wp:attachment":[{"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/media?parent=267"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/categories?post=267"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/tags?post=267"},{"taxonomy":"series","embeddable":true,"href":"https:\/\/www.velocity-xl.com\/blog\/wp-json\/wp\/v2\/series?post=267"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}