Elijah V4: Our newest UAV, purpose-built for cloud seeding

This season, Rainmaker introduces Elijah V4, the newest version of our cloud seeding drone. Elijah is the world’s only sub-55 lb. UAV that is purpose-built for cloud seeding, optimizing field endurance, deployability, and seeding efficiency.

Recently, Rainmaker released our first peer-reviewed study in the journal Atmosphere, which evaluated our 2025-2026 winter cloud seeding campaign. The learnings and data we gathered across Utah, Idaho, and Oregon helped inform the next generation of our vehicle.

These changes maximize our ability to generate precipitation. V4 was field-tested this summer in Alaska, producing an additional 19 million gallons of snow-water-equivalent — enough water to supply 150 households for an entire year.

RUGGEDIZED & WEATHER-PROOF

Seeding conditions are often detected during winter storm systems. This poses a challenge for any aircraft, calling for the ability to survive repeated flights into cold, wet, and windy conditions.

Icing –when liquid droplets freeze onto hardware components– is a threat to flight safety and mission success. For this reason, Rainmaker developed a custom Icing Protection System (IPS) that dynamically detects and prevents ice accretion on Elijah’s rotor blades. This enables up to 10 minutes of flight in severe icing conditions, including clouds from –20° to –6° C with a max supercooled liquid water (SLW) concentration of 0.4 g/m3.

Drone hardware has been ruggedized, with extended longevity of high-wear components. For instance, the IPS is optimized to withstand delamination due to airflow over the propeller. This is qualified via full-spectrum testing from benchtop to lab to in-situ trials. Rainmaker’s testing infrastructure ensures reliability before each V4 drone reaches the field: flight simulation in our vehicle testing system (VTS) and SLW chamber, with constant tuning by our Testing and Quality Assurance (TQA) team.

V4 also features an extended battery life, with a maximum flight time of 30 minutes using a single set of batteries. This increases its total vertical range to 18,000 feet AGL.

Rainmaker custom builds its own components, going beyond our vendors’ standard SKUs and investing in extensive R&D to build a better machine. We also maintain close relationships with vendors, which helps to expedite machining and prototyping timelines. In this way, Rainmaker’s engineers achieve turnaround times not normally seen in industry, especially under supply chain constraints: for example, new PCB designs in under a week.

FIELD-READY

Elijah is designed to solve a second engineering challenge: rapid deployment and re-deployment in the field. Seeding windows often last just several hours, leaving little time to waste.

V4 is portable, fitting in the back of a Ford F-150. Once at the launch site, field teams use a stream of telemetry data from the drone, compiled in Rainmaker command-and-control platform Stratus. This speeds up pre-flight checks. Elijah can be ready for takeoff within 15 minutes.

Between flights, the drone’s consumable components (such as batteries and flares) are accessible and easily swapped. This allows field teams to alternate or “juggle” two to three drones at a time and achieve continuous dispersion, even during hours-long missions.

Sensor upgrades also unlock higher operational efficiency through more precise identification of seeding conditions. This includes an integrated pressure, temperature, and humidity (PTH) sensor, nicknamed “Jonah,” housed in a forced aspiration chamber whose physical design is optimized to keep moisture out of the sensor, even when operating in high humidity (even fully saturated) conditions, and to increase sampling speed. V4’s onboard camera also sends a live feed back to ground, using infrared mode at night. This helps field teams visually confirm in-cloud conditions.

Additional hardware components maintain performance even in GPS-denied areas; operators can manually override Elijah’s automated flight paths at any time, ensuring safe and successful mission execution.

OPTIMIZED DISPERSION

Rainmaker is building a foundation for zero-human-intervention cloud seeding, including autonomous dispersion. V4 is equipped with four pyrotechnical seeding flares housed in aluminum shrouds. The flare shrouds, custom designed and fabricated by Rainmaker, serve several important functions: (1) directing the flare plume into SLW and avoiding recirculation due to prop wash, (2) protecting the drone from flare combustion, (3) optimizing particle dispersion, and (4) collecting post-combustion material.

A dedicated Flare Controller Board utilizes a Capacitative Discharge Ignition (CDI) circuit to safely ignite each flare. It also records each flare’s start and end time, data which is critical to our validation workflow.

Right now, flare ignition is triggered manually by field operators. But our engineers are exploring the ability for V4 to ignite autonomously upon contact with seedable conditions, as detected by Elijah’s onboard sensors.

INTEGRATED ATMOSPHERIC INTELLIGENCE

Elijah’s data integrations optimize mission safety, efficiency, and research utility.

Seraph, our command-and-control platform, flies Elijah with full autonomy and live status reporting. It monitors V4’s Automatic Dependent Surveillance–Broadcast (ADS-B) receivers, detecting nearby aircraft, and automatically directs the drone to climb or descend as needed to avoid collision. This complements visual airspace awareness by our field teams.

Onboard sensors also record over 8,000 parameters throughout a flight, visualized in Rainmaker’s “Parable” dashboard (pictured below). These data provide a window into drone health, mission progress, and in-cloud conditions. They are monitored at all stages of an operation, including post-op review, and are a critical input to drone design and CONOPS refinement.

Telemetry data are also highly valuable for scientific research. With V4 and other field instrumentation, Rainmaker is building a comprehensive dataset of atmospheric observations to unlock a deeper understanding of natural storm processes, cloud microphysics, and cloud-aerosol interactions.

V4 takes flight this month in Utah, Idaho, Oregon, and other operational theatres. We look forward to sharing further updates on Elijah’s design and performance throughout the season.