XFOIL and gross separation

[nmasters]

Can XFOIL model gross separation like you'd see behind a spoiler or vortex flap?

--Norm

[HELModels]

My guess is it would look like "convergence failed" which is XFOIL way of saying no solution. I dont know maybe if you set it to 1,000,000 iterations? Maybe if you run it in inviscid at a large reynolds?

[nmasters]

Richard Kline sent me a paper concerning an XFOIL analysis of a stepped airfoil and asked me what I thought of it. Basically I told him that, considering it was written by a high school kid, it's pretty good but not very informative. Among all the other errors question his modeling of the airfoil and the results.

--Norm

[HELModels]

Are those co-ordinates available? That looks like a flatbed truck.

[raptor22]

Well, considering that xfoil isn't entirely accurate at modeling the drag of separation bubbles, I think it's a pretty safe bet that it wouldn't model this accurately at all.

--Alex

[nmasters]

That's what I thought but I don't have any personal experience with this type of application and haven't found an authoritative explanation. Since stepped airfoils haven't proven promising enough to get the heavy computer centers to devote MIPs to it Richard will just have to be satisfied with the little wind tunnel work that has already been done and the subjective results from the RCrs that are playing with them.

--Norm

[nmasters]

Are those co-ordinates available? That looks like a flatbed truck.
He didn't include the ordinates but he did describe his design procedure. He cut full depth step into the lower surface of an NACA 4515 at 30%c and made the corners as close to square as XFOIL would let him. The paper is posted here (http://www.rcgroups.com/forums/showpost.php?p=10100172&postcount=90) if you would like to read it.

--Norm

PS Someone else patented a similar idea a while earlier but with moving parts.

[Ralph Walton]

Are those co-ordinates available? That looks like a flatbed truck.

No, Someone has traced the outside of their shoe :D