Fly-By-Wire Flight Controls

"Casey Wilson" N2310D @ gmail.com wrote in message news:qokpf.21228$eI5.17594@trnddc05...

"Keith W" wrote in message ...

"Dan, U.S. Air Force, retired" wrote in message news:yDepf.66209$sg5.26836@dukeread12...
Charles Talleyrand wrote:



For one thing you'd be hard pressed to get 30 minutes of glide time from any airliner.

Dan, U.S. Air Force, retired

The Air Transat Airbus that ran out of fuel glided for 20 minutes
to get to the Azores

Keith


And there is the 1983 (?86) story of the "Gimli Glider." An Air Canada B-767 that ran out of fuel and landed on an
X-ed out runway in Canada that was, at the time, in use by sports car racers. See:

http://www.silhouet.com/motorsport/tracks/gimli.html

for a great photo. They talk about the RATS but I couldn't find any remarks about elapsed glide time in this story.

For giggles, read the post script story about the mechanics who went to rescue the airplane.


Here is a link to the RAT:
http://www.hamiltonsundstrandcorp.co..._PRD38,00.html

We make the hydraulic pump portion:
http://www.parker.com//ead/cm2.asp?cmid=2841

Skywise wrote:
Damned good flying.

I would have officially christend that plane the "Gimli Glider"
and painted it's nose with it. I wonder if it's still in service
today. That plane's got good karma.

http://www.airliners.net/search/phot...eywords=C-GAUN

Still in service

Steve schrieb:

Its located just behind the left main wheel but stalls when the gear is
lowered, so its a wheels up landing if you've got the balls.

Well done ;-)

Benjamin

"James Hart" wrote in
:

Skywise wrote:
Damned good flying.

I would have officially christend that plane the "Gimli Glider"
and painted it's nose with it. I wonder if it's still in service
today. That plane's got good karma.

http://www.airliners.net/search/phot...es=500&keyword
s=C-GAUN

Still in service

Thank you!

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?
Like censorship and not getting support help? Switch to Supernews!
They won't even answer questions through your ISP!

Benjamin Gawert wrote:
Eunometic schrieb:

The PA200 Tornado is fully FBW with a mechanical linkage backup system...

Benjamin


Then why does it need a thermal backup battery to remain airborn?

Because besides power for certain important instruments and the radio
the EPS battery also powers an electric motor that powers a hydraulic pump.

"Mechanical linkage" does not mean that the stick is connected to
pushrods and levers that move the control surfaces (which would be silly
on a fighter/bomber aircraft with up to ~55000 pounds weight).

Which means that PA200 Tornado when using 'mechanical' backup is
actually fully power opperated as opposed to power assisted (power
assisted can be designed to connect into a fully manual system with
limited movement). Given the need for power it doesn't seem to make
much sense to bother to use a mechanical system at all. An additional
layer of redundancy and an 'analog' backup would be better use of the
weight. Perhaps Panavia was worried about Electromagnetic Pulse or
Weapons. I believe F-16 uses fiber optics.

When in
so-called "mech mode" the stick is connected to several hydraulic valves
that control the hydraulic actuators. So you need hydraulics pressure,
and in cases of double engine out this hydraulic pressure comes from an
electric pump that powered by the EPS battery.

In normal operation the potentiometers connected to the stick submit
stick position data to the flight control system (CSAS and SPILS) which
calculate the necessary control surface deflection and control the
corresponding actuators.

They use potentiometers? I though LVDT were normally used.

The mechanical linkage is inactive (in
emergencies the stick gets linked to the mechanical controls through a
honeycomb block which gets squeezed by the stick movement applied by the
panicing pilot ;-)

This applies to the GR versions (bomber), I don't know if the F versions
are somewhat different.

Benjamin

A higher flying Airbus or B747-400 at 44,000ft might have glided nearly
30 minutes. This suggests that a fighter plane with its lower glide
ratio probably only needs half the amount of time (10 minutes) which
suggests that a thermal battery is possibly more efficient or at least
adaquet whereas an airliner may need twice as much.

What seems extraordinary is that both airbus and boeing designers have
provided insufficient RAT power to opperate all systems: spoilers,
flaps, undercarriage seem to be neglected. This makes an emegency
landing much harder. In both the airbus A330-200 azores and boeing 767
gimli fuel out landing case the lack of spoilers added a great deal of
risk as pilots manouvered agressively to loose altitude and speed for
runway lineup.

"Eunometic" wrote in message
ups.com...
A higher flying Airbus or B747-400 at 44,000ft might have glided nearly
30 minutes. This suggests that a fighter plane with its lower glide
ratio probably only needs half the amount of time (10 minutes) which
suggests that a thermal battery is possibly more efficient or at least
adaquet whereas an airliner may need twice as much.

What seems extraordinary is that both airbus and boeing designers have
provided insufficient RAT power to opperate all systems: spoilers,
flaps, undercarriage seem to be neglected. This makes an emegency
landing much harder. In both the airbus A330-200 azores and boeing 767
gimli fuel out landing case the lack of spoilers added a great deal of
risk as pilots manouvered agressively to loose altitude and speed for
runway lineup.


If you add more power to the RAT you increase drag and reduce the
glide distance, the record suggests they made the right trade offs.

Keith

"Eunometic" wrote in message
oups.com...

Benjamin Gawert wrote:
Eunometic schrieb:

Eunometic schrieb:
It does apply for the PA200 Tornado. The APU is not operable
in-flight,
if you loose both engines and the one-shot battery is down you have to
get out of that thing...


I didn't think Tornado was fully FBW?

The PA200 Tornado is fully FBW with a mechanical linkage backup
system...

Benjamin

Then why does it need a thermal backup battery to remain airborn?

The One Shot Battery is there to provide electrical power to a Fuel pump (or
in combination with a Hyd pump). The engines also need electrical power to
keep their systems running - without electrics, the engines will "run
away" - Very bad thing if you're not near a nice big bit of tarmac......

Eunometic schrieb:

"Mechanical linkage" does not mean that the stick is connected to
pushrods and levers that move the control surfaces (which would be silly
on a fighter/bomber aircraft with up to ~55000 pounds weight).


Which means that PA200 Tornado when using 'mechanical' backup is
actually fully power opperated as opposed to power assisted (power
assisted can be designed to connect into a fully manual system with
limited movement).

correct.

Given the need for power it doesn't seem to make
much sense to bother to use a mechanical system at all.

The mechanical linkage backup is there if the 2x redundant fly-by-wire
system fails or gets damaged. When in "mech mode" (FBW dead but engines
are running) the aircraft is fully controllable (but of course reacts
more sensible due to the lack of CSAS and also lacks things like spin
prevention and AOA limiter etc). Loosing the FBW does not mean the
aircraft can't return safely...

An additional
layer of redundancy and an 'analog' backup would be better use of the
weight. Perhaps Panavia was worried about Electromagnetic Pulse or
Weapons.

Correct. Thanks to the mechanical linkage the aircraft is still operable
even when suffering from an EMP or with a damaged electronics system.
Even 4x redundant FBW wouldn't provide this safety, and the weight
penalty isn't really big.

I believe F-16 uses fiber optics.

The Eurofighter Typhoon uses fiber optics. The F-16 used a wire harness
(don't know if that has been changed in a later block but I doubt that).

In normal operation the potentiometers connected to the stick submit
stick position data to the flight control system (CSAS and SPILS) which
calculate the necessary control surface deflection and control the
corresponding actuators.


They use potentiometers? I though LVDT were normally used.

No, it's some sort of potentiometer, but of course a bit more
sophisticated than what you can find in consumer electronics ;-)

Benjamin

On Mon, 19 Dec 2005 19:59:21 +0100, Benjamin Gawert
wrote:

Eunometic schrieb:

"Mechanical linkage" does not mean that the stick is connected to
pushrods and levers that move the control surfaces (which would be silly
on a fighter/bomber aircraft with up to ~55000 pounds weight).


Which means that PA200 Tornado when using 'mechanical' backup is
actually fully power opperated as opposed to power assisted (power
assisted can be designed to connect into a fully manual system with
limited movement).

correct.

Given the need for power it doesn't seem to make
much sense to bother to use a mechanical system at all.

The mechanical linkage backup is there if the 2x redundant fly-by-wire
system fails or gets damaged. When in "mech mode" (FBW dead but engines
are running) the aircraft is fully controllable (but of course reacts
more sensible due to the lack of CSAS and also lacks things like spin
prevention and AOA limiter etc). Loosing the FBW does not mean the
aircraft can't return safely...


Hmm sounds sensible in a Cold War environment with buckets of canned
sunshine being thrown around.

But now a question to pilots or folks in the know:
Do they train flying "mech mode" and if so how?
Just in the sims or sometimes for real as in.
"IP to student: I flipped the switch to mech mode. Show me how you
smooth you can land this baby"?

And if a pilot can apparently fly safe in "mech mode" does that mean
that the Tornado is not inherent unstable like the F16? Or at least
not very inherent unstable?

Because flying a F16 in "mech mode" (if that beast would exist) THAT
would be a real challange.

Greetz Mu




Greetz Mu