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Fly-By-Wire Flight Controls



 
 
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  #1  
Old December 15th 05, 07:43 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls

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?

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?

-Charles Talleyrand

  #2  
Old December 15th 05, 08:13 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls


"Charles Talleyrand" wrote in message
oups.com...
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?

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?

-Charles Talleyrand



On the A-6E and EA-6B aircraft, the Emergency Ram Air Turbine (RAT) only
powers the Emergency DC Bus which in turn provides power to a small set of
essential instruments. It does not provide any hydraulic power for the
flight controls.


  #3  
Old December 15th 05, 08:42 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls

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?


The same way on a BAE Hawk.

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?


Some years ago there was an Airbus A330 FBW fly by wire widebody that
ran out of fuel crossing the atlantic. It had to make an emergency
landing at (I thnk) the Azores I think from over 100km out without
fuel.

A leaking fuel delivery pipe in the engine pylon drained the aircrafts
fuel: the pilot didn't believe his instruments and thus kept
transfering fuel from the good side to the bad side rather than
shutdown the bad engine. He thus drained both wings.

When fuel cut out (I saw a dramatisation ogf the events) the ram air
turbine deployed and the pilots, after finally acknowledging their fuel
situation went through their checklist.

Lights and pressurisation was lost with the power.

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.
This made the one chance of making the runway even harder as there
would be no go arounds.

To cap it all of the runway in the azores ends in a 300ft shear cliff.
They stopped a few dozen meters short with blown tyres.

Airbus changed their software and though the pilot was clearly not
making the best decisions that day it was easier to given him awards.

The ram air turbine provides very little power. I think the idea of
giving the APU its own reserve fuel supply is tempered by the fact that
it is perhaps better to keep the engine lit for a few seconds longer.

Perhaps a cartriedge or two of of rocket-gas generator turbine could be
used to provide pressure for flap and spoiler deployment

  #4  
Old December 15th 05, 09:32 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls

Perhaps a cartriedge or two of of rocket-gas generator turbine could be
used to provide pressure for flap and spoiler deployment


Why not just load more fuel. It would not weigh any more and would be
far less complicated. Also have sirens which screech at the pilot.

  #5  
Old December 15th 05, 10:03 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls

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.

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

Benjamin
  #6  
Old December 15th 05, 11:54 AM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls


"Eunometic" wrote in message
ups.com...


Some years ago there was an Airbus A330 FBW fly by wire widebody that
ran out of fuel crossing the atlantic. It had to make an emergency
landing at (I thnk) the Azores I think from over 100km out without
fuel.


70nm at 34,500 ft

A leaking fuel delivery pipe in the engine pylon drained the aircrafts
fuel: the pilot didn't believe his instruments and thus kept
transfering fuel from the good side to the bad side rather than
shutdown the bad engine. He thus drained both wings.

When fuel cut out (I saw a dramatisation ogf the events) the ram air
turbine deployed and the pilots, after finally acknowledging their fuel
situation went through their checklist.

Lights and pressurisation was lost with the power.

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.
This made the one chance of making the runway even harder as there
would be no go arounds.

To cap it all of the runway in the azores ends in a 300ft shear cliff.
They stopped a few dozen meters short with blown tyres.

Airbus changed their software and though the pilot was clearly not
making the best decisions that day it was easier to given him awards.


Airbus did not change their software which had behaved correctly, they
re-issued the flight manuals emphasizing the advice that was already
present to close the cross feed valves in the case of unexpectedly high
fuel consumption on one engine.

Transport Canada fined the airline C$250,000 (about US$165,000)
for maintenance infractions relating to an improper installation of a
hydraulic pump on an engine of the incident aircraft.


Keith



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  #7  
Old December 15th 05, 01:28 PM posted to rec.aviation.piloting,rec.aviation.military
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Default Fly-By-Wire Flight Controls

The F-16 uses a Hydrazine/Platinum (IIRC) APU to generate electricity.

Les


"Charles Talleyrand" wrote in message
oups.com...
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?

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?

-Charles Talleyrand



  #8  
Old December 15th 05, 02:15 PM posted to rec.aviation.piloting,rec.aviation.military
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Posts: n/a
Default Fly-By-Wire Flight Controls

Glide speed generally provides sufficient windmill RPM on the engine(s) to
provide sufficient hydraulic power so that the controls (they don't have to
be fly-by-wire, any irreversible hyd flight control system is effected) have
sufficient pressure and volume to operate normally with moderate control
inputs.

R / John

"Charles Talleyrand" wrote in message
oups.com...
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?

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?

-Charles Talleyrand



  #9  
Old December 15th 05, 03:00 PM posted to rec.aviation.piloting,rec.aviation.military
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Posts: n/a
Default Fly-By-Wire Flight Controls

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



  #10  
Old December 16th 05, 02:57 AM posted to rec.aviation.piloting,rec.aviation.military
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Posts: n/a
Default Fly-By-Wire Flight Controls

"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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