Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Re: Old Textbooks, etc.
By:NPenney
Date: 7/10/1998, 2:53 pm
In Response To: Re: Old Textbooks, etc. (Mark Kanzler)

Interesting. To me, a non aero type, that intuitively makes sense from a knife cutting perspective. A sharp knife continues to cut well even if you move it slowly. Dull edges like axes cut only when moving rapidly, and "stall" more easily and abruptly at slower speeds. Probably a wrong analagy, but hey, it works for me! :-) That's a test emoticon, to see if it sticks.

I wonder about dartyness with sharp leading edges though, for both boats and airplane wings. I was working with or on something recently where that was an issue. A sharp edge being able to cut through the media better, but being far more unstable because of the drastic reaction to slight angle changes. For the life of me, I can't remember what it was! But it was far more stable with a rounded nose.

I can relate to incorrect notions and such. Heck, wanna talk about centrifugal force? That's another test emoticon.

> I have an old aero book (ca. 1930) that shows that as leading
> edge radii get sharper, the stall gets gentler. This matches my experience
> with models, even though populsr opinion runs opposite. One of my
> aerodynamics profs (who works as an aerodynamicist) agreed with the
> book, and he showed me why it's so.

> When I looked at data from wind tunnel tests and Abbot and Von
> Doenhoff's theoty of wing sections, it shows that the sharp leading
> edge tends to give a gentler stall. Where the popular myth started,
> I don't know. Another prof (PhD from M.I.T.) tried to tell me I, and
> Warner (I didn't tell him about the other prof) were wrong. He couldn't
> back it up with data though.

Messages In This Thread

Mayday Mayday! boat goes left
David Walker -- 7/6/1998, 9:17 pm
Re: Try another paddler
Jay Babina -- 7/7/1998, 2:32 pm
Re: Mayday Mayday! boat goes left
Mark Kanzler -- 7/7/1998, 11:51 am
Re: rudders
NPenney -- 7/8/1998, 8:17 am
Re: Aspect ratio.
Mark Kanzler -- 7/8/1998, 11:21 am
Re: Aspect ratio.
NPenney -- 7/8/1998, 2:34 pm
Re: Aspect ratio.
Nick Schade -- 7/8/1998, 3:17 pm
Re: Higher Aspect ratio = No Steering
NPenney -- 7/9/1998, 7:49 am
Re: Higher Aspect ratio = No Steering
Mark Kanzler -- 7/9/1998, 10:38 am
Re: Higher Aspect ratio = No Steering
NPenney -- 7/9/1998, 11:50 am
Re: Old Textbooks, etc.
Mark Kanzler -- 7/11/1998, 12:52 am
Re: Old Textbooks, etc.
NPenney -- 7/10/1998, 2:53 pm
Re: Here's a sketch of one possible solution (as described in prev post)
Mark Kanzler -- 7/8/1998, 12:41 am
Image link still not working.
Mike Spence -- 7/7/1998, 1:28 pm
Re: Image link still not working. (Sorry)
Mark Kanzler -- 7/7/1998, 1:56 pm
Re: Image working.(?)
Mark Kanzler -- 7/8/1998, 1:26 am
Not yet. - Don't despair!
Mike Spence -- 7/8/1998, 1:19 pm
Re: Not yet. - Don't despair!
Mark Kanzler -- 7/8/1998, 2:18 pm
Re: Here it is! (Satisfaction Guaranteed)
Mark Kanzler -- 7/8/1998, 10:23 pm
Re: Here it is! (Satisfaction Guaranteed)
David Walker -- 7/10/1998, 10:28 am
Re: Surfbard skegs.
Mark Kanzler -- 7/10/1998, 11:58 am
Re: Surfbard skegs.
David Walker -- 7/10/1998, 1:49 pm
Re: Surfbard skegs.
David Walker -- 7/10/1998, 5:30 pm
Re: Surfbard skegs.
Mark Kanzler -- 7/12/1998, 11:08 am
Re: Surfbard skegs.
Paul Jacobson -- 7/12/1998, 7:18 pm
Re: Surfbard skegs site (try it again please).
Mark Kanzler -- 7/10/1998, 2:50 pm
Re: Surfbard skegs site (try it again please).
Mike Spence -- 7/10/1998, 6:51 pm
Re: Here it is! (Satisfaction Guaranteed)
Nick Schade -- 7/9/1998, 4:12 pm
Re: Here it is! (Satisfaction Guaranteed)
Mark Kanzler -- 7/11/1998, 12:37 am
Re: Mayday Mayday! boat goes left
Mark Kanzler -- 7/8/1998, 12:39 am
My $0.02
CHad -- 7/7/1998, 11:29 am
P.S.
CHad -- 7/7/1998, 11:56 am
Re: P.S.
Guy Wright -- 7/7/1998, 1:46 pm
Me Too!
Shawn Baker -- 7/8/1998, 11:01 am
Re: Mayday Mayday! boat goes left
NPenney -- 7/7/1998, 7:33 am
how I solved mine.
R. N. Sabolevsky -- 7/6/1998, 11:56 pm
Re: Mayday Mayday! boat goes left
Duane Strosaker -- 7/6/1998, 11:38 pm
Re: Mayday Mayday! boat goes left
Mike Spence -- 7/7/1998, 12:11 pm
Re: Mayday Mayday! boat goes left
Paul Jacobson -- 7/6/1998, 11:20 pm
Off center fins and water flow
David Walker -- 7/8/1998, 5:28 pm
Re: Off center fins and water flow
NPenney -- 7/9/1998, 11:57 am
Re: Off center fins and water flow
Mike Spence -- 7/9/1998, 5:56 pm
Re: Off center fins and water flow
Paul Jacobson -- 7/11/1998, 2:53 am
Re: Off center fins and water flow
Mark Kanzler -- 7/10/1998, 11:47 am
Re: Off center fins and water flow
NPenney -- 7/10/1998, 6:22 am
Re: Skegs and water flow.
Mark Kanzler -- 7/8/1998, 6:10 pm
Re: Skegs and water flow.
David Walker -- 7/8/1998, 6:42 pm
Re: Skegs and water flow.
Mark Kanzler -- 7/8/1998, 7:07 pm
Re: Skegs and water flow.
David Walker -- 7/10/1998, 10:37 am
Re: Skeg attachment w/ silicone.
Mark Kanzler -- 7/10/1998, 11:34 am
Re: Mayday Mayday! boat goes left
Wes Boyd -- 7/6/1998, 10:36 pm