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It has been claimed that the reflex/no-reflex flap difference has little affect on speed, perhaps 2-3 mph. My feeling was that is was greater since I use small flap increments to knock down the speed when approaching an airport. It was also postulated that I may see a greater indicated air speed difference that may be due solely to a change in the airflow over the fuselage near the static ports. Thus, I should look at ground speeds. The following experiment was performed today.
-The static ports on my 320 are in the Lancair recommended location.
-The flap was marked at 7* down from the faired in reflex position.
-A target test speed of 160 Kts would be used to lessen the twist applied to the outboard end of the flap.
-A digital level was carried aloft for additional information and coordination with AOA (Proprietary Software) readings.
-All data collected in trimmed level flight with autopilot and alt hold engaged.
The following baseline was used:
6500 ft (6110 p alt), -7*C, 25.1" MP, 2490 RPM, 180 KIAS, 192 KTAS
Longeron Angle = +0.6*, wing AOA = 1.9, Tail AOA = -0.15*
At 5500 ft, heading East, 20.5 " MP, 2380 RPM
In Reflex (-7*) - 153 KIAS, 169 GS - Longeron= +1.2*, wing AOA = 2.7, Tail AOA = -.45*
No Reflex (0*) - 142 KIAS, 154 GS - Longeron= -1.2*, wing AOA = 1.0, Tail AOA = -1.95*
11 Kts indicated slower, 15 Kts slower over the ground.
At 5500 ft heading West, 20.5" MP, 2380 RPM
In Reflex (-7*) - 153 KIAS, 155 GS - Longeron= +1.0*, wing AOA = 2.7, Tail AOA = -.25*
No Reflex (0*) - 144 KIAS, 144 GS - Longeron= -1.2*, wing AOA = 1.0, Tail AOA = -1.95*
9 Kts indicated slower, 11 Kts slower over the ground.
The wing has a tremendous pitching moment when the flap is engaged, with quite a bit of nose up trim (tail down load) needed to fly level.
Note: If aircraft has rear CG problems, a little flap should help with elevator control issues at a small loss in speed.
Scott Krueger
N92EX
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