Michael McGee wrote:
I chopped this up because I thought I saw something in here that might
warrent discussion. I may have had too much coffee this morning but:
Has anyone thought about combining the IVO's adjustable twist with the
conventional CS prop "adjustable gross pitch". The gross pitch and twist
are related something like a phase angle relation that is dependent on
airspeed. Your gross pitch is a function of airspeed so the twist could be
controlled in relation to the gross pitch.
If your pitch change motor in the electric prop had a concentric, gear
reduced, secondary actuator fork that would work the twist levers while the
primary actuator fork moved the gross pitch change levers you could
theoretically have close to perfect pitch in a broader speed range. It
won't come out perfect because your twist ratios change on a square
function and the secondary actuator would just be linear. Between 0 and
150 mph you would be making substantial improvement. After 150 the
benefits get smaller.
The electric prop would be suited for this as opposed to the hydraulic.
I'm thinking about a tiny planetary set inside the hub that would create a
changing phase angle relation between the gross pitch adjusting fork and
the twist twist adjusting fork. Grab a cup of coffee before you ponder
this. It's probably way too complex for the return on investment, but then
I'm a physicist with an engineer's license..and I'm goin' to make a pot of
decaf now...
Mike
Six foot diameter prop and 2700 RPM
Prop radius is in feet.
Circ MPH is the velocity of the prop segment at that radius.
MPH = 40.9
Twist = 36.28 Ratio Twist/Root = 0.90 Ratio Twist/Tip = 8.96
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MPH = 54.5
Twist = 43.15 Ratio Twist/Root = 0.89 Ratio Twist/Tip = 8.01
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MPH = 68.2
Twist = 48.02 Ratio Twist/Root = 0.88 Ratio Twist/Tip = 7.14
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MPH = 81.8
Twist = 51.45 Ratio Twist/Root = 0.86 Ratio Twist/Tip = 6.39
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MPH = 95.5
Twist = 53.84 Ratio Twist/Root = 0.85 Ratio Twist/Tip = 5.74
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MPH = 109.1
Twist = 55.48 Ratio Twist/Root = 0.84 Ratio Twist/Tip = 5.19
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MPH = 122.7
Twist = 56.58 Ratio Twist/Root = 0.83 Ratio Twist/Tip = 4.72
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MPH = 136.4
Twist = 57.27 Ratio Twist/Root = 0.81 Ratio Twist/Tip = 4.32
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MPH = 150.0
Twist = 57.65 Ratio Twist/Root = 0.80 Ratio Twist/Tip = 3.96
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MPH = 163.6
Twist = 57.79 Ratio Twist/Root = 0.79 Ratio Twist/Tip = 3.66
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MPH = 177.3
Twist = 57.75 Ratio Twist/Root = 0.77 Ratio Twist/Tip = 3.39
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MPH = 190.9
Twist = 57.56 Ratio Twist/Root = 0.76 Ratio Twist/Tip = 3.15
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MPH = 204.5
Twist = 57.26 Ratio Twist/Root = 0.75 Ratio Twist/Tip = 2.94
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MPH = 218.2
Twist = 56.87 Ratio Twist/Root = 0.73 Ratio Twist/Tip = 2.75
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MPH = 231.8
Twist = 56.41 Ratio Twist/Root = 0.72 Ratio Twist/Tip = 2.58
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MPH = 245.5
Twist = 55.89 Ratio Twist/Root = 0.71 Ratio Twist/Tip = 2.43
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