flyboyseven
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747-200 Gear Extention

Sun Dec 18, 2011 7:07 am

I just found this video. In it, a 742 pilot attaches a camera to the nose-gear. The picture is sped up, and it makes quite a cool video.

http://www.youtube.com/watch?v=6Du513WwUmg&feature=related

The question I have is that at one point in the movie, the nose-gear is extended, but the mains are not. It only occurs for a few seconds at around 2:20, but there is another video "Belly of the Beast" that is just an extended version of the first video with an even more obnoxious song that shows it going on for quite a while, seemingly tens of minutes.

Can the 747 extend just the nose-gear? My understanding was that it could not, and I cannot think of a good reason to be able to do that. I thought that the large handle to the right of the center console was the control for the gear.


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Starlionblue
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 7:38 am

I don't see what you see. At around 2:20 the body gear doors open to make way for the retracing body gear. Then the nose gear starts retracting before the mains start to retract.

In "The Belly of the Beast" (https://www.youtube.com/watch?v=_DcoVBj7pyU&feature=related) this occurs around 2:30.



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AJ
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 7:48 am

I don't think that's the original:
http://youtu.be/_DcoVBj7pyU

He did a 'making of' video that showed configuring the landing gear to extend/retract the nose gear independently of the mains.
 
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 7:49 am

 
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Starlionblue
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 8:58 am

Aaaaaaaaaaaaaaaaaaah. I see it now.

So the pilots used the alternate gear extension, which has individual controls for each strut.

[Edited 2011-12-18 01:01:19]
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CCA
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 10:45 am

ALT GEAR EXTEND switches just left of center.


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[Edited 2011-12-18 02:47:41]
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DocLightning
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RE: 747-200 Gear Extention

Sun Dec 18, 2011 8:05 pm

Quoting Starlionblue (Reply 1):
I don't see what you see.

The very first scene shows you a view of the belly of a 747 in flight with the gear up. Except the camera is mounted on the NLG so the NLG has to be down.

Quoting Starlionblue (Reply 4):
So the pilots used the alternate gear extension, which has individual controls for each strut.

I'm assuming they would have had to clear this with the company before doing it. How difficult would that be?
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tb727
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RE: 747-200 Gear Extention

Mon Dec 19, 2011 12:16 am

Quoting DocLightning (Reply 6):
I'm assuming they would have had to clear this with the company before doing it. How difficult would that be?

Better to beg for forgiveness than ask for permission on that one. I was looking at this very camera yesterday...hmmm...
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Fabo
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RE: 747-200 Gear Extention

Mon Dec 19, 2011 10:25 pm

Quoting tb727 (Reply 7):
Better to beg for forgiveness than ask for permission on that one.

with the drag penalty... and associated fuel penalty...

I personally guess it would be easier to get a permission from marketing or whatnot if you know who and how to impress, rather than feel the wrath of bean counters that tell you this many thousand dollars of fuel was wasted...

but that is just my guess.
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tb727
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RE: 747-200 Gear Extention

Tue Dec 20, 2011 2:40 am

Quoting Fabo (Reply 8):
with the drag penalty... and associated fuel penalty...

I personally guess it would be easier to get a permission from marketing or whatnot if you know who and how to impress, rather than feel the wrath of bean counters that tell you this many thousand dollars of fuel was wasted...

but that is just my guess.

That's the problem, the bean counters, we all know they aren't any fun. We would never see cool videos like this if it was up to them!  
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gunsontheroof
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RE: 747-200 Gear Extention

Tue Dec 20, 2011 6:05 am

Quoting Fabo (Reply 8):
with the drag penalty... and associated fuel penalty...

Probably why there isn't very much in-flight footage on this video. They probably dropped the NLG for a few minutes to get a shot and called it good there.
 
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RE: 747-200 Gear Extention

Tue Dec 20, 2011 11:58 am

Quoting Gunsontheroof (Reply 10):
Probably why there isn't very much in-flight footage on this video. They probably dropped the NLG for a few minutes to get a shot and called it good there.

Curios. Is there a way to retract the gear after manual extension? I was under impression there was not, at least on certain types, but I am not familiar enough with the 747.

Quoting tb727 (Reply 9):
That's the problem, the bean counters, we all know they aren't any fun. We would never see cool videos like this if it was up to them!  

Well true that. But if you had the paper from say Marketing I could see them reasoning that obviously those guys calculated the marketing benefit big enough... And I know that marketing for one are open for some crazy ideas if you know how to talk to them. This one was fully sponsored by SkyEurope and was used for marketing purposes up to the demise.


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767eng
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RE: 747-200 Gear Extention

Tue Dec 20, 2011 12:32 pm

I guess with a freighter you can get away with just cable tying a camera to the nose gear!

Great video though, very impressed with the camera quality given the way its held on.
 
tdscanuck
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RE: 747-200 Gear Extention

Tue Dec 20, 2011 2:34 pm

Quoting Fabo (Reply 11):
Curios. Is there a way to retract the gear after manual extension?

I'm not sure about the 747-200 but, on some aircraft, if you have hydraulic power and command the gear up it should come up even if you manually extended it.

Tom.
 
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Jetlagged
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RE: 747-200 Gear Extention

Wed Dec 21, 2011 12:47 am

Quoting Fabo (Reply 11):
Curios. Is there a way to retract the gear after manual extension? I was under impression there was not, at least on certain types, but I am not familiar enough with the 747.

Manual extension doesn't compromise the normal hydraulics, it's just a means of releasing the uplocks so the gear falls under its own weight. So you could manually extend the gear (with the landing gear lever in the OFF position), position the landing gear in the DOWN position to pressurise the system and close the gear doors, then retract as normal. You might be able to do this purely by selecting the gear lever to UP, but I wouldn't want to risk that on a 747. You'd want to be sure the gear was fully pressurised so the doors fully open for retraction and the main gear trucks are properly tilted to fit in the wheel wells.
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AA737-823
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RE: 747-200 Gear Extention

Sun Dec 25, 2011 9:31 am

Quoting Jetlagged (Reply 14):
Manual extension doesn't compromise the normal hydraulics, it's just a means of releasing the uplocks so the gear falls under its own weight. So you could manually extend the gear (with the landing gear lever in the OFF position), position the landing gear in the DOWN position to pressurise the system and close the gear doors, then retract as normal. You might be able to do this purely by selecting the gear lever to UP, but I wouldn't want to risk that on a 747. You'd want to be sure the gear was fully pressurised so the doors fully open for retraction and the main gear trucks are properly tilted to fit in the wheel wells.

Indeed; the alternate extension won't work with the lever in the UP position, as they're still powered UP.

But yes, you can go straight from free fall to up- the sequencing valves wont let the strut move until the doors are in place anyhow.

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