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xbraniffone
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737 Wheel Well

Sat Feb 25, 2006 5:24 am

Why was the 737 designed with no wheel well covers that close over the landing gear when retracted? When 737 fly overhead, you can see the wheels retracted against the belly of the plane.

Is there an engineer in the house that can answer this?

As far as I know, this is the only commercial Boeing product with this feature.
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jamesbuk
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RE: 737 Wheel Well

Sat Feb 25, 2006 5:31 am

Hi,
Im no engineer but i know the answer!. The reason Boeing didnt install the covers is because the cost to carry all the door the hydraulic pistons ETC outweighed the cost of just putting an aerodynamic cap on them. So thats what boeing did and its worked very well!!

Rgds --James--
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MrChips
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RE: 737 Wheel Well

Sat Feb 25, 2006 5:31 am

Quoting Xbraniffone (Thread starter):
Why was the 737 designed with no wheel well covers that close over the landing gear when retracted? When 737 fly overhead, you can see the wheels retracted against the belly of the plane.

You don't need to be an engineer to figure this one out - no gear doors reduces complexity and saves weight.

Landing gear doors require microswitches and a hydraulic or electric means of motion, all of which add a layer of complexity to the aircraft, not to mention weight. Quite simply, if you can do the job just as well without the doors, why put them in?
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OPNLguy
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RE: 737 Wheel Well

Sat Feb 25, 2006 5:32 am

This has been covered repeatedly (so feel free to search for a more-detailed discussion) but the simple answer is that doing it the way they did was the lesser of two evils.

Yes, there's a fuel penalty associated with the way they did it, but that was still cheaper than the cost designing and maintaining the stuff associated with enclosing the gear.

The 737 isn't the only aircraft like this, and I thing one of the RJ types as well as some bizjets also use the same design philosophy...

Cheers...
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nonfirm
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RE: 737 Wheel Well

Sat Feb 25, 2006 8:01 am

One less thing to break.
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whitehatter
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RE: 737 Wheel Well

Sun Feb 26, 2006 9:57 am

Quoting OPNLguy (Reply 3):
The 737 isn't the only aircraft like this, and I thing one of the RJ types as well as some bizjets also use the same design philosophy...

Pretty sure the Embraers are the same. It did raise a few eyebrows in the late 1960s but Boeing was poved right. No point having what you don't actually need.
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2H4
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RE: 737 Wheel Well

Sun Feb 26, 2006 10:26 am




Quoting WhiteHatter (Reply 5):
No point having what you don't actually need.

A la nosewheel brakes...




2H4


Intentionally Left Blank
 
jetstar
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RE: 737 Wheel Well

Sun Feb 26, 2006 10:30 am

The early 737’s had an inflatable ring around the outer ring of the landing gear wheel well. This ring would inflate and create a better aerodynamic seal when the landing gear was retracted.

This inflatable ring proved to be more of a headache than what is was worth and was eliminated and also removed from these airplanes if the operator so desired.

Considering how much extra weight is carried if the 737’s had main landing gear doors and the associated mechanisms, its probably breaks out even with the slight amount of fuel needed to offset the drag from the exposed landing gear. The savings is from not having to maintain and overhaul the mechanism and hydraulic components over the life of the airplane.
 
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Starlionblue
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RE: 737 Wheel Well

Sun Feb 26, 2006 11:38 am

Quoting Jetstar (Reply 7):

Considering how much extra weight is carried if the 737�s had main landing gear doors and the associated mechanisms, its probably breaks out even with the slight amount of fuel needed to offset the drag from the exposed landing gear. The savings is from not having to maintain and overhaul the mechanism and hydraulic components over the life of the airplane.

There's also a space issue. All those doors and actuators would take up space.
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raffik
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RE: 737 Wheel Well

Fri Mar 03, 2006 10:24 am

If this was the case, why is this only applied to the 737 series? Why not save weight across the range- 777,767,747,757,717?
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joness0154
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RE: 737 Wheel Well

Fri Mar 03, 2006 10:40 am

Quoting Raffik (Reply 9):



If this was the case, why is this only applied to the 737 series? Why not save weight across the range- 777,767,747,757,717?

Well, I'm going to guess its beccause all the rest of them are newer designs or are long range widebody aircraft which need to be fuel efficient. The 737, as a domestic airliner, doesn't need to be as efficient as, say, a 777. Also the 717 was designed by MD. Just a guess though.
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Starlionblue
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RE: 737 Wheel Well

Fri Mar 03, 2006 10:49 am

Quoting Joness0154 (Reply 10):
Quoting Raffik (Reply 9):



If this was the case, why is this only applied to the 737 series? Why not save weight across the range- 777,767,747,757,717?

Well, I'm going to guess its beccause all the rest of them are newer designs or are long range widebody aircraft which need to be fuel efficient. The 737, as a domestic airliner, doesn't need to be as efficient as, say, a 777. Also the 717 was designed by MD. Just a guess though.

It's not just a weight issue, it's a space issue. Adding wheel well hatches to the 737 would taken space better needed for some other component. Most of the planes you list are larger.
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ilikeyyc
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RE: 737 Wheel Well

Sat Mar 04, 2006 8:09 am

Quoting Xbraniffone (Thread starter):
As far as I know, this is the only commercial Boeing product with this feature.

Negative. The Bombardier CRJ series have exposed wheels, just like the 737.

Also, a quick search of the phot DB shows that the ERJ series of RJs also have exposed wheels


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Buzz
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RE: 737 Wheel Well

Sat Mar 04, 2006 2:33 pm

Hi XBranniffone,Buzz here. I've got a booklet describing the New Boeing 737-100 (from the mid 60's) and it addresses this issue, as well as how common the New 737-100 is with the 727.
They describe the penalty of having landing gear doors (like the 727) and determined that it would exact a 4% penalty between the extra weight of the doors, mechanism, wires and switches, extra body thickness. Then they determined that the inflatable ring and nice smooth hubcap would only exact a 3% penalty in drag. So the trade-off is a little less machinery, a little more drag here but less drag over-all.

The 737-100 was made for 250 mile legs, so it'll be a slower, lower altitude flight. All the longer-range Boeings seem to have more attention paid to drag reduction - you've been able to buy winglets for several years.

And they were happy to point out "eye-level maintenence" - that open wheel well (on the ground at least) is a good place to put all sorts of goodies.

Yes, the inflatable ring is long gone. In it's place is a series of stiff rubber blades that pretty much never need attention.

Does that make more sense?
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jeffry747
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RE: 737 Wheel Well

Sun Mar 05, 2006 12:18 am

Quoting Raffik (Reply 9):
777,767,747,757

Not only are these larger aircraft with longer ranges, but they have more than one set of wheels on each set of bogies (except the nose gear of course). A two wheel bogie closes its well much more efficiently than a four wheeler. With a four wheel bogie there would be large drag-inducing gaps in the well if it were left open, thus the reason for covering it.
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HAWK21M
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RE: 737 Wheel Well

Mon Mar 27, 2006 2:18 pm

Considering the Weight saved & purpose served.An effective system.Also the B737s were built to land on unpaved surfaces too.Dumping of as much weight would be welcomed.
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citationjet
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RE: 737 Wheel Well

Thu Mar 30, 2006 11:49 am

Quoting Ilikeyyc (Reply 12):
Quoting Xbraniffone (Thread starter):
As far as I know, this is the only commercial Boeing product with this feature.

Negative. The Bombardier CRJ series have exposed wheels, just like the 737.

Ilikeyyc, I think you misunderstood Xbraniffone's response.
He is saying that the 737 is the only Boeing aircraft with this feature.
He is not saying that the 737 is the only aircraft with this feature.
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ilikeyyc
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RE: 737 Wheel Well

Fri Mar 31, 2006 8:58 am

Quoting CitationJet (Reply 16):
Ilikeyyc, I think you misunderstood Xbraniffone's response.
He is saying that the 737 is the only Boeing aircraft with this feature.
He is not saying that the 737 is the only aircraft with this feature.

Oops. He did say "Boeing". My bad.
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HAWK21M
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RE: 737 Wheel Well

Fri Mar 31, 2006 11:36 pm

http://www.b737.org.uk/wheelwellboth.jpg
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MEL
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jamesbuk
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RE: 737 Wheel Well

Fri Mar 31, 2006 11:51 pm

Hawk21M that is one wicked picure, really shows off the detail of the MLG bay!!

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