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JSBSim Engines: Difference between revisions
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** <numboostspeeds> zero (or not present) for a naturally-aspirated engine, either 1, 2 or 3 for a boosted engine. This corresponds to the number of supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late Griffon engine apparently had 3. No known engine more than 3, although some German engines apparently had a continuously variable-speed supercharger. | ** <numboostspeeds> zero (or not present) for a naturally-aspirated engine, either 1, 2 or 3 for a boosted engine. This corresponds to the number of supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late Griffon engine apparently had 3. No known engine more than 3, although some German engines apparently had a continuously variable-speed supercharger. | ||
** <boostoverride> IGNORED | ** <boostoverride> IGNORED | ||
** <boostmanual> whether a multispeed supercharger will manually or automatically shift boost speeds. On manual shifting the boost speeds is accomplished by | ** <boostmanual> whether a multispeed supercharger will manually or automatically shift boost speeds. On manual shifting the boost speeds is accomplished by controlling propulsion/engine/boostspeed | ||
** <takeoffboost> - takeoff boost in psi above ambient. Many aircraft had an extra boost setting beyond rated boost, but not totally uncontrolled as in the already mentioned boost-control-cutout, typically attained by pushing the throttle past a mechanical 'gate' preventing its inadvertant use. This was typically used for takeoff, and emergency situations, generally for not more than five minutes. This is a change in the boost control setting, not the actual supercharger speed, and so would only give extra power below the rated altitude. When TAKEOFFBOOST is specified in the config file (and is above RATEDBOOST1), then the throttle position is interpreted as: | ** <takeoffboost> - takeoff boost in psi above ambient. Many aircraft had an extra boost setting beyond rated boost, but not totally uncontrolled as in the already mentioned boost-control-cutout, typically attained by pushing the throttle past a mechanical 'gate' preventing its inadvertant use. This was typically used for takeoff, and emergency situations, generally for not more than five minutes. This is a change in the boost control setting, not the actual supercharger speed, and so would only give extra power below the rated altitude. When TAKEOFFBOOST is specified in the config file (and is above RATEDBOOST1), then the throttle position is interpreted as: | ||
*** 0 to 0.98 : idle manifold pressure to rated boost (where attainable) | *** 0 to 0.98 : idle manifold pressure to rated boost (where attainable) | ||
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** Adjust <volumetric-efficiency> first to achieve desired fuel flow rate, leaning engine as required. | ** Adjust <volumetric-efficiency> first to achieve desired fuel flow rate, leaning engine as required. | ||
** Adjust <bsfc> to achieve desired power. | ** Adjust <bsfc> to achieve desired power. | ||
** Some piston engines will have power curves that will need to be altered from default depending on operating conditions. For example engines with multi-speed superchargers will produce less horse power on high speed at the same manifold pressure compared to low speed. Functions can be setup to alter <volumetric-efficiency> and <bsfc> at run time to get the power and fuel consumption curves correct by using different values for high and low supercharger speeds. | |||
== FGTurbine == | == FGTurbine == | ||