Dear Karp and others,
I am about to fit the Europa 'speed kit' and I will happily report any
improvements
which I have achieved. In order to do this I must once again accurately
measure TAS in
my own aircraft, prior to fitting.
I will ensure that the figures will be an honest and fair reflection of my
aircraft
performance.
There are a variety of ways of measuring accurate TAS available to members
on the Web. These
take into account affects of wind on GPS measured speed over the ground.
The one I have chosen measures GPS speed over a triangular course and uses
complex
trigonometry to produce a TAS result, whilst also giving wind direction and
speed.
The pilot is required to fly an accurate track, at constant altitude and RPM
setting
and to record the GPS ground speed and direction flown. The three tracks
flown need not be equally seperated, though for my purposes I have chosen
000, 120, 240 degrees.
Hear is the raw data, based on two sucessive weekends of flying.
NB.
1/ The raw data was mph. Rounding produced (.5) fraction of knots.
2/ One of the tests produced results inconsistent with the others.
3/ I found I was typically able to hold track to +-1.5 degrees.
4/ Speed did vary due to thermals and wind gusting. I measured averages from
figures which varied by +-2 mph.
5/ Max S&L RPM achieved was circa 5750.
6/ I have confidence that the Flydat RPM figures are correct.
7/ The aircraft uses around 17 litres/hr at 5200 RPM.
Unmodified Europa 912 'Classic'
Fixed pitch Warp Drive prop @ around 18 degrees.
Full fuel
Rear C of G
Take off weight: around 1110 lbs.
Test height: circa 1200ft AMSL
Ground Temp: around 15 degrees C
Test 1.1 - Low cruise setting. 4800 RPM (14/07/01)
Track GPS speed (knots)
120 120
240 108
360 103
Result: TAS 111 kts Wind 316 degrees 10 knots.
N.B. This result is slightly discrepant. I have placed a lower reliance on
it.
Test 1.2 - Following week. (22/07/01)
Track GPS speed (knots)
120 111
240 99
360 111
Result: TAS 107 kts Wind 240 degrees 8 knots.
Test 2.1 - Normal cruise setting. 5200 RPM. (14/07/01)
Track GPS speed (knots)
120 129
240 117
360 113
Result: TAS 120 kts Wind 313 degrees 10 knots.
Test 2.2 - Normal cruise setting. 5200 RPM. (22/07/01)
Track GPS speed (knots)
120 123(.5)
240 109(.5)
360 124(.5)
Result: TAS 119 kts Wind 237 degrees 10 knots.
Test 3.1 - Maximum continuous. 5500 RPM. (22/07/01)
Track GPS speed (knots)
120 130(.5)
240 121
360 129(.5)
Result: TAS 127 kts Wind 245 degrees 8 knots.
Test 3.2 - Maximum continuous. 5500 RPM. (22/07/01)
Track GPS speed (knots)
120 128
240 119
360 131
Result: TAS 126 kts Wind 225 degrees 8 knots.
Based on these results, I have concluded the following.
Power TAS.
4800, 107 kts 123 mph.
5200, 119 kts 137 mph.
5500, 126 kts 145 mph.
Frwl 136 kts 156 mph.
These figures are consistent with previous results I've obtained.
It'll be interesting to see how much of an improvement I get with
the new fairings.
Alan
I can supply anyone with a copy of the self installing binary for this. It
comes
in the form of a 26Kb zip file.
Alternatively, I have an Excel spreadsheet and accompanying PDF description.
Alan. D. Stewart
14 Goddard Way 'phone : +44 1245 264186
Chelmer Village work : +44 1245 275104
Chelmsford, Essex CM2 6UR email :
alan.stewart@blueyonder.co.uk
office email : alan.stewart@marconi.com
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