Proficiency Improvement

Now that I have landed safely solo and feel reasonably comfortable in Sierra Charlie, I need to begin a process of improving skills.

On Friday, September 5, I took the plane up for two take offs and landings. I saw improvement in my pattern precision and turn coordination, and my attitude/descent control during landings was acceptable. But, I continue to see a pull to the right at touchdown.

Note in a previous post I address the issue of head placement or "aiming" and after reviewing the video, I am convinced I am simply aiming incorrectly, with my head to the right, causing me to land with a slight 2-3 degree crab to the right.  I think I am aiming correctly, but because of my scoliosis and my preference to lean right, my head is off to the right and my sight line is not down the center of the plane---this causes me to unconsciously put more "right" input than appropriate and I am leaning right, or flying with a right crab. (Noticed and commented on by all my CFI's!) 

Note in the video, there is a gauge reading "% grade".  My commentary speaks incorrectly to "degrees".  % grade is actually the tangent of the pitch angle in degrees. Since the plane is a tail dragger, the tail is down 10 degrees at rest, so the camera sensor reads 0% grade at rest.  Translating % grade to degrees:   Tail down 10 degrees = 0% grade;  Tail down 18 degrees in steep climb =15% grade;  Tail level = -15% grade.  Rule of thumb is figure a change 15% change in the camera % grade reading is 9-10 degree change in pitch and tail level is 8-10 degrees difference (negative) from three point attitude.

Keep in mind that the camera sensor has a bit of a lag.  The pitch attitude is easily seen on the reading of the left side inclinometer that reads zero (middle of range) when tail is level. This gauge shows a 5 degree nose down attitude during descent and more or less tail level at about 10 feet above runway--with a slight 1-2 degree tail down attitude at touch down. My guess is the camera % grade indicator is much less accurate than the inclinometer. 

  

Note the green line is the pilot's (incorrect) sight line. Since his head is to the right of center, he must cause the nose to go right to line up with the runway reference he is eyeballing.  The effect can be illustrated by aiming a rifle and changing the eye used to aim. 

2 or 3 degrees off may not seem like much, but it creates a 2 or 3 degree slip angle on the tires at touch down.  I have done quite a bit of research on tire slip angles on race cars. A 2% slip angle creates an estimated 20% "cornering" force or side thrust. So for the Sport Cub, that translates to 90 pounds of force per main tire.  In a crosswind landing, with touchdown on only the upwind tire, that is 90 pounds, but if the touchdown occurs with a level left/right attitude, that is 180 pounds.  In either case--a 90 pound force is enough to cause the plane to turn.  On pavement, whether is it a tail wheel or tricycle, a misaligned touch down makes for a sloppy landing--and even if directional control is maintained--it is hard on tires and landing gear. (Alignment is just as important as decent rate and landing attitude at touchdown.) 

The bad news is I veer off to the right...away from center line...not a good thing on a narrow runway...the good news is my rudder control is quick and efficient enough to maintain control. (Many thanks to Damien DelGaizo's advice to start wiggling feet (at least mentally) from 15 feet above the runway until the plane comes to a stop. His advice to practice balancing a stick/pole on my finger was/is also helpful. I still need to improve my "multi-tasking" of stick and rudder movement (response speed and amplitude) in those last few feet before and after touchdown but getting the alignment correct reduces the need for larger rudder movements.)

For my next flight, I have installed an "aiming sight assist" by placing two "rails" on the glare shield and marks/decals on the cowl to force me to reposition my head and aim the plane correctly. 

Here is the "aiming sight assist". The first is in the hangar--ignore the reflection on the windshield--the second picture is probably more "normal".

I installed two "rails" inside the cockpit on the glareshield, about 2.5 inches apart. In addition, I added three small black decals on the cowl.  The purpose of the two rails is to: a) frame the cockpit "bubble" and to provide line of sight for each eye---when perfectly aligned, the vertical portions of the "rails" are identical---if misaligned, there is a full side view of the vertical inside portion of one and the side view of the other vertical portion is not visible.  

I noticed that I had to move my head 2 inches to the left from my "normal" position in order to "aim" correctly. 

On October 26, I took Sierra Charlie up to try out the new "aimsight" in challenging crosswind conditions. My first time taking off and landing at KTHV's runway 17.  And my first time in gusty crosswinds with an 8 mph crosswind component--the figure I had chosen as my "maximum" as part of my present "Performance Limits/Minimums". 

The good news is the "aimsight" worked perfectly and "cured" my right crab tendency.  But, I must say, the "busy-ness" of all of the control inputs with that high of a gusty crosswind was difficult and I did not round out soon enough. I was pulling the nose up slightly with stick back at touchdown for my wheel landing, so my stick forward lift killing move was late, with the plane taking a small "hop".  I recovered OK and the landing was "safe", but I still need more practice.  Positives: Good Alignment; Good Speed Control (landed pretty much at 1.3 Vstall with minimum energy); Good recovery from the hop with stable stick, good rudder and throttle inputs.