Payload-Range Analysis

We can provide critical analysis of manufacturers' data with accurate results. The FLIGHT software provides the key operational points in the available payrange charts, including initial and final cruise altitude and weights breakdown.

Parametric studies can be carried out by changing the wind speed, the outside air temperature, the engine deterioration, the reserve fuel policies, etc.

 

Analysis of the Airbus A380-861

We consider the case of the Airbus A380-861, powered by GP7200 high-bypass turbofan engines. It is a difficult task to match the performance claimed by the manufacturer, not least because the conditions under which the data have been determined are not fully specified.

Some consultancy companies claim they can match the reference data exactly, but this is questionable, and we demonstrate why. First, the full performance envelope requires to determine the most suitable combination of cruise Mach and initial cruise altitude (this is not specified by the manufacturer). Second, the cruise options require to switch altitudes, and the final cruise altitude is not specified. Third, the reserve policies taken into account are not always available in full. The specification of 200 n-mile diversion trip should be given with the diversion altitude (final cruise altitude or otherwise). Fourth, not least critically, the numerical simulation should be able to determine with sufficient accuracy the specific air range (see separate discussion in ) and the sensitivity of the range with respect to the payload (this is the derivative of the payload with respect to the required range at fixed brake-release gross weight).

The case presented here has another incongruence. Airbus has published data in which the maximum structural payload (MSP) is 90,718 kg, but the payload-range charts are presented for a value of the MSP equal to 83,700 (about 7 tons lighter!).

We have performed the calculations with both structural payloads and found the result shown in the figure below. The good news is that the ferry range is almost exactly equal to the performance claimed by the manufacturer. The maximum-payload range is sufficiently close to the published data with both values of the MSP, but the maximum fuel range is calculated in excess of the manufacturer's data.

 

Airbus A380-861 payload range analysis