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> >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. I do not know that the IVO would move all that much,
> unless it was flexing as well...........
> The aperture shutters found in smaller, cheap cameras wouldn't
> "bend" rotating stuff.. Were you using the same sort of camera both
> times?
>
> Dan
Same camera was used on both props. A Nikon single reflex, the shutter
moves from side-to-side. I bought it new in about 1985....before the
digitals came out.
Russell Sherwood
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Re: IVO prop dyn. balancing
