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-   -   convert inchs to degrees please help (https://www.rcuniverse.com/forum/questions-answers-154/7968441-convert-inchs-degrees-please-help.html)

mike07 09-18-2008 08:39 PM

convert inchs to degrees please help
how do u convert inchs to degrees i have the hanger 9 digal meter thank mike

bkdavy 09-18-2008 09:30 PM

RE: convert inchs to degrees please help
Assuming you're trying to find inches of control surface movement. Its a simple right triangle. The control surface is the hypotenuse of a right triangle, and you're measuring one angle.

From basic trigonometry, sine of the angle = Length of the opposite side (deflection)/length of the control surface. Therefore, multiply the length of the control surface by the sine of the deflection angle, and you'll get the deflection distance.


Clint H 09-18-2008 09:58 PM

RE: convert inchs to degrees please help
Nicely described, bkdavy.

Actually, if you want to convert inches to degrees, I think you'll want to do exactly what bkdavy said - but backwards. Start with the deflection distance and divide it by the width of the control surface. Next, you'll want to take the inverse sine of this value to determine degrees.

It all depends on what you start with - inches or degrees.


mike07 09-18-2008 10:21 PM

RE: convert inchs to degrees please help
ok confused here my book says elev on low rate is 3/16 and so on but i want to use my hanger 9 digal meter i really dont want to level up the plane and use a rule to set all the throws like my funtana it give u degrees ie like elev 23 degrees up for low rate thats what i am trying to figer out

JohnW 09-18-2008 11:26 PM

RE: convert inchs to degrees please help
K, I assume you either are too young to have had trig yet, or don't understand trig. So go to this web site. http://www.carbidedepot.com/formulas-trigright.asp

Where it says side a, put in the contol throw in inches.
Where it says side b. put in the chord, or lenght of the control surface, from font to back, measuered in inches. You'll have to measure this yourself.
Hit calculate.
The degrees you want is 'Angle A'

For example, if you put in a control throw of 1" for a 3" cord control surface, you should get 18.4 degrees.

bkdavy 09-19-2008 05:54 AM

RE: convert inchs to degrees please help
Don't make life harder than it has to be. Measuring deflection distance is the easiest thing to do. Just set the plane on a table, and hold a ruler against the trailing edge, with the end of the ruler on the table. Read the ruler when the control surface is neutral, and then at full diflection. Its not an exact science, and you'll want to change it anyway once you get a feel for the plane. The plane doesn't need to be level to do this.


mike07 09-19-2008 07:13 AM

RE: convert inchs to degrees please help
thank no other help needed i used the old rule and measured each surface and got them match,,, and john w i did have trig and i just dont remeber it and as for age i am 35 but thanks anyway. can close this forum

CoosBayLumber 09-19-2008 07:51 AM

RE: convert inchs to degrees please help
I came up with a note the other day on a plan.

Although drawn straight, it says to tilt the motor 1/8 inch to give some down thrust. Now is that measured at the motor hub, at teh firewall, at the top of motor mount.

Where? For each would give a different angle to sweat out.


JohnW 09-19-2008 08:39 AM

RE: convert inchs to degrees please help
Heh, down thrust in inches (should be in degrees)... I know it is just easier for most to measure in inches, hence many manuals written that way, but it is just so wrong IMO. Coos, if the instructions don't clearly say where to measure the 1/8" down thrust (can't believe I just said that), I'd measure it at the center line of the prop, which would be slightly in front of the thrust washer.

MinnFlyer 09-19-2008 10:43 AM

RE: convert inchs to degrees please help
Buy one of these:


OldRookie 09-19-2008 11:29 AM

RE: convert inchs to degrees please help
Geez...for the price it should be wireless.


JohnW 09-19-2008 01:55 PM

RE: convert inchs to degrees please help
Oooo... that thing is super sweet. Two axis even. That would have saved me a bunch of time setting socket tubes a few weeks ago. I may have to get one of those.

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