From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Michael Dunning
Sent: Friday, March 4, 2022 5:05 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Preliminary analysis of aerodynamics of sparrow strainers (or not)

 

Jay,

In typical engineer fashion, I don't get the chance to do this at my day job and got my references confused. Appreciate the patience while I double-checked everything....

The NLF development papers are what mention the hinge moment concern. This is the airfoil Somers tweaked for the Lancair 360. You'll notice the Abstract points squarely at correcting the shortcomings in the GAW-turned-LS series of airfoils:
 
 

Totally agree that a new canard using the R1145MS is the "correct" solution. As Mike Dwyer rightly pointed out, that's not really practical for most of us with built hardware. Personally, at that point I'd rather just start a new design with known design allowables rather than guess at the QAC numbers (Waddelow).  However, I will concede that if you have the fuselage shells the wing and canard are largely segregable.

Can you send me the Reynolds numbers, stock LS coordinates, and hinge location you're using as a baseline? XFOIL will calculate the hinge moments for speculative comparison (i.e. relative, not absolute design values).

Footnote: Selig worked with Somers on the NLF development (1995) and later had Ashok as a grad student (1998+), thus I view the AS504X and later airfoils as the current "gold standard" for EAB airfoil comparisons. The AS504X airfoils have the advantage of published (if primitive) wind tunnel test results as compared to the non-existent ones for the NLF(1)-0115.
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)