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Author Topic: Tangential line angular difference to circular velocity.  (Read 784 times)

Offline Chris Wilson

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Tangential line angular difference to circular velocity.
« on: December 10, 2022, 11:57:07 PM »
Hi all,
           Is there a formula for considering the angle the models roll axis sits on compared to the circular flight path?
  For example the problem to me is that if the model is set at a tangent, thrust, model centre line  rudder etc but it's forced to fly in a circular path then surely there is a measurable angular difference between the two?
Thanks, Chris
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Offline BillLee

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Re: Tangential line angular difference to circular velocity.
« Reply #1 on: December 11, 2022, 06:08:46 AM »
Should be easy to figure:

Alpha = arcsin ( D/L )

where

D is the distance from the CG to whatever point where you want to know. E.g., to the nose of the model, or to the rudder, or ....

L is your line length

(Or arctan. At these small angles, they are essentially the same.)

Howard, is this correct?

Bill
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Offline Chris Wilson

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Re: Tangential line angular difference to circular velocity.
« Reply #2 on: December 11, 2022, 12:00:27 PM »
Thanks very much Bill!
I got lost in a world of slope calculations that didn't solve the question.

Chris.
MAAA AUS 73427

You have enemies? Good. That means you've stood up for something, sometime in your life.
 Nothing in life is so exhilarating as to be shot at without result.  It's not enough that we do our best; sometimes we have to do what's required

Offline L0U CRANE

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Re: Tangential line angular difference to circular velocity.
« Reply #3 on: January 11, 2023, 11:34:47 AM »
If the CG is where you start and the roll axis is considered tangent to the flight circle, that puts the prop and the 'rudder' at a very slight angle out.- rudder's angle about twice as great as prop's . This calculation relates to straight lines not radians. (IMHO part of 'springiness' sensed includes the difference in pull as we apply more force on one line than the other to move the surfaces for control input...)

We know the length along that axis from CG to, say, prop and 'rudder'. Even on small stunters and shorter lines, THAT makes very small angles. Of course, any built-in offsets add or subtract...

How important? These angles may be smaller than errors in construction or estimated line sweep angle reaching the leadouts- which also may vary depending on presentation to wind..
\BEST\LOU


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