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On 8 Nov 2005 16:23:06 -0800, Dan_Thomas_nospam@yahoo.com wrote:
> >When ground testing my auto engine with an old style 3 blade IVO prop, I
> >took several still photos. Some of the photos appeared to show the blades
> >advancing or retreating much like that of a helicopter.....not sure if this
> >was a trick of the camera or actually happening. After about 10 hours of
> >ground time I found damage to the base of the blades. Now that the engine
> >is flying with an MT prop I've been unable to duplicate that effect in any
> >of my photos.
>
> The focal plane shutters used in many good cameras would give
> that bent-prop effect. As the shutter gap moved across the plane,
> either side-to-side or top-to-bottom, one side or edge of the film was
> exposed before the other, so a rotating prop or rotor would be caught
> over a rather long time, spread across the film, and would appear bent
> or out of phase.
A rather extreme example:
http://www.bowersflybaby.com/takeoff.mpg
(Cheap digital video camera).
Ron Wanttaja
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Re: IVO prop dyn. balancing
