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(Quartz)   What happens when a drone gets sucked into a jet engine? Well, remember that video of a brick being thrown into a washing machine?   (qz.com) divider line 67
    More: Interesting, New York metropolitan area, passenger aircraft, mid-air collision, Scenario Testing  
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12761 clicks; posted to Main » on 15 May 2014 at 9:00 PM (27 weeks ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2014-05-16 12:10:39 AM  

The One True TheDavid: Someday a hobbyist will invent a drone bomber. Or a fleet of baby kamikazis. Or a flying machine gun.


We already have that last one.  It's called the A-10.
 
2014-05-16 12:53:35 AM  
Is it bad that I was more entertained by watching the follow-up video clip titled "cliff jumps" ?
 
2014-05-16 12:57:43 AM  

Hermione_Granger: ...if these should hold their peace, the appliances would immediately cry out.

https://www.youtube.com/watch?v=gbh6DZHyMCU

That is a lot like what happens when my aunt catches the Holy Spirit in Church. Except when she falls over her wig usually comes off.


OMG! That is one of the funniest things I've seen in a long time. Thank you!
 
2014-05-16 01:16:47 AM  

OlderGuy: NightSteel: TuteTibiImperes: Why don't plane engines have grills to protect against things entering them?  Would it disrupt the air too much and reduce engine efficiency, would they be ineffective at the speeds the planes travel, or is there some other reason?

Imagine the grill you'd need to absorb and/or deflect a 12 pound bird, and remain aerodynamic during all stages of flight.  It'd have to be huge, both to have the structural strength necessary, and to allow enough air through.  For example, a 777 engine takes in more than 2,000,000 CFM of air at full power.  I can't even imagine a way to deflect birds while still allowing 2 million CFM of airflow.

How about a net of high strength small gauge wire.. only issue is vibration...


At the speeds in question, the wire would slice through the bird and you'd end up feeding 12 lbs of bird guts into the engine in bite-size chunks. It would have about the same effect as the bird passing through the first fan stage in the engine.
 
2014-05-16 01:50:37 AM  

ski9600: stratagos: TuteTibiImperes: Why don't plane engines have grills to protect against things entering them?  Would it disrupt the air too much and reduce engine efficiency, would they be ineffective at the speeds the planes travel, or is there some other reason?

Then you'd have a drone and a grate ducked into the engine

I've seen a video of a Naval airman going through the engine and coming out with minor injuries.  It's not a problem.


(you know he didn't go all the way through, right?)
 
2014-05-16 02:38:34 AM  
Certification standards for weather balloons (radiosondes) include 'frangibility" the ability to get sucked into a jet engine and not cause uncontained failure. Total mass less than X, no metal parts bigger than Y, and the circuit boards are a weird paper-thin laminate that's not even fiberglass.I'd imagine we could come up with similar standards for civil drones, at least the ones sold to unlicensed pilots. Or we could if the country still had a functioning government and regulatory system.
 
2014-05-16 03:02:40 AM  
Actually, there's already a real-world example.  The F117 has mesh across its intakes, and it has the same problems that others here have already mentioned; they restrict airflow enough that secondary intakes, which close after takeoff, are necessary.  The mesh is also prone to icing, requiring an electrical deicer, which adds bulk and weight.  And this is mesh for *stealth* reasons, not for protecting the engines from FOD, so it isn't built for durability.

I'm not a math genius, so I might be using the wrong measure or terminology, or calculating incorrectly here (and a smarter Farker can feel free to and correct me as necessary), but If I'm doing the math right, the aforementioned 12-pound bird (the approximate average weight of a Canada goose) at 400 mph would be roughly equivalent to 64,000 ft-lbs of energy.  For comparison, to get the same amount of energy at highway speed (60 mph) you'd need a ~533 lb object (say, an adult male grizzly bear).

If you want another few comparisons, I've done some Googling for figures.  The bullet from a .50 cal Barrett M82 has a muzzle energy of almost 15,000 ft-lbs.  The M61 Vulcan cannon has a muzzle energy of almost 42,000 ft-lbs (varies somewhat with ammo type).  The M82's powerful enough to shred a human being and disable lightly armored vehicles, and the M61 is effective versus armor (though not as effective as the A-10's GAU-8, with a muzzle energy of over 180,000 ft-lbs, which also varies with ammo type).

So yeah, I know birds, bears and bullets are all very different objects, but my point is, 64,000 ft-lbs of energy is nothing to sneeze at.  Even if you could make a screen that could take an impact with that kind of energy without allowing debris through, the screen has to be mounted to the engine and/or cowling, so the mount points, and the structure of the engine and/or cowling, would also have to be strong enough to withstand that energy.

And again, remember, jet engines move a LOT of air, which any solution cannot restrict too much.

If someone asked me to design something to keep birds out of jet engines, I'd start with a very pointed cone, which would have a better chance of deflecting whatever might hit it head on, but it'd still be possible for an impact right on the point of the cone, and of course, the longer the cone, the more susceptible it would be to lateral force, and the less rigid it would be overall.

I've spent way too much time researching and thinking about this.. lol.
 
2014-05-16 03:05:27 AM  
FTFA: In a jet engine there are several concentric rings of high-speed fan blades that simultaneously push air backwards and compress it for combustion.

Someone needs to learn the difference between concentric and coaxial.
 
2014-05-16 07:17:07 AM  
Once had a Tomcat (F-14) come back from flying with a birdstrike, center windscreen (The Glass One) punched a hole in it about the size of a dime, cracked the rest of it. When the pilot opened the canopy the rim was packed with bird meat jelly and the pilots face looked like he had his face sandblasted. Never forget the tiny white feathers poking out of his skin. Thankfully he had his visor down so it didn't blind him. Was a seagull of some sort, inside of the cockpit smelled like cleaners and rotten meat after that. Never did get that smell out of there.
 
2014-05-16 07:21:50 AM  

UberNeuman: What happens when you throw a jet engine into a jet engine?  Does it open a vortex into another realm?


You get Xzibit.
 
2014-05-16 07:44:38 AM  
 
2014-05-16 07:59:23 AM  

Cthulhu_is_my_homeboy: OlderGuy: NightSteel: TuteTibiImperes: Why don't plane engines have grills to protect against things entering them?  Would it disrupt the air too much and reduce engine efficiency, would they be ineffective at the speeds the planes travel, or is there some other reason?

Imagine the grill you'd need to absorb and/or deflect a 12 pound bird, and remain aerodynamic during all stages of flight.  It'd have to be huge, both to have the structural strength necessary, and to allow enough air through.  For example, a 777 engine takes in more than 2,000,000 CFM of air at full power.  I can't even imagine a way to deflect birds while still allowing 2 million CFM of airflow.

How about a net of high strength small gauge wire.. only issue is vibration...

At the speeds in question, the wire would slice through the bird and you'd end up feeding 12 lbs of bird guts into the engine in bite-size chunks. It would have about the same effect as the bird passing through the first fan stage in the engine.


Well I think it wouldn't be quite the same effects. If normaly the first stage makes bite size chunks, and the having a screen makes bite sized chunks before they hit the 1st blade, then the 1st blade should turn the bite sized chunks into kibble, which would be easier for the rest to handle. (Note, I said *easier* not *easy*)

By the way, if you  ever wondered what it looked like if a person got sucked into a jet engine...
(Grusome image warning. May be NSFW or stomach)
 
2014-05-16 10:11:27 AM  

Satan's Dumptruck Driver: TuteTibiImperes: Why don't plane engines have grills to protect against things entering them?  Would it disrupt the air too much and reduce engine efficiency, would they be ineffective at the speeds the planes travel, or is there some other reason?

Because you'd rather have "something" get pulled into the engine at 500-MPH than "something plus a grill." It's not like a grill is going to hold up to a collision at those speeds.

And yes, efficiency is #1. You should see the brake systems for large jets. Not an ounce is wasted, and they they work reliably. Very good example of how to refine a product right up to the edge of what is possible.


Oh man, this brought back memories from first year structures class in college.  Professor was an engineering prof. teaching a class of architects...about 3/4 through every problem he would get to the part where you enter the safety factor, which is large for buildings, typically about 50% but in reality it is complicated by lots of different live loads, and he would laugh maniacally and state 'good enough for architects'...but one day he explained that for airplanes the safety factor was more like 1%...so he wasn't wrong in giving us some grief...

/I try not to think about that too much when flying though.
 
2014-05-16 11:09:49 AM  

MythDragon: Well I think it wouldn't be quite the same effects. If normaly the first stage makes bite size chunks, and the having a screen makes bite sized chunks before they hit the 1st blade, then the 1st blade should turn the bite sized chunks into kibble, which would be easier for the rest to handle. (Note, I said *easier* not *easy*)

By the way, if you  ever wondered what it looked like if a person got sucked into a jet engine...
(Grusome image warning. May be NSFW or stomach)


Yeah but the problem is the size of the chunks doesn't matter nearly so much as the total momentum of the pile of bird gibs. Animal flesh is "mostly" water so at the impact speeds in question the turbine blades basically carve through it like it was a liquid (except the bones, of course, but bird bones are really fragile compared to mammalian bones), but that blob of "liquid" is still hitting with the force of a small cannonball, and the energy is transferred in a tiny fraction of a second. For a 12-lb bird at 400 mph we're talking about close to 50 megawatts of power for the duration of the impact.
 
2014-05-16 11:32:58 AM  

Cthulhu_is_my_homeboy: MythDragon: Well I think it wouldn't be quite the same effects. If normaly the first stage makes bite size chunks, and the having a screen makes bite sized chunks before they hit the 1st blade, then the 1st blade should turn the bite sized chunks into kibble, which would be easier for the rest to handle. (Note, I said *easier* not *easy*)

By the way, if you  ever wondered what it looked like if a person got sucked into a jet engine...
(Grusome image warning. May be NSFW or stomach)

Yeah but the problem is the size of the chunks doesn't matter nearly so much as the total momentum of the pile of bird gibs. Animal flesh is "mostly" water so at the impact speeds in question the turbine blades basically carve through it like it was a liquid (except the bones, of course, but bird bones are really fragile compared to mammalian bones), but that blob of "liquid" is still hitting with the force of a small cannonball, and the energy is transferred in a tiny fraction of a second. For a 12-lb bird at 400 mph we're talking about close to 50 megawatts of power for the duration of the impact.


So what you are saying is that if we used piezoelectric fan blades, we could save money of fuel costs by usings some sort of bird-scoop induction system?
 
2014-05-16 01:37:31 PM  

gilatrout: I fly with a couple of local clubs here. If anyone tried to fly near an airport, or intentionally near a manned aircraft they'd be beaten senseless.

Some of these guys love to fly and any asshat that threatens their hobby is in deep shiate


Came here to say this.  I'm with a local club and if you so much as joked about getting your "drone" near a manned aircraft, you'd be beaten senseless, and removed of your gear.

We put a rather large amount of time and effort and money into this hobby.  We are very careful to protect it.

/we also have insurance for club members flying at our airfield to cover damages should there be any.
//only 1 claim in 4 years, for a car windshield that got a ARF .30 trainer shoved through it.  Luckily the car was parked.
 
2014-05-16 03:54:01 PM  

ski9600: stratagos: TuteTibiImperes: Why don't plane engines have grills to protect against things entering them?  Would it disrupt the air too much and reduce engine efficiency, would they be ineffective at the speeds the planes travel, or is there some other reason?

Then you'd have a drone and a grate ducked into the engine

I've seen a video of a Naval airman going through the engine and coming out with minor injuries.  It's not a problem.


He was sucked into the intake, but his life vest and helmet jammed the engine before it had a chance to turn him into chutney.  http://news-hound.org/man-sucked-into-a-jet-engine-survives/
 
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