{"id":1242,"date":"2018-09-09T22:19:57","date_gmt":"2018-09-09T12:19:57","guid":{"rendered":"http:\/\/leederville.net\/rocket\/?p=1242"},"modified":"2018-10-28T20:43:10","modified_gmt":"2018-10-28T10:43:10","slug":"creating-the-fins","status":"publish","type":"post","link":"https:\/\/leederville.net\/rocket\/index.php\/2018\/09\/09\/creating-the-fins\/","title":{"rendered":"Creating the fins"},"content":{"rendered":"

Getting the basic fin cut out<\/h2>\n

The fins are created from 2.4mm thick G10 plate. I created a clipped delta design and created a jig that I would use to sand the three fins down to the correct IDENTICAL size. Below is a picture of this jig.<\/p>\n

\"Jig<\/a>
Jig with nothing in it. Right angle Iron back is what we use as a guide when sanding.<\/figcaption><\/figure>\n
\"Jig<\/a>
Jig with Fin it. We use a G-Clamp to hold it in place.<\/figcaption><\/figure>\n

I have used a Steel right-angle bar to sand up against. Here are some pictures of the fins.<\/p>\n

\"Cut-out<\/a>
Cut-out to give us approx dimensions to cut the G10 material.<\/figcaption><\/figure>\n
\"All<\/a>
All fins cut out and sanded using the jig and all identical.<\/figcaption><\/figure>\n

 <\/p>\n

Profiling the fins<\/h2>\n

I wanted the fins to have a profile suitable for less than speed of sound. While they will travel greater than speed of sound for some motors, for the majority of the flight they will be travelling below the speed of sound. I also choose this design because it is relatively simple to produce.<\/p>\n

 <\/p>\n

\"Taped<\/a>
Taped up ready for sanding. Areas taped are the areas we do NOT want sanded.<\/figcaption><\/figure>\n

I did all this work by hand. I started by drawing the boundaries of the sanded regions. I even drew a line down the thickness (half way) on leading and trailing edge.<\/p>\n

Here are a tonne of photos showing this process.<\/p>\n

\"Carefully<\/a>
Carefully sanding the rear of the fin.<\/figcaption><\/figure>\n
\"Carefully<\/a>
Carefully sanding the forward section of the fin.<\/figcaption><\/figure>\n
\"Reviewing<\/a>
Reviewing the sanded surface.<\/figcaption><\/figure>\n
\"Carefully<\/a>
Carefully sanding the rear of the fin.<\/figcaption><\/figure>\n

 <\/p>\n

Surface Preparations for Epoxy<\/h2>\n

It is very important to do all fin preparations BEFORE we attach them to the air-frame; it is a lot easier to do.<\/p>\n

I\u00a0sanded the entire surface of the fins with Grit 60 sand paper. This is so that the epoxy fillets adhere well to the fins and also so the CF Fin-to-Fin material adheres properly.<\/p>\n

Little cuts were made on the root of the fin every 10 mm, approx 1 mm deep with a hack-saw to encourage a good bond to the air-frame.<\/p>\n

I\u00a0also scribed 45 degree\u00a0incisions every 10 mm from the root, to ~7 mm up from the root. This provides extra place for the epoxy fillet to ‘grab’ on to the fins. I used the following “tool” to do this.<\/p>\n

 <\/p>\n

\"Tool<\/a>
Tool I made to score the fins.<\/figcaption><\/figure>\n

Here\u00a0is a photo of one of the fins I scored.<\/p>\n

 <\/p>\n

\"45<\/a>
45 degree scoring of the Tang of the fin.<\/figcaption><\/figure>\n

I also used a hack saw to cut 1mm deep incisions into the root of the fin every 10mm. No photo available.<\/p>\n","protected":false},"excerpt":{"rendered":"

Getting the basic fin cut out The fins are created from 2.4mm thick G10 plate. I created a clipped delta design and created a jig that I would use to sand the three fins down to the correct IDENTICAL size. Below is a picture of this jig. I have used a Steel right-angle bar to … Continue reading Creating the fins<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[21,15],"tags":[],"_links":{"self":[{"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/posts\/1242"}],"collection":[{"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/comments?post=1242"}],"version-history":[{"count":7,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/posts\/1242\/revisions"}],"predecessor-version":[{"id":1360,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/posts\/1242\/revisions\/1360"}],"wp:attachment":[{"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/media?parent=1242"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/categories?post=1242"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/leederville.net\/rocket\/index.php\/wp-json\/wp\/v2\/tags?post=1242"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}