Why no screens on Jet engines??

[Moose-LandTran]

4th gen Camaros send deer straight over the roof if you're going fast enough!

 

[neblinc]

F-16 vs Bird

Randy

 

[Diesel-Mech]

Birds just do not get along well with aircraft.

 

[CenTex52Chevy]

What if the screen was not designed to stop the bird just cut the bird up before the turbine has to digest it. stretch some piano wire over the intake that way the 30 lb candian goose become 10- 3lb candian goose chunks, might cause less damage that way. Yes I know piano wire would really work but you get the idea.

 

[Stuey]

You guys are making it sound like smaller bird chunks flying into an engine aren't still almost as hazardous and damaging as larger objects.

 

[Moose-LandTran]

Wouldn't 1-2 damaged blades be better than 5-10 damaged ones? I'd imagine they'd want to minimise the damage. 10 decent-sized bird bits would ****** the entire engine, as opposed to one big bird bit damaging part of an engine and it still running.

 

[nebben]

With the numbers of fatalities being directly attributed to power loss from bird ingestion into one or all engines of a turbine commercial aircraft... I can't imagine that numbers would go down by placing anything in front of the engine inlet.

Putting a screen of any type in front of a turbine seems like it would just be inviting problems related to ice, and FOD . I think there would be far more damage when a jet loses an engine because its "bird screen" loosens and gets sucked in.

I know JFK has full time bird control crews that use a manner of techniques to reduce birds' preferences of hanging out in the path of aircraft. Falcons, shotguns, horns, air cannons...etc.

 

[aerobb]

Hey something I can answer, I haven't used my aerospace degree in years, so here you go.

screen would cause the inlet air to have turbulence and reduce the effectiveness of the engine. I can talk about laminar boundry layer theory if you really want to. But then again maybe I've killed those brain cells

 

[Charles (in GA)]

Wouldn't 1-2 damaged blades be better than 5-10 damaged ones? I'd imagine they'd want to minimise the damage. 10 decent-sized bird bits would ****** the entire engine, as opposed to one big bird bit damaging part of an engine and it still running.

Won't matter, you get a damaged blade, or if one breaks off, the engine is coming apart, its just that simple. As someone noted, you plan for one failure, not for both.

If there were some simple method of preventing bird strikes in engines, it would have been done long ago. It just isn't there. Most engines will handle small birds, but as also noted, a goose is big and heavy, **** in one or two of them, and its all over.

Charles

 

[5wndwcpe]

Well, since you asked.

"Question - What is the highest flying bird?
----------------------------------------


from here.

An SR-71 I believe.

 

[e-tek]

OMG, the US just declared war on Canada!!!!!

They determined it was canadian geese that brought this plane down, FN terrorists birds anyways

First thing Mrs E-tek said: "They'll be blaming us now and forcing all the Canada Geese out of US airspace!!"

 

[GDA]

I saw a show several years ago about the design and engineering that went into the 777 and one segment was them doing extreme thunderstorm/hurricane rain testing on the engines and another test shown was them engulfing thawed chickens in super slow motion. Very cool to see the turbine blades not deflect/crack or break under such duress of such FO ingestion under full (take off) power.

Anyone else see that show?

 

[Charles (in GA)]

"Question - What is the highest flying bird?
----------------------------------------
I am not aware of any documentation for regularly occurring highest flying
species; the greatest altitude documented as of the mid 1980's was a
Ruppell's griffon, an African vulture, struck by an airliner at 37,000 feet.
Another vulture, a lammergeyer was seen over "its mountain home" at 25,000
feet over Mt. Everest; alpine choughs have been recorded nesting at 27,000
feet on Mt. Everest. A mallard was struck by an airliner at 21,000 feet over
Nevada. Records of smaller birds, also from hitting airplanes, are mostly
from 7,000 to 12,000 feet."

A number of years ago, probably 15, the airline I work for had a Lockheed L-1011 hit several geese (that is what the flight crew described them as, they were large whatever they were, I know that). The airplane had leveled out in cruise, between Soul and Tokyo, I seem to recall they were at 38,000 ft. The nose cone was cracked by a glancing blow, while one more hit right at the juncture of two leading edge slats. Tore those up pretty bad. At least one more hit the leading edge of the horizontal stabilizer and did not break it open but severely dented it in. The nose cone was replaced in Asia and the airplane was ferried back to Atlanta for repairs.

Charles

 

[ddawg16]

--------------------------------------------------------------------------------

Quote:
Originally Posted by Marc Shaw
Well, since you asked.

"Question - What is the highest flying bird?
----------------------------------------


from here.


An SR-71 I believe.

From the history archives of the SR71.......

"One day, high above Arizona , we were monitoring the radio traffic of all the mortal airplanes below us. First, a Cessna pilot asked the air traffic controllers to check his ground speed. "Ninety knots," ATC replied. A twin Bonanza soon made the same request. "One-twenty on the ground," was the reply. To our surprise, a navy F-18 came over the radio with a ground speed check. I knew exactly what he was doing. Of course, he had a ground speed indicator in his cockpit, but he wanted to let all the bug-smashers in the valley know what real speed was "Dusty 52, we show you at 620 on the ground," ATC responded. The situation was too ripe. I heard the click of Walter's mike button in the rear seat. In his most innocent voice, Walter startled the controller by asking for a ground speed check from 81,000 feet, clearly above controlled airspace. In a cool, professional voice, the controller replied, "Aspen 20, I show you at 1,982 knots on the ground." We did not hear another transmission on that frequency all the way to the coast."

 

[Junkman]

Hey something I can answer, I haven't used my aerospace degree in years, so here you go.

screen would cause the inlet air to have turbulence and reduce the effectiveness of the engine. I can talk about laminar boundry layer theory if you really want to. But then again maybe I've killed those brain cells

I believe that I would like to hear more about this theory, and any others that you might care to bring into the discussion. I have the time, if you have the inclination....

 

[ddawg16]

According to Wikipedia...
"Laminar flow, sometimes known as streamline flow, occurs when a fluid flows in parallel layers, with no disruption between the layers. In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion, low momentum convection, pressure and velocity independent from time. It is the opposite of turbulent flow. In nonscientific terms laminar flow is "smooth," while turbulent flow is "rough."

Go to this Link. there is a picture which gives you a good idea of what laminar flow is.

Or, you could go to your central heating/air system, remove the air filter and see what it does for the air flow.

 

[nyjets53]

Way back when - while working at Grumman, I was helping out the engine test crew and watched them test the plane engines with and without screens...They used screens when they had to be in the area during testing and no screens if all the testing was done remotely...They could see a difference in the performace of the engines...These screens had like a 5" x 5" mesh of heavy duty wire, to keep people from flying in the inlet...

 

[Bencrx91]

OMG, the US just declared war on Canada!!!!!

They determined it was canadian geese that brought this plane down, FN terrorists birds anyways

LOL !!!!

You get our birds, we get your pollution.

Just kidding.

 

[chaingang]

Here in central Texas we call 'em bumpers. When I see the number of deer dead on the roads each morning, I'm thinking maybe "bumper" is the wrong term!

The one thing that was unscathed in 2 of our families 3 deer kills in the last six months was the BUMPER. I won't count the 3 kill since the deer ran into the side of my wifes Explorer. My son and I both hit deer a week apart. Did $1800 dollars damage to his Ranger and $2800 to my Explorer. Both bumpers are fine. Everything above the bumper however, not so good. Man I've had hunting seasons that I didn't get three deer. Cost a lot less too.

 

[Pritch]

Remember this frightening video?

A crewman on an aircraft carrier getting sucked into a jet's engine-and lived!

In a kinda related to the whole bird strike thing-when I was a kid, maybe 10 or 12, that woulda been '68 or '70 or so, I saw a duck take out a helecopter. This 'copter was a crop-duster, spraying some fields by where we lived and a few of us kids were there just watching it flying around and coming back and re-filling and taking off-all the stuff that kids love to watch. One time as it was taking back off, it got up about a hundred feet or so and not to far away, a duck flew up out of this little pond that was there and straight into the rotor! Of course the duck just exploded into a ball of feathers, but the 'copter started vibrating and making a wierd noise and the pilot set it down as quick as he could right in the middle of the field. We all ran over, and the rotor-it was some kind of laminated wood-had a chunk out of it as big as a man's fist. I'll never forget the look on that pilot's face when he climbed out-he was shook right up!

 

[BigK600]

My brother is a engineer for Boeing and has worked on chicken tests I could ask him. But I think the question has been answered on here. Bottom line is: there is alot of good reasons why. Just like why a plane seats are so small, my brother gets asked that one alot.

 

[Stuey]

From the history archives of the SR71.......

"One day, high above Arizona , we were monitoring the radio traffic of all the mortal airplanes below us. First, a Cessna pilot asked the air traffic controllers to check his ground speed. "Ninety knots," ATC replied. A twin Bonanza soon made the same request. "One-twenty on the ground," was the reply. To our surprise, a navy F-18 came over the radio with a ground speed check. I knew exactly what he was doing. Of course, he had a ground speed indicator in his cockpit, but he wanted to let all the bug-smashers in the valley know what real speed was "Dusty 52, we show you at 620 on the ground," ATC responded. The situation was too ripe. I heard the click of Walter's mike button in the rear seat. In his most innocent voice, Walter startled the controller by asking for a ground speed check from 81,000 feet, clearly above controlled airspace. In a cool, professional voice, the controller replied, "Aspen 20, I show you at 1,982 knots on the ground." We did not hear another transmission on that frequency all the way to the coast."

Great story!

The Blackbird really was an awesome aircraft. It had what, a 110,000 mile operating ceiling and mach 3.5 speed? Sweeeeet.

 

[Blown71X]

While not quite on the same scale of velocity as a modern turbine, sometime when you are bored, grab a common household window screen and hold it in front of fan and feel not only the difference in air flow, but more to the point, the resistance as fan speed is increased.
This simple test will will put a perspective on and show just one of the things involved in considering inlet shielding on a turbine engine.

Rick

 

[russlaferrera]

OMG, the US just declared war on Canada!!!!!

They determined it was canadian geese that brought this plane down, FN terrorists birds anyways

I hate to correct you...but the Canadian Geese all had green cards.

2nd point, If we went to war with Canada, we would loose. Most of our military is overseas, all that's left are old Americans and Mexicans.

 

[Willy Victor]

Great story!

The Blackbird really was an awesome aircraft. It had what, a 110,000 mile operating ceiling and mach 3.5 speed? Sweeeeet.

Try a 110,000 ft. ceiling.

 

[Willy Victor]

We regularly hit Gooney Birds taking off from Midway Is. in the 50's. Those big 3350's would grind birds up pretty good. We did have one plane get the upper radome knocked off once.


WillyVictor

 

[wantedabiggergarage]

Try a 110,000 ft. ceiling.

I prefer the previous one. Might help our aging space shuttle dilemma.

 

[fattogatto]

The only bird avoidance method used on an aircraft is the spiral paint motif on the inlet cone. The theory is that the birds can see this (yes, even at the high rotational speeds) and they associate it with a large bird of prey and will try to avoid it. The theory used to be that airborne radar would cause the birds to avoid aircraft but as modern radars get better the emminations are less detectable. Bird strikes are not uncommon. I've had two in the last month. It is, however, less common for the gods to have the bird go into the engine.

However, it does happen . . . .

 

[fattogatto]

But has anyone thought about this scenario: Birds take out #1 (left) engine causing a fire and numerous cockpit alarms. Tons of confusion in the cockpit and the non flying pilot shuts down the wrong engine. Too low on altitude to restart it, so they ditch the airplane. It's very unlikely for birds to take out both engines and shutting down the wrong engine does happen.

I hope after the investigation concludes, that the pilot is truly the hero everyone is calling him.

So why do you bring this up? Sounds like typical media frenzy to me. It is not unlikely for a FLOCK of geese to cause ingestion into both engines. It may be unlikely for an aircraft to hit a FLOCK of geese, but that did happen.

Stop the ugly innuendos and give the guy a break.

 

[Charles (in GA)]

NTSB has already said that both engines spooled down together. This is not from the pilot shutting down the wrong engine (which HAS happened before, on a couple of occasions I know of), as there would have been a time lag from the first one spooling down to an accidental shut down of the second engine. With a jet, there is no hurry in shutting down or securing a dead engine (unless it is shaking like a wet dog).

Charles

 

[dylan22]

I was thinking about this issue as well, and assuming it was possible to make an airfilter-like cone shaped screen, wouldn't the suction from the turbine firmly suction any birds or and debris to the screen. Imagine if the screen went though a flock of birds, it would exit the flock with them all firmly suctioned to the filter, which I assume would quickly stall the engine.

 

[C G]

Interesting snopes call on chicken cannons: http://www.snopes.com/science/cannon.asp

Someone mentioned a bird strike at 38,000 feet and I was thinking no way birds fly that high. Well according to a google search there are a few birds that do...I learn new stuff everyday around here.

And lastly I thought it was funny when someone asked if the geese were wearing turbans because I got this pic in email...I hope no one is offended

 

[nissan_crawler]

updrafts can cause birds to be much higher than they would normally fly at.

 

[29bowtie]

OMG, the US just declared war on Canada!!!!!

They determined it was canadian geese that brought this plane down, FN terrorists birds anyways

We've been expecting this accusation,ever since they stated it was "Canada Geese".

 

[Matti]

I work with a guy that used to work for Rolls Royce. He told me once that they also do hurricane tests which involve flooding the engine with water. I don't have details on the procedure. I'm sure the risk of a double engine failure is very low. There are plenty of risks just getting out of bed and going to work everyday.

 

[GarageDreamer]

The news stated that 200 people have been killed since 1980 due to bird strikes. 90% happen around airports. Not all that rare.[/QUOTE


its rare when you consider that 200 people have died during the time we have spent talking about this thread. I've been flying in the military for 18 yrs and have taken bird, deer, coyote and moose strikes.. it happens but I feel safer in the air then crossing the street with some teenager with her cell phone glued to her ear driving a Ford

 

[GarageDreamer]

I'm very curious why both engines died at once.. sure a bird will choke a engine to death but two at once. I'm suspious of the Airbus computer.. I'm betting it shut them down after the strikes threw the engines off balance.. When a Boeing operated engine plane would have had the pilot shut the engine down.. again I'm just wondering, I've never flown a Airbus.

 

[nissan_crawler]

It hit two big flocks of birds, what's hard to understand?

 

[Worsedog]

I'm very curious why both engines died at once.. sure a bird will choke a engine to death but two at once. I'm suspious of the Airbus computer.. I'm betting it shut them down after the strikes threw the engines off balance.. When a Boeing operated engine plane would have had the pilot shut the engine down.. again I'm just wondering, I've never flown a Airbus.

This is nearly as stupid as the comment about the pilot shutting down the wrong engine. Why in the world would you shut automatically shut down an operating engine on a two engine plane if one failed. Big heavy planes fall out of the sky with no power

 

[Worsedog]

..............................