Wind Tunnel Tests Were Carried Out On A 1/17 Scale Mig-21 M Aircraft Model (With No Vortex Plate On The Wing) With Trailing Edge Flaps Deflected At 3,6,9,12 And 15 Degrees And Horizontal Tails Set At 5,0,-5,-10 And -13 Degrees. Tests Covered A Mach Number Range Of 0.5 To 1 .1 And Incidence Range Of -5 To 15 Degrees. Reynolds Number Based On Mac Varied From 3 .9 To 6 .3 Millions. Analysis Of The Test Data Indicate The Following:
1. Flap Effectiveness Studies Show A Constant Value Of Cl B F At .011 Per Degree (0 46f 4 15) Up To M = 0 .8 ; Cl 6 F However Decreases Beyond M = 0 .8 And At Higher Incidences.
2. Results With Tail Deflections Show A Constant Value Of Cm 5 ht At .005 Per Degree (-13 < 6 Ht 4 5)Up To Cl Of 0 .5 In The Range Of Mach Numbers Tested.
3. At A Free Stream Mach Number Of 0.7, Results With The Optimum Flap Deflection Schedule Show An Increase In (L/D) Trim Of 15 Percent Compared To That Of Flap Deflection Zero Degree . Also The Increase In (L/D)T Im For Optimum Flap Deflection Schedule Is Higher When Compared To Thai Obtained With Vortex Plate On The Wing
