Birds and planes and crashes.

[Marc]

Imagine if you will an aircraft taking off at a minimum of 160 knots, anything that comes in contact is a projectile. Here is a picture of a bird strike on a Blackhawk helicopter.
Maximum speed: 159 kt (183 mph, 295 km/h)
Cruise speed: 150 kt (173 mph, 278 km/h)

Boeing 757
Cruise speed .80 Mach (530 mph, 458 knots, 850 km/h at 35,000 ft cruise altitude)

I'm not sure what the take off speeds are but I'd guess its 160 knots or better. With a screen on the front of the engine you'd have just that much more FOD for the engine to ingest.

It's probably a balancing act between prevent in bird strikes and risk assocites with mesaures such as meshes etc to stop ingestion.

Anyone know what the maximum altitude birds fly at is? Would of thought that you're soon be out of the bird space fairly quickly as the plane climbs.

 

[J.T.B.]

Just remebered that the inverse of that design has been used.

The Boeing 727 used an S-tunnel for the intake on the 3rd engine. The nacelle was on top of the fuselage but the actual engine was in the fuselage.

Hawker Siddely Trident, Lockheed L-1011 and Tupolev 154, too. It's usually called the number two engine.

The problem with various "bird deflector" ideas is that the bird doesn't have to physically wreck the engine, its mass (whole or in pieces) can simply disrupt airflow enough that, put simply, the compressor doesn't push as much air as the engine needs, a compressor stall. There are varying levels of compressor stalls and most are recoverable, however, on takeoff when the engines are at their heaviest loading and there isn't much airspeed or altitude built up, a sudden loss of power can be pretty serious. Unfortunately, takeoff and landing are the most likely times to encounter birds.

And, no offense, but does anyone really think that in over 60 years nobody in jet propulsion engineering ever thought "Uh, could we put something on the front of the engine?"

--Justin

 

[Marc]

Just remebered that the inverse of that design has been used.

The Boeing 727 used an S-tunnel for the intake on the 3rd engine. The nacelle was on top of the fuselage but the actual engine was in the fuselage.

Hawker Siddely Trident, Lockheed L-1011 and Tupolev 154, too. It's usually called the number two engine.

Well the TU-154 is a knock off of the 727 so does that count? My brother flew on with Aeroflot ("and survived") as his facebook comment went First time he'd been on plane that was older than him.

The problem with various "bird deflector" ideas is that the bird doesn't have to physically wreck the engine, its mass (whole or in pieces) can simply disrupt airflow enough that, put simply, the compressor doesn't push as much air as the engine needs, a compressor stall. There are varying levels of compressor stalls and most are recoverable, however, on takeoff when the engines are at their heaviest loading and there isn't much airspeed or altitude built up, a sudden loss of power can be pretty serious. Unfortunately, takeoff and landing are the most likely times to encounter birds.

Some airports have devices to try and scare them away but they only tend to work for the ones on the ground that might suddenly take flight. The seagulls are a pest at Adelaide Airport in South Australian (depending on the heading for take off or landing you're over the sea seconds after leaving the runway) but I don't recall every having any aircraft taking major bird strikes.

And, no offense, but does anyone really think that in over 60 years nobody in jet propulsion engineering ever thought "Uh, could we put something on the front of the engine?"

Well man has been watching the birds for millenia but it wasn't until radar came along that ti was realised they flew at night

 

[J.T.B.]

Well the TU-154 is a knock off of the 727 so does that count?

Or are they both knock-offs of the Trident?

--Justin

 

[Marc]

Well the TU-154 is a knock off of the 727 so does that count?

Or are they both knock-offs of the Trident?

--Justin

I read the wiki entry on the Trident last night after seeing your post and there was a comment in there about the 727 being built to airline specs and then selling 10x as many (1700 v 117) and given the similar looks you're probably right.

 

[Gaseous Anomaly]

Imagine if you will an aircraft taking off at a minimum of 160 knots, anything that comes in contact is a projectile. Here is a picture of a bird strike on a Blackhawk helicopter.
Maximum speed: 159 kt (183 mph, 295 km/h)
Cruise speed: 150 kt (173 mph, 278 km/h)

Boeing 757
Cruise speed .80 Mach (530 mph, 458 knots, 850 km/h at 35,000 ft cruise altitude)

I'm not sure what the take off speeds are but I'd guess its 160 knots or better. With a screen on the front of the engine you'd have just that much more FOD for the engine to ingest.

It's probably a balancing act between prevent in bird strikes and risk assocites with mesaures such as meshes etc to stop ingestion.

Anyone know what the maximum altitude birds fly at is? Would of thought that you're soon be out of the bird space fairly quickly as the plane climbs.

That's a good question! The majority of bird strikes are at landing and takeoff with some on low level high speed runs. I don't think they are a real factor over 15,000 feet since the air is very thin.

Many airports have active bird management programs to control where the birds are hanging out. Always seems to be some that just don't want to work with the airports though.

I don't claim to be an expert on this subject but I've worked on more bird strike aircraft than I care to think about.

Not sure on what happened to my photo in yesterdays post so here it is.