Drones generally fall into two categories: military weapons and annoying toys. Everyone seems to have an idea for making them useful—Amazon wants to use them for deliveries, Facebook sees them beaming the Internet to remote areas—but so far it all seems so very outlandish.

A California startup called Zipline has a practical plan to use the devices for good.

Later this year the company, working with UPS and vaccine distributer Gavi, plans to deploy a fleet of drones in Rwanda, where the machines will deliver medical supplies. The goal is to see 15 autonomous aircraft flying out of a centralized hub make 150 deliveries each day to 21 medical stations throughout the western half of the country.

The Rwandan government, which has embraced drone technology and recently approved remarkably progressive guidelines for its use, is working with Zipline to measure the success of the venture.

Zipline designs, builds, and tests its drones in northern California, where it can perform test drops without disturbing anything beyond grazing cows. The drones look like the prototypes they are, with payload mechanisms that use primitive materials like rubber bands for ejection springs and wax paper for a parachute.

The low-tech approach minimizes cost and complexity, essential when working in rugged, remote areas. The payload carrier and parachute are made in-house for 50 cents and designed to be used once, then chucked.

Zipline favors fixed-wing drones because the more common quadcopters "only operate in perfect weather, and tend to fall out of the sky unpredictably," says founder and CEO Keller Rinaudo. "People do not wait for perfect weather to get sick or to have medical emergencies, so if we're going to build something that's useful, it has to be able to operate all the time."