# Boeing **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 17, 2020, 4:13am UTC](https://boards.straightdope.com/t/boeing/846547 "2020-01-17T04:13:05Z")\ **Posts on this page:** 16\ **Page:** 4
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [January 20, 2020, 11:01pm UTC](https://boards.straightdope.com/t/boeing/846547/61 "2020-01-20T23:01:17Z")
If most airplanes have become 2-engine designs, how hard would it be to make a 2-engine T-tail based on the 727? Is there a major downside to fuselage-mounted engines? ---
**Author:** ![WildaBeast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wildabeast/32/6_2.png) [@WildaBeast](https://boards.straightdope.com/u/WildaBeast)\ **Post date:** [January 20, 2020, 11:19pm UTC](https://boards.straightdope.com/t/boeing/846547/62 "2020-01-20T23:19:34Z")
> [@eschereal](#): > > If most airplanes have become 2-engine designs, how hard would it be to make a 2-engine T-tail based on the 727? Is there a major downside to fuselage-mounted engines? I think the biggest downside is that modern high-bypass turbofans have gotten so big and heavy that mounting them on the fuselage would require a lot of extra structural reinforcement where the engines are mounted. I’ve read that having the engines right next to the fuselage also disrupts the airflow into the engines and makes them run a bit less efficiently. Some of Boeing’s early designs for the 737 had a t-tail and fuselage mounted engines like a 727, but Boeing figured out that they run more efficiently if you put them on the wings. Fuselage mounted engines makes maintenance more difficult since they’re higher off the ground. I doubt any of those would be insurmountable, though. I think the main reason you never see fuselage mounted engines on new planes is that there’s simply no good reason to have them, while there are some minor downsides. The main reason they were used on 1960s designs like the DC-9 and 727 was so the landing gear could be lower, to make the plane easier to service at smaller airports that might not have stairs or baggage belts tall enough to reach a bigger plane at the time. ---
**Author:** ![Daylate](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@Daylate](https://boards.straightdope.com/u/Daylate)\ **Post date:** [January 21, 2020, 4:34am UTC](https://boards.straightdope.com/t/boeing/846547/63 "2020-01-21T04:34:45Z")
[QUOTEOr to compare it to another airplane, the DC-10 was grounded in 1979 after the horrific American Airlines crash at O’Hare, plus a string of crashes before that due to the cargo door blowing off inflight. I wasn’t alive then, but reportedly many people back then said they’d never fly on a DC-10, too. But when it returned to service most people did anyway.] [/QUOTE] I remember that very well. I had to fly to Chicago from Seattle, and the flight happened to be on the first day that the DC-10 went back into service. And naturally we flew on a DC-10. It was very tense (like almost not breathing) in the cabin on take-off. When we landed at O’Hare there was loud clapping from the passengers. ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [January 21, 2020, 5:13am UTC](https://boards.straightdope.com/t/boeing/846547/64 "2020-01-21T05:13:48Z")
> [@eschereal](#): > > If most airplanes have become 2-engine designs, how hard would it be to make a 2-engine T-tail based on the 727? Is there a major downside to fuselage-mounted engines? The danger of a T-tail design (like the 727) is that it runs the risk of a deep stall, where the wing angle prevents airflow from getting to the elevators mounted high on the tail. Then the airplane cannot recover from its stall because the pilots are unable to push the airplane nose downwards (necessary for stall recovery,) and it will inevitably pancake-crash. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [January 21, 2020, 6:08am UTC](https://boards.straightdope.com/t/boeing/846547/65 "2020-01-21T06:08:48Z")
> [@WildaBeast](#): > > According to the Forbes article pullin posted, if you’re flying Ryanair you probably won’t know whether or not you’ll be getting a MAX when you book, as they don’t allocate specific planes to routes until the night before. One more reason to detest Ryanair. > [@](#): > > Here in the US, Southwest is both the largest airline domestically, and the largest operator of MAX (and the largest operator of 737s in general, for that matter). Many fliers here are very loyal to Southwest due to their generally good customer service and policy of not charging extra for checked bags and ticket changes, even if their fares aren’t necessarily the cheapest anymore. It will be interesting to see if those fliers change their loyalty in order to avoid the MAX. It will be interesting indeed. Good points, thanks. ---
**Author:** ![MarvinKitFox](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@MarvinKitFox](https://boards.straightdope.com/u/MarvinKitFox)\ **Post date:** [January 21, 2020, 6:39am UTC](https://boards.straightdope.com/t/boeing/846547/66 "2020-01-21T06:39:33Z")
> [@Yakamaniac](#): > > The two units that crashed both had single Angle Of Attack sensors, False Information > [@Yakamaniac](#): > > The 737Max is inherently unstable, but the software corrects for that. False Information > [@Yakamaniac](#): > > When the sensors fail, the software …can be switched off… Boeing had not told the airlines about the software Ok, at least you know **something** about the situation. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 21, 2020, 8:10am UTC](https://boards.straightdope.com/t/boeing/846547/67 "2020-01-21T08:10:34Z")
> [@eschereal](#): > > If most airplanes have become 2-engine designs, how hard would it be to make a 2-engine T-tail based on the 727? Is there a major downside to fuselage-mounted engines? One downside is that the wing structure needs to be stronger. The more of the aircraft weight you spread over the wings, the less stress is on the wing roots. Engines and fuel on / in the wings is a good thing structurally. Regardless, if Boeing was prepared to design a new plane, they could’ve just designed one with under-slung engines and the appropriate length of undercarriage. The core problem with the B737 MAX is that the B737 undercarriage is too short. On the subject of avoiding flying on a MAX, you just avoid flying with airlines that own any of them. Yes there may be the rare occasion that you end up code sharing unknowingly on a MAX but overall you’d be good. Instead of flying Ryanair, fly Easy Jet. ---
**Author:** ![MarvinKitFox](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@MarvinKitFox](https://boards.straightdope.com/u/MarvinKitFox)\ **Post date:** [January 22, 2020, 7:58am UTC](https://boards.straightdope.com/t/boeing/846547/68 "2020-01-22T07:58:18Z")
> [@eschereal](#): > > If most airplanes have become 2-engine designs, how hard would it be to make a 2-engine T-tail based on the 727? Is there a major downside to fuselage-mounted engines? T-tail designs are subject to Deep Stall, where when stalled the tail elevators fall in the wings’ wind shadow, making the stall unrecoverable. Example: 1963 BAC One-Eleven test crash. This is a _big_ \* deal\*. Yes there are countermeasures, but it does introduce a scary failure mode that need not exist. Engine on fuselage _behind_ the wings is subject to ice/debris ingestion from the wings and fuselage. example: Scandinavian Airlines Flight 751 In addition the engines inevitably get more turbulent air intake, reducing efficiency and increasing complexity. and in front of the wings not practical due to airflow disruptions over the wings. Tail (or fuselage) mounted engines present **much** greater danger to the plane in the event of catastrophic failure. When a wing-mounted engine fails, it tries to shred just that one area on the wing. And the more shreddable parts of the engine actually project ahead of the wing, further reducing the danger. Tail or fuselage mounted engines _inevitably_ expose more of the plane to engine failure debris. In addition… tail-mounted engines could be a problem with the sheer SIZE and MASS of modern engines. It sure would void the current sort of wing layouts, the resultant airplanes would look completely different. Not a show-stopper, but definitely not a trivial change. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [January 30, 2020, 2:06am UTC](https://boards.straightdope.com/t/boeing/846547/69 "2020-01-30T02:06:33Z")
Article in Business Insider: Boeing posted its first full-year loss in more than 20 years: > **[Boeing posted its first full-year loss in more than 20 years, as the 737 Max...](https://www.businessinsider.com/boeing-earnings-737-max-first-annual-loss-more-than-20-years-2020-1)** > > "We recognize we have a lot of work to do," Boeing's newly-installed CEO David Calhoun said in a statement. Went from a profit of $10.46 billion in 2018 to a loss of $636 million in 2019. No matter how many other profitable products they have, those kinds of numbers are … worrisome … for investors. ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [January 30, 2020, 7:19am UTC](https://boards.straightdope.com/t/boeing/846547/70 "2020-01-30T07:19:51Z")
> [@Richard\_Pearse](#): > > …The core problem with the B737 MAX is that the B737 undercarriage is too short… The undercarriage length is tied closely into the basic structure of the wing. Making the landing gear taller would mean redesigning almost the whole wing. Very very expensive. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 30, 2020, 9:59am UTC](https://boards.straightdope.com/t/boeing/846547/71 "2020-01-30T09:59:38Z")
> [@Rocketeer](#): > > The undercarriage length is tied closely into the basic structure of the wing. Making the landing gear taller would mean redesigning almost the whole wing. Very very expensive. Yeah. I didn’t mean to imply they could simply lengthen the undercarriage, ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [January 30, 2020, 6:26pm UTC](https://boards.straightdope.com/t/boeing/846547/72 "2020-01-30T18:26:46Z")
> [@Rocketeer](#): > > The undercarriage length is tied closely into the basic structure of the wing. Making the landing gear taller would mean redesigning almost the whole wing. Very very expensive. Well, maybe they could redesign the undercarriage to fold, like with, sort of, knees, so that a longer undercarriage would fit in the same space. Still pretty costly and an extra point-of-failure, though. ---
**Author:** ![WildaBeast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wildabeast/32/6_2.png) [@WildaBeast](https://boards.straightdope.com/u/WildaBeast)\ **Post date:** [January 30, 2020, 9:41pm UTC](https://boards.straightdope.com/t/boeing/846547/73 "2020-01-30T21:41:26Z")
> [@eschereal](#): > > Well, maybe they could redesign the undercarriage to fold, like with, sort of, knees, so that a longer undercarriage would fit in the same space. Still pretty costly and an extra point-of-failure, though. This is exactly what they did with the [MAX10](https://en.wikipedia.org/wiki/Boeing_737_MAX#737_MAX_10), which is still in in the test phase of development and hadn’t yet flown at the time of the grounding. As an even further stretch beyond the MAX9, with the old undercarriage design it would be too long to take off without scraping the tail on the runway. So they designed a telescoping undercarriage that fits in the same space as the old design. ---
**Author:** ![Daylate](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@Daylate](https://boards.straightdope.com/u/Daylate)\ **Post date:** [January 31, 2020, 12:06am UTC](https://boards.straightdope.com/t/boeing/846547/74 "2020-01-31T00:06:38Z")
IIRC, that (too long of an undercarriage) was the exact problem that faced the designers of the Vought Corsair back in WWII days. The prop was so big that in order to keep the tips from grinding into the runway they would have had to make the landing gear struts too long. So they just turned the straight wing into an inverted gull wing, and ended up with a very beautiful plane that knocked a LOT of Zeros out of the air. ---
**Author:** ![WildaBeast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wildabeast/32/6_2.png) [@WildaBeast](https://boards.straightdope.com/u/WildaBeast)\ **Post date:** [January 31, 2020, 1:49am UTC](https://boards.straightdope.com/t/boeing/846547/75 "2020-01-31T01:49:15Z")
My last post might have been confusing, to just to clarify, the problam with the MAX10 was the the _fuselage_ was too long for the old, short landing gear. Thus Boeing had to design new, telescoping landing gear struts to make them longer while also fitting into the same space as the old design. ---
**Author:** ![GreenWyvern](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/greenwyvern/32/2834_2.png) [@GreenWyvern](https://boards.straightdope.com/u/GreenWyvern)\ **Post date:** [March 7, 2020, 4:15am UTC](https://boards.straightdope.com/t/boeing/846547/76 "2020-03-07T04:15:06Z")
The Preliminary Report from the House Transportation Committee has been released [Boeing’s ‘culture of concealment’ led to fatal 737 Max crashes, report finds](https://www.theguardian.com/business/2020/mar/06/boeing-culture-concealment-fatal-737-max-crashes-report) > [@](#): > > In a blistering 13-page report the committee found Boeing’s Max design “was marred by technical design failures, lack of transparency with both regulators and customers”. > > According to the report, in 2011 the manufacturer was “under tremendous financial pressure” to compete with its rival Airbus’s A320neo aircraft. The speediest solution was to update its 737 fleet rather than develop a new plane. > > As a result of those pressures, and in order to get the Max certified as quickly as possible, the manufacturer misled and withheld information from the Federal Aviation Administration (FAA) and even “the very existence” of the MCAS anti-stall software system, blamed for the crashes, from pilots. > > The report, based on internal documents, whistleblower testimony and public hearings, faults the FAA, too. The congressional committee cited conflicts of interest among Boeing employees who were authorized to perform certification work on behalf of the FAA and said Boeing’s influence over the FAA’s oversight had resulted in FAA management “rejecting safety concerns raised by the agency’s own technical experts at the behest of Boeing”. > > The regulator’s oversight was “grossly insufficient” and it “failed in its duty” to both uncover critical problems and make sure Boeing fixed them, the committee found. “The combination of these problems doomed the Lion Air and Ethiopian Airlines flights,” the report concluded. [PDF of report](https://transportation.house.gov/download/ti-preliminary-investigative-findings-boeing-737-max-march-2020) [Previous page](https://boards.straightdope.com/t/boeing/846547.md?page=3)