The following mass properties were identified using a bifilar pendulum setup and can be used as initial guess in simulations.

Flapper Nimble+ configuration measured:

• Flapper Nimble+ without body shells/panels,
• ~2-gram radio receiver was mounted close to the center of mass,
• standard battery was mounted,
• landing gear was NOT attached

Center of mass:

• ~60 mm below the wing leading edges

Mass and inertia:

Thrust data measured on a test bench with a single wing pair (multiply by 2 for total thrust):

A battery discharge curve measured with a new 2S 300mAh Flapper Drones battery with XT30 connector:

Near-hover flight dynamics of Flapper Nimble+ can be modeled using linear-drag models.

Scientific papers with models of the Delfly Nimble from TU Delft (a smaller predecessor of the Nimble+):

• Matěj Karásek et al., A tailless aerial robotic flapper reveals that flies use torque coupling in rapid banked turns. Science 361, 1089-1094 (2018).
• Karl Martin Kajak et al., A minimal longitudinal dynamic model of a tailless flapping wing robot for control design. Bioinspiration & Biomimetics 4, vol. 14 (2019).

Scientific paper with linear drag model and the drag coefficients of the Nimble+ (see Appendix 1):

• Sven Pfeiffer et al., Three-dimensional relative localization and synchronized movement with wireless ranging. Swarm Intelligence 17, 147–172 (2023).

Linear drag coefficients [bx, by, bz] and Center of Pressure position with respect to the Center of Mass [rx, ry, rz] used in the updated EKF filter:

bx = 4.2 N*s/m
by = 1.8 N*s/m
bz = 0.3 N*s/m
rx = ry = 0
rz = 0.03 m