stall strips
09-06-2004, 02:35 PM
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stall strips
I have a semi symetrical airfoil . When adding stall strips should the sharp point of the triangle strip line up with the chord center line? Is it Ok if slightly off ? Better higher or lower . Tks
09-07-2004, 04:34 PM
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RE: stall strips
What is a stall strip? Is this a boundary layer tripping device that allows higher AOA flight? If so, you want to position it on the top surface somewhere upstream of where the flow would normally separate during a stall, which would be somewhere around 50% chord. It would be better to err towards the upstream side... tripping the boundary after the stall wouldn't help much 
If you didn't already know, while such a device would allow higher AOA flight, it would also create higher overall drag.
If I mis-interpreted the question, sorry.
If you didn't already know, while such a device would allow higher AOA flight, it would also create higher overall drag.
If I mis-interpreted the question, sorry.
09-07-2004, 10:48 PM
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RE: stall strips
Here's one..
Usually a short section of leading edge can be sharpened instead of rounded on both sides of the fuselage about like on this U-2.
On the U-2 it's riveted on.
On a model of course it can be blended into the rest of the wing section.
Usually a short section of leading edge can be sharpened instead of rounded on both sides of the fuselage about like on this U-2.
On the U-2 it's riveted on.
On a model of course it can be blended into the rest of the wing section.
09-08-2004, 03:36 AM
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RE: stall strips
A stall strip is an appendage which induces a premature stall.
Typically they are put on the roots of tapered wings to provoke a root originating stall before the tips stall.
The negative side is they add a little drag even when the plane is not stalled.
Typically they are put on the roots of tapered wings to provoke a root originating stall before the tips stall.
The negative side is they add a little drag even when the plane is not stalled.
09-08-2004, 06:15 AM
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RE: stall strips
ORIGINAL: mulligan
Paul, throw me a bone... what is this stall strip?
Paul, throw me a bone... what is this stall strip?
On some airfoils with no washout whatsoever and/or on critical airfoils, the wing can stall all at once which leads to a sudden (and undetectable by the pilot) snap roll that can destroy the aircraft.
By adding stall strips, the inboard portion will begin to stall BEFORE the outboard wing which gives the pilot some input where the planes gets a little mushy WHILE HE STILL HAS CONTROL of the aircraft. When you feel (see) the mushy, you have time to drop the nose and keep flying rather than to have to build a new aircraft.
MOST aircraft of all types use washout which serves the same purpose.
Here's a clearer picture of a stall strip.
Highflight
09-08-2004, 08:57 PM
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RE: stall strips
The best description for the purpose of a stall strip is to modify or "tune" the stall characteristics of a plane.
On the only aircraft production that I worked on, they were initially taped to the wing with duct tape, and for the few production test flights on each plane the pilots would stall them and report the results. The positions of the strips were changed to achieve a straight-ahead stall break. Once the thing was trued up, the strips were permanently mounted. I was surprised that a single location could not be determined for the design. Each plane had custom installations for the stall strips.
Sometimes they are used to stall one part of the wing before the other. Sometimes they are used to create a different feel for the pilot leading up to the stall. If the stall is unusually sudden, strips can cause buffeting that can be felt or heard before the stall occurs.
On the only aircraft production that I worked on, they were initially taped to the wing with duct tape, and for the few production test flights on each plane the pilots would stall them and report the results. The positions of the strips were changed to achieve a straight-ahead stall break. Once the thing was trued up, the strips were permanently mounted. I was surprised that a single location could not be determined for the design. Each plane had custom installations for the stall strips.
Sometimes they are used to stall one part of the wing before the other. Sometimes they are used to create a different feel for the pilot leading up to the stall. If the stall is unusually sudden, strips can cause buffeting that can be felt or heard before the stall occurs.
09-12-2004, 09:58 AM
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RE: stall strips
Does it matter a lot if I dont blend the triangle strip to the wing LE ? I would like to try it out by just pinning or taping the stall strips to the wing LE.
