When the main wheels on the 737 are retracted are they still exposed to the outside of the plane? I didn't think so, but the above picture sort of looks like it in both the -200 and the -300. If they aren't, what are the black circles under the body?
KLASM83 From United States of America, joined Aug 2005, 584 posts, RR: 0 Reply 1, posted (4 years 8 months 2 days 9 hours ago) and read 9316 times:
It is a cool pic, is it not? . As I remember, the 73's do not come with a MLG door, saving on weight, thus making it so that the tires make an aerodynamic seal with the fuselage. Hope that helps!
->Edited for spelling. And Grammar. This post talk gooder now.
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 3, posted (4 years 8 months 2 days 9 hours ago) and read 9285 times:
Quoting SuseJ772 (Thread starter): When the main wheels on the 737 are retracted are they still exposed to the outside of the plane? I didn't think so, but the above picture sort of looks like it in both the -200 and the -300. If they aren't, what are the black circles under the body?
That would be the tires. They lie flush with the fuselage of the aircraft when retracted, and there is an aerodynamic "hubcap" in the middle of the outboard wheel to minimize drag. It saves on weight and landing gear system complexity. IIRC, there is even a piece of rubber trim inside the wheel well to keep the seal tight once the gear are retracted.
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 5, posted (4 years 8 months 2 days 9 hours ago) and read 9243 times:
Quoting SuseJ772 (Reply 4): This would seem to be real prone to problems.
I can't believe I never knew this. I guess you learn something new everyday.
Less prone to trouble than an additional hydraulically actuated door that has to be closed when the gear is both retracted and extended (not to mention the weight of the additional aluminum in the door, additional hydraulic tubing, electronic sequencers, etc. etc.)
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
September11 From United States of America, joined May 2004, 3623 posts, RR: 23 Reply 7, posted (4 years 8 months 2 days 9 hours ago) and read 9132 times:
RoseFlyer From United States of America, joined Feb 2004, 8746 posts, RR: 52 Reply 8, posted (4 years 8 months 2 days 9 hours ago) and read 9020 times:
Quoting KLASM83 (Reply 1): It is a cool pic, is it not? . As I remember, the 73's do not come with a MLG door, saving on weight, thus making it so that the tires make an aerodynamic seal with the fuselage. Hope that helps!
Just a correction, but there are main landing gear doors. They just don't cover the tire and wheel. The main landing gear doors cover the strut as it moves into the wing/body/wing to body fairing.
Quoting KELPkid (Reply 5): (not to mention the weight of the additional aluminum in the door, additional hydraulic tubing, electronic sequencers, etc. etc.)
You overestimate the 737. There aren't electronic sequencers. It's manually driven by cables, solenoids and a transfer valve.
If you have never designed an airplane part before, let the real designers do the work!
113312 From United States of America, joined Apr 2005, 537 posts, RR: 1 Reply 11, posted (4 years 8 months 2 days 8 hours ago) and read 8904 times:
When the B737 first went into service, it had an inflatable skirt to seal the main gear wells after the gear was retracted. It was later decided that this was too complex and not worth the small drag advantage. From then on, the 737 series has had a simple exposed wheel with a smooth hubcap on the outside wheel.
Quoting SpeedBirdA380 (Reply 12): Why is it only a few aircraft that do this and not all of them?
A "real" gear door will result in better aerodynamics. But it will be heavier and more complex. For a short range aircraft a small cruise aerodynamic penalty may be outweigh by the extra weight and complexity.
OTOH, given that the range of the 737 has increased rather significantly since the early days, I'd not be at all surprised to see its replacement have "real" gear doors.
United787 From United States of America, joined May 2005, 2346 posts, RR: 1 Reply 14, posted (4 years 8 months 2 days 7 hours ago) and read 8565 times:
Quoting SuseJ772 (Reply 4): I can't believe I never knew this. I guess you learn something new everyday.
I saw the same pic and wondered why I never knew that either.
Although the more I look at the picture, the odder it looks...gives another meaning to hanging dirty...too exposed...but some underpants on that thing for pete's sake...
DocLightning From United States of America, joined Nov 2005, 16824 posts, RR: 57 Reply 15, posted (4 years 8 months 2 days 6 hours ago) and read 8427 times:
Quoting United787 (Reply 14):
Although the more I look at the picture, the odder it looks...gives another meaning to hanging dirty...too exposed...but some underpants on that thing for pete's sake...
And so being endowed with the rather filthy and yet amusing organ that occupies my skull, I immediately flashed to mental images of various retractable...
AV8orWALK From United States of America, joined Nov 2006, 174 posts, RR: 0 Reply 16, posted (4 years 8 months 2 days 5 hours ago) and read 8277 times:
I honestly can't believe that I've looked at THOUSANDS of pictures of 737's on a.net, let alone worked on every a/c in WN's fleet when I was a FA 6 years ago, and failed to realize those were the tires themselves, not a bay door.
Wow, that's the one thing I've learned today!
Cheers!
Drew MCO
The safest place to be in an airplane crash is on the ground.
Pilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 10 Reply 17, posted (4 years 8 months 2 days 5 hours ago) and read 8190 times:
Quoting SuseJ772 (Reply 4): This would seem to be real prone to problems.
Really? So why is the 737 the most popular commercial aircraft in the world?
AA737-823 From United States of America, joined Mar 2000, 5340 posts, RR: 11 Reply 18, posted (4 years 8 months 2 days 1 hour ago) and read 8026 times:
Quoting AV8orWALK (Reply 16): let alone worked on every a/c in WN's fleet
Totally thought you were about to say you'd been a WN mechanic and never noticed a lack of doors.
Glad that's not the case!!!!! Lol.
Quoting Pilotboi (Reply 17): Really? So why is the 737 the most popular commercial aircraft in the world?
Calm down- the most popular aircraft in the world isn't without design flaw (trust me, I work on them). But the gear door thing is really a non-issue.
AND, folks, it makes things WAY more convenient and even SAFE when you're servicing things in the wheel well. On other aircraft, you have to drop the doors to service those systems. I've had coworkers (in the past) been given concussions when they didn't hear the warning that the doors were about to drop open. No exaggeration.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 19, posted (4 years 8 months 1 day 19 hours ago) and read 7864 times:
Lower view.
The Hub cap present helps reduce drag by providing a smoother surface.
The b737 has got Three Doors per MLG....Inner/outer & Middle.These doors are attached to the strut directly or via linkage depending on the door & move with it.
Blackbird From , joined Dec 1969, posts, RR: Reply 20, posted (4 years 8 months 1 day 13 hours ago) and read 7766 times:
From what I remember the drag-penalty of the gears being exposed was actually less than the weight-penalty of having doors that covered the whole landing gear.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 21, posted (4 years 8 months 1 day 12 hours ago) and read 7739 times:
Quoting Blackbird (Reply 20): From what I remember the drag-penalty of the gears being exposed was actually less than the weight-penalty of having doors that covered the whole landing gear.
Any idea,what caused this......I thought Weight saving & simple mechanism overruled complicative sequencing & added weight.
G4Doc2004 From United States of America, joined Feb 2004, 123 posts, RR: 0 Reply 22, posted (4 years 8 months 1 day 9 hours ago) and read 7671 times:
The fastest business jet flying right now is the Citation X (Mach .92) and it's wheels are exposed a-la the B-737 as well. When retracted, the edge of the tire sits just below the fairing.
"Failure to prepare is preparing to fail"--Benjamin Franklin
RoseFlyer - look at the photo in Hawk's post. I think you were right on the issue of extending the wheel well on the thread in CivAv on the GTF. While there might be room for a gain of a couple of inches, I don't think it would be enough to overcome the issues faced by a longer LG strut because of the keel structure.
FlyASAGuy2005 From United States of America, joined Sep 2007, 6520 posts, RR: 11 Reply 24, posted (4 years 8 months 1 day 8 hours ago) and read 7638 times:
Didn't hear brush seals mentioned.
I know there is a specific purpose (hence the name brush SEAL) but what exactly? I first noticed it working for a regional on the CRJs. I asked a mech and he gave me a pretty detailed response but this was 2 years ago so I don't really remember .
CAM2:"Lightning coming out of that one." CAM1: "What?"
25 Starlionblue: Bigger aircraft have more space for a door and the related mechanism. Also, widebodies have big bogies, meaning it's not a simple round shape in a ro
27 Pilotpip: The Global Express has exposed mains as well. BTW, on Embraers the brushes can't be deferred.
28 HAWK21M: Whats the reason stated? On the B737,there is a tolerance to the amount of wear permitted on the rubber seals. regds MEL
29 2H4: Some airplanes leave their main gear hanging out in the wind even after they're retracted: 2H4
30 Rwessel: True, although I'm almost tempted to make a distinction based on why you move the gear. In those cases it's not for drag reduction in flight, rather
31 2H4: And to get out of the way of the radar, sure. I was just pointing out some fun and quirky exceptions to the usual objective of retractable landing ge
32 JetMech: This is what happens when you do land on water with the wheels extended ! Regards, JetMech
33 2H4: That guy just needs more practice. Here's what you can do if you've got proper technique: 2H4
34 JetMech: True. I bet the plane was not the only thing hung out to dry after that incident! I remember those pictures! I think there was great debate at the ti
35 2H4: No, I don't even recall that discussion. I know what those airplanes are doing can be done, though, and I can't imagine someone would go to such Phot
36 JetMech: Fair enough. A little bit of Googling and Youtubing brought up this. Regards, JetMech
37 Don81603: Holy ***!!! Talk about no room for error! This has to be a pucker factor of at least 250. Thanks for sharing though. .
38 KELPkid: Here's one for you all to consider (and I ask this innocently, since I'm a single-engine piston GA pilot, and darn near 100% of the time, we'd be able
39 HAWK21M: On the -NGs the "frangible fitting" will avoid that gear to retract.If its a tire burst,to protect the wheel well components. regds MEL
40 MD11Engineer: To elaborate, it is a thumbsize piece of pipe sticking outfrom the outer edge of each main wheel well, which is close at one end and with the other e
41 Mender: When the gear retracts the pressure to the retract actuator applies the brakes. This is known as retract braking. The frangible fitting only prevents
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. As I remember, the 73's do not come with a MLG door, saving on weight, thus making it so that the tires make an aerodynamic seal with the fuselage. Hope that helps!
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