Apr 10, 2014, 02:45 PM Sailplane Mafia United States, SC, Summerville Joined Jun 2001 2,020 Posts Discussion Degrees to inches help I am building an Albatros from Top Model and the throws are in degrees. I don't have an incidence meter and never ran into a manual before with degrees. I read that I can take the degrees times the sin of the chord. My aileron for example has a chord of 2.5" and the throw is 18 degrees. 2.5 x sin(18) = .77" Is that correct? I am not sure how to measure the elevator. It's a full moving type. Would I measure the chord from the pivot point to the trailing edge?
 Apr 10, 2014, 04:07 PM Registered User United States, CA, Altadena Joined Sep 2013 87 Posts Looks like a good conversion to me. Pivot to either edge should be the same if they suggest symmetrical throws.
 Apr 10, 2014, 05:41 PM If it flies - I want one! Werribee, Victoria, Australia Joined Jul 2008 962 Posts One in sixty A good approximation used in pilot navigation is the 'one in sixty' rule: One mile (inch, mm, whatever) deviation in 60 subtends near enough to one degree - so if chord is 180mm and you want the wing at two degrees, raise the LE by 6mm (180/60 times 2). For your example: if surface chord is 60mm and angle of deflection 18 degrees, deflection would be around 18mm (~.72"). Your chord is a smidgen more, so your calculation looks about right. Yes, you would use as chord the distance from hinge line or pivot to where the deflection is measured. The 1:60 rule becomes less accurate as angles increase, but given that most design measurements are educated guesses anyway, it works well for most practical purposes. Cheers, PeteM
 Apr 10, 2014, 07:53 PM TheyreComingToTakeMeAway! USA, ID, Coeur D'Alene Joined Dec 2003 5,406 Posts i have a cheater app on my phone for doing triangles
Apr 10, 2014, 11:32 PM
Thermal Junkie
Joined Sep 2008
3,214 Posts
Or you could just print this to the size you want.

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 Apr 11, 2014, 12:01 AM Balsa + glue + bluesky= fun Phoenix AZ USA Joined Jan 2009 815 Posts This thing made all my degree problems easy. It has a zero button. You can set it to any orientation (straight, 90, 142.5, what ever) and hit zero then move it to what you want. So easy. Last edited by leaktech; Apr 11, 2014 at 12:07 AM.
 Apr 11, 2014, 06:21 AM Registered User Joined Apr 2012 2,208 Posts One can pick up a protractor at any place that has school supplies for a buck or two or, as Leadchucker suggests, just print one. I found one that includes a locking swing arm that can be set wherever one wants and it makes a perfect gauge.
 Apr 11, 2014, 09:00 AM Deniable plausibility Derbyshire, UK Joined Aug 2008 2,307 Posts Some Old Hangers Can Almost Hold Ten Old Aeroplanes...
 Apr 11, 2014, 09:26 AM Registered User Joined Mar 2013 7 Posts Here is a very cheap and simple device that makes measuring control throws in degrees easy. Since I got it, I go the other way and convert any suggested throws in inches/mm to degrees. http://www.hobbyking.com/hobbyking/s...row_Gauge.html
Apr 11, 2014, 10:32 AM
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