Fly-By-Wire Flight Controls

Benjamin Gawert wrote:
Charles Talleyrand schrieb:

Suppose a smaller airplane with it's fly-by-wire controls goes runs out
of fuel. All the engines quit. On a larger jet a ram air turbine
would drop into the airstream and power the controls. How does it work
on smaller planes like the Dassault Falcon or the F-16?

The Panavia 200 Tornado has a EPS battery (one shot battery) that in
case of double engine out situations supplies a few instruments and an
electric pump to have some hydraulic pressure. This allows maintaining
control over the a/c for ~5-7 (max 10) minutes.

These EPS (Emergency Power System) Batteries are usually known as
"Thermal Batteries". They have an eutectic electrolyte of salts that
are melted by a pyrotechnical charge. Because the electrolyte is inert
and sold untill melted shelf lives of 20+ years are possible. Because
of the high opperating temperature very high power densities are
possible.

20 years would not be full life for an airliner and a ram air turbine I
suggest would require less maintenance. (ie it doesn't ever need
replacement)

Thermal batteries appear to be the battery of choice for missiles. I
did read though that the early MANPAD Stingers handed over to the
Mujahidine had thermal batteries that would now be failing and thus
(thankfully) rendering the missiles inopperational.

The Panavia Tornado also has Nickel Cadmium Secondary rechargeable
batteries (perhaps upgraded to NiMH now?) for APU starting and other
power. I suspect that these could keep the system up for a few minutes
on their own if in good condition.


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?

I a lot of airplanes the APUs (resp. their intakes and exhausts) are
mounted in a way that they can't be used inflight.

This would hardly apply to the Tornado. Tornado however uses its
entire slab sided botton fueselage for weapons: there is little room
for ram air turbine.

Besides that, if
there still is fuel in the tanks it's better served for keeping the
engine alive than just the APU...

Benjamin

Carl Orton wrote:
"Mu" wrote in message
...
F16's have a EPU, and according to this link
http://www.f-16.net/f-16_forum_viewtopic-t-1056.html you've got
around 10 minutes in Hydrazine mode, to find a nice piece of concreet.
After those 10 minutes it's gonna be a membership of the Martin Baker
Fanclub.
Love the reference to Baker!!!

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Eunometic schrieb:

These EPS (Emergency Power System) Batteries are usually known as
"Thermal Batteries". They have an eutectic electrolyte of salts that
are melted by a pyrotechnical charge. Because the electrolyte is inert
and sold untill melted shelf lives of 20+ years are possible. Because
of the high opperating temperature very high power densities are
possible.

The original PA200 EPS battery used liquid acid which when activated
flowed in precharged battery chambers. Due to several hazards that these
batteries incorporate they have been replaced by thermal batteries.

20 years would not be full life for an airliner and a ram air turbine I
suggest would require less maintenance. (ie it doesn't ever need
replacement)

Nope. A RAM air turbine _does_ indeed need maintenance, not only because
of aging seals and other items that have to be replaced from time to
time but also because it's a quite complicated mechanical part that has
to be checked in certain intervals to make sure it is in working condition.

RAM air turbines are certainly not a put-it-in-and-forget-it thing...

The Panavia Tornado also has Nickel Cadmium Secondary rechargeable
batteries (perhaps upgraded to NiMH now?) for APU starting and other
power. I suspect that these could keep the system up for a few minutes
on their own if in good condition.

Nope, the master battery (which is indeed NiMH now) only feeds certain
busbars that are required for start and is not suitable for emergency
operation...

I a lot of airplanes the APUs (resp. their intakes and exhausts) are
mounted in a way that they can't be used inflight.


This would hardly apply to the Tornado.

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...

Tornado however uses its
entire slab sided botton fueselage for weapons: there is little room
for ram air turbine.

Nope. It would be possible to integrate a RAM air turbine into the PA200
Tornado by relocating and re-arranging equipment in the lower
electronics bays. However, the efforts and also the cost are not
justifyable because a RAM air turbine would bring no real safety
imrpovement on the Tornado which already has a really very good safety
record, not to forget that it's old now and most airforces are planning
and/or already working on replacing it.

Benjamin

"Benjamin Gawert" wrote in message
...
Eunometic schrieb:

These EPS (Emergency Power System) Batteries are usually known as
"Thermal Batteries". They have an eutectic electrolyte of salts that
are melted by a pyrotechnical charge. Because the electrolyte is inert
and sold untill melted shelf lives of 20+ years are possible. Because
of the high opperating temperature very high power densities are
possible.

The original PA200 EPS battery used liquid acid which when activated
flowed in precharged battery chambers. Due to several hazards that these
batteries incorporate they have been replaced by thermal batteries.

20 years would not be full life for an airliner and a ram air turbine I
suggest would require less maintenance. (ie it doesn't ever need
replacement)

Nope. A RAM air turbine _does_ indeed need maintenance, not only because
of aging seals and other items that have to be replaced from time to
time but also because it's a quite complicated mechanical part that has
to be checked in certain intervals to make sure it is in working
condition.

RAM air turbines are certainly not a put-it-in-and-forget-it thing...

The Panavia Tornado also has Nickel Cadmium Secondary rechargeable
batteries (perhaps upgraded to NiMH now?) for APU starting and other
power. I suspect that these could keep the system up for a few minutes
on their own if in good condition.

Nope, the master battery (which is indeed NiMH now) only feeds certain
busbars that are required for start and is not suitable for emergency
operation...

I a lot of airplanes the APUs (resp. their intakes and exhausts) are
mounted in a way that they can't be used inflight.


This would hardly apply to the Tornado.

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...

Tornado however uses its
entire slab sided botton fueselage for weapons: there is little room
for ram air turbine.

Nope. It would be possible to integrate a RAM air turbine into the PA200
Tornado by relocating and re-arranging equipment in the lower
electronics bays. However, the efforts and also the cost are not
justifyable because a RAM air turbine would bring no real safety
imrpovement on the Tornado which already has a really very good safety
record, not to forget that it's old now and most airforces are planning
and/or already working on replacing it.

The F3 (ADV) has a RAT

Mu

Don't you mean the Caterpillar Club? I'm a member and people are
always asking me what the Pin is.

Big John
`````````````````````````````````````````````````` ```````````

On Thu, 15 Dec 2005 14:00:30 GMT,
(Mu) wrote:

On 14 Dec 2005 22:43:21 -0800, "Charles Talleyrand"
wrote:

Suppose a smaller airplane with it's fly-by-wire controls goes runs out
of fuel. All the engines quit. On a larger jet a ram air turbine
would drop into the airstream and power the controls. How does it work
on smaller planes like the Dassault Falcon or the F-16?


F16's have a EPU, and according to this link
http://www.f-16.net/f-16_forum_viewtopic-t-1056.html you've got
around 10 minutes in Hydrazine mode, to find a nice piece of concreet.
After those 10 minutes it's gonna be a membership of the Martin Baker
Fanclub.

greetz Mu

Ian schrieb:

The F3 (ADV) has a RAT

Really? Well, I only have experience with the GR versions which have a
one shot battery...

Benjamin

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

Most pointedly they lost spoilers and flaps; they really only had a few
instruments, ailerons, tail surfaces and the undercarriage. As a
result of being without flaps the landing speed was very high and
becuase there were no spoilers they couldn't loose speed or altitude
and actually had to circle and zig zag to loose both speed an altitude.

What powered these controls?

I assume the insturments were powered by the ram air turbine, but
ailerons are BIG. What powered those?

-Thanks

"Benjamin Gawert" wrote in message
...
Ian schrieb:

The F3 (ADV) has a RAT

Really? Well, I only have experience with the GR versions which have a
one shot battery...

Benjamin
Can't find a pic of where it is, but here's a pic of one of the external
gauges checked during pre-flight
http://www.tornado-data.com/History/.../pressures.htm

Benjamin Gawert wrote:
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?