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Propeller As A Generator (Gimli Glider)  
User currently offlineYousef727 From Denmark, joined Apr 2004, 22 posts, RR: 0
Posted (9 years 11 months 2 weeks 6 days 13 hours ago) and read 1781 times:

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.


Aviation all the way.......
14 replies: All unread, jump to last
 
User currently offlineAAR90 From United States of America, joined Jan 2000, 3451 posts, RR: 47
Reply 1, posted (9 years 11 months 2 weeks 6 days 13 hours ago) and read 1759 times:

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.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineQantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 26
Reply 2, posted (9 years 11 months 2 weeks 6 days 11 hours ago) and read 1678 times:

Try this...

Cheers,
QantasA332


User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 3, posted (9 years 11 months 2 weeks 6 days 7 hours ago) and read 1621 times:

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?


View Large View Medium
Click here for bigger photo!

Photo © Roel Reijne




Chris  Smile



"Just a minute while I re-invent myself"
User currently offlineCPH-R From Denmark, joined May 2001, 5909 posts, RR: 3
Reply 4, posted (9 years 11 months 2 weeks 6 days 6 hours ago) and read 1607 times:

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!)


User currently offlineLiamksa From Australia, joined Oct 2001, 308 posts, RR: 0
Reply 5, posted (9 years 11 months 2 weeks 6 days 3 hours ago) and read 1574 times:

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).


User currently offlineMD11Engineer From Germany, joined Oct 2003, 13792 posts, RR: 63
Reply 6, posted (9 years 11 months 2 weeks 6 days 3 hours ago) and read 1569 times:

Actualy the A340 has a RAT as well.

Jan


User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 7, posted (9 years 11 months 2 weeks 6 days ago) and read 1536 times:

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



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineCPH-R From Denmark, joined May 2001, 5909 posts, RR: 3
Reply 8, posted (9 years 11 months 2 weeks 5 days 20 hours ago) and read 1503 times:

I know about the BA - but I think they managed to restart the engines.

User currently offlineBragi From Iceland, joined May 2001, 218 posts, RR: 0
Reply 9, posted (9 years 11 months 2 weeks 5 days 18 hours ago) and read 1478 times:

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



Muhammad Ali: "Superman don’t need no seat belt." Flight Attendant: "Superman don’t need no airplane, either."
User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 10, posted (9 years 11 months 2 weeks 5 days 14 hours ago) and read 1435 times:

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


Chris  Smile



"Just a minute while I re-invent myself"
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 11, posted (9 years 11 months 2 weeks 5 days 13 hours ago) and read 1429 times:

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."
User currently offlineChdmcmanus From United States of America, joined Mar 2001, 374 posts, RR: 2
Reply 12, posted (9 years 11 months 2 weeks 5 days 12 hours ago) and read 1408 times:

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



"Never trust a clean Crew Chief"
User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 13, posted (9 years 11 months 2 weeks 5 days 11 hours ago) and read 1403 times:

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


Chris  Smile



"Just a minute while I re-invent myself"
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 14, posted (9 years 11 months 2 weeks 5 days 10 hours ago) and read 1389 times:

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."
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