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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. I didn't like the IVO's thin-skinned
sandwich construction, either. Seemed to be a lot of load on very
little fiber and a lot of foam.
The aperture shutters found in smaller, cheap cameras wouldn't
"bend" rotating stuff.. Were you using the same sort of camera both
times?
Dan
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Re: IVO prop dyn. balancing
