flow strip ?

[dvint]

I was reading about the piper tomahawk on Airliners .net. It had unpredictable
stall problems and flow strips were added to later models to correct this. Are
flow strips the same as stall strips ? When using stall strips,where should they
be placed and how thick should the stall strips be ?
Thanks

[Sparky Paul]

Stall strips are usually fairly small, and placed close to the fuselage. Their purpose is to create noise by stalling the wing immediately behind the strip, that alerts the pilot to the approaching stall.
U2s use them, for instance.
On a model such a device will have little practical use.
Some planes have a vibrating reed in the leading edge for the same purpose.

[markmm]

While I couldn't say with any certainty that stall strips do work on RC models, I was just reading an article from an experienced, expert RC modeler that uses a variety of tip stall elimination/reducing devices and in his article he swore by stall strips as a great way of reducing or eliminating tip stalls. Stall strips do not alert a pilot of impending tip stall, they actually force the middle of the wing near the fuselage to stall way before the tips do, forcing the plane to stall around it's center and lose altitude evenly (thus no wingtip dropping faster than another).

I can't recall the name of the author or where I read it, but I'll try to find the article again. It was in a modelling book my son got from the library. He took it back, but not before I photocopied some info (that article being one).

Anything that can help reduce tip stalls should be employed...not the least of which is a well balanced, "light for it's size" plane with perfect CG, and of course, flown correctly with adequate speed and AOA. But I do believe that most, if not all, devices on real planes can be effectively employed on scale models. After all, aerodynamics does not distinguish from 1/1 or 1/50 scale.

[Flight Engineer]

"After all, aerodynamics does not distinguish from 1/1 or 1/50 scale."

You may wish to re asses this statement.

STALL STRIPS have several uses.
Sparky is correct in saying they are used in some applications to give an indication of impending stall to the pilot.
Another application is to modify the stall characteristics. This is not exclusively to prevent "tip stall" although that can be one of the uses.
Consider a swept wing without a tendency to drop a wing but with a stall that raises the nose therefore making the stall "deepen" this is often corrected by the use of stall strips that initiate the stall closer to the root and therefore further forward hence causing a nose down pitching moment.