RAWAvCon Fuel Mission Modelling - First Successful Run

Last weekend, RAWAvCon ran for the first time with the Fuel Cell propulsion model included on an in-house ATR42-500 base aircraft model.

Since then, the development focus shifted to bug elimination, error handling and output generation of the fuel cell data, which is now complete (for now). The fuel cell model is now easily applied to any other existing RAWAvCon aircraft models that currently also include other various turboprop models covering the ATR-42 ATR-72, Beech 1900D, Dornier 328, and DHC-8-100, -200, -300 and 400.

The following are a quick view of the results from a simple comparison of different FC configurations - the only change is the inclusion of an inlet compressor on the second option. The current model uses Hydrogen fuel, but changing the fuel's gravimetric and volumetric density (plus associated tank and handling systems) permits any fuel to be considered.

The first picture is the through-mission fuel cell power chart for uncompressed inlet flow flying a short regional flight. The values ate for one of two fuel cell systems onboard.

The data point at each time point represent an aircraft performance calculation, i.e. aircraft drag and propulsion characteristics assessed to determine the fuel flow rate.

More data points are used during climb and descent where the flight conditions are rapidly changing. The cruise uses fewer points due to more constant operation.

The graph includes:

the aircraft secondary power requirement (user inputs for on-ground, during take-off and in-flight);
the propeller's maximum power absorption limit;
the propulsive power demanded or available (as required);
The Maximum Rated Fuel Cell Stack Power at the flight condition.

A second picture shows the same fuel cell stack with a compressor attached to the inlet air system.

The lines represent the same as the previous image. The extra green line shows the FC stack's power output, i.e. propulsive power + secondary + Balance of Plant (BoP). BoP power is required to drive the compressor, the humidifier cooling systems, but recovers some with a turbine.

The FC stack power output was not shown on the previous chart as it is very close to the Propulsive power.

Interestingly, the compressed system consumes significantly higher hydrogen fuel to complete the same mission - the compressor draws significant power.

BUT, the comparison is a simple system check. The compressed air system enables a smaller fuel cell stack (it could be scaled back to around 4kW(saving significant weight and volume) - this is not included in this study. The reduced volume benefit might permit more passengers in a common existing airframe, or a smaller fuselage for a new aircraft.

Further work:

Further checks to ensure the model is providing reasonable results - I make no claim on it being perfect yet;
Define and include the drag penalties associated with cooling the fuel stack and the compressor outflow (if a compressor is included);
Ducted propulsors to model small regional jets is targeted for mid-late March. RAWAvCon baseline (gas turbine) models already exist for the CRJ, EJet and EJet2, plus older types including the BAe146/RJ and Fokker 70/100.

The RAWAvCon capability is available for customer usage, but involves me driving it. The tool is not for sale. If this capability is of interest to your organisation, please get in touch via mail@RAWAviationConsulting.com or +44 7814 604175 to discuss.

Potential Outputs:

Study results supporting aircraft conceptual integration studies.
Standalone aircraft marketing models that deliver block fuel as a function of aircraft Zero Fuel Weight, mission ESAD (Equivlanet Still Air Distance) and reserve policy.
I can tailor the models to integrate with customer sales systems.
These marketing models include no RAWAvCon elements or ability to change the FC characteristics.

Intellectual Property

The model is my IP and always will be. Any customer inputs and results remain the customer's IP until published (by the customer or someone else). Any novel features defined by the customer and included in RAWAvCon for use in a proprietary basis remain the customer's IP (in a bespoke model sub-variant) and will be subsequently removed at the end of any engagement.