4 ms·

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 neglig

by szx 11y ago

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?

DataJunkie 11y ago
Disclaimer: Aviation hobbyist but not an expert. 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.
- iofj 11y ago
  The airflow would be trying to prevent a collision with the front of the wing, and a drone would simply go where the wind blows. Which is to say if a drone flew straight for an airplane wing, it would fly around the wing and suddenly explode in the massive turbulence behind the wing. This would look very surprising because to the naked eye there is nothing behind the wing. 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.
  - nether 11y ago
    There isn't really any "turbulence" behind any modern wing in typical flight regimes. They're very low drag, so flow off the trailing edge is as smooth as the upstream flow.
    - throwaway_xx9 11y ago
      Well, except for those pesky wingtip vortices that can down a smaller airliner.
    - nightski 11y ago
      This was near landing, so I assume flaps were deployed. That changes things a bit.
  - tzs 11y ago
    30 seconds of Googling turns up numerous examples of bird strikes on the leading edge of wings, some with very substantial damage. Why would airflow around the wing keep a drone from hitting it but not a bird?
    - nether 11y ago
      Nothing. Upstream flow stagnates at the leading edge, excess bug splatter there attests to that.
      - mveety 11y ago
        It can stagnate to the point of bugs not having much of an issue staying on the wing during flight. I remember a case when I was flight training where we had a little spider as a passenger on the top of the starboard wing for the duration of the flight. The little guy didn't fall off until the wing stalled out when we were landing.
        ajross 11y ago
        That's a different effect. The region just above the surface is a turbulent boundary layer without much net flow. But it's very thin.
- hanniabu 11y ago
  Anybody know what the protocol is in the event of a blown out windshield/windscreen? 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?
  - MaxScheiber 11y ago
    https://en.wikipedia.org/wiki/British_Airways_Flight_5390 https://en.wikipedia.org/wiki/British_Airways_Flight_5390
    - hanniabu 11y ago
      That is damn impressive on both pilot's accounts, thanks for the link
cptskippy 11y ago
I would imagine hitting the engine is probably the safest thing that could happen. The engines are made of titanium alloys and designed to not fail catastrophically. The rest of the aircraft is made of soft materials by comparison.
- tanishq1 11y ago
  And even in the event of an engine failure, they could still probably land safely.
  - deleted 11y ago
    [deleted]
  - TheSpiceIsLife 11y ago
    So flying drones in flight paths is fine, gotcha.
  - vectorjohn 11y ago
    "probably" sounds really good for a commercial airliner. For some idiot to fly a drone around an airport.
- mynameishere 11y ago
  That seems like the least safe thing that could happen. If a drone hit the wing or windshield it would just break and fall to earth.
- Animats 11y ago
  A jet engine that ingests any metal object the size of a drone motor will take serious damage. The engine may continue to run, but there will be blade damage. Vibration sensors indicate how bad the problem is. Most likely, there will be an engine shutdown and a precautionary landing. The plane goes out of service, the engine is replaced, and the damaged engine goes in for a major overhaul. 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] [1] http://fodnews.com/fod-defined/ http://fodnews.com/fod-defined/
nether 11y ago
One thing to remember is that commercial jets have very thin aluminum skin. It's very unlike your car door which is typically thicker steel sheet. When jets crash the wreckage is shredded metal laying flat on the ground. So they're more fragile than they seem.
- SixSigma 11y ago
  Thee skin is aluminium lithium alloy. 1mm generally but in some places on the craft it is milled down to 0.5mm The latest jet liners A380 / 787 are made from composites, even their body. Many other craft have composite wings.
zyxley 11y ago
Remember the speed differentials involved here. Landing speed for large passenger jets is fast. Picture a 5-pound drone hitting a stationary plane at 250 miles per hour and ask if the damage would be "negligible".
- baby 11y ago
  So you mean the drone would be destroyed.
- x5n1 11y ago
  Would not expect it to be any worse than a bird strike, which I hear are common enough. Eventually the firmware of the drone would know to avoid airplanes at all cost and perhaps have some sort of equipment in there to limit them ever flying close to airplanes. The regulation should ideally force this, for drones to have sensors and firmware to avoid airplanes. https://en.wikipedia.org/wiki/Bird_strike https://en.wikipedia.org/wiki/Bird_strike
  - JoeAltmaier 11y ago
    Bird strikes are bad enough. And lots of efforts made to lure birds away from airports. 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?
- StringyBob 11y ago
  Can't help of thinking of the foam strike causing the Columbia space shuttle disaster "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."
  - JoeAltmaier 11y ago
dumbguy 11y ago
One word, birds. We hit them frequently, and a goose weighs a lot more than most drones. This is panicking over shark attacks while commuting in your car while smoking cigarettes. Sure we need to set limits, but most of this is FUD.
- WalterBright 11y ago
  Yeah, but drones are harder than geese. I would speculate that one could easily break an engine, and smash out the cockpit windshield. I doubt it would cause critical structural damage otherwise, but it would be illuminating to do some tests (bird strike tests are done). One possibility is to limit the weight of the drones, which will limit the damage they can inflict.

by szx 11y ago

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?

DataJunkie 11y ago

Disclaimer: Aviation hobbyist but not an expert. 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.

iofj 11y ago
The airflow would be trying to prevent a collision with the front of the wing, and a drone would simply go where the wind blows. Which is to say if a drone flew straight for an airplane wing, it would fly around the wing and suddenly explode in the massive turbulence behind the wing. This would look very surprising because to the naked eye there is nothing behind the wing. 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.
- nether 11y ago
  There isn't really any "turbulence" behind any modern wing in typical flight regimes. They're very low drag, so flow off the trailing edge is as smooth as the upstream flow.
  - throwaway_xx9 11y ago
    Well, except for those pesky wingtip vortices that can down a smaller airliner.
  - nightski 11y ago
    This was near landing, so I assume flaps were deployed. That changes things a bit.
- tzs 11y ago
  30 seconds of Googling turns up numerous examples of bird strikes on the leading edge of wings, some with very substantial damage. Why would airflow around the wing keep a drone from hitting it but not a bird?
  - nether 11y ago
    Nothing. Upstream flow stagnates at the leading edge, excess bug splatter there attests to that.
    - mveety 11y ago
      It can stagnate to the point of bugs not having much of an issue staying on the wing during flight. I remember a case when I was flight training where we had a little spider as a passenger on the top of the starboard wing for the duration of the flight. The little guy didn't fall off until the wing stalled out when we were landing.
      - ajross 11y ago
        That's a different effect. The region just above the surface is a turbulent boundary layer without much net flow. But it's very thin.
hanniabu 11y ago
Anybody know what the protocol is in the event of a blown out windshield/windscreen? 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?
- MaxScheiber 11y ago
  https://en.wikipedia.org/wiki/British_Airways_Flight_5390 https://en.wikipedia.org/wiki/British_Airways_Flight_5390
  - hanniabu 11y ago
    That is damn impressive on both pilot's accounts, thanks for the link

cptskippy 11y ago

I would imagine hitting the engine is probably the safest thing that could happen. The engines are made of titanium alloys and designed to not fail catastrophically. The rest of the aircraft is made of soft materials by comparison.

tanishq1 11y ago
And even in the event of an engine failure, they could still probably land safely.
- deleted 11y ago
  [deleted]
- TheSpiceIsLife 11y ago
  So flying drones in flight paths is fine, gotcha.
- vectorjohn 11y ago
  "probably" sounds really good for a commercial airliner. For some idiot to fly a drone around an airport.
mynameishere 11y ago
That seems like the least safe thing that could happen. If a drone hit the wing or windshield it would just break and fall to earth.
Animats 11y ago
A jet engine that ingests any metal object the size of a drone motor will take serious damage. The engine may continue to run, but there will be blade damage. Vibration sensors indicate how bad the problem is. Most likely, there will be an engine shutdown and a precautionary landing. The plane goes out of service, the engine is replaced, and the damaged engine goes in for a major overhaul. 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] [1] http://fodnews.com/fod-defined/ http://fodnews.com/fod-defined/

nether 11y ago

One thing to remember is that commercial jets have very thin aluminum skin. It's very unlike your car door which is typically thicker steel sheet. When jets crash the wreckage is shredded metal laying flat on the ground. So they're more fragile than they seem.

SixSigma 11y ago
Thee skin is aluminium lithium alloy. 1mm generally but in some places on the craft it is milled down to 0.5mm The latest jet liners A380 / 787 are made from composites, even their body. Many other craft have composite wings.

zyxley 11y ago

Remember the speed differentials involved here. Landing speed for large passenger jets is fast. Picture a 5-pound drone hitting a stationary plane at 250 miles per hour and ask if the damage would be "negligible".

baby 11y ago
So you mean the drone would be destroyed.
x5n1 11y ago
Would not expect it to be any worse than a bird strike, which I hear are common enough. Eventually the firmware of the drone would know to avoid airplanes at all cost and perhaps have some sort of equipment in there to limit them ever flying close to airplanes. The regulation should ideally force this, for drones to have sensors and firmware to avoid airplanes. https://en.wikipedia.org/wiki/Bird_strike https://en.wikipedia.org/wiki/Bird_strike
- JoeAltmaier 11y ago
  Bird strikes are bad enough. And lots of efforts made to lure birds away from airports. 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?
StringyBob 11y ago
Can't help of thinking of the foam strike causing the Columbia space shuttle disaster "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."
- JoeAltmaier 11y ago

dumbguy 11y ago

One word, birds. We hit them frequently, and a goose weighs a lot more than most drones. This is panicking over shark attacks while commuting in your car while smoking cigarettes. Sure we need to set limits, but most of this is FUD.

WalterBright 11y ago
Yeah, but drones are harder than geese. I would speculate that one could easily break an engine, and smash out the cockpit windshield. I doubt it would cause critical structural damage otherwise, but it would be illuminating to do some tests (bird strike tests are done). One possibility is to limit the weight of the drones, which will limit the damage they can inflict.