A doctor dashes off a text message and within minutes a tiny robotic airplane catapults into the sky. Its cargo? A padded package of blood supplies, ready for a lifesaving transfusion.

The drone can cover up to 45 miles in 30 minutes and release a parachute of medical supplies. In Rwanda, where 75 percent of roads are unpaved, aerial drones can avoid routes that frequently wash out during the rainy season.

“People do not wait for perfect weather to get sick or to have medical emergencies,” said Keller Rinaudo, the founder and chief executive officer of Zipline International Inc., the California-based startup building the medical delivery system in Rwanda. “So if we’re going to build something that’s useful, it has to be able to operate all the time.”

Zipline partnered with the government of Rwanda to test its medical-supply drone fleet. This summer the company plans to fly 15 planes to 21 medical stations across half of the landlocked East African country. It will start by delivering blood products, which spoil quickly and require strict temperature controls. Starting in July, Zipline’s speedy drones will make up to 150 deliveries per day from their hub in western Rwanda.

Rwandan Minister for Health Dr. Agnes Binagwaho cites many advantages: “I’m also hopeful that as pioneers we learn by doing,” she said. “Although I can’t predict how many lives will be saved, even saving one life is crucial.”

Little wings, big job

The company’s drones, or “Zips,” look like flying tadpoles. Built with lightweight carbon fiber and Kevlar, Zips have a big wingspan — almost 2.5 meters — but weigh only 10 kilograms.

After launching from a catapult, drones fly at 100 meters altitude before dropping down to release their packages, which float to the ground under a disposable paper parachute. The drones don’t actually land until they return to the hub — no runway required.

Each Zip costs about as much as a motorcycle, but can operate even in areas without roads.

Check out a Zip in flight:

Zipline recruited top engineers from Google, Stanford University, Boeing Co. and SpaceX to get its Zips off the ground. Public-private partnership GAVI, a vaccine distributor, contributed to the effort, as did delivery company UPS Inc. and the government of Rwanda.

Rwanda’s plan to become a tech hub for East Africa helped attract Zipline, says co-founder William Hetzler. “Projects like ours fit very well with that strategy.”

Rinaudo hopes to expand drone-based medical delivery wherever terrain and logistics make medical deliveries challenging.

Drones aren’t the only innovative vehicles that can deliver medicines to isolated communities. One young scientist’s bike-powered vaccine refrigerator recently caught the eye of President Obama at the 2016 White House Science Fair.