[roc-chat] Re: Rounding Fins
- From: Richard Dierking <richard.dierking@xxxxxxxxx>
- To: roc-chat@xxxxxxxxxxxxx
- Date: Fri, 31 Aug 2012 12:00:48 -0700
Yup, that's a clipped design. I use the same shape of fins on my rockets
because it prevents ground damage during landing.
The end is clipped, like someone took a saw and cut off the tip of a
triangular-shaped fin.
Again a flat edge seems to prevent the vortices formed when air is
moving pass a rounded surface on the fin edge. Think of little whirlwinds
forming parallel to the rocket originating at the tip of the fins.
Hopefully, that's clearer than mud.
Frankly, I'm not sure if tip vortices would be considered a type of base
drag or if the major problem is surface drag.
Richard
On Fri, Aug 31, 2012 at 11:41 AM, Dave M <muldavea@xxxxxxxxx> wrote:
> Not sure what you mean by clipped but the best I can describe is that the
> bottom edge is inclined upward from the base of the rocket. I attached a
> photo. It is a Madcow DX3.
>
> *From:* Richard Dierking <richard.dierking@xxxxxxxxx>
> *To:* roc-chat@xxxxxxxxxxxxx
> *Sent:* Friday, August 31, 2012 11:35 AM
> *Subject:* [roc-chat] Re: Rounding Fins
>
> If the fins are clipped, like a clipped delta (what's the shape of the
> fins?), rounding the leading and trailing edges will help. Rounding the
> clipped edge will create more drag. Flat is better for this edge because
> rounding creates more turbulence.
>
> Richard Dierking
> On Fri, Aug 31, 2012 at 11:22 AM, Dave M <muldavea@xxxxxxxxx> wrote:
>
> I have a 4" diameter rocket with three 1/4" glassed fins. I've flown it
> successfully a few times and now I'm thinking about rounding the top edge
> of the fins. Maybe the side and bottom edges too. Just experimenting
> with fabrication techniques and seeing if I get much of a boost in
> altitude. Any thoughts/recommendations?
>
>
>
>
>
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