Does anyone know what the formula is to make the conversion from degrees of throw to inches?Thanks in advance.

I'm thinking that it would depend on the width of the control surface -- the radius of the circle so to speak. In other words, at a given number of degrees, the distance you'd measure would get greater the farther away from the hinge line you get. I'm not a math guy, but it would seem to me that degrees would remain constant.
Sam

You need to dust off your high school trigonometry book, or better yet ask your son/daughter.

Joe

Stuka,

I think you need to use the tangent function on any calculator that does trig functions. The distance of the trailing edge deflection equals the tangent of the angle deflected multiplied times the width of the control surface.

Keep in mind that it has been more years since I had trig than I want to think about and I did not stay in a Holiday Inn Express last night, although I am in a Best Western tonight.

Cary

Cary,
I think that works only in the case of a right triangle. I believe you have to use the law of sines or law of cosines. After more years than I'd care to admit I had to brush up on it to help my daughter get through college trig. last year. If I get energetic tomorrow I'll see if I can find her book.

Joe

SOH-CAH-TOA will work to find distance in whatever units you are using. I wish I could use whiteboard here to show you, it will work on any triangle that is a right triangle as Joe said. You will use the tan function as well, that is because you know the angle and you know the lenght of the adjacent, you want the length of the opposite. Trust me on this though this is way way way more complicated than using the degrees of deflection because you will end up with having to draw an arc equal to the radius then using calculus to figure the arc length to just draw a triangle into the circle cause your numbers will be very small. Degrees are precise and accurate. grab a protractor if you don't have anything else to measure angles of deflection.

I know reading what I said is as confusing as all get out but somewhere in there if you can picture a right triangle and then picture the sides as opposite and adjacent and hypotenuse(the longest side) it will make some sense.

Eric

Basicaly, you are working with two sides of a right triangle, the opposite and the hypotenuse, and the adjacent angle. In the case of a unit triangle with a hypotenuse of 1, the opposite side = sine(adjacent angle) On a control surface, the cord (width) is the hypotenuse, the inches of throw is the opposite side, and the degrees of throw is the adjacent angle. Unless the width is exactly 1, you have to convert your inch measurements to that of a unit triangle by dividing the opposite side (throw) by the hypotenuse (width) before calculating degrees. Likewise, when finding the inches of throw, you have to multiply the sine of the angle by the hypotenuse (width) to find the opposite side (throw)
.
You can convert back and forth using a couple of measurements and the MS Windows calculator in scientific, decimal, degree mode.

Degree of throw = inv(sin(inches of throw / cord of control surface)). For example, if you have a 3" wide control surface and 5/8" throw, the degrees would be inv(sin((5/8) / 3) = inv(sin(.625/3) = inv(sin(.2083333) = 12.025 degrees.

Inches of throw = sin(degrees) * cord of control surface. For example if you have a 2" wide control surface and 20 degrees of throw, the inches would be sin(20) * 2" = .342 * 2" = .684" or approx 11/16"


Scott

The easiest way is to simply draw out on a piece of paper. Measure the width of the surface at a point you want, then draw it, the surface its hinged to and the surface deflection you require, then measure the the distance at the trailing edge and Voila!!!

Much more tame on the brain cells, unless of course you want to do it the hard way!!

Ian.

Gees way over my head. The EASIEST way to do it is use the good old L.A.R. method.(Looks about right)
When ever i see degrees listed for the angle i always start with
Ailerons 3/4inch with 25% expo
Elevator 1 inch with 25% expo
Rudder all i can get with 35% expo
Flaps 1 inch and work my way up from there
Always worked for me. Now if i wanted to get REALLY fussy i do have a Mitutoyo digital protractor 3600pro but never use it.
Pat