SECTION 15 FINAL INSPECTION AND FLIGHT TEST
RV AIRCRAFT
15-25
SEC 15r8 12/23/10
A
IRSPEED
C
ALIBRATION
R
UN
#1
Conditions & Data:
8,000' MSL
42 deg. F.
156 IAS
2675 RPM
20.5'' Man. Pres. Sensenich 68x78 prop
E6B computations show that:
156 mph IAS at 8,000' and 42 deg. F. = 178 mph True Indicated AS.
(ie: no calibration for system errors)
Run #1 from north to south:
Start
45
q
41.0' Lat.
Finish
45
q
31.0' Lat.
Distance = 10 NM
time = 3 minute 55 seconds = 235 Seconds.
Speed (knots)=Dist/time=(10 NM/235 sec) X 3600 sec/hr = 153.2 NM/Hr.
Speed (mph) = speed (NM/Hr) x 1.15 = 176.2 mph
Run #2 from south to north:
Start
45
q
31.0' Lat.
Finish
45
q
41.0' Lat
Distance = 10 NM
time = 3 minutes 52 seconds = 232 Seconds.
Speed (knots)=Dist/time=(10 NM/232 sec) X 3600 sec/hr = 155.2 NM/Hr.
Speed (mph) = speed (NM/Hr) x 1.15 = 178.5 mph
Average speed = (176.2 + 178.5) / 2 = 177.35 mph True airspeed.
(from above) True Indicated Airspeed = 178.5 = Approx. 1 percent calibration error.
A
IRSPEED
C
ALIBRATION
R
UN
#2
Conditions and Data:
1000' MSL
76 deg. F.
171 IAS
2650 RPM
24'' Man. Press.
E6B computations shown that:
171 mph at 1000' msl and 76 deg. F. = 177 mph True Indicated AS
. (ie: no calibration for system errors)
Downwind leg: 3 miles in 55 seconds.
Speed (mph)=Dist/time=(3 miles/55 sec) X 3600 sec/hr = 196.4 mph.
Upwind leg:
3 miles in 75 seconds.
Speed (mph)=Dist/time=(3 miles/75 sec) X 3600 sec/hr = 144 mph.
Average speed = (196.4 + 144)/ 2 = 170.2 mph.
This sample shows a TIAS of 177 as opposed to a true calibrated speed of 170.2, or an airspeed indicator reading of
about 4% high.
Erroneous calculation would be:
Average speed =
(distance 1 + distance 2)/(time 1 + time 2
) =
(3 miles + 3 miles)/55 sec+75 sec)
X
3600 sec/hr
= 166 mph.
TEST RUNS USING LORAN OR GPS MAY BE USED TO CALIBRATE THE AIRSPEED SYSTEM
SECTION 15 FINAL INSPECTION AND FLIGHT TEST
RV AIRCRAFT
15-26
SEC 15r8 12/23/10
NOTES
