Flying-V Landing Gear: A Physics-Based Design Exploration

Abstract

The Flying-V is a novel aircraft concept that has improved fuel efficiency through its distinctive V-shaped structure containing the pressurised cabin, fuel tanks and cargo hold. This configuration presents several key design challenges, one of them being the design of the landing gear. Previous studies indicate that the Flying-V landing gear significantly contributes to the total mass of the aircraft and its placement influences overall aircraft design, both of which impact the viability of the concept. Landing gear designs have been proposed, but are based on outdated requirements, and have notable shortcomings when it comes to feasibility, reliability of mass estimates, aircraft integration and family design commonality. This research aims to explore landing gear designs to identify the best solution for the Flying-V family.

A novel conceptual landing gear design framework is developed, incorporating a gear positioning and sizing optimisation algorithm and physics-based structural sizing. The gear positioning and sizing algorithm allows for efficient exploration of various design features, and can quickly adapt to changing aircraft requirements, making it particularly suitable for the conceptual design phase and the development of family design derivatives. The algorithm is validated using five different reference aircraft with distinct specifications and landing gear configurations, and demonstrated its ability to accurately predict gear positions and lengths. The use of physics-based structural sizing reduces the reliance on statistics-based mass estimation methods, which are known to yield inaccurate results for large and unconventional aircraft. Reference aircraft gear mass data is used to derive a finite-element mass correction equation, improving the accuracy of the mass estimation.

Several Flying-V landing gear concepts are evaluated, each designed with different features, or optimised for a different set of aircraft requirements representing any of the Flying-V family members. For the FV-1000, this resulted in a final design that has a double folding strut, a four-wheel articulated bogie and a strut shortening mechanism, offering a feasible solution with optimal mass and stowage properties. The gear weighs 13.6 tonnes, which is 5.1% of the aircraft maximum take-off mass (MTOM). A derivative design for the FV-900 features the same structural components, but without an articulation mechanism and includes dedicated rolling stock sizing, resulting in a gear weight of 13.3 tonnes, or 5.7% of MTOM. The FV-800 landing gear design follows the same concept as for the FV-1000, but with dedicated structural and rolling stock sizing, significantly reducing mass compared to using the FV-1000-sized common gear. The FV-800 is more constrained by fuel tank capacity and range, which justifies deviating from the commonality principle. The dedicated FV-800 gear weighs 9.2 tonnes which is 5.0% of the MTOM.