EngineNProp for general aviation pilots, mechanics, instructors, and students

The purpose of EngineNProp is to:

simulate the manufacturer's engine charts for traditional general aviation engines in the 160 to 300 horsepower range when used with constant speed propellers.

simulate the classical propeller efficiency charts.

⁃ estimate the net thrust for an engine and propeller combination and a set of operating conditions.

⁃ explore the effect on performance of changes in key engine and propeller operating and configuration variables.

⁃ estimate the activity factor of an actual propeller.

For example, when choosing propellers, use EngineNProp to examine the combined effect on net thrust of choices in operating conditions and propeller shape and diameter. The net power estimate can also be used as an input for the design or performance analysis of a complete aircraft.

With EngineNProp, the manual procedure for interpreting the sea level and altitude performance is automated and applied to the built-in Propeller Performance Chart. The user can then explore the performance of an engine and propeller combination with changes in engine manifold pressure, RPM, altitude, airspeed, temperature at altitude, propeller diameter, and propeller activity factor. A tool is included by which the activity factor of a propeller can be inferred from its diameter and planform shape. The user has a choice of using either English or metric units.

For convenience, EngineNProp comes with the data built-in for simulating each of five engines having a BHP rating in the range of 160 to 285 horsepower and for several propeller shapes used in historical wind tunnel research. Methods are also included for the user to:

⁃ add any engine of comparable rating for which the manufacturer's engine charts may be available in a similar format, and

⁃ add an actual propeller.

EngineNProp is document-based, so engine and propeller data are saved to file. In addition, the user has the option to export and import engine chart data in a 'plist" file format. EngineNProp is for Apple computers using OS X 10.8 or higher.

Interactive Automation of Legacy Graphs

Orcas Engineering also produces applications offering interative automation of legacy design and performance graphs. Many long-established processes continue to use such graphs because they concisely represent valued empirical or experiential data. However, they are also often cumbersome to interpret for changing conditions.

Below is an example that applies interactive automation to legacy engine performance graphs for general aviation aircraft engines. This application is intended for use in aviation technician training and by pilots and owners of high performance general aviation piston-powered aircraft.


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