On 22/01/13 11:31, Tim Streater wrote:
In article ,
The Natural Philosopher wrote:

On 22/01/13 10:13, Tim Streater wrote:
In article ,
The Natural Philosopher wrote:

On 21/01/13 20:16, John Williamson wrote:
Andy Champ wrote:
On 21/01/2013 01:37, Steve Firth wrote:
Andy Champ wrote:
On 19/01/2013 23:56, Steve Firth wrote:
Indeed, the plane was incapable of doing what the pilot
commanded.
So it
did the best that it could. Without the digital controls it
would
simply
have crashed a bit earlier.

That's the way I've always heard it - he overrode the
computer. But
there
seems to be some dispute and fiddling with evidence. Do you
have a
link
to the official reports anywhere?

The official report is he

http://www.bea.aero/docspa/1988/f-kc...f-kc880626.pdf

snip

Bien, merci, et... ah. Wrong overlay. I would have preferred it in
English, but the practice does me good

That's pretty clear it was pilot error. Too low power setting, too
late.

Power setting was correct for the maneouvre during the fly by,
but when
he became aware of a problem, the pilot applied TOGA power a
couple of
seconds too late for the engines to spool up in time to make enough
thrust to lift the plane above the height of the trees.

It took a LONG time for carrier based jets to become accepted, for
that very reason. No instant throttle response for a go-around.

You mean turbine blades don't feather?

Is that a joke?

Well I dunno. I'm assuming that the reason for your comment is that a
jet when landing will tend to have the engine on low thrust, meaning
that it takes a few seconds to get the turbine wound up - too slow.

yes.

Whereas a prop plane can come in to land with the engine on full but the
prop feathered. If there's a problem he just changes the prop pitch -
instant thrust.


yes.

I used to notice this at Cambridge Airport when taking the Suckling
AIrways 07.00 flight to Schiphol. It was a 20 seater or so Dornier and
he'd stop at the end of the runway, wind up the engines - and only then
change the prop pitch. Then you'd get thrust.

yes.
The mechanical inertia of the turbine is the problem. IN a turboprop it
can be spooled up on low load /low throttle because as you say, the
props are in super fine pitch. (not feathered- that's super coarse
pitch). With (I assume) constant sped props, the opening of the throttle
will coarsen the pitch to keep RPM constant, adding massive thrust.

TurboJETS cant do that..they are very much one speed devices. And dont
take kindly to being revved up rapidly.

--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.