Multi-media transition dynamics of natural and human-made aerial-aquatic systems

Nature’s Inspiration

The flying fish, which are fish of the taxonomical family Exocoetidae, is a remarkable creature for its ability to fly for long distances – being able to glide up to 400 meters at a time1 – while simultaneously possessing the speed and agility characteristic of fish while swimming. Another notable characteristic of the fish is its ability to smoothly transition from swimming to flight. This renders it especially interesting to study during the design of UAAVs, particularly their transition dynamics. However, scientific study of the flying fish can be  challenging partly due to the difficulties of keeping these fish in captivity. For this reason, it is in the interest of the BAM Lab to develop an analytical model of the locomotory dynamics of flying fish as a way to understand the physics behind the fish’s trademark skills.

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Figure 1 An artist's sketch of a flying fish

Engineering Challenges

Unmanned Aerial-Aquatic Vehicles (UAAVs) are vehicles capable of swimming underwater, flying in the air, and independently transitioning between the two media. Systems like these can offer more mission flexibility for marine surveying and sampling, exploration of shores’ littoral zone, and surveillance. Like other vehicles that combine several modes of locomotion, UAAVs can be quite challenging to design. These challenges are even further amplified due to the requirement for the vehicles to move through multiple media – in this case, water and air. The transition dynamics of UAAVs moving between water and air are complex and not yet fully understood. Some modeling has been performed for specific UAAV designs, but the field lacks an analytical framework for the dynamics of an arbitrary UAAV system. This is where the BAM Lab is stepping in using a bio-inspired approach.

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Figure 2 The stages a flying fish takes to transition between swimming and flying.

BAM Approach

We are unraveling the science of water-air transition of UAAVs by beginning with a multibody dynamic study of the flying fish. Our modeling framework can then be expanded for UAAVs. This approach not only provides insight into the mechanics of the flying fish, but also sets the stage for more generalized modeling and design of aerial-aquatic systems.

References

  1. Park, H., & Choi, H. (2010). Aerodynamic characteristics of flying fish in gliding flight. Journal of Experimental Biology, 213(19), 3269–3279. https://doi.org/10.1242/jeb.046052