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WASP TESTING

FEBRUARY 2004

On Tuesday, 24th of February 2004, SPERWILL joined forces with WASP FLIGHT SYSTEMS in Cumbria to perform some last minute changes and settings on the latest developments on the WASP SP and SPT models of powered hang glider harnesses. The aim was to finally break the 60kg static thrust barrier using the RADNE RAKET 120 AERO engine and to carry out all the relevant flight testing.

PILOT

Chris Taylor was our test pilot - he has been flying hang gliders for 26 years, the last 7 years under power. With all his kit and boots, he weighs 86kg. The WASP powered harness weighs 23.8kg, reserve system weighs 2.2kg and 4.6L the fuel tank that was used weighing 5kg filled. The AEROS Stealth KPL2 14m² hang glider weighing 34kg was used for all the testing. This equates to a total of 151kg take-off weight.

TESTS

Despite being the coldest week on record for the year, all the ground thrust testing were carried out outside the WASP workshop with a wind chill often dipping below freezing. Initial test results were not satisfying, but after some calibration and reorganising of test equipment, testing commenced with consistent readings. Between 3 and 6 readings were taken for each test to determine the average test result. Seven different configurations were tested in order to get some comparative results. On several occasions, we broke the 60kg barrier and recorded up to 62kg although tests showed consistent 58-59kg averages. We discovered that the results were affected by the increase in wind speed when it would gust up to 8Mph. Our objective now is to achieve 62kg constant by fine tuning this set-up.

Test Model Carb Exhaust Reduction Ratio max rpm Static Thrust Prop Manf Prop Type / diameter * pitch

1 SP Walbro WG8M  Sperwill M1   1:3.69  9140 51 kg  FlyToSky  Fibre Glass / 120 cm 2 SP  Walbro WG8M   Sperwill M1    1:3.69 9140  50 kg  GeoK  Wood / 135 cm * 22"  3  SP  Walbro WG8M   Sperwill M1    1:3.69 9420  49 kg  GeoK  Wood / 135 cm * 20"  4  SP   Walbro WB21  Sperwill M2  1:3.69 8950  53 kg  GeoK  Carbon Fibre / 131 cm  * Pitch adjustable set at 28" 5  SPT  Walbro WB21  Sperwill M2  1:4.0 9180  52 kg  GeoK  Carbon Fibre 3 blade / 120 cm  * Pitch adjustable set at 32"  6  SPT  Walbro WB21   Sperwill M2  1:4.0 9150  58 kg  GeoK  Carbon Fibre / 131 cm  * Pitch adjustable set at 32"  7  AerosportN RG Walbro WG8M   Radne stock   1:3.54 8400  43 kg  Explorer   Carbon Fibre Folding 2 Blade

	STATIC TESTING	FLIGHT TESTING
Outside Temperature	6° C	5° C
Atmospheric Pressure	1009 mBar	1023 mBar
Humidity	60%	64%
Wind Speed	5 Mph	7 Mph

Flight testing commenced at 14h55 on the Monday afternoon after relocating to the beach site of Morecambe Bay in Lancashire Northwest coast of England. We chose this location because of the wind direction being southwest to westerly with constant windspeed of 7Mph blowing straight of the sea. This provided the ideal testing conditions with laminar flow without any thermic activity so we could carry out some conclusive testing.
The first test was with the SPT model. Whilst warming up the engine, Chris discovered he could not hold the harness back on full rpm check so consecutive run-ups where only to ¾ throttle. All well and ready to go Chris signalled and started his take-off, with only a few steps his feet left the ground, but he was still running waiting for his normal run distance to come up. His climb started off with a good 2.5m/s and continued to climb to 1100m at 2.2m/s average. This took just under 9 minutes. Chris throttled back to continue his climb at 1.2m/s average up to 2200m and switch of the engine to commence with his descent. The sink rate for this set-up showed an average of 1.4m/s down on the barograph which is average for this glider and weight set-up. The streamline design of the WASP harness showed no decrease in performance from excess drag. No carburation adjustments were made during these flight and as expected the climb rate decreased steadily with a promising average of 1.85m/s up at 2000m. Back on the ground a very happy Chris commented on his amazement of how quick he was whipped off the ground and how memories of his microlight days were flashing before his eyes.

A Braüniger vario was used to record all flight testing. On the right is a barograph chart from a typical SPT test flight. 1120m in under 9 minutes Maximum climb rate – 2.5m/s (500ft/min) Average climb over first 1000m – 2.2m/s (435ft/min) Average sink rate – 1.4m/s (275ft/min) At 2000m still climbing at 1.8m/s (350ft/min) Fuel consumption using Walbro WB21 carburettor under maximum revs climb out – 4.8L/hr Fuel consumption under normal use – 2.2 – 2.5L/hr HEAVY-FOOTED PROPELLORHEADS “Local WASP pilot has demonstrated on several occasions that it is possible to fly for over 3 hours and come home with more than 2L fuel left in his tank without even switching of the engine, FREAK!? His answer - don't give in to the temptations of the FOOT.”

All the above WASP testing was achieved using the standard SPERWILL engine/exhaust/carburettor setup for the Raket120 engine. Further developments currently undergoing field trials will be offered as options at first but should be standard feathures on all WASP models this season.
REDHEAD During the past winter, SPERWILL had been developing the new cylinder head “REDHEAD” upgrade for the Radne Raket 120 in conjunction with Ken Osage WASP dealer for Northwest USA. The aim was to produce an upgrade that would not affect the reliability of this well proven engine but to provide that sought after increase in power of approximately 30% that people are longing for on take-off. Combined with the SPERWILL tuned exhaust system already offering a 20% improvement over stock engines, SPERWILL will install all the WASP harnesses with a true 15Hp Raket120 engine.

REDHEAD

With the increase in power it is essential to cool the engine more efficiently with the addition of more cooling fins on top, since the stock Raket120 already runs with a CHT reading of 320°C (610°F) at maximum rpm under load of a propellor, a little high by average standards. The REDHEAD consistently demonstrated a reduction in temperature of 82°C (180°F) at maximum rpms with similar ave reduction in EGT readings. Dyno testing were performed by an independent third party specialist with astonishing results. The new REDHEAD was tested with 6 different configurations of exhaust systems and carburettors. Even with the REDHEAD the stock Radne exhaust consistently showed high CHT readings of 200-215°C (390-415°F). With the SPERWILL exhaust a significant reduction in tempuratures were evident, 177-183°C (350-360°F) using the standard WG8 carburettor.

The Raven exhaust also ran cooler at 167-170°C (332-338°F). However the addition of a Walbro WB style carburettor that is fully adjustable a further improvement in horsepower were seen and ran cooler again at 124-130°C (255-266°F).
Although these temperature readings were low, it is known that readings would look somewhat different under full load.
During load testing a maximum of 218°C (425°F) were recorded, quite acceptable. Unfortunately these developments always have their side affects, which means our exhaust system is out of tune since it was designed for much higher exhaust gas temperatures. SPERWILL will continue to produce the current exhaust system for the WASP models.
Development of a new exhaust system to compliment the REDHEAD is already in process and should be commercially available late spring.

PARAMOTORS

The REDHEAD upgrade is designed to be fitted on any current Radne Raket120 engine thus not unique to hang gliding and will be avaible upgrade for all paramotor pilots as well. Below is one of the first field trials.