Removal of Aircraft.Engine.REFERENCE_DIAMETER#1047
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xjjiang wants to merge 26 commits intoOpenMDAO:mainfrom
Open
Removal of Aircraft.Engine.REFERENCE_DIAMETER#1047xjjiang wants to merge 26 commits intoOpenMDAO:mainfrom
xjjiang wants to merge 26 commits intoOpenMDAO:mainfrom
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…or engine sizing. still a work in progress.
…to engine_ref_diameter
xjjiang
changed the title
ehariton
reviewed
Mar 31, 2026
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Summary
Engine reference diameter never existed in GASP. This PR replaces it with a different algorithm.
Suppose
AE= Engine cross-sectional area (inlet/frontal area). The current GASP algorithm computesAEas follows:AE = 0.3×WG/1500/ENP, whereWGis the gross weight andENPis the number of engines. The factor0.3is the Thrust-to-Weight ratio and1500.0is engine size constant.From our existing engine library, we establish the following table:
See the graph below:
Today’s engines are in the 1.4 to 1.65 range.
If we know the fan pressure ratio, then we can do a curve fitting (polynomially or exponentially):
The problem is that the fan pressure ratio is not always available. Notice that for the modern engines, this ratio usually stays in the upper range in which a value of
800for the engine size constant is pretty close. Therefore, it is recommended that we pick800to replace1500. When we do so, we get an equation:AE = 0.3×WG/800/ENP = 0.000375×WG/ENPThis result is very close to our models.
Related Issues
Backwards incompatibilities
None
New Dependencies
None