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#12
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IVO prop dyn. balancing
Hey Russ... what are you flying and where?
Dave Houston (EFD), Rotary powered Velocity under construction.. R&R Sherwood wrote: The blades, being held by only two bolts each, can move (or swing) chordwise in the hub...... Even with those bolts torqued to spec we had blade movement between the plates. Fretting was evident on the blade bushings and mating plate surfaces. Scared us. 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 have been unable to duplicate that effect in any of my photos. Russell Sherwood Houston, TX |
#13
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IVO prop dyn. balancing
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 have 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 don't 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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