Shortround6
Major General
Why was it SUPER impressive?
Lets take an engine and fit it with a hydraulic "clutch/torque converter" and another identical engine and supercharger with a two speed box. Lets say we set up the Hydraulic unit to give a max gear ratio of 10.39 to 1 and a minimum gear ratio and maximum slip of 7 to 1, and yes there was a minimum speed ratio. Then we set ou the mechanical drive set up with a set of 10.39 to 1 gears and another set of 7 to one gears. Now with Engine "A" (hydraulic clutch) at minimum slip (98-100%) it has a full throttle height of 5,000 meters. Engine "B" with it's two speed box in high gear will also have a full throttle height of 5,000 meters. Both supercharger impellers are turning the same speed. At sea level both engines will give the same power, or nearly so. Both engines will require their throttles to be partially closed to prevent over boost. As both engines climb to say 1800 meters the throttles can be opened (automatically in both cases by a barometric capsule) until they are fully opened and again both engines are making the same power or nearly so. Both superchargers are taking just under 1/2 the power to drive them than will be needed at 5000 meters. Engine "A" may deleiver a fraction less power to the prop because of the power lost in the Hydraulic clutch at maximum slip. As both engines climb higher engine "B"s power falls of in a straight line. It's impeller is turning at a fixed speed which is no longer fast enough to keep up with the thinning air. Engine"A" on the other hand is having it's barometric capsule (second one) adjust the hydraulic clutch to less and less slip and so speeding up the impeller to keep the boost constant or nearly so. At some point, lets call it 3500meters, Engine "B" shifts supercharger gears to high ratio. It's throttle is part closed to prevent over boosting because it's impeller is now turning maximum revolutions. The loss in efficiency in the supercharger is balanced by the loss of power if the engine had continued to use low gear in the the thinning air. This is the low point seen on the power graph of two speed engines between the two peaks. This is also the point of PEAK advantage of the hydraulic clutch. It's supercharger is turning at an almost optimum speed instead of being at the point of worst compromise in the two speed system. However as the two engines continue to climb engine "B" gains power as it's throttle is opened more and more until, at 5,000 meters both engines have fully opened throttles and are making the same power. As the engines climb above this point they both loose power at the same rate because the supercharger is already maxed out and cannot supply any more air.
That is the advantage of the hydraulic clutch as a supercharger drive, it eliminates the big dip in the power curve or turns it into a curve instead of a "V". It's onther advantage is that the pilot does not have to manually shift or select "hi' or 'Low" supercharger while in combat.
It does nothing for take-off or sea level power and does nothing for power above the rated altitude of an engine and it does not change the rated altitude from what the engine would have with a fixed gear ratio that was the same.
Lets take an engine and fit it with a hydraulic "clutch/torque converter" and another identical engine and supercharger with a two speed box. Lets say we set up the Hydraulic unit to give a max gear ratio of 10.39 to 1 and a minimum gear ratio and maximum slip of 7 to 1, and yes there was a minimum speed ratio. Then we set ou the mechanical drive set up with a set of 10.39 to 1 gears and another set of 7 to one gears. Now with Engine "A" (hydraulic clutch) at minimum slip (98-100%) it has a full throttle height of 5,000 meters. Engine "B" with it's two speed box in high gear will also have a full throttle height of 5,000 meters. Both supercharger impellers are turning the same speed. At sea level both engines will give the same power, or nearly so. Both engines will require their throttles to be partially closed to prevent over boost. As both engines climb to say 1800 meters the throttles can be opened (automatically in both cases by a barometric capsule) until they are fully opened and again both engines are making the same power or nearly so. Both superchargers are taking just under 1/2 the power to drive them than will be needed at 5000 meters. Engine "A" may deleiver a fraction less power to the prop because of the power lost in the Hydraulic clutch at maximum slip. As both engines climb higher engine "B"s power falls of in a straight line. It's impeller is turning at a fixed speed which is no longer fast enough to keep up with the thinning air. Engine"A" on the other hand is having it's barometric capsule (second one) adjust the hydraulic clutch to less and less slip and so speeding up the impeller to keep the boost constant or nearly so. At some point, lets call it 3500meters, Engine "B" shifts supercharger gears to high ratio. It's throttle is part closed to prevent over boosting because it's impeller is now turning maximum revolutions. The loss in efficiency in the supercharger is balanced by the loss of power if the engine had continued to use low gear in the the thinning air. This is the low point seen on the power graph of two speed engines between the two peaks. This is also the point of PEAK advantage of the hydraulic clutch. It's supercharger is turning at an almost optimum speed instead of being at the point of worst compromise in the two speed system. However as the two engines continue to climb engine "B" gains power as it's throttle is opened more and more until, at 5,000 meters both engines have fully opened throttles and are making the same power. As the engines climb above this point they both loose power at the same rate because the supercharger is already maxed out and cannot supply any more air.
That is the advantage of the hydraulic clutch as a supercharger drive, it eliminates the big dip in the power curve or turns it into a curve instead of a "V". It's onther advantage is that the pilot does not have to manually shift or select "hi' or 'Low" supercharger while in combat.
It does nothing for take-off or sea level power and does nothing for power above the rated altitude of an engine and it does not change the rated altitude from what the engine would have with a fixed gear ratio that was the same.
