To iterate over designs we should try to isolate the one parameter we are iterating on. And indeed there are way more parameters that area.
So I should rephrase my previous statement into: “Area should replace the depth parameter.”. Of course depth is still a parameter with influence, but it is neglectible compared to area.
Maybe we could come up with a list of significant parameters for traditional fins. Because the power is in reducing the variables to a set that is workable.
For the somewhat scientific orientated people, I’d like to refer to the following wikipedia page: Dimensional analysis - Wikipedia
Speaking of fins, just scored a quad set of fibreglass Curtis Hesslgrave fins, love the templates, finish is superb.
Want to keep them, however, think I need to give them to a local young charger for use on his 10’6 quad Nelscot Reef gun. He’s young, broke, and the fins he’s currently using are wonky as hell.
The root connection is very important for performance. A lot of performance will bleed off without that root/base connection.
I hope you can get something to work. I can only imagine a pretty different fin shape might work.
Since you still need to connect the fin to the board.
You’ll still need to foil the tabs. And to make them strong enough their thickness to chord ratio will be very hight, so that it might be better to make one big tab. And guess what, now you have a standard fin.
I don’t want to stop you from trying, please go ahead with this. I just don’t understand the reasoning, so please explain more ;).
By the way, why is this turbulence bad? Do you know how turbulent the flow is (Reynolds number)? Airplanes almost always fly through turbulent flow.
If you are designing and making your own fins, why not share in a way that can always be accessed? Sure you can start a thread, and eventually it moves down the roster, on to the back pages, and gets forgotten.
There is, on the other hand a VASTLY UNDER-UTILIZED feature of the website that allows us to enter into the public record an easily accessed file for future reference - the “BOARD ARCHIVE”, with a special category for FINS!
Check it out - last entry was Oct. 2012 - time to start using this feature again, and let’s get some custom fin pictures up, with dimensions, descriptions, design theory, etc.
consider this a CALL FOR SUBMISSIONS to the fin file
Hey Greg - if that was directed to me for the picture I posted, it is a Tim Stafford fin that is on file in the Fin Archive.
What I am trying to achieve with this fin is to gain some interest in the FIN ARCHIVES, and hopefully get some of you fin people to post up some pics, dimensions, explanations, etc. Seems to me like it could be a great resource for sharing / expanding knowledge of fin design, but its largely overlooked / ignored at present.
I think it’s always fins area, when that. ITerry Hendricks paper or thickness, it can be any shape you like, wingtips to counter vortices, 3 dimensional shapes, whatever ! Each fin is class=“thread-image” src="http://www.swaylocks.com /></
Thanks for the link to that great old thread about fin design Brett. As you said, it is a long one. You do not find many threads like that at Sways anymore – too much tech, too much science.
I am looking forward to seeing what you come up with for the mounting posts, and how you foil them. Interested in how you perceive differences in performance with them.
Do you have a link to the Dr. Hendricks paper about the 20-mm turbulence layer?
Maybe you could use a cotton flock-epoxy matrix for your fin core to embed your mounting posts/struts. It would fairly easy to sand/shape the flock/epoxy matrix and you could add carbon or FG skins to the shaped core for an exo-skeleton of sorts. Duuude used this type of matrix to make fin boxes.
