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# Steelsmasher

Member Since 29 Mar 2013
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### In Topic: The rate of change of an angle

31 March 2013 - 02:25 PM

http://en.wikipedia.org/wiki/Centripetal_force

Unfortunately, I don't think this would help me achieve getting my arrow at the right angle.

A Euler spiral is definitely the way to go.

Anyway, I've spent quite some time and I've amassed the following formulas:

X= (Ls/100)*(100-0.0030462*θs2)

Yc = (Ls/100)*(0.58178θs-0.000012659*θs3)

θs = Ls*Dc/200

D= 200*θs/Ls

D= 1800/pi/Rc

I know Xc and Yand Rc but I need Dc.

So I'm hoping I will find Dc  if I rearrange the formulas.

### In Topic: The rate of change of an angle

30 March 2013 - 05:52 PM

It made me manage to find this... http://www.wikiengineer.com/Transportation/SpiralCurves

From what I can tell, I need to look for 'θs' (which is the total angle my arrow would have to rotate), and divide it by 'ls'(this is the length of the red line, which I believe I can adjust ). That way I get the rate at which my angle should change.

But finding the right formula is proving difficult.

Or maybe I'm just doing it all wrong?

### In Topic: The rate of change of an angle

30 March 2013 - 04:30 PM

Thanks.

A Euler spiral definitely seems to be what I'm looking for, but I imagine I'll be spending quite some time trying to apply it.

If maybe you could be kind enough to figure out a formula I could use?

I want the velocity of the arrow to stay constant, but need to figure out the rate at which it rotates so it manages approach the circle in a motion forming that beautiful euler spiral.

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