Fly-By-Wire Flight Controls

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

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?

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). 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. 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

"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......

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?

Alternatively, I've always wondered if one could not keep a special
reserve tank for the APU. When the engines quit, the APU
automatically starts to power the controls. Would such a system be
safe and would it be certifiable? Would it weigh less than the
existing system?

In a lot of airplanes the APUs (resp. their intakes and exhausts) are
mounted in a way that they can't be used inflight. Besides that, if
there still is fuel in the tanks it's better served for keeping the
engine alive than just the APU...

I know that most Boeing and Airbus planes can run the APU in the air.

I'm just asking if 30 minutes of fuel for the APU might not weigh less
than
the ram air turbine. The APU would clearly produce more power than the
ram air turbine.

If the choice was between flight controls powered for 30 minutes or the
main
engines powered for another one minite, I would take the former.

I must assume that there are some very smart aircraft designers who
have already
considered and rejected my idea. But WHY was this? Is it a
fundementally
bad idea, is it a good idea that's against the rules of certification,
or what?

-Charles Talleyrand

Charles Talleyrand wrote:
Alternatively, I've always wondered if one could not keep a special
reserve tank for the APU. When the engines quit, the APU
automatically starts to power the controls. Would such a system be
safe and would it be certifiable? Would it weigh less than the
existing system?


In a lot of airplanes the APUs (resp. their intakes and exhausts) are
mounted in a way that they can't be used inflight. Besides that, if
there still is fuel in the tanks it's better served for keeping the
engine alive than just the APU...


I know that most Boeing and Airbus planes can run the APU in the air.

I'm just asking if 30 minutes of fuel for the APU might not weigh less
than
the ram air turbine. The APU would clearly produce more power than the
ram air turbine.

If the choice was between flight controls powered for 30 minutes or the
main
engines powered for another one minite, I would take the former.

I must assume that there are some very smart aircraft designers who
have already
considered and rejected my idea. But WHY was this? Is it a
fundementally
bad idea, is it a good idea that's against the rules of certification,
or what?

-Charles Talleyrand


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

Dan, U.S. Air Force, retired

"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

"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.

"Casey Wilson" N2310D @ gmail.com wrote in
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.

HAHAHAHAA...too funny....I'd quote it but don't want to be
a spoiler.

I also liked the part about what was heard on the voice recorder
after the EICAS went "bong"..."Oh F___".

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.

Brian
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