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HAWK21M
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Bird Hit Chances At SOF/LBSF

Mon Oct 08, 2012 11:29 am



Considering the number of birds and the location,Shouldn't ops be restricted in such times,Is this common out at this airfield.....
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jumbojim747
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RE: Bird Hit Chances At SOF/LBSF

Fri Oct 12, 2012 5:56 pm

Wow that's a lot of birds MEL.
One thing that's always plays on my mind is why cant engine manufacturers come up with a design to the front intake that would keep birds out.
Now i know the airflow would be restricted.
But can it be done.
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Starlionblue
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RE: Bird Hit Chances At SOF/LBSF

Fri Oct 12, 2012 9:19 pm

Quoting JumboJim747 (Reply 1):
One thing that's always plays on my mind is why cant engine manufacturers come up with a design to the front intake that would keep birds out.
Now i know the airflow would be restricted.
But can it be done.

Interesting as a thought experiment. You'd need some way to "filter out" the bird before it reaches the blades.

However in the case of props you don't want them to hit the prop anyway so while a bird filter would help the turbine or reciprocating engine it wouldn't help the prop blades.
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fr8mech
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RE: Bird Hit Chances At SOF/LBSF

Sat Oct 13, 2012 1:02 am

Quoting JumboJim747 (Reply 1):
One thing that's always plays on my mind is why cant engine manufacturers come up with a design to the front intake that would keep birds out.

I don't think airflow is a big a problem as yuou may think....until the ice starts to form on whatever media you use to filter the birds. You can anti-ice, but you are starting to add complexity, weight and cost.
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dandaire
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RE: Bird Hit Chances At SOF/LBSF

Sun Oct 14, 2012 9:44 am

Quoting JumboJim747 (Reply 1):
One thing that's always plays on my mind is why cant engine manufacturers come up with a design to the front intake that would keep birds out.

Some turboprop aircraft already do have such a design. The Saab 340 intake does have a "bird-catcher" design. Any birds or other debris is routed away from the engine into the bird catcher and down into the bottom of the nacelle away from the engine inlet.
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AF1624
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RE: Bird Hit Chances At SOF/LBSF

Mon Oct 15, 2012 1:09 pm

Didn't old(er) 707 and 727 engines have some kind of fairing in front of the main fan?

It looked like a fan itself but was fixed.
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flyingturtle
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RE: Bird Hit Chances At SOF/LBSF

Mon Oct 15, 2012 3:42 pm

Quoting AF1624 (Reply 5):

These might be stator vanes - they stabilize the airstream before it hits the fan. Normaly, stator vanes are behind the fan.

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AF1624
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RE: Bird Hit Chances At SOF/LBSF

Tue Oct 16, 2012 8:44 am

Quoting flyingturtle (Reply 6):
These might be stator vanes - they stabilize the airstream before it hits the fan. Normaly, stator vanes are behind the fan.

Thanks David.

These being in the front, would that be strong enough to prevent a bird ingestion? Or at least to slow the bird down enough so that the blades don't get damaged?

Unless the bird actually gets stuck there. Hum.
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flyingturtle
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RE: Bird Hit Chances At SOF/LBSF

Tue Oct 16, 2012 10:29 am

Quoting AF1624 (Reply 7):

No, at takeoff speed these stator blades will slice through the bird like a knife through hot butter.

Add to that the suction of the fan behind.



However, your idea (or sort of) was accidentally tested in the real world... http://www.youtube.com/watch?v=5jxcSY1AwrM , and the guy has survived to tell his tale:

Sailor Sucked Into An A6 Engine (by A5XX May 4 2005 in Military Aviation & Space Flight)


David
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HAWK21M
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RE: Bird Hit Chances At SOF/LBSF

Wed Oct 17, 2012 7:29 am

Quoting JumboJim747 (Reply 1):
he front intake that would keep birds out.

as long as its not at a compromise to performance , finally its about $$$.  
Quoting flyingturtle (Reply 6):
These might be stator vanes - they stabilize the airstream before it hits the fan. Normaly, stator vanes are behind the fan.

the Bird strike to a low bypass turbofan can be more expensive as the bird can damage multiple layers beyond....On a High bypass Turbofan the chances are less & 1st stage fan blades can be replaced on line.
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PHX787
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RE: Bird Hit Chances At SOF/LBSF

Thu Oct 18, 2012 8:54 pm

Quoting HAWK21M (Reply 9):
the Bird strike to a low bypass turbofan can be more expensive as the bird can damage multiple layers beyond....On a High bypass Turbofan the chances are less & 1st stage fan blades can be replaced on line.

I've heard of some people designing some type of cover that keeps debris from entering the intake of the fan....but wouldn't that just restrict airflow too? I recall an older model of the Learjet or Cessna Citation that had something similar to that but I'm not 100%.


Also: don't airports use noises that only birds can hear to keep them away?
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larshjort
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RE: Bird Hit Chances At SOF/LBSF

Thu Oct 18, 2012 10:17 pm

Quoting PHX787 (Reply 10):
Also: don't airports use noises that only birds can hear to keep them away?

Some probably do. in SGD and ODE they use shoot with blanks from a shotgun before aircrafts arrives and departs.

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HAWK21M
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RE: Bird Hit Chances At SOF/LBSF

Fri Oct 19, 2012 7:46 am

Quoting PHX787 (Reply 10):

Also: don't airports use noises that only birds can hear to keep them away?

The Fireworks guy lighting fire crackers at fixed intervals are common at most places....The better Airports use Noise generating Vehicles that roam the runways producing sound waves that affect birds.....
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Dufo
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RE: Bird Hit Chances At SOF/LBSF

Sun Oct 21, 2012 8:23 pm

I was based in Sofia for a few months in 2010 and don't remember any special problems with birds.
Ducks in Marseille were much more problematic and unpredictable  
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pilotpip
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RE: Bird Hit Chances At SOF/LBSF

Mon Oct 22, 2012 5:03 am

Why not make a puncture-proof tire? Tires fail. Planes hit birds. The results are seldom any worse than mx cleaning guts off the airframe.

Bird strikes happen quite often. Looking back through my logbook I average 2 per year over 12 years. My personal high was 7 when I was instructing in 2007. Biggest was a red-tailed hawk. That left a mark.
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HAWK21M
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RE: Bird Hit Chances At SOF/LBSF

Mon Oct 22, 2012 7:24 am

Quoting pilotpip (Reply 14):
Why not make a puncture-proof tire

Weight penalty.......& the concern of bird hits is not tire damage but rather bird strike or worse bird ingestion.
Airports should have a residential cleared area of 1-2 km ideal to curb birds.
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pilotpip
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RE: Bird Hit Chances At SOF/LBSF

Sat Oct 27, 2012 5:24 am

I think you missed my point, Mel. It's not a new problem. Bird strikes happen. They happen all the time as I'm sure you know. There have been only maybe a handfull of flights in 100 years of aviation where bird strikes caused a threat to the safety of passengers. If it were a greater issue it would have been addressed decades ago but it hasn't because it's cost prohibitive and quite honestly, one of the smaller risks to the safety of flight.
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HAWK21M
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RE: Bird Hit Chances At SOF/LBSF

Sat Oct 27, 2012 10:19 am

Quoting pilotpip (Reply 16):
There have been only maybe a handfull of flights in 100 years of aviation where bird strikes caused a threat to the safety of passengers.

Agreed bird strike leading to a disaster is rare,but in todays times the impact on the financial strength of the airline is a concern too.
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flanker
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RE: Bird Hit Chances At SOF/LBSF

Thu Nov 08, 2012 10:30 pm

Seems like a bunch of Swallows... I don't ever recall there being problems with birds at SOF.
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