I've gone through all the posts and between them all the reason(s) that
screens etc. are not used in front of the engines were touched on in one way
or another.
I have been involved in bird ingestion of a jet engine. Ran a test where we
fired a bird into the engine to evaluate it's response to the bird strike
and then its ability to recover and achieve a minimum level of thrust.
Thrust recovery of the engine, both in time and power level, is aimed at
obtaining enough power to successfully be able to complete a take-off and
achieve a minimum altitude.. Don't want to get into the specifics of
"requirements".
You can't put anything in the front of the engine for a number of
reasons--Ice build up, inlet air distortion, potential for FOD. The only
aircraft that I've seen with a screen in front of the engine inlet was the
F117 (the small black stealth bomber). In fact, it has a wiper blade to
keep the screen clean.
The big bang that people heard was the engine as it went into a
"stall"--that's when the flow of air is interrupted and because of the high
pressure at the back end of the compressor, a reversal of flow occurs and
out the front it comes--like a gigantic blurb. Things happen very
fast--give you an example--In the test I was involved in, fifty people or so
were seated so as to observe the engine inlet during the bird strike. No
one observed anything unusual, however when the film was reviewed --taken at
1000 frames per sec (each frame therefore was .001 sec) the inlet of the
engine filled with a large fireball that burst out of the front (with a few
floating feathers) and then was sucked back into the inlet. And no one saw
the flame. BTW, the bird was not alive.
Jet engines go through significant testing in order to meet and exceed
requirements relative to a bird strike, however, there are limits with
respect to size and number of birds that an engine can tolerate. We
actually x-rayed the birds during the selection process in order to ensure
that there was nothing inside of them (pieces of metal or any other type of
foreign objects) that would have a negative impact of the results of test
results. Whenever there is an aircraft incident when both (or all) engines
are involved, especially a power loss, you can just about bet the farm that
it's not primarily an engine fault but more so related to some other outside
influence--fuel contamination, fuel starvation, FOD, inlet air distortion
etc.
MLD


"Jimw" wrote in message
...
Off Topic, but hardware related.

It's been all over the news about the plane that crashed into a river
in (I think) New York. They said it was caused by birds flying into
the engine. Then they showed a report of the number of bird caused
plane accidents and deaths each year. From 1990 to 2007 there were
almost 80,000 accidents caused by birds. There have been numerous
deaths and millions of dollars of damages.

OK, looking at the engines they showed on tv, I immediately thought
***Why dont they put some sort of screening over the engine***
It would only seem like a couple hundred dollars worth of hardware
cloth would solve the problem. Why dont they think of simple
solutions like this?

Jim