RE: Formula for percentage arcs anyone?

From: John Barker <john.barker783_at_ntlworld.com>
Date: Wed, 4 Sep 2013 15:51:00 +0100

Mike,

Don has shown how to do the arc in Autocad but if you want a formula to
solve the problem then one can be written from the geometry of intersecting
chords and I give it below.

 

Radius of Arc = 0.5(C^2/4h + h) where C is the chord of the arc and h is
the height at the centre of the camber.

Example: A 6" chord with a 5% camber height at the centre.

Then camber height, h = 0.05 x 6 = 0.3".

Radius = 0.5(6^2/(4 x 0.3) + 0.3) = 15.15".

 

John Barker - England

 

 

From: Indoor_Construction_at_yahoogroups.com
[mailto:Indoor_Construction_at_yahoogroups.com] On Behalf Of
mkirda_at_sbcglobal.net
Sent: 04 September 2013 05:04
To: Indoor_Construction_at_yahoogroups.com
Subject: [Indoor_Construction] Formula for percentage arcs anyone?

 

  

Greetings.

I am trying to reproduce a 5% airfoil in AutoCAD and I'm not having a lot of
luck. Everything seems to default to degree arcs, which isn't a problem,
however I cannot find a formula to convert between the two.

Anyone have the formula handy?

Regards.
Mike Kirda
Received on Wed Sep 04 2013 - 07:51:05 CEST