Challenging Issues With The Blanik, L-23 (and all gliders)
Recently, I flew with Dale Igram for my Flight Review. When we did stalls, the characteristics were very much altered from when I observed them from the back seat. The reason is the affect of the Weight and Balance shift with me in the front versus the rear seat, even though the gross weight would be the same either way. Sensitivity to weight and balance impacts on flights is a real safety concern.

In addition, Blanik, N809S was painted and reweighed - AND CAME OUT SOME 30 POUNDS HEAVIER EMPTY WEIGHT! This is not a rare occurrence. The same thing happened when we weighed the white SGS-2-33 some years ago. It also "gained weight". In my military experience, I flew with an aviation company that had 17 similar DeHaviland Beavers. One of them flew "very ugly" for me, and I asked the maintenance officer to check the weight and balance. The record showed all OK.

I was unconvinced and asked that it be reweighed. It had gained more than 300 pounds over its brothers since its last weighing, even though the required "additions and subtractions" were done. Apparently, in real life, aircraft accumulate paint, patches, dirt and a few "extra" items that make them put on pounds, just like people, as they grow older.

Philosophically, I have trouble with finding that an aircraft that I flew "comfortably" with some folks last year is now "over gross weight" by a bunch this year and, thus, unable to fly with that combination legally. From another perspective, it fits in with our efforts to maintain the best level of safety that we can in our operation.

KNOWLEDGE IS POWER. SO HERE IS SOME SOUND WEIGHT AND BALANCE INFORMATION

In single place gliders, the maximum and minimum pilot weights are normally placarded somewhere in the cockpit. This does provide the proper weight limits (if the glider has not put on pounds).

In two place gliders placards do not work because the amount allowable in one seat is dependant upon the amount carried in the other seat. Of course, the combined weight to remain under maximum gross weight will be the same, but the balance condition can shift outside of limits depending on who sits where.

Consequently, the first issue is to find out what the REAL empty weight and center of gravity condition of the glider is so that you can determine what you can carry where. It is possible to be operating UNDER maximum gross weight and be out of Center of Gravity (CG) limits. It is possible that the same people "switching seats" can make the CG condition unsafe.

The REAL weight and balance information is found on a paper document that is signed by an A&P mechanic and is dated. It should state the "N" number of the glider, the Empty Weight (usually in pounds) and the center of gravity location at the empty weight (usually in inches, but Blanik is in %MAC). This document or a copy of it must be on board the glider in the aircraft "papers package".

From that basic information, you use the procedure in the Glider Flight Manual/Operators Manual and calculate what your condition of flight will be. For those going for a rating, calculating the weight and balance of the aircraft is ALWAYS tested.

I will leave it to ground school or an instructor to give specific training on how to complete the calculations.

THERE ARE TRAPS!

On more than one occasion, I have had a pilot determine his weight and balance condition using the "Sample Weight" published in the Flight Manual. For instance, the L-23 book says that the "Empty weight with standard equipment" is 683 lbs + 2%. That would seem to make you safe considering the empty weight at 697 lbs. N809S is now an empty weight of 722.25 lbs, and N303BA is 713.2 lbs! A similar "sample" center of gravity is indicated. DO NOT USE THESE NUMBERS! Go to the real document.