IVO prop dyn. balancing

[abripl]

I got a IVO magnum prop in-flight adjustable - no spinner. Did anyone
do a dynamic balance on one of these?
------------------------------------------------------------------------------------------------------------------
SQ2000 canard http://www.abri.com/sq2000

[stol]

I rebalance mine every time I switch blades or any combination. They
are real close right from Ivo but the last touch of precise balancing
makes it VERY smooth.... I get mine done at Jackson Hole Aviation. Most
good FBO'S have a dynamic balancer..

Ben
www.haaspowerair.com

[abripl]

I don't have a spinner on mine. Where would you add the balancing
weights (washers)?

[stol]

Hmmmm, If you are running the paddle blades you can slightly shorten
one to get it in balance because the paddle blades are blank on the
ends, if you are running the rounded blades then your only choice is to
place the weights under a prop bolt. I guess the question is,,,why no
spinner???

[[email protected]]

stol wrote:
> Hmmmm, If you are running the paddle blades you can slightly shorten
> one to get it in balance because the paddle blades are blank on the
> ends, if you are running the rounded blades then your only choice is to
> place the weights under a prop bolt. I guess the question is,,,why no
> spinner???

We had an IVO prop on a Glastar and couldn't get it to stay
balanced. The blades, being held by only two bolts each, can move (or
swing) chordwise in the hub just enough that the assembly ends up being
off-balance chordwise, and no amount of spanwise balancing will fix it.
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.
Too bad, since the prop pulled well, better than the Warp Drive
that replaced it. The Warp was so much easier to balance but presented
more hassle when changing pitch.

Dan

[Drew Dalgleish]

On 8 Nov 2005 09:09:27 -0800, wrote:

>
>stol wrote:
>> Hmmmm, If you are running the paddle blades you can slightly shorten
>> one to get it in balance because the paddle blades are blank on the
>> ends, if you are running the rounded blades then your only choice is to
>> place the weights under a prop bolt. I guess the question is,,,why no
>> spinner???

When my warp drive prop was balanced they added weight to the
flywheel.

[[email protected]]

On 8 Nov 2005 09:09:27 -0800, wrote:

>
>stol wrote:
>> Hmmmm, If you are running the paddle blades you can slightly shorten
>> one to get it in balance because the paddle blades are blank on the
>> ends, if you are running the rounded blades then your only choice is to
>> place the weights under a prop bolt. I guess the question is,,,why no
>> spinner???
>
> We had an IVO prop on a Glastar and couldn't get it to stay
>balanced. The blades, being held by only two bolts each, can move (or
>swing) chordwise in the hub just enough that the assembly ends up being
>off-balance chordwise, and no amount of spanwise balancing will fix it.
>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.
> Too bad, since the prop pulled well, better than the Warp Drive
>that replaced it. The Warp was so much easier to balance but presented
>more hassle when changing pitch.
>
> Dan
Did you have the knurled plates? Early IVOs did not. All late
production have knurled plate front and back - much better blade
affixment.

[R&R Sherwood]

> 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

[[email protected]]

>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. 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

[stol]

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



This is all VERY interesting.........Thanks for the feed back...

Ben
www.haaspowerair.com

[Ron Wanttaja]

On 8 Nov 2005 16:23:06 -0800, 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 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.

A rather extreme example:

http://www.bowersflybaby.com/takeoff.mpg

(Cheap digital video camera).

Ron Wanttaja

[Dave S]

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
>
>

[R&R Sherwood]

> >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