Bigger Removable Fin Assembly

The rockets we are building are starting to get longer and heavier and so for 3 pressure bottle and higher wrockets we are probably going to need bigger fins to put the centre of pressure where we want it for stable flight.

We are very happy with the trapezoidal fin shape so we have scaled this design up approx 50% to make the fins based on a 12cm side instead of 8.5cm side. Also the length of the RFA body we have extended slightly so that the nozzle when attached to the rocket doesnt extend past the RFA body. This also makes it easier to stand up when not flying.

The build was very much the same as the previous RFA build procedure.  The fins were cut out in a trapezoidal shape

Bigger RFA Cutout

Bigger RFA Cutout

Notice the channels of the corrugated plastic are in the direction of the airflow when in flight. Leaving these open seems to work well.

Here are the three fins and the 6 support attachments. The support attachments are 10cm long and 8 channels wide.

RFA Parts

RFA Parts

Instead of using metal wire to attach the fins to the RFA body, this time we have used PL Premium glue. This is the water rocketeers glue of choice and was very easy to work with. We will see how it goes during flight but I am quite confident it wont come off. The RFA body was cleaned with Mineral Turpentine, then washed with soap and water to give a nice clean finish for the glue to adhere to.

Here is the finished RFA sitting on a bottle drying.

Bigger RFA finished

Bigger RFA finished

Bigger RFA Top View

Bigger RFA Top View

The unit weighs in at a hefty 45grams

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This entry was posted on Monday, November 3rd, 2008 at 11:47 pm and is filed under Development. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

 
 

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