Post on 15-Aug-2015
transcript
Cherokee II Sailplane
• Gottingen 549 Airfoil• 40 ft wingspan• 125 ft2 wing area• 14.4 ft2 tail area• 2.5:1 taper ratio• 600 lb weight• 6.66 G ultimate load
Objectives
• Determine Glide Polar• Determine actual performance• Compare to expected performance• Find Aerodynamic Characteristics• Find Stability Derivatives
Calibrate Instruments
• Airspeed and Altimeter–WWII Vintage
• Constructed Manometer to calibrate Airspeed
• Used test set to calibrate Altimeter
Calculate Polar
• Determine Altitude change on each run
• Time between start and finish• Calculate descent rate• Plot descent rate vs speed• Calculate L/D ratio at each speed
Find Aerodynamic Characteristics
2
sin12
D
WC
V S
21cos
2
L
WC
V S
2
,0L
D D
CC C
eAR
,0L L L L eC C C C
,00m m m m eC C C C
Process CL
• All variables known, find CL vs V
• Know δe vs V
• Calculate CLα and CLδ
• Take CL,0 from Lockheed code
• Find CL vs. α
21cos
2
L
WC
V S
,0L L L L eC C C C
Calculate CLα and CLδ
• Use pitch attitude and flight path angle change to find change in alpha
• Use stick position measurements to find change in elevator angle
Process CD
• Know everything for Weight based CD
• Use Minimum Sinking condition to find CD,0 , e
2
sin12
D
WC
V S
2
,0L
D D
CC C
eAR
,0
1
4D DC C
Process Cmδ
• Cm = 0, trim condition
• Know Cm,0 and Cmα from Lockheed
code
• Know α and δe for each speed
• Find Cmδ
,00m m m m eC C C C
Future Work
• Better camera setup• Digital Level• More accurate stick position• Automated processing• More glider types!