yousef727
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Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 3:50 am

Hello

We have all heard the story about Air Canada's Gimli glider and probably seen the movie about on TV. In the movie you see this little propeller coming out from the bottom of the fuselage when the aircraft ran out of fuel. This should generate power for the electrical systems and hydraulics. So far so good, now my question is if such a propeller is mounted on all big jets?
I know it's also mounted on the A330 because it was on the Air Transat A330 that ran out of fuel and landed on the Azores.
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AAR90
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 3:59 am

So far so good, now my question is if such a propeller is mounted on all big jets?

In a word... no. Only those that require the additional redundancy a RAT [Ram Air Turbine] provides.
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QantasA332
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 5:43 am

Try this...

Cheers,
QantasA332
 
Mr Spaceman
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 9:24 am

Hi guys.

Apparently some fighter jets have RATs too.

Check out this photo of a USA Airforce F-4C Phantom II.

It has just performed an Emergency Landing, and you can clearly see a RAT sticking up from a pair of red doors above the left side engine.

Is it just me, or does it appear to be on a strange angle to the relative airflow?


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CPH-R
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 10:22 am

Reading through the above mentioned post, it seems like only twin-jets & tri-jets are fitted with the RAT. So no RAT's for the quads?

Of course, if you were on a flight that suffered 4 dead engines, I think I would visit my bookmaker and place some bets. Because what are the odds of that happening  Wink/being sarcastic

Oh, and Yousef, welcome to A.net - you seem to be one of the latest in a surge of Danish members (seriously - for every 5 or 10 threads I read, there's a new member from Denmark  Wow!)
 
liamksa
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 1:11 pm

Of course, if you were on a flight that suffered 4 dead engines, I think I would visit my bookmaker and place some bets. Because what are the odds of that happening

It has happened though. Both KLM and BA (I think) lost all of 'em on B747 thanks to volcanic ash.

A bad batch of fuel could do it aswell (although it seems these engines will run on just about anything).
 
MD11Engineer
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 1:53 pm

Actualy the A340 has a RAT as well.

Jan
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FredT
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 4:28 pm

Yes, plenty of jet fighters have RATs. Others have chemical batteries (thermal batteries) to provide emergency hydraulic and electrical power for at least as long as it takes to get a restart underway or get the APU going should the engine(s) flame out.

Running out of fuel would provide a nice silence even in a quad... it does happen, as we've seen.

The placement of the RAT on the F4 isn't strange I think. Remember, unless extreme angles of attack cause flow separation, the airflow will follow the fuselage nicely. Yes, it might be more effective somewhere else but jet fighter design is largely about cramming about four times more things into the fuselage than there is really room for. If that is where there's a few litres of room to spare then that is where the RAT will end up.

Cheers,
Fred
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CPH-R
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 8:31 pm

I know about the BA - but I think they managed to restart the engines.
 
bragi
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RE: Propeller As A Generator (Gimli Glider)

Tue May 04, 2004 10:31 pm

The crew of the BA B747 managed to restart two of their engines, which was sufficient to get them to the nearest airport.
What a difficult announcement to make; "Ladies and gentlemen, we have appearantly lost all engines"! Smokin cool
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Mr Spaceman
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RE: Propeller As A Generator (Gimli Glider)

Wed May 05, 2004 2:33 am

Hi guys.

> FredT, Thanks for your reply. Regarding the placement of the RAT on the F-4C Phantom II, I understand what you're saying about how if there's a few litres of room to spare somewhere in the airframe, then that's where the RAT will end up. That makes sense to me. Big grin

I was actually curious about how the angle of the prop blades on the RAT appear to not be in-line with where the blast of relative airflow / ram air would come from ........ the nose of the F-4.

The RAT on the F-4 appears to me to be positioned sideways as though it is pointing towards the left wingtip instead of the F-4's nose. However, I understand that perhaps it was in the transition of being stowed away when the photo was taken and that it might rotate about 90 degrees while retracting. Just an observation. Not a big deal. Big grin


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Starlionblue
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RE: Propeller As A Generator (Gimli Glider)

Wed May 05, 2004 3:06 am

I was actually curious about how the angle of the prop blades on the RAT appear to not be in-line with where the blast of relative airflow / ram air would come from ........ the nose of the F-4.

I'm not entirely sure, but the airflow is probably going slightly towards the centre in that location. Same reason that tailmounted engines are toed out.

Also, it probably whirrs about fast enough even with a slight alignment imperfection, and this position was the best compromise between space saving and power generation.

"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
chdmcmanus
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RE: Propeller As A Generator (Gimli Glider)

Wed May 05, 2004 5:00 am

Looks like an illusion with the photo to me, the red section looks to be the aft motor, not the prop spinner, in which case the RAT is indeed parallel with the airflow.

ChD
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Mr Spaceman
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RE: Propeller As A Generator (Gimli Glider)

Wed May 05, 2004 5:26 am

Hi guys.

>> Starlionblue, I understand what you're saying, however, I believe Chdmcmanus is on to something! Big grin

I automatically assumed that the red part was the RAT's prop spinner. Now that I'm looking at it as if the red part was the aft motor, it now looks perfecly alligned with a small black spinner.

Good eye Chdmcmanus.  Big thumbs up I believe I was being tricked by an illusion!  Laugh out loud


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Starlionblue
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RE: Propeller As A Generator (Gimli Glider)

Wed May 05, 2004 6:41 am

I will align myself with the consensus here  Big grin I agree.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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