testing grounds, not the final site yet

Humanitarian delivery drone

Preston Innovation Laboratory, Rice University · Undergraduate UAV Researcher · May 2025 to present

A small delivery UAV for humanitarian use, built around an edible, biodegradable composite I formulated myself. The idea: a commercial drone can only carry about 10 to 30% of its own mass as payload, so if the frame itself is food, the nutrient-to-mass ratio of a delivery goes up and a drone that goes down in the field leaves nothing harmful behind. My job was to make that material strong enough to fly and then design the airframe around it. Presented as "3D-Printed Edible Drones for Life-Saving Nutrient Delivery" with Nicholas Kraemer, Neethu Pottackal, and Prof. Daniel Preston.

The problem

• Strength, weight, and manufacturability pull against each other. Every material and structural decision was a trade between the three.
• No off-the-shelf material met the biodegradable requirement, so the material had to be developed before the airframe could be designed.
• The composite had to survive flight loads and still be printable. [add: the load case or failure that drove the design most]

What I did

1. Requirements and roadmap. Owned the system requirements, the technical roadmap, and the design decisions from concept to a flight-ready vehicle.
2. Material selection. Screened edible candidates on Young's modulus against density. The frame has to be stiff but not brittle, light enough to fly, and viscous enough to extrude. A pasta dough base (flour and water) won on stiffness and density, then the recipe was iterated with egg white, oil, and gelatin additives for strength and moisture retention. [confirm you want the pasta wording on the site; the resume says "edible, biodegradable composite"]
3. Characterization. Rheology on a rheometer (storage and loss modulus, viscosity, shear stress) to prove the dough prints, and tensile testing of printed coupons on day 2 and day 3 of drying to get the mechanical properties. Data compiled in Python and fed straight into the structural sizing. Tensile strength keeps rising as the part dries, which set the cure schedule. [add: the property values you are allowed to share]
4. Airframe design. Modeled the airframe in SolidWorks around the composite's properties and the additive manufacturing constraints.
5. FEA. Validated stiffness-to-weight and vibration suppression before committing to hardware. [add: the mode or stress case that mattered most, and the margin]
6. Build and integration. Printed the frame on a Procusini 5.0 food printer, dried it on a two-day schedule, and integrated the motors, flight controller, and battery from a commercial drone into a flying demonstrator.

Design iterations

The geometry was worked out in PLA first, because a print in PLA takes an hour and a print in dough takes two days to dry. Once the frame shape was settled and the composite recipe was refined, the same design moved to the edible material.

1. PLA iteration 1. Printed motor mounts on a stock cross-arm with a round hub. Proved the electronics and motor spacing before any custom frame existed. [add: what it taught you]
2. PLA iteration 2. Added a square perimeter (wooden dowels) around the cross to stiffen the arms. The perimeter-plus-cross geometry stuck from here on.
3. PLA iteration 3. The full frame as one printed part: square perimeter, X cross, integrated motor pads and a center bay. This is the geometry the edible versions inherit.
4. Edible versions 2 and 3. The PLA geometry re-cut for extruded dough: thicker members, the CAD in the viewer above. Version 3 was the first edible frame that flew.
5. Second flying edible iteration. Thinner members and a lighter build once the material data justified it.

Results

• 41% more payload capacity than an off-the-shelf equivalent.
• [add: all-up weight, payload mass, flight time, number of flights]

What went wrong, and what comes next

What went wrong

• The first material numbers were not the real numbers. Early tensile data looked strong enough to start the build, but it did not account for deposition reliability in the printing process. The strength we were quoting was not the strength a printed part would actually have. I argued for halting the build and recharacterizing. That cost weeks and it is the reason the airframe worked. [confirm this is how you want to tell it]
• Designing the structure before the material was settled. The airframe and the composite had to be solved together. Every time the formulation moved, the sizing moved with it. [add: one concrete example of a redesign the material forced]
• [add: the biggest thing that broke, failed, or surprised you on the Gen-1 build or flight]

How I would improve it

• Characterize printed coupons, not cast ones. The property set has to come from parts made the way the airframe is made.
• Lock the material before sizing the structure, and write down the property values the design is allowed to assume.
• [add: one process change you would make on the next build]

Next steps

• Environmental testing. A biodegradable composite has to hold its properties through humidity, heat, and time in the field. Nobody has measured how fast it loses strength. [confirm this is an open question]
• Flight testing with real payload masses to turn the 41% number into flight time and range figures.
• Gen-2 airframe: [add: the target, e.g. weight reduction, larger payload bay, fewer printed parts].

Tools

SolidWorks · FEA · Python · additive manufacturing [add: printer and process]

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