The `_engine_` library serves as the core analysis tool for engine data within UNICADO. It provides access to engine data. The data can be fixed for an engine or at a given operating point. The data output depends on various factors such as the scale factor and power and bleed offtakes from the engine. The primary objective is to establish a **single source of truth** for engine data retrieval.
## Role in `propulsionDesign`
Within the `propulsionDesign` module:
- Engines for the aircraft are selected, and their respective files are copied to the engine directory.
- The **scale factor** is calculated, determining how the engine's thrust is adjusted to meet aircraft requirements (refer to the `propulsionDesign` documentation).
The `engine` library applies this scale factor, ensuring that aircraft parameters can be accessed without further manual adjustments.
## Engine Data Formats
The engine data is stored in:
-`engine.xml` — Contains data **independent** of the operating point.
- CSV files — Store values **dependent** on:
-**Mach number**
-**Altitude**
-**Engine power setting**
> **Note:** The data in these files is **raw and unscaled**. The only modification made in `propulsionDesign` is to the fuel flow CSV file, reflecting user-defined efficiency improvements.
## Functionality of the `engine` Library
The library is responsible for:
-**Reading engine data**
-**Applying scaling factors to the data**
-**Modifying values based on performance-influencing factors like bleed and power offtakes**
### Factors Affecting Engine Performance
The `engine` library incorporates the following factors, either by default or as optional parameters:
-**Scale factor** from `propulsionDesign`
-**Temperature variations** (non-ISA standard conditions)
-**Engine derating**
-**Bleed air extraction** (for turbofan engines)
-**Spool shaft offtake** (for turbofan engines)
## How the Library Retrieves Data
- If data is **not dependent** on the operating point → Uses `engine.xml` in a simple readout.
- If data is **dependent** on the operating point → Uses CSV files and requires:
- Mach number
- Altitude
- Engine power setting (e.g., N1 for turbofan engines)
A **linear interpolation** is performed between existing operating points when retrieving values from CSV files.
