Flight Training - July 2011 - 8

LETTERS

Talk back
WE APPRECIATE YOUR COMMENTS. Please email lettters to flighttraining@aopa.org. Letters will be edited for style and space.

IS IT BERNOULLI OR CASH?

OF WINGS AND THINGS

very much enjoyed your article “Of Wings and Things” by Budd Davisson (May 2011 Flight Training). I now have a better understanding of the actual workings of all those big parts I’m building for my airplane. Some of it left me a bit curious and maybe a little bit confused. I’ll be reading that one again. I did have a slight conflict with one of the closing statements. Davisson
wrote, “...smart people still argue over what makes an airplane fly.” I read a quote once from an unknown source that seemed to sum it up for me and I’m sure many others. It read, “Forget all that stuff about lift, thrust, and drag. An airplane flies because of money.” Now that I’m buying aircraft parts, that statement is more true than ever! Mark Gardner Mason Shelton, Washington After reading your article on wing camber in the May issue, I was disturbed in the way the discussion was framed. While it is true that high-camber wings generate more lift than low-camber wings, using control surfaces to describe it does a disservice to the student. Control surfaces work by changing the angle of attack of that section of the wing (or tail), which either increases or decreases lift. Using the example of a left-hand turn from the article, the aircraft rolls because, when the right aileron is deflected down, its angle of attack is increased, which increases lift on that portion of the wing. This lift imbalance causes the airplane to roll. The graphic showing camber and angle of attack is wrong. Angle of attack is the angle between the relative wind and the chord line of the wing, not the camber line. Jonathan Graff Palmdale, California
POWER EXPLOSION

should read, “The resulting compression of igniting gases pushes the piston down.” At no time should there be an explosion in the cylinder. If you feel or heard explosions or sounds like pinging, then you should have it checked by a mechanic. An airplane will not fly long with explosions occurring. Explosions occur with detonation and pre-ignition, and can generally be corrected with a richer mixture, assuming the timing is correct. Tom Evans Tampa, Florida A sidebar to Jill Tallman’s story states that an oxygen sensor measures the amount of oxygen in the exhaust gas. This

is not what this sensor does. It measures the fuel mixture by switching from high to low voltage at the point of stoichiometric mixture. It actually switches to high voltage when it begins to use oxygen from the outside air. Thus the name oxygen sensor was given to it. It was named Lambda sensor by its inventor and this is a more accurate name. Fred Wilson Seattle, Washington
ERRATUM

In the May 2011 Flight Training “What It Looks Like” we erred in describing dihedral. Flight Dynamics Principles by Michael Cook has a good, simple explanation. In essence, the dihedral angle helps an airplane to right itself after a lateral disturbance (let’s say turbulence that causes a sideslip). The downwind wing will naturally go down, and the dihedral angle, combined with the angle of attack, will cause the airplane to right itself.

Connect with Flight Training on Facebook
www.facebook.com/AOPAflighttrainingmag

In Jill W. Tallman’s description of the power stroke (“Technique: Leaning the Mixture,” May 2011 Flight Training) it

“I LOVE HAVING A SNEAK PEAK [OF FLIGHT TRAINING MAGAZINE] HERE ON FACEBOOK, BUT I STILL CAN’T WAIT FOR IT TO COME IN THE MAILBOX.”
—BARBE PARK

“I THINK AMELIA EARHART WAS THE ONE WHO SAID WE SHOULD NOT WORRY IF WE FEEL LIKE IT'S SLOW LEARNING, BECAUSE MANY OF THE BEST PILOTS WERE SLOW LEARNING IT. AND I LOVE TO RECALL RICHARD BACH'S QUOTE, 'ANOTHER TAKEOFF, ANOTHER LANDING, ANOTHER BIT OF KNOWING TUCKED AWAY.'”
—LISA MARTIN

FLIGHTTRAINING.AOPA.ORG

http://www.facebook.com/AOPAflighttrainingmag http://FLIGHTTRAINING.AOPA.ORG

Flight Training - July 2011

Table of Contents for the Digital Edition of Flight Training - July 2011