You don’t need to know how gravity works to understand that being hit in the head by a falling drone will hurt.

But it turns out that drone crashes aren’t as dangerous to humans as being hit by in the head by steel shrapnel or a wood blocks. At least, that’s according to new research released on Friday by the Federal Aviation Administration along with a group of colleges including University of Alabama, University of Kansas, and Mississippi State University.

Under current FAA rules, businesses are forbidden from flying drones over people unless companies first get government approval. The FAA is currently considering letting companies fly drones above people, but it is evaluating the risks before deciding.

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One of the first tests by the FAA and its university research teams involved dropping a drone on the head of a crash test dummy. They found that a drone’s impact is “dramatically different” from other materials that weighed about the same.

Both steel debris and the wood block caused significantly more damage to the dummy than the drone, which absorb much of the impact because it’s made of more flexible materials.

Additionally, the drone’s impact was reduced by drag, the air resistance that slowed its decent more than the steel and wood.

Still, the research indicates that it’s still unsafe to be hit by a drone.

For one, the propeller blades attached to quadcopter drones can slice skin, and the researchers said “blade guards are critical to safe flight over people.” Moreover, drone batteries, motors, and potential cargo could raise the risk of injury because such objects “are dense, and not likely to be made to come apart to dissipate impact energy,” the report said.

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The new research report is the first of several studies that the FAA plans to learn how to minimize the risk of injuries caused by falling drones. The FAA plans to conduct more research in June to verify the first report’s findings.

This article was originally published on FORTUNE.com