NJA_Capt
Well-Known Member
Both of the above arguments are accomplishing the same thing. Stall strips are there to insure control is available to recover from a stall, ie...the root needs to stall first. If a stall strip was added to "create turbulent air/buffet," you can surmise that you needed that buffet because if it were not present you would lose aileron effectiveness. It is the turbulent air at the wing tip that is the problem. By causing this turbulence (air flow separation) at the root first, aileron authority is maintained.
I would say the Dept of the Navy trumps FSI. (Page 56-57)
"The stall strip is usually a small angular strip attached to the root leading-edge of the wing as depicted in figure 52. By using a stall strip the flow is disturbed near the root such that root area stall is induced first. This method is not preferred because it limits rather than improves CLmax It turns out that the use of stall strips is usually a design "after-thought" to improve stall warning cue characteristics found to be unsatisfactory during flight testing."
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA235994&Location=U2&doc=GetTRDoc.pdf
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA235994&Location=U2&doc=GetTRDoc.pdf
STALL STRIPS
Leading edge stall strips are small, sharp edged, triangular shaped flow trippers that are attached to the front of the wing leading edge close to its stagnation point. (N). These shed a vortex at high angles of attack so as to both selectively initiate stall at that wing station and to send a buffeting vortex aftward to tremble the tail control surfaces and thus provide a stall warning to the pilot.As referenced above, the strip is attached near the stagnation point. It doesn't necessarily mean that it is where the wing joins the fuselage. If the wing has a "cuff" (PA28s, Mooneys and Bonanzas) the stagnation point is farther out. Regardless, as quoted above, they are to create airflow separation to induce stall in a desired location. In other words, they make the inboard(root) stall before the tip.My problem is a lot of people teach that it creates the stall at the root instead of the tip, when the stall strip is installed centered in the middle of the wing. Trying to provide a reference for credibility.