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| FlyGas Supercharged engine at full power |
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| Turbo Charged engine at full power |
There have been questions raised about the selection of a supercharger that I would like to answer.
The main reason is illustrated above :
The Flygas supercharger allows the Rotax 912 ULS to develop 140 hp at the prop for two minutes and a 130 hp for the climb with less than 5 HP begin absorbed by the supercharger at full power. Turbos are not totally unrestricted as increased back pressure on the exhaust in operation that will consume some power in operation.
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| 97 kts [180 kph] - 400 f/m - 12000 ft Factory supercharged aircraft |
FlyGas has delivered about 80 of these units to date and has had no reported issues with their installations in 14 years and worked with Flying Legend to develop the ring mount to suit the Tucano. The factory aircraft now has in excess of 300 hours of operation on this engine with no issues other than the normal maintenance.
The system features a separate oil pump and allows the engine to operate developing 82 HP in the event of supercharger failure.
The simplicity of operation in the fact you open the throttle and like a normally aspirated engine your power is governed by altitude and throttle position. Examination of the power curve shows that a supercharger produces a linear throttle response where a turbo will display a small peak and the rate of power development drop off a little in the last 1000 revs. The other thing I found flying the factory turbo 914 was a constant need to adjust the boost as it crept over the flight.
The final reason is a turbocharger itself while they develop power they have to be controlled as they are effectively only controlled by he wastegate and it is known that is the wastegate failes in any way the pilot only has a small window to control the runaway boost while a supercharger is mechanically controlled by it mechanical drives ratio.
The weight of the supercharged engine is 73kg compared to 78kg for a turbocharged Rotax 914 and 84 kg [est] for a Rotax 915 but that does include an intercooler but watch that space.
Downside
A downside to any supercharger is that it will lose manifold pressure at the rate of 1'' / 1000 feet meaning that this engine developing a 100 hp at 6000 feet, this is where a turbocharger shows its advantage.
For maximum power, at any height above 6000 feet, a turbo develops a steady output until the turbos physical capacity is reached with the Rotax 915 rated at 130 hp to 16000 feet and this is where oxygen is a factor above 10,000 feet with MOTW raising its ugly head. This will increase the complexity of operation not to mention the problem of recharging the bottle during a trip with this begin the largest issue.
At altitudes below 10000 feet, the engine will develop its maximum design horsepower and as a "What if" type I am comfortable with that, to run a modified engine continuously at higher power settings you have to consider the risks or use the 915.
The installation planed for this aircraft will result in a lot of items hung under the engine and most do not like red hot items another reason why I chose the lower power to avoid any issues later - it just the conservatives option.
By the way, CASA dose do ramp checks in Australia and if you are found non-compliant on a range of issues you will be issued with a significance fine on the spot and if there are too many issues you will be in a world of financial grief and have a new hobby - plane spotting.
Read the article on the FlyGas supercharger from the EAA Experimenter for a more detailed review of the FlyGas product.
Reference
Discussion on the power consumption of supercharger - very technical but go the last few posts for the wash-up - CLICK HERE
The weight of the supercharged engine is 73kg compared to 78kg for a turbocharged Rotax 914 and 84 kg [est] for a Rotax 915 but that does include an intercooler but watch that space.
Downside
A downside to any supercharger is that it will lose manifold pressure at the rate of 1'' / 1000 feet meaning that this engine developing a 100 hp at 6000 feet, this is where a turbocharger shows its advantage.
For maximum power, at any height above 6000 feet, a turbo develops a steady output until the turbos physical capacity is reached with the Rotax 915 rated at 130 hp to 16000 feet and this is where oxygen is a factor above 10,000 feet with MOTW raising its ugly head. This will increase the complexity of operation not to mention the problem of recharging the bottle during a trip with this begin the largest issue.
At altitudes below 10000 feet, the engine will develop its maximum design horsepower and as a "What if" type I am comfortable with that, to run a modified engine continuously at higher power settings you have to consider the risks or use the 915.
The installation planed for this aircraft will result in a lot of items hung under the engine and most do not like red hot items another reason why I chose the lower power to avoid any issues later - it just the conservatives option.
By the way, CASA dose do ramp checks in Australia and if you are found non-compliant on a range of issues you will be issued with a significance fine on the spot and if there are too many issues you will be in a world of financial grief and have a new hobby - plane spotting.
Read the article on the FlyGas supercharger from the EAA Experimenter for a more detailed review of the FlyGas product.
Reference
Discussion on the power consumption of supercharger - very technical but go the last few posts for the wash-up - CLICK HERE
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