Eiri KY PIK-20 E - Page 47

PIK-20 E Flight manual
6.1.2. "Actual pilot weight range" -criteria
To use the actual pilot weight range as criteria for loading, the range
must be calculated according to Service Manual Chapter 5. After chan 
ging equipment or fixed ballast, it is not enough to determine the new
actual empty weight and empty weight C. of G., but also the new actual
pilot weight range should be calculated and marked on Weight and Ba 
lance Record, see 6.4.
6.2 Calculations for actual C. of G. location
The actual C. of G. location can be calculated according to Sample
Problem as follows:
1. Take the last empty weight (including all equipment and fixed bal
last) and corresponding moment (Record sheet 6.4) and write them
down.
2. Put the weights of the fuel m, (kg) = 0.725 x fuel quantity (I), water
ballast and pilot on the left column.
3. Calculate the corresponding moments by multiplying the arms given
in the columns with the weights.
Note: The moment arm of the pilot depends on his length ie.
1.42 m for short pilot (lenght below 1.60 m)
1.50 m for tall pilot (lenth over 1.90 m)
Calculate all the weights and moments together and you get the total
weight and moment. Divide the moment by weight to get the arm
-- ° ment j JSfll l? 1 = arm (m) = location of C. of G. (m)
Weight (kg)
The difference in the maximum L/D of the sailplane between the back 
most and the foremost C. of G. location is 2 digits induced by the nega 
tive lift at the tail.
Therefore for maximum gliding performance it is better to have the
C. of G. location rather near the backmost position.
The backmost C. of G. cannot be reached with a heavy pilot and hea
vy equipment in the instrument panel. In this case it can be helpedt by
fitting max. 3.0 kg lead to the tail wheel spring.
EIRI KY -
Kisällinkatu 8
SF-15170 Lahti 17
___________________ J
page I-39