When someone comes up with the Ideal design for a turbine blade, I would sure like to know.
I have been researching the subject on the Sandia Labs website.
At first I thought they had finally come up with the perfect shape.
They called it the SG5061.
They gave all the chord lengths and it appeared that the chord at the root for a 20' rotor would be about 18" wide.
Upon further investigation, what they were calling the SG5061 did not really look like that airfoil at all.
It looked almost identical to the NC 4412 here is a pic of what they ended up with:
As you can see by my next two pics the root had a huge pitch...
But then I noticed that the report was done in 2002.
Upon further research I found a report in 2004 that used an entirely new airfoil design that looks like the NREL S823 at the root:
This Airfoil is very similar to the one Sammopower used for his alumiinum blades.
After scanning through the the report I noticed that they left out all the loft info so others could not easily duplicate it.
But it looks like to me that it does not have the extreme pitch at the root.
I know on the first rotor it was designed for a semi vairaible pitched blade for Jacobs, where overspeed was corrected by counter weights.
The 2004 report was surley designed for a full blown variable pitched rotor.
While I almost had the 2002 blade drawn up in CAD, I am going to scrap it and go with the NE S823 with the NC 4415 from about 60% of the radius to the tip. This seems to be about what has been done on all the new turbine blades being manufactured at the present time. I am using Proe for the design and the TSR, pitch and chordal scale can be all be easily modified.
The over all plan view shape of the rotor blades has not changed since 2002, so I think the groundwork is already done. It is documented in the Sand2002-3101 report.
One just needs to be able to sift through the massive amount of data out there to come up with a solution.
I will be machining a mold out of laminated basswood to make the foam core, fiberglass skinned blades.