Why does the Boeing 737 not have any landing-gear doors?
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- Опубликовано: 20 июн 2024
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Have you ever seen a Boeing 737 take off and noticed that the wheels are still visible after the gear has been retracted?
In this video I will tell you all about the reason for this, the aerodynamic impact and some protection systems that you might not know about.
Enjoy!
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Never ask a pilot a question unless you have plenty of time.
Precisely
@Vergolia Elcompa People at chernobyl didn't ask enough questions then
this comment is cute asf tbh
True, we get carried away, sorry.
Haha the last time I did, I got like don't know we don't design 'em, now please get off my plane so we can get the next flight prepared...
I never knew I'd be so interested in hearing an answer to a question I never wondered about.
lmao
This is because most things are fascinating, you just need a great teacher to make them accessible
There where he's very strong, is the moment he told us, right at the begining, the reason why they decider to take this solution. And the most of us pursuit the lesson watching the entire video, because of the torrent of precisions he give us. Master.
It always bugged me. In flight simulators, I fly the 737-800 most of the time, and I always hated seeing the gear.
@@tomhutchins7495amen to this
I've been lying awake at night for more than a year asking myself this question. Now finally you have answered it.
bc it doesnt FUCKING NEED A LANDING GEAR DOOR
ITS SOOO SIMPLE
ikrrr
My uncle was one of the primary design engineers for one of the planes in the 737 family. I believe it was mid to late 70's. I love to see some of these quirky ideas they came up with!
Thank you. I’m a medically retired airline pilot, nearly 15 years since I left the cockpit. Thanks you for the good info. It’s hard to believe but I had forgotten some of what you covered. It’s amazing how quickly ones mid can dump information. Keep up answering some of these more common questions and being a great ambassador for pilots.
yep a great ambassador for boeings nose up nose down nose up nose down down down do....... plain
@@mokuzu993 he does a good job for the forest clearing A320 also.
@@mokuzu993 well when you fit new larger engines you alter the weight balance of the aircraft In the case of the 737 Max it wants to go more up so you correct that tendency with elevator pitch What Boeing did not do was execute this properly Be failed to insist that pilots were trained in this ; how it worked ; how to recognise and system failure and how to manually overcome any failure off the pitch control system. That failure to explain and train cost 2 aircraft and 350 lives .And if another 737 Max crashes in the next few years for any reason it risks the very existence of Boeing .potentially. It used to be "if it is not Boeing I am not going " -now it risks becoming "If it is Boeing I am very definitely not going " !!!
I'm a pecuniarily retired pilot and i can hardly remember the 12 things he told us to do to land a 737. I still remember the radio, oh and the full flaps, but what about the seat belt sign?
If you don't use it, you lose it
Unreal the amount of hoses and exposed stuff inside of that wheelwell.
Like maintenance renegade said, the intire landing gear and supporting systems like anti-skid valves ect. and a large area of the hydraulic system is accesed from the wheel well. Absolute bitch to work in tho
@Maintenance Renegade Dunno how it is on the 737 since I only worked on the 707 in training but I'm quite short (5"8) and some parts are hard to reach for me ;D. Especially the walking beam.
@Maintenance Renegade When the Aircraft is on the ground the landing gear tire is no longer covering the wheel well opening giving complete access all components. The original design engineers missed this feature and added a serving door for hydraulics (probably for an external hydraulic mule) which was generally never used and subsequently deleted. Debris generally enters the wheels wells when the gear is down (unusually on landing and thrust reversers applied). The perimeter seals mitigate noise and aerodynamic drag. The original bag seal material was attacked by residual hydraulic fluid residue and change order was issued correcting the problem with the present system.
I know they often have exposed equipment in military aircraft because of ease of access in case of emergency.
Looks scary as f*ck lol
20 years ago, on a 737 flight, the pilot notified passengers to buckle up, extreme turbulence ahead. He said he was going to try to fly to avoid it. The plane went into a roller coaster ride from hell as the pilot took the plane straight up, to where we were almost flying in the stratosphere, then suddenly turning into a speeding nose dive. This went on for almost half an hour - straight up, straight down. Passengers were terrified & screaming. I was new to flying but the guy sitting next to me flew often & said this was not a turbulence issue - it's something else. He was scared. The plane finally leveled out & we landed shortly at Newark. But my legs were like rubber, I was so scared & stressed I could barely walk. After deboarding, I was waiting at the gate for a friend to pick me up & overheard our flight attendants nervously joking & one say, "Thank God *pilot name* knew what to do - I wasn't up for a belly landing today!" Found out later, from a small plane pilot friend, that the landing gear was likely not working properly & the pilot was maneuvering/pitching the plane up & down to get them to drop. All was forgiven :)
Wow, good thing no one got severely hurt in the flight
Holy yeah, that would scare the life out of me, but I'd pick that over belly scraping a fuel-filled tube at jet speeds.
See the crashes in 2018-2019 ?
Sounds like many of my skydiving flights.
Should told it was to get the landing gear out, less scary than doing stuff like that for no reason.
Was on an plane who was able to retract the gear.
We was worried about getting it out and was told it just fell out then released but needed hydraulic to retract.
That's what I love about engineering--they found a solution to their problem that was as good as it needed to be but not more. I'm sure the small cost in drag was compensated for in weight (fuel $$) and complexity (maintenance and manufacturing $$)
In the 1980s (actually in the electronics industry, but exactly the same principle), I used to be the one who said things like, "Get rid of the doors".
Everyone thinks I'm completely mad. "We need doors" "Gotta have doors" "Ben's spent two years working on the doors, we can't get rid of his doors" "Get this guy outta here, he wants us to get rid of the doors!".
I persist: "Seriously, run the calculations without the doors. I think they'll work out. And with no doors, we won't have to solve the problems with the doors".
The calculations do work out. Ben loses respect. I gain it.
Heehee yX-D! But it's interesting even tho it could be said in two sentences y:-D
Exactly...! Designing has the biggest challenge up ahead which is not about the best materials and best performances to get out, but the best compromise. That's key to success!
Worked on many 737's & was aware of the main landing gear brakes & hydraulic systems but I learned so much more from this video.
I mostly did APU overhauls, hydraulic troubleshooting, slat, flap & rudder checks & maintenance & on wing engine checks (fan & last stage t-wheel). Fun stuff!
I still look anytime I hear a plane flying.😊👍
Very cool to see how different manufacturers tackle the same problems. I work on CRJ-200 and -900 and they have brushes instead of those flaps lining the wheel bays. Also they have "wheel bins" which surround the gear inside to protect structure and components.
Thank you, I have often wondered about this, but did not realize that even the most recent 737s use this system. Very used to seeing the 737-400s, but seldom anything more recent than that. Your videos are hugely informative - thank you.
Yep, even the latest MAX-series has it.
@@sprucegoose6933 The 737 MAX planes on ethiopian airlines and lion air crashes MCAS is programed incorrect.
Just before getting on this presentation video, I watched a video of inside the well cam of a B737 in a take off. The moment the landing gear moved to come inside the well, the brakes were applied on the fast moving wheels stopping them instantly before they got inside the wheel well.
I was pleased to see you pointed out the same in your presentation.
Good eye. A landing gear hydraulic line that is pressurized only when the gear handle is in the "UP" position, during gear retraction, is also connected to apply the brakes. After the gear is completely retracted, the flight crew moves the handle to the "OFF" position, removing pressure from the retract cylinders and wheel brakes. The gear is mechanically locked in the up position until the handle is moved from "OFF" to "DOWN," at which point the gear extend side of the hydraulic actuators are pressurized. After the gear reaches the fully extended position, it is held in that place by both mechanical locks and hydraulic pressure.
@@Hopeless_and_Forlorn Thank you so much for sharing this information. I am amazed and I really appreciate your care. :)
This is one of the many reason why you should NEVER take for granted seeing these beautiful machines fly overhead!!
I love the look of the exposed tires beneath the 737. Obviously, it’s all about function, but it’s still a function that gives a distinctive, maybe more rugged appearance to the plane (like having a spare tire mounted outside of a SUV).
Haha I love that analogy
Thank you. Having flown planes for over 50 years, I appreciate your videos and organized presentations.
Hi Carol: Have you written up your story anywhere? I'm interested!
I was in the Air Force, and a lowly First Officer in the KC-135. Heading toward Beale AFB, a 737 flew over the top of us, on the way to Sacramento. I helpfully told him that his main landing gear doors were missing. I thought the laughing would never quit.
LOL
One of the first things I learned when I first joined Air Traffic Control was about the Boeing 737. It was built to be "self-sufficient" at smaller airfields. That meant that it could start it's own engines using it's on-board APU (Auxiliary Power Unit), it has it's own on-board mechanically operated stairs so it doesn't need airfield steps or the start up truck just the fuelling bowser. I think it can or used to be able to, power back off the stand without the use of a tug. A very forward looking design that has lasted decades, that's why it's still being used albeit in more modern guises. Another airliners that had their own stairs were the DC-9, the BAC 1-11 and the Boeing 727 if I"m not mistaken, all at the back of the aircraft between the rear engines. My friend was on a flight from London to Madrid once on a DC-9 when the back door/air stair seal blew causing an explosive decompression of the cabin. They landed safely but very shaken. Another good reason to keep your seat belt loosely fastened in flight when you're not moving around the cabin.
I don't know why ppl fret so much to wear their sear belts. Loosely fastened should be the way at all times. Ppl unlock their seatbelts the moment the seat belt sign is off, as if they are gonna get paid for it
@@coronarahul Same reason they don’t get covid vaccinated…
It’s outrageous! I mean my seatbelt has been locked on every airliner since iI did flight training and learned what clear air turbulence was…
It landed in St Louis, they were stolen.
The enginer was smoking pot the day he designed wheel wells
boat show 😂😂😂😂 the lou do get crazy.
I thought they did that so they can save money...
😂
or Rome/Rio/Liverpool/Jo'burg/Kolkata/KL?
I'm scared to ask for he long explanation.
Great answers and explanations love the way you go into so much detail, I’m not a pilot or have anything to do with working on aircraft but the understanding I get from your videos are great, keep up the good work.
Thanks for the video. I've heard that sound of the snubbers stopping the nose wheel spinning, after it was retracted, just never knew what it was. :)
Great! Now you know.
Never noticed it, though I do notice the Airbus "dogs".
I live nearest from the Airport in my city, and some days ago i saw an 737 and i was thinking why the wheels have not doors, thanks a lot for explain it! Im from Silao Guanajuato México.
Pretty amazing to take this chance at a time where computer simulation was a dream. They certainly had to spend numerous hours in wind tunnel to validate this design, to avoid drag and awful whistling noise, making the plane unusable. They saved weight and landing gear complexity, all my respect to the design engineers.
saju mathew
I discovered this channel a week ago and it clears all my doubts,and am very keen to watch the vedios,thank you Captain....
Wow Petter very detailed explanation... amazing video!
Thanks so much!
Thank YOU for your support!
Glad I stumbled on this. Thank you for in-depth explanation. Very interesting!
Great to hear! I’m happy you are here.
I am so pleased that I read this, because I was thinking about buying o e of these to fly the 3 miles to work each day. But the hub caps have put me off the purchase. Yobs nick hubcaps down my road.
This is not the in-depth explanation. It is the executive summary
Well done for taking time away from your off duty moments and creating these videos. Very much appreciated.
I just found your channel but your videos are extremely informative and comprehensive and you get sraight to the point. I love videos like these. I hope you continue making videos as you're a role model for many young aviation enthusiasts like me :D
Excellent piece, just like the rest of your videos. Thank you SO much for doing these! As a total airplane junky, I love this sort of easily digestible education.
Excellent explanation and very informative as always. Thank you
Thank you! It’s really nice to hear!
Outstanding. You explained everything in an easy to comprehend way. Thank you.
Dude!! I am so loving this video series Answered so many questions I have always wanted to ask!!!
Very informative for any flight student or otherwise, GOOD Share......God Bless
Thank you! Im glad you like my little videos.
I like you very much. You offer very good and clear explanations. Keep feeding us with more videos. Big thanks to you!
Thank you! I will do my best!
@@MentourPilot No doubt by now someone has suggested this, but I'll make the point anyhow. For instance, much of Northern Canada airstrips such as in the Yukon or NWT have been mostly gravel strips and the 737 was able to land and take off from these strips with only slight modifications to add rock deflection above the nose wheel. I suggest that the 737 aircraft was one of Boeings best short field models ever produced.
Amazing video very educational. Unbelievable how many hydraulic lines inside that wheel well.
Beautifully explained.....Good Job
Thank you Yasir!
Very funny. Great details and your straight face. That shot of all the tubes in the wheel well is damn scarry. Appreciate the inserted very clear pictures. Every followup question clearly answered. Love these super technical trainings. OH.... do captains routinely know all this or did your research this topic?
I'll make certain that I watch all of your videos before I ask any more questions! No manual brakes needed! Thanks Mentour 360!
Enjoyed your easy to follow presentation. You’re the best I’ve seen thus far. Learning a lot from The Bahamas. God bless and thank you.
Do more of this untouched stuff in aviation more than the popular stuff. As always the video was absolutely fantastic just like you. No suggeations on quality of vids coz its best :)
Thank you!! I’m so glad you like them! I will continue!
Thank you very much for your service, Captain Petter!
Thank YOU for supporting the channel my friend.
I was always wondered why the 737's main gear was exposed. Now this video answers me. Thank you!
Love these video's. I wish they had been about when I was still young enough for flight training. Thanks Peter. Keep up the good work
Speaking of the 727, I remember many years ago I flew first class in an old 727. Since the engines were way at the back of the plane, the take off was the quietest I've ever experienced.
Yep, great for the people in the front, less great in the back :)
Yeah, those old engines were noisy af! lol
It's quiet for those in the front of the plane, but definitely not for those at the back of the plane or on the ground outside. In fact, it seems that tail-mounted engines are MUCH louder than their wing-mounted counterparts, even ones that appear to be the same size and from the same time period. I wonder if there's a scientific explanation for why that is the case, perhaps having to do with the sound waves bouncing off each other and amplifying. Could this explanation be a future Mentour Pilot video?
Glenn, the main reason tail-mounted engines seem louder is because they are indeed louder -- they're earlier-generation engines. They were either turbojets or low-bypass turbofans.
JT8Ds... low bypass turbofans.
super
good presentation sir ... Pilot
Extremely detailed! Always asked myself that question, thanks for the answer!
Mr. Mentour Pilot, what is your name? This video brings me alive, I was an aircraft mech on the A7-B's during Vietnam. I was an AMH, structures mechanic, and good too. Boeing tech specs, OMG!!! Bring 'em on!!
Thank you for explaining this. I've see 737s fly over head so many times, and I've noticed that I could see the wheels, but didn't think it possible from an aerodynamic perspective. I thought maybe they painted black circles on the landing gear doors, but that didn't make any sense either.
Yes! And this is the reason.
I hope you liked the video!
If given the opportunity I would totally paint weird stuff on the bottom of a plane.
One extra step when changing the outboard tire/wheel assembly because of wheel fairing. Also wheel nuts are not visible on walk around inspection before flight. Not great. But it works.
Thank you for a wonderful explanation and going over the evolution of the various solutions incorporated over the years. Subscribed!
thank you for the explanation Mentour Pilot. I've been working in the ramp for 8 years now and I have this same question. Now I know the answer. Good job sir
Great video. You are good at explaining things.
Very well stated. Thank you for this information.
Thank YOU for supporting the channel!
I’m not a plane enthusiast but I cannot stop watching these clips.
Very well delivered info on very interesting subjects.
Good job.
you are now, if you watching a lot of these clips....
The landing gears on the C5 Galaxy is something, amazing to not hear of many problems with this setup.
Nice to see some video's about construction of an aircraft. That's a different approach.
Great to hear that you like them.
Another GREAT video Petter, thanks!
Thank you! I’m so happy that you guys seem to be enjoying these little videos.
Don't know how can 1.1k people dislike his video when he is explaining everything very clearly with images and videos.....!!
Really a hard working person..
I have the same question too. It s a simple clear explanation and it s about the reasons of the manufacture behind those design ideas , not his own personal opinion or something. What makes people unhappy, argue or complain?
Wow!!! I learned something I never even thought about. Thank you!!
Great video as usual. We call the Citation X the “Citation Ten” FYI.
As far as stuff entering the wheel well's when retracted, I'd be more concerned with stuff entering the well's when the gear is down during taxing or take off , like rain, slush, snow etc.
ROCKS and stuff thrown up from the tarmac!!
Or Stowaways.
I’ve been an avian nerd my whole life ! Thanks for your videos and briefings on how airplanes work ?
Fascinating. Growing up I lived under the landing pattern of the local airport. I found it interesting I could see the wheels.
Thanks mentour ..
Nice video.
Thank you!
You should read about the nose gear and the main gears of the space shuttle. On landing, there are pyro charges to make sure the gear doors open up. On one landing, one of the main tires blew while the shuttle was coming to the wheel stop. This happened only one time when landing at Kennedy Space Center.
A great explanation and it has really answered my question about the 737, thank you
You answer the question and answer every question related I would have asked regarding it.Bravo!Thank you for your knowledge and willingness to share Sir.
I love how you can make giving the answer “because that’s how the Boeing engine engineers design it” last 11+ minutes. Lol
Well in reality he is answering the question "Why did the Boeing engineers design is like that" which is much more interesting than what amounts to "because I said so"
You need to stretch the video beyond 10 minutes to put midroll ads in.
Tyre pressure : I am under the impression that it is around 200 psi. You mentioned 14 psi which is half of what I have in my car tyres.
He probably meant to say 14 atmospheres 🤔
@@jonathanmoreno1945 Thanks. :)
@@Amonginsanity 14 psi is maybe correct, you want a low pressure to have a good contact patch to the ground. Drag of the tyre is not a major concern here
@@guigui045 Sorry ... 14 psi is not a correct figure. The correct figure is 200 psi which is equivalent to 14 bars pressure.
Thanks for your comment though.
@@Amonginsanity yep, i've checked and the impact force of a landing building is mainly why theses have such high pressure. Thanks for correcting me ;)
I had been told by a friend who works at Boeing that the exposed wheels increase survivability in the event of a water landing. If you look at the at-rest angle of the Airbus in the Hudson River incident, you will see that the plane settles alarmingly low in the water very quickly. Simulations at Boeing have demonstrated that, in the same situation, the at-rest angle of a 737 would place the floor of the cabin 3 to 4 feet higher than the Airbus. This is, my friend tells me, because of the exposed wheels. I am glad you have taken the time to correct this misinformation. Now I don't feel so bad about sleeping with his wife.
Great info brother . Just finished ground school . Can't wait to get up there
You're videos are always such amazing, they teach me so much about aviation!
Great to hear! I’m happy you like them.
:) You're simply the best!
I enjoy listening to talented and knowledgeable people ...that is YOU!!!
I had wondered about this. Thanks for answering my question.
SO informative! Thank you !
Damn that's a lot of pipework
Scitimar that's what she said😂😭
@ John Beer LONG is good, many might not be! lol Take it from a horse. :)
The B737 main wheel well doubles as the plane’s nervous center. A separate compartment for such task didn’t fit in the 737 elsewhere because it’s a such small airplane and thus they had to combine main wheel wells with the nervous center into 1 compartment.
First thought was, "messy data centre" :D
Mostly hydraulic systems.
This channel answers so many of my questions I never even asked! Simply amazing!
To long explained and very completely! So nice
Thanks for taking the time and trouble to produce such interesting videos. As someone with an automotive maintenance background, I like to hear all the technical detail. 👍👍👍
Thanks; that's very cool to learn about! And it's great that Boeing has those scrappy engineers: very practical minded.
Cut to the 737max
Peter, I love the 737 and have flown in it more than any other aircraft from the 737-100 to the 737 Max. The United and Norwegian pilots knew how to fly it, I wonder why the others didn't have the training on the system so they didn't have the episodes that led to their crashes? I love your very informative videos. I wish I could be a pilot but at 56 it's a little late in the game to pursue that path. I love at least learning and you are a great teacher. Thank you for creating these videos.
Only mentour can turn such a seemingly basic concept into an 11 minute video. Earned a like!
Excellent video and answer to the question. It never occurred to me the main driver behind the lack of wheel doors was the height of the aircraft when the gear was extended (and the complexity to engineer such a solution for that scenario)
it's amazing to think how Boeing engineers designed 747s and 737s decades of years ago.
Yep, they were some seriously smart people. I love how they though “out of the box” when designing.
could you make a video explaining different autopilot modes? Like Level Change, Vertical Speed, LNAV, VNAV ,etc?
So smart they even thought to include coffee cup holders in the cockpit.
Mentour Pilot Little wonder Boeing is contracted for defense then and now. Though I can’t help but wonder where innovation like that happens today, seems very esoteric ☹️
FlakeTillman SpaceX
Great explanation as usually
Thank you! I’m so happy that you guys like this series.
737 CA here, great job professor! 😉
Always enjoy your videos, your range of knowledge is admirable!
not much extra drag [hub caps in place] less the weight of the doors and equipment.
less time in the repair hanger too.
Correct!
About the fuel efficiency issues, think of it this way: You have slightly more drag but at the same time you ditch the weight of the doors and thus in total, the fuel efficiency remains the same as if you added a bit of extra weight and reduced a bit of drag by adding doors
The drag isn't "slightly more" and the door probably doesn't weigh enough to create the difference. I'm no engineer though, so I might be wrong
@Mentour Pilot, I really enjoy your videos: keep it up please!
I love this channel man, I'm not a pilot but I do love mathy things so aviation falls into that well. This guy is seriously fantastic as explaining the technicalities. I get as much enjoyment out of watching this channel as I did watching MC videos when I was 14 years old. Really cool!
Interesting video with a good explanation of why there are no doors on the MLG. As for the exposed tires, I wouldn't think anything would happen to them as there have been many other aircraft designs that have had exposed wheels. WWII aircraft may not have flown at speeds of today's modern aircraft but many flew at altitudes at 30K + with no problems of the wheels or tires exposed to extreme temperatures. The B-17 didn't have any landing gear doors and the tires were filed with compressed air, nothing much happened to them due to altitude or temps. Flak and Fighter damage was another problem, but not having landing gear doors eliminated weight and problems caused by damaged doors. But Boeing has always build superior aircraft, built like tank armor.
As for icing on the underside of the wing, I've seen this only once on a B-52 Bomber. I doubt that it formed during high altitudes, but rather after it was at lower a altitude or after it landed. I was stationed at Seymour Johnson AFB and we had a B-52G that had just landed with some mechanical problems. It was summer, very humid and the aircraft was very cold from flying at high altitude. When I got out there the underside of the entire aircraft had a thick layer of frost and some ice. But like I said, it could have formed at landing speeds, at low altitude or after it had landed during taxi.
Given what we know now, I think it's safe to say that Boeing definitely do not build superior aircraft.
i never even noticed that they dont have doors. interesting :) btw i always find it funny how low-tech some solutions are in the aviation, and space/military world. some rubber things to stop the noseweel motion and to seal the compartments...shows that the simplest way often is the best one in engineering :)
Engineering is about asking the right questions. Once you identify what performance/design criteria you really have for something, you can boil it down to its simplest parts and go from there.
Digi20 I guess you NEVER LOOK UP, that was the1st thing I noticed when they came out.
Never noticed. After all the wheels are down when they are close and on the tarmac . However next time I see a 737 circling I’ll get my binoculars. On second thoughts I am not that interested. One thing , the Stuka : why did it not have retractable wheels?
Less to fuqupp is a good thing.
KISS -- Keep It Simple, Stupid
This should be applied to software, also. But it seems that such is made complicated on purpose these days, because... Gee Whizz!, would you look at that! Bah!
(I'm a software/network guy. But I started in Electronics. And should probably have done Mech. or Industrial.)
@@peterdavidasige8073 helps braking the dive during bombing and stabilizes the diving attitude
Great video, MP. Very interesting.
I didn't know I needed to know this but very well detailed as are all your vlogs.
I love your videos so much!!!
Thank you very much for the interesting cideo :)
Great!
I have actually rewatched this today because I remembered it was interesting and didn’t remember enough of it!
Fantastic video tutorial on the motivation that Boeing engineers have adopted not to cover the wheels of the landing gear.. Continue to explain other topics of B737 and aviation in general....
Thank you...!
I learnt something new today. Thanks