Project Sunrise Analysis - A RAWAvCon View

The following is an attempt to back figure how the A350-1000 will operate this route using the RAWAvCon A350-1000 performance model. I have no access to any proprietary data but combine my model with various reported aircraft and mission attributes, and industry-standard assumptions and practices to try to determine how it will work.

WHAT KNOWLEDGE IS PUBLIC?

It happened: Airbus and QANTAS agreed a sale for aircraft specifically configured for these routes. Hence, my experience dealing with Airbus and Qantas’s reputation gives me confidence that the aircraft, as sold, can operate the route SYD-LHR-SYD routes.

Seat Count and Class Mix

The recent Project Sunrise press releases specify just 238 seats for the A350-1000 on these routes, compared to the nominal Airbus 365 seat arrangement and 330-400+ seat airline arrangements. The lower seat count reduces the passenger payload considerably to enhance range capability.

Despite premium seating (1st class, business and premium economy) accounting for >40% of the seats, enough cabin space remains for various “wellness” zones to enable passengers to stretch and move.

Flight Time

Various press articles mention a 20hr 20min flight time for the longer SYD-LHR flight (against the winds). The RAWAvCon A350-1000 data model estimates the associated headwind to be about 30kts, although a lower value linked to a longer ground track assumption is likely. The Qantas 787-9 Project Sunrise test flights required about 19hrs 30 min for the LHR-SYD flights.

Fuel Tank Capacity

The relatively low Project Sunrise nominal passenger payload results in the aircraft’s range capability being fuel volume constrained rather than MTOW limited. Hence, the RAWAvCon model of the Project Sunrise A350-1000 needs the A350-900ULR’s additional centre tank fuel capacity to achieve the necessary >20hr flight time.

Aircraft Weights

Maximum Take-Off Weight (MTOW): The Airbus website lists a 319t MTOW for the A350-1000. The aircraft’s TCDS does not yet include this, suggesting a link to Project Sunrise. However, the SYD-LHR fuel tank range limit means the additional MTOW mainly benefits the shorter SYD-JFK-SYD route (and LHR-SYD wind-assisted route).

Operating Empty Weight (OEW): No specific Project Sunrise values are available publicly. However, various OEW weight-saving targets are likely as a 1t OEW reduction offers significantly better range increments than 1t of extra MTOW; especially if fuel volume constrained.

There are two primary elements. Firstly, those associated with reduced passenger count. For example, Airbus offer various A350-1000 door configurations that yield, I believe, about 400kg lower OEW. It reduces the aircraft's maximum occupancy limit, but it remains well above 238 seats fitted. Other changes might include adopting the A350-900ULR option to deactivate the forward freight hold and deleting the associated freight handling system.

Further, fewer passengers also offer weight savings due to reduced galley space, fewer overhead bins, seats, lifejackets, catering provisions (including fewer carts), potable water (and smaller tank), cabin crew, etc. However, the longer flight time might push some of these savings back up a little.

I also recall a report of Project Sunrise initiatives targeting lower weight cabin equipment, e.g. seats, service carts and even cutlery, at the expense of higher purchase costs.

The assumed OEW used for the analysis is largely based on what is needed to make the route viable.

WHAT WE DO NOT KNOW?

Performance Standards

It is quite likely that Airbus and Rolls-Royce have ‘sharpened their pencils’ to improve the aerodynamic, engine, and airframe efficiency levels, driven by the combination of almost 10-years of A350 operational experience and the competitive pressure to deliver range for the Project Sunrise campaign. Such improvements are an inherent part of aircraft and engine product life cycles. Structural improvements are usually less clear-cut as surplus structural strength typically mitigates the OEW penalty required for adding MTOW.

For the engines especially, minimising the inevitable performance deterioration is also critical for maintaining performance as the engines age. In addition to in-built design features, ‘core washing’, operational thrust derate usage, and possibly shorter service intervals can reduce the average degradation.

Fuel policy

Using standard ICAO/EASA reserves, i.e. 5% trip fuel, a 200nm diversion and a 30-minute hold at the alternate airport, results in an A350-1000 on the SYD-LHR landing with over 12t (~10% of the mission fuel) of fuel still aboard (at least in the flight plan). Clearly, converting some of the reserve fuel to mission fuel improves the aircraft’s range capability; switching 6t of reserve fuel delivers 400-500nm extra range.

Many airlines already target reduced reserve fuel provisioning to improve fuel burn and range, often driven by data science (operational fuel usage) and improved route planning capabilities. There are also various options, especially on the longer SYD-LHR route, due to the availability of various diversion airports across Europe en route to LHR should a “splash and dash” occasionally become necessary. Note: The risk is economical (the substantial cost and time of the fuel stop) rather than safety-related.

ANALYSIS CONCLUSIONS

There are various levers to pull for the Project Sunrise aircraft to reliably achieve the 20hr 20min SYD-LHR flight.

The RAWAvCon A350-1000 model indicates that a 20hr flight is achievable with the following assumptions:

i) a 100% load factor:

ii) the A350-900 fuel tank capacity;

iii) an in-service Qantas OEW similar to the nominal Airbus 155t OEW value;

iv) 2% deterioration;

v) 1-2% improved airframe and engine efficiencies relative to the EIS standard;

vi) a fuel policy of 3% trip fuel contingency, 100nm diversion and a 30 minute hold.

The above assumptions are all estimates. However, extending the flight time to 20hrs 20 minutes target should be reasonably straightforward through modest changes to the above assumptions. For example, using the statistical approach defined by ICAO to reduce the contingency fuel, or assuming a more typical 80-90% passenger load factor might extend the range capability to the required flight time.

The defined flight time itself might also regularly be shorter than specified 20hr 20 min due to less adverse headwinds or more favourable routings. Performance deterioration may also be less (or more) than assumed based on the engines' time since their delivery, or most recent overhaul or core wash.