This might be a naive question, but what would happen if a hobby drone collided with a jet? As long as it doesn't hit the engines, wouldn't the damage be negligible?
It depends on the size of the drone and where it hits.
I am not sure how large these drones are, but if they have the mass of a flock of large seagulls, say, it could disable an engine (like the US Airways jet).
A collision with a wing could cause substantial damage to the wing which would change the aerodynamics, and that could be potentially dangerous at low altitudes because of the neighborhoods underneath. Debris could fall from the sky and injure or kill someone. I doubt it would come close to tearing off a wing.
A collision with the fuselage could breach the cabin which is dangerous in itself, but would not cause a decompression at that altitude.
A collision with the windscreen of the flight deck would be dangerous for obvious reasons. In the minor case, it can blind the pilots temporarily. In the worst case, debris from the drone would incapacitate the pilot during the most dangerous phase of flight: landing or departure.
What is really dangerous is the speed at which the aircraft hits the mass of the drone. It may seem like the aircraft would just kill the drone, and that is probably the case with most drones, but if it has large mass, it wouldn't.
The most dangerous scenario is if a drone hits the control surface like the flaps (very important for landing), or the horizontal stabilizer in the tail, it could be disastrous.
Hitting the fuselage, or entering an engine is probably more realistic. Both would be expensive, but won't be a threat to the passengers. Maybe hitting the wingtips would be doable ... not sure.
Why would airflow around the wing keep a drone from hitting it but not a bird?
Would the pilots be sucked out even at a low altitude such as 5k feet? Whether they are our aren't, how will the plane be landed?
One possibility is to limit the weight of the drones, which will limit the damage they can inflict.
The latest jet liners A380 / 787 are made from composites, even their body.
Many other craft have composite wings.
The aircraft operator will be looking for someone to stick with the repair bill. Each engine on the A-380 today costs about $13 million.
That's the good case. Here's a picture of an A-6E which crashed after an engine ingested a pencil-sized hex wrench.[1]
Not particularly relevant.
J52 engines weren't tested or certificated for bird-strike tolerance or turbine-blade containment.
The later civil derivative, the JT8D, shared a core but was a new design outside the hot-section and had to meet all the FAA-mandated requirements.
Picture a 5-pound drone hitting a stationary plane at 250 miles per hour and ask if the damage would be "negligible".
Consider if you loaded the drone into a cannon and fired it at a stationary airplane, hitting at 250MPH. That's 366 feet per second. Like a low-velocity bullet. Into an aluminum airframe. A BB going that speed will puncture a pop can. A 5lb drone going that speed may puncture the skin of an airplane?
"Investigators into the Columbia accident have estimated that the dislodged foam was about 19 by 11.5 by 5.5 inches (48 by 29 by 14 cm), weighed about 26.7 ounces, or 1.7 lb (0.75 kg) and impacted the Shuttle at nearly 530 mph (850 km/h). For the sake of a rough comparison, this block of foam would be about the same size and weight as a large loaf of bread."
http://www.spacesafetymagazine.com/space-disasters/columbia-...