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Mistakes

Sage Advice - Mistakes: The shortest path to disaster

Mistakes! They will absolutely kill you in this hobby. Usually, the shortest path to winning a contest is to avoid errors. In other words, the win doesn’t go to the best pilot and certainly not to the best equipment. The pilot that makes the best decisions during the contest normally wins and the pilot that makes mistakes is usually relegated to a spot well down in the standings.

Even the so-called "Master" pilots make serious blunders occasionally. Nobody is invincible in this sport. To highlight this fact, and since I really don’t care to point out other’s mistakes, I would like to focus on a couple of beauties I made last weekend. The first could have cost me my glider and the second eliminated me from the contest. I mention these mistakes to give you encouragement in that you are not alone when you do something that is "less than brilliant", but more so in the hope that you will learn form my errors.

Bonehead #1: The Case of a round pin being in NO hole

One of the problems with cruciform tails is that after a hard dork landing, the two halves of the horizontal stab separate from the vertical stab and leave a gap. Unless the stabs are reseated before each flight, amplified interference drag is the result.

There are many methods of fixing this problem if you’re using metal pins, but since I’m using carbon fiber, my solution has been to apply bees wax or bow string wax to the horizontal stab drive and locator pins. This helps to keep the stabs tightly seated against the vertical stab.

As I was getting tired of reseating my stabs prior to each flight, I jumped at Bren Lugo's generous offer to use his bow string wax. Applying the wax entails removing the horizontal stabs and liberally coating the locator and drive pins. Reseating the stabs normally completes the process.

As several of us were in the middle of a practice landing contest, I was in a hurry to get back into the air, and I only felt with my fingers to confirm that my horizontal stab drive pin was through the bell crank. At 54, I need reading glasses to see close detail. Because I was too lazy to walk to my car to get my glasses, I never took the time to visually confirm the stab drive pin location.

After taking a short bungee launch to rejoin the practice-landing contest, I noticed that I didn’t have pitch control and immediately realized the problem. The horizontal stab drive pin wasn’t through the bell crank hole but was resting on top of it. In this configuration, I had up pitch available but not down. Fortunately, by running the pitch trim fully down and switching to high rates, I was able to move the bell crank out of the way and the stab faired into the relative wind to a near normal position. By manipulating the flaps, I was able to marginally control pitch and landed the glider with no resultant damage.

Incidentally, this failure can also occur with the stab drive pin resting on the bottom of the bell crank in which case only nose down would be available. Assuming sufficient altitude, this is usually a less serious scenario. Allowing the glider to continue nose down through an outside loop to an inverted position and landing upside down can be safely accomplished with only nose down pitch available.

I’ve seen numerous pilots crash their glider in exactly the same circumstances and consider myself lucky not to have suffered the same fate.

LESSON: PRIOR TO LAUNCHING YOUR PLANE, CHECK ALL CONTROL SURFACES TO INSURE THEY ARE FULLY FUNCTIONAL AND MOVE IN THE PROPER DIRECTION.

Bonehead #2: All stabs are not created equal

After reseating the drive pin in the bell crank, I took a couple of bungee launches and noticed the glider wasn’t behaving normally. Since I was making practice landing approaches and because the day had turned windy and turbulent, I attributed my glider’s strange handling to these factors.

On the day of the contest, I also noticed my glider was handling peculiarly. It was launching differently, wasn’t pitch stable and was an absolute bear to land.

Since the tasks for the contest weren’t daunting, I continued to compete thinking that I could stay close to the winner even with my glider flying poorly; a prime example of the "God Complex" at work. However, being a typical TPG contest, there’s no room for error and a near perfect performance is required to win. I finished the contest well down in the standings.

After a detailed inspection of my glider that evening, my second mistake became apparent and was actually related to the first. I’ve switched to SD 8025 asymmetrical stabs recently in an attempt to improve performance.

The rationale for using these downward lifting or negative camber stabs is to allow a pilot to fly with a more aft CG thereby opening up the speed envelope and making the glider more efficient. I’ve noticed subtle improvements and had been able to shift the CG so far aft that I also had to move the tow hook position ¼ inch aft to continue getting steep launches.

Of course, all these improvements only apply if you mount the stabs so they lift downward. With symmetrical stabs like the SD 8020 or NACA 9000, the consequence of reversing accurate stabs is unnoticeable. However, if you mount asymmetrical stabs upside down, your trim and tow hook positions will be so far off that the glider is difficult to control.

Yes, that was my mistake. Not only did I miss the bell crank hole, but I had also mounted my stabs upside down. In the future, to ensure that the stabs are mounted correctly, I have an identifiable left and right stab.

LESSON: PRIOR TO LAUNCHING YOUR PLANE, CHECKALL CONTROL SURFACES TO INSURE THEY ARE FULLY FUNCTIONAL AND MOVE IN THE PROPER DIRECTION.

Tenets of a fighter pilot

Pilots have a rigorous pre-flight checklist of items to be inspected before they ever ignite an engine. The primary purpose of the checklist is to insure the plane functions as it should. You usually pay for shortcuts, which is why these checklists are so important.

I should have taken the following tenets from my days as a fighter pilot and applied them to the situation:

• When things don’t seem quite right, something is probably wrong.
• If you’re being hurried and pressured, that’s when mistakes occur.
• Overconfidence will kill even the best pilot!

No matter what our level of experience, we all make mistakes. The difference between the champions and the contenders has a lot to do with how each deals with his mistakes. Learn from them and don’t repeat them.