David Carter wrote:

I was going to stay out of the IVO prop thing until I talked to fellow in my
EAA chapter today who is flying his new Lancair 180hp with the newest IVO 3
blade Magnum "High Pitch" (or some such title - denoting greater selectable
pitch than before).  He as indicating around 210 IAS at 5500MSL last week at
23 inches MAP - NOT full throttle.  The "brick wall" has been eliminated by
this new iteration of the IVO prop.

I just called to confirm his blade length:  70" (3 blades).  With his 180hp
engine, he gets his maximum cruising speed at approximately 80% of max pitch
available, i.e., he speeds up as he increases pitch up to that point, then
starts slowing down as he approaches max pitch.
    -  Would anyone venture to suggest that he trim his blades a bit shorter
to be able to use higher blade angle?  I'm not versed in the details and
tradeoffs of prop characteristics to assess this issue.

David Carter

Level the airplane fore and aft with one blade  horizontal. 
Mark off the blades with masking tape at 1, 1.5, 2, 2.5 foot radius
intervals and at the end of the blade since there is no 3 foot radius.
 
Use a bubble level type machinist protractor and measure the pitch angles
on the back side of the blade.

Rotate the prop until another blade is horizontal on the other side
of the spinner. Check the blade on the other side and see if the angle 
is the same at the one foot radius position. If it is not the airplane 
is not level. Re-level the airplane and try again.

Run the pitch both ways and measure the angles with high and low pitch.
It take longer to describe it then it takes to do it.

Write down the angles and we will compare them with what we have to 
see if indeed the prop design has been changed. 

Note the position of the pitot system static source or if an aircraft
pitot tube is used, its location.

Paul Lamar
 
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