TU Delft’s SquirrelDrone Morphs Its Whole Body to Fly, Ditching the Bird Playbook Everyone Else Copies

A research team at Delft University of Technology has built a drone that changes the shape of its entire body in flight the way a flying squirrel does, and the data says the trick works. The aircraft, called the SquirrelDrone, stretches its limbs, bends its spine, flicks its tail, and lets a soft skin-like membrane deform in the airflow, all to steer instead of relying on rigid wings and separate control surfaces. In wind-tunnel runs and outdoor flights, that full-body morphing measurably improved agility, maneuverability, and stability at the same time.

What makes this worth reading past the cute-animal headline is the choice of animal. For decades, bio-inspired drone work has chased birds. I have covered a long line of it on DroneXL, from feathered morphing wings to flapping ornithopters. The Delft group went the other direction on purpose and studied gliding mammals, the flying squirrels and colugos that have no feathers and steer with their skin and skeleton instead.

The team published the work in the peer-reviewed journal Nature Communications, and the drone is the first robot to show, with hard aerodynamic measurements, what whole-body morphing buys you. The short version: a soft, reconfigurable body can do jobs that stiff wings and discrete flaps cannot.

The SquirrelDrone Copies Three Tricks From Gliding Mammals

The drone reproduces three things gliding mammals do in the air, and each one earns its place in the design. Coordinated front- and rear-limb motion reshapes the flying body. Spine and tail movement continuously changes the posture and orientation of the wing surface. A soft passive membrane, the robotic stand-in for a squirrel’s patagium, deforms under airflow on its own to add lift and drag when the situation calls for it.

Put together, those three create a fully morphing aerial body rather than a conventional aircraft with fixed wings and bolt-on rudders and elevators. That distinction is the whole research question. Birds inspired most morphing-drone work to date, but the aerodynamic payoff of whole-body morphing combined with a deformable membrane, the way mammalian gliders actually do it, had not been studied in a flying robot before this.

The work comes out of TU Delft’s BioMorphic Intelligence Lab in the Faculty of Aerospace Engineering, a group whose stated thesis is that copying both the body and the brain of flying animals beats throwing heavier hardware at the problem. That brain-side work has surfaced on DroneXL before, in the lab’s neuromorphic image-processing drone that ran its flight AI at a fraction of the power a conventional processor needs. The same lab’s animal-inspired research has been featured by CNN and won the indoor event at the IMAV 2024 drone competition.

Gliding Mammals Steer Differently Than Birds, and That Is the Point

Birds and gliding mammals solve flight control with different hardware, and the researchers built around that gap rather than ignoring it. Birds lean on feathered wings; squirrels and colugos commit the whole body to the job.

“For decades, research on bio-inspired drones has focused primarily on avian-inspired flight: morphing wings with adjustable sweep and twist, flapping motion, or feather-inspired structures. But gliding mammals achieve flight control differently. They morph their entire body as an integrated aerodynamic system.”

Salua Hamaza, Associate Professor in Aerial Physical Interaction and Embodied Intelligence, TU Delft

That framing matters for anyone who has watched a flying squirrel clip from a nature documentary and wondered why drones do not move like that. The animals adjust body and wing shape continuously to control both where they are going and how steady they stay, and they do it at night, in cluttered forest, between trees. Translating that into a machine is the part that took real work.

Four Prototypes and Many Wind-Tunnel Rounds Got It Flying

A shape-shifting aircraft cannot be tested like a normal one, so the evaluation took an unusual path. The team could not treat a body that is constantly changing shape the way it would treat a fixed-wing plane with known, static surfaces. That ruled out the standard playbook.

“Because the drone changes its entire body shape during flight, we could not evaluate it like a conventional fixed-wing aircraft. We developed four prototype versions and combined many rounds of wind-tunnel experiments with indoor and outdoor flight tests. It was a challenging process, but essential for turning a biological concept into a working robotic system.”

Liming Zheng, PhD candidate, TU Delft

The testing ran across the university’s Open Jet wind tunnel and both indoor and outdoor flights, with a dedicated pilot handling the outdoor runs. The payoff showed up as gains in three flight characteristics that usually trade against each other, with different body movements driving different aerodynamic effects.

• Agility: the morphing body enables rapid rotations and fast reorientation mid-flight.
• Maneuverability: coordinated changes in body configuration support sharper turns and steeper pull-up trajectories.
• Stability: passive membrane deformation plus tail and body morphing improves stability, while coordinated limb morphing adds rolling stability on top.

Getting all three to improve together is the result worth noting. On most aircraft, more agility costs you stability, and you tune the compromise. A body that can reshape itself moment to moment loosens that constraint, which is exactly why a squirrel can be both twitchy and steady in the same glide.

Soft Morphing Points Toward a Different Kind of Drone

The researchers argue the findings open a path to aircraft that lean on soft, deformable structures instead of stiff airframes and discrete control surfaces. Such drones could be more adaptive, more efficient, and more resilient, switching between stable gliding and sharp maneuvering in messy, obstacle-filled spaces.

This is the same instinct behind the Delft group’s other recent headline. Days ago I wrote about the university’s Bee-Nav drone, a separate project from the school’s Micro Air Vehicle Laboratory that flies home without GPS on a honeybee-inspired memory of a few kilobytes. Different lab, different animal, same underlying bet: study how a small biological flier actually solves a problem, and you can often replace a heavy engineering stack with a lighter, smarter idea.

It is worth being precise about how new the mammal angle is. The avian approach is well-trodden. DroneXL has covered Switzerland’s EPFL building drones with morphing feathered wings and tails, the Groningen team’s PigeonBot II flying on real pigeon feathers, and China’s RoboFalcon 2.0 flapping its way into the air. The mammalian glider, steering with skin and skeleton instead of feathers, is the road far fewer teams have taken.

DroneXL’s Take

The industry delta here is about which animals the field copies, and the SquirrelDrone widens it in a useful way. The morphing-wing canon I have written up over the years is overwhelmingly avian, EPFL’s feathered wings back in 2020, PigeonBot, RoboFalcon, on down the list. Birds got copied because birds are the obvious teacher. Gliding mammals do something birds cannot, committing the whole body and a soft membrane to control at once, and until this paper nobody had measured what that approach delivers in a real flying robot. Now there are wind-tunnel and flight numbers attached to it. That is a genuine addition to the toolkit, not a restyle of the existing one.

I have a useful comparison point in my own archive, and it is worth being honest about. Back in April 2025 I covered South Korea’s POSTECH and its flying-squirrel drone with foldable silicone wings. That one bolted squirrel-like membrane wings onto an otherwise standard quadcopter to kill lateral momentum in tight spaces. The Delft work is a different animal, literally and figuratively: the squirrel principle is not an add-on to a quadcopter here, it is the whole airframe. Same inspiration, much deeper commitment to the idea. Seeing two serious labs arrive at the flying squirrel from opposite directions tells me the mammalian glider is not a novelty, it is a design space people are going to keep mining.

The open question this research does not answer is the one that matters for pilots and operators: does whole-body morphing survive contact with a real mission. This is a research result, four prototypes and controlled tests, and the paper is careful to frame it as a framework for understanding flight control rather than a product. A soft, many-jointed morphing body is mechanically complex and, on its face, harder to manufacture and maintain than a rigid airframe with a few servos. Whether that complexity pays for itself outside a wind tunnel, and where it lands first if it does, is not something the paper claims to settle. The BioMorphic lab’s broader work points at lightweight drones for jobs like environmental monitoring and operating safely around people, which is the kind of setting where agility plus gentleness beats brute payload. If I were watching for where this goes next, I would watch that lab’s follow-up flight testing rather than any single milestone, because morphing either earns its keep in messy real-world air or it stays an elegant lab demonstration. The measurements say the idea is sound. The engineering road from sound idea to fielded drone is the part still being driven.

Source: Delft University of Technology. Study: Zheng, L., van Zuijlen, A. & Hamaza, S., “A squirrel-inspired drone with enhanced stability, agility and maneuverability via whole-body morphing,” Nature Communications (2026).

DroneXL uses automated tools to support research and source retrieval. All reporting and editorial perspectives are by Haye Kesteloo.