<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
         <<  Lancair Builders' Mail List  >>
         <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>

Well, we invited an experienced aeronautical engineer from NASA Dryden to
help us tuft the wings, fuselage, and empanage, which he did.  I then flew
photo chase on Jim while he cycled the flaps.

The airspeeds and altitudes closely agreed between the two airplanes.  The
C182 I was flying wasn't a calibrated pacer, but it was probably close
enough for what we were looking for.  The instruments agreed within 50 feet
and 2 mph between speeds of 85 to 140 at 7500 msl.

He flew past at his cruise speed (I couldn't keep up with my 182).  The
elevator was nicely faired and the trim tab was neutral.

When he deployed the flaps, the tufts remained rock solid except for the
flap trailing tufts at flap settings beyond 25 percent.  Those tufts pointed
inward at that point.  At about 50 percent flaps, most of the flap tufts
were flopping around.  Of course, none of that is unexpected.  The nose up
pitching moment caused by the flow separation over the flaps at high
settings is more than overpowered by the nose down pitching moment caused by
the profile drag of the flap.  The elevator deflection was about 10 degrees
trailing edge up, with the trim tab fully extended trailing edge down.  At
50 percent flaps, he estimated about 15 lbs. aft stick force was required.

In a nutshell, we found absolutely nothing to explain the high stick forces.
I now think the airplane has extremely high elevator hinge moments and the
"leverage" the pilot has to move it is small.

Stay tuned.....

Naf
N7PN

LML homepage:   http://www.olsusa.com/Users/Mkaye/maillist.html