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Anti-drone mesh

  [vote for,

Aircraft are at greatest risk from drones (and, indeed, from birds) during takeoff and landing. These are the times when engine failure would be most disastrous, and also when the plane is travelling slowest (making it easier for someone to fly a drone into an engine). Also, planes tend to come in quite low for landing (and start out low for takeoff), putting them within range of drones and birds.

Suggested, therefore, is a simple mesh of fine wires across the engine intakes. The mesh would be coarse enough to allow reasonable airflow, but just fine enough to stop drones and birds. After takeoff, the mesh would be retracted to allow unrestricted airflow and hence more economical flight. It would be re-deployed just before landing.

MaxwellBuchanan, Dec 30 2018

Diaphragm https://en.m.wikipe...AIris_Diaphragm.gif
[xenzag, Dec 30 2018]


       Retracting mesh.... that may be difficult to realise, so I suggest a type of camera iris who's individual segments are covered with perforations like a colander. The perforations would be large enough to allow sufficient air to flow for take off and landing, and the iris would retreat completely into the surrounding engine cowling when not in use. See link.
xenzag, Dec 30 2018

       //and start out low for takeoff// In fact, they start off so low that rabbit sweepers are also required to prevent these foolish creatures from being run over and entangled by the aircraft wheels.
xenzag, Dec 30 2018

       //Retracting mesh.... that may be difficult to realise//   

       I have a cunning plan. Have individual wires on small spring-loaded spools, attached in a ring around the intake. Each wire runs to a fixed attachment point. The spools can move around the rim of the intake. To deploy the mesh, each spool travels around the rim until it's opposite its wire's attachment point, stretching the wire across the intake. To un-deploy, each spool travels back around the rim until it's next to its wire's attachment point, the wire spooling in as it does so.
MaxwellBuchanan, Dec 30 2018

       Mechanical spiders could also generate a rapid web when there was a threat.
xenzag, Dec 30 2018

       Equally, a grandmother strapped to each engine could knit something when necessary.
MaxwellBuchanan, Dec 30 2018

       Now you're getting there..... Pratt and Knitney engines.
xenzag, Dec 30 2018

       OK, an update and improvement. The wires are now all fixed at one end to a single attachment point on the leading edge of the wing or, if the engine is mounted forward of the leading edge, to a small forward-pointing thing. In either case, all the wires are anchored to one point above and in front of the engine.   

       The other ends of the wires are, as before, attached to spring-loaded spools that can be moved around the rim of the engine intake.   

       Now, when deployed (the spools having distributed themselves evenly around the lower 2/3rds of the intake) you have a sort of skewed 2/3rds cone extending from above-and-in-front-of the engine to around the lower 2/3rds of the intake. This arrangement will actually deflect any oncoming debris downwards, below the intake.   

       When retracted (the spools having all moved up to the top of the intake rim) you have a narrow bundle of wires that are largely out of the intake stream, and hence won't impact performance.
MaxwellBuchanan, Dec 30 2018

       This is clearly a work in progress, and risks becoming a bird's nest of entangled wires if just one of them breaks, so I'm not convinced, but the rabbit sweepers should be easier. I'm thinking wide yard brushes, that are attached to the front of the wheel structures, and turn sideways for storage as the undercarriage is retracted.
xenzag, Dec 30 2018

       //clearly a work in progress// We prefer to think of it as an endeavour of constant improvement.
MaxwellBuchanan, Dec 30 2018

       Trained eagles could predate rabbits, hares (very common at Schipol) and drones.   

       Small, armed UAVs could peform the same role, although onlookers would not be able to enjoy the spectacle of a magnificent bird of prey perched on top of a lighting gantry and tearing its kill apart.
8th of 7, Dec 30 2018

       //Trained eagles could predate rabbits//   

       No, it seems that rabbits predate eagles. The first fossil evidence for rabbits is from about 40 million years ago; for eagles, 36 Mya. _Trained_ eagles, of course, are much more recent.
MaxwellBuchanan, Dec 30 2018

       A big heavy hammer that swings out and knocks away anything approaching the engine? To save weight it can be filled with fuel.
Voice, Dec 30 2018

       "What? No, it's fine, really. Just need to bolt this robotic hammer on, about here. Sheesh - wish I'd remembered to bring the cordless drill. No, no, really, it's perfectly safe - see? It can't quite swing round enough to hit the... ah, well, OK, but it won't actually swing that far in use. Probably."
MaxwellBuchanan, Dec 30 2018

       Sticking anything in front of a jet engine creates new safety risks which will require further mitigation, so on the whole I think it's probably a bad idea. Engines have to be able to deal with a range of bird strike events already and perhaps ingesting a drone would actually be less severe. In any case I think the solution is to prevent aircraft/drone collisions in the first instance.   

       I'm not convinced the wires will cause a significant downward deflection at almost 200mph, so really they'll just be slicing the bird/drone before it gets properly chopped up by the fan. The wires would need to be pretty substantial to survive a high speed collision with a stray bolt sucked up off the runway.   

       Also any pressure loss in the intake system will reduce the engine thrust thereby prolonging the take-off manoeuvre. Generally you want to get off the ground as quickly as possible and out of the way of near-ground threats.
EnochLives, Dec 30 2018

       Wise words.   

       // ingesting a drone would actually be less severe. //   

       No, it wouldn't. In practical tests, small metallic components cause disproportionate damage to the N2 spool if they get that far; damage to N1 is bad enough.   

       Observers may have noted that, thus far, we have abstained from launching a painstaking, merciless and devastating technical critique* of the idea.   

       That can change. We do hope that [MB] has a nice New Year present for us ...   

       *including numerous explanatory footnotes.
8th of 7, Dec 31 2018

Voice, Dec 31 2018

       If you are going to go this way, should not this device be two non touching conductive interleaved filters?
wjt, Dec 31 2018

       // doitdoitdoitdoitdoitdoitdoit //   

       No doubt it was your ancestors who patronised Roman amphitheatres, to watch the wild beast fights, executions and gladiatorial combats, revelling in the stench of blood and the sight of gore, and all the while munching on snack foods in between baying for yet more violence and cruelty.
8th of 7, Dec 31 2018

       I wonder if this applies to bagpipes?
not_morrison_rm, Dec 31 2018

       //We do hope that [MB] has a nice New Year present for us //   

       Oh yes, we certainly do. Can I just check that you have some Vaseline, a packet of fish-fingers and two AA batteries? If not, I'll add those.
MaxwellBuchanan, Dec 31 2018

       No, we have a good stock of all three items, and have also purchased extra curtain rings this year.
8th of 7, Dec 31 2018

       You did remember to get the brass ones this time? Only the plastic ones tent to get brittle at low temperatures. I don't want to have to take you to A&E for the third year running.
MaxwellBuchanan, Dec 31 2018


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