heavy lift drone

THE CHALLENGE

The DARPA Lift Challenge tasked teams with developing a small Unmanned Aircraft System (sUAS) capable of lifting heavy payloads under extreme operational constraints. While conventional multirotor drones are simple and reliable, they suffer from a severe heavy-lift bottleneck, typically maxing out at a payload-to-weight ratio of 1:1 or less.

DARPA aimed to shatter this limitation by seeking novel aircraft designs capable of carrying more than four times their own weight, all while staying strictly under the FAA Part 107 maximum takeoff weight threshold of 55 lbs. Achieving a 4:1 payload-to-weight ratio within this strict envelope required abandoning conventional battery setups in favor of an entirely new power and control architecture.

Initial tandem design

Quadcopter layout

Risk analysis identifying potential failure points during operation. Each failure point is evaluated by severity and likelihood, pairing critical engineering vulnerabilities with actionable hardware and software mitigations.

pre-competition conclusion

reality

Upon arriving in Dayton, Ohio, from Houston, Texas, during competition week, we discovered that one of the main motor ESCs was not functioning properly. Faced with limited resources, we spent three days troubleshooting and reconfiguring our craft's layout, adapting our design from a quadcopter to a tricopter.

Because we lacked a servo to tilt the tail motor for yaw control, we repurposed components from our auxiliary control system. We implemented a counter-rotating motor and blade setup on the tail arm to actively counteract the standard yaw torque inherent to tricopters. Additionally, we mounted two forward puller motors to handle directional propulsion. Both the puller motors and the yaw control motor were strategically positioned to extend past the prop wash of the main lifting propellers, ensuring clean airflow and maximum control response.

Our goal was to keep the craft completely level relative to the ground during forward flight rather than pitching the frame forward. We theorized that keeping the airframe level would direct 100% of the main motors' thrust toward vertical lift, preventing power loss during forward translation.

Due to mounting incompatibilities on the reconfigured frame, we bypassed the gas-electric hybrid system. Stripping away the fourth motor and ESC, twin-stroke engine, M30 BLDC generator, fuel payload, and power conversion electronics resulted in massive weight savings. We utilized this weight margin to expand our onboard battery bank, stepping up from two 6S LiPo batteries to a 6-battery bank wired in a series-parallel configuration.

not so final results

Ultimately, our craft crashed and burned directly on the launch pad. Despite the setback, we were determined to prove whether this accidental tricopter design configuration could actually succeed. After the competition, we built a scaled-down prototype to test and validate our concepts and thrust theories. This research directly laid the groundwork for our next-generation platform: ARGUS V2.