Eiri KY PIK-20 E - Mccready Curves

PIK-20 E Flight manual
From the curves can be seen that the use of +12° flaps decreases the
curve radius by 30 — 50 m compared to 0° flaps. This means clear in 
crease in the rate of climb in any normal thermal.
Thus the use of even maximum positive flap setting +16 is recom 
mended when thermalling.
The difference in radius depends on the difference in stalling speeds
with different flap settings. A 10 % marginal to the stalling speed is in 
cluded to the curves.
Note: The aileron efficiency decreases with higher positive flaps set 
tings. The use of +8. . . + 4 flaps setting is recommended in gusty ther 
mals where is needed also more marginal to the stalling speed.
7.4 McCready curves
Following graph give the McCready values with the flying speed calcu 
lated as normal from the polar curve. The values are given in two altitu 
des with two weights.
1000 m height is recommended for normal purposes. The atmosphere
is 5°C warmer than the normal standard (20° C at sea level).
The airspeed is given in V EAS -scale which the airspeed indicator is
showing. The McCready values are true sinking speeds.
By plotting the speeds on the ring at the sinking speed shown by the
graph
taking the variometer scale into account you will get the McCrea 
dy ring.
These curves can also be used for electric "Speed to fly"-variometer.
EIRI KY
J
Kisällinkatu 8
SF-15170 Lahti 17
page I-52