Helicopter Blades

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# 1 22-05-2003 , 05:01 PM

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Join Date: May 2003

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Just a quick question, how do I make some helicopter blades that spin and don't stop. I have been fiddling with the rigid body attributes and I have got the blades to accelerate but they eventually start turning the other way round which isn't so bad since the speed they are going at it isn't so noticable but then they slow down and stop before starting the cycle again. The bit with them accelerating is useful but I need them to keep going rather than stopping, at least long enough for me to finish the animation, it's 720 frames long if that helps you work out how to change it.

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# 2 22-05-2003 , 05:09 PM

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They are not slowing down I think.

That´s actually an optical illusion of the blades, much like the spikes of a wheel that we know is turning forwards while we look at it going backwards.

It has to do with the eyes "refresh rate". user added image

adldesigner
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# 3 22-05-2003 , 07:12 PM

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try writting an expression, should work pretty easily..

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# 4 22-05-2003 , 07:17 PM

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here is a test example, it was made in Maya 5.0, but i exported it as a ma, so it should be ok on 4.5 If it isn't let me know and I will write it out, THanks,
Brian
Hope this helps

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expression test.ma (53.3 KB, 410 views)

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# 5 23-05-2003 , 10:10 PM

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the expression:

pCylinder1.rotateY=time*300

what does that mean.

It will rotate in y 300 times the amount of frames in the scene, hmm I know what i mean but i cant explain what im thinking

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# 6 23-05-2003 , 11:11 PM

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"time" is time in seconds (a floating point number) so it'll rotate in y 300 degrees in one second...

Kari
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# 7 24-05-2003 , 10:03 AM

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cheers mate, is that thing really going 300 times pers second...geezz

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# 8 24-05-2003 , 10:44 AM

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Hehe, no. Not 300 times per second. 300 degrees per second...

Kari
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Do a lot, Fail a lot and Learn a lot!

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# 9 24-05-2003 , 12:23 PM

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hmm..how the hell did i not see that, cheers mate

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# 10 26-05-2003 , 04:46 AM

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try also this expression:
first add an attribute to your object name it RPM,

if (frame == 1)
{ object.rotateY = 0 ;}
else
{ object.rotateY += (( object.RPM * frame * 360 )/(30*60))/frame;}

now you can key when your object will stop or go faster or slower base on the value that you enter in RPM attribute.

i got this stuff in highend3d.com

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