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Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

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Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#81

Post by umvi »

blakesterz wrote: post #4

"Dutch Roll is a coupled out of phase movement of the aircraft as result of weakened directional stability (provided by the vertical tail and rudder), in which the aircraft oscillates around its vertical as well as longitudinal axis (coupled yaw and roll)." That sounds pretty scary. I wonder why it wasn't bigger news when it happened last month?

Not as scary as flying upside down which is what I originally thought based on title alone. Most people are familiar with "barrel roll" but by comparison this just looks like wiggling.

Counterintuitively though my understanding is that barrel rolls are generally safe even for large planes since it's a stable 1G maneuver (some jock irresponsible air force pilot used to regularly barrel roll B-52s until he did one too low and killed himself and the crew)...

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#82

Post by kcplate »

JWlrCk9PkipFTDq wrote: post #43
kcplate wrote: post #27

Earlier quoted context omitted.

I guess it’s worse than it looks? The video was kind of a dramatic let down to be honest. I preferred the mystery.

It looks a bit more intense in real footage. https://www.youtube.com/watch?v=2tgfkGiHhxs

Agreed.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#84

Post by afavour »

amarant wrote: post #25

It kinda bothers me that airlines are still placing orders for new Boeing airplanes. Taking delivery of old orders is one thing, since they can't really back out of those, but placing new orders implies that some level of trust remains for this company, and I just don't see how that makes any sense at all?

Such is the state of the airline business/capitalism. There are basically only two manufacturers: Boeing and Airbus. The airlines place orders years in advance and if you cancel a Boeing order now you’re a) out of a lot of money and b) joining the back of the line with Airbus.

The simple reality is that the airlines (and their shareholders) consider a) and b) to be greater risks than the safety record of Boeing planes. Given the parameters they have they’re not wrong. Air travel is still incredibly safe, even if these Boeing incidents make it ever so slightly less safe. To be blunt, the market can absorb it and individual airlines have little motivation to change. If there is going to be a big change it’ll need to come from the FAA.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#85

Post by AnimalMuppet »

ragebol wrote: post #75
shdon wrote: post #22

Earlier quoted context omitted.

Ice skating... Interesting... My guess was it having to do with ships rocking side to side. Maar waarom een schaatsterm?

Maybe the ice skaters took it from ships, also an old Dutch tradition I suppose.

I'm not sure if this is relevant, but: I have read that back in the day (1500s-1700s), the Dutch built flat-bottomed boats that could carry a lot, and the English built round-bottomed boats that handled better in the ocean. Maybe the way a Dutch boat handled in heavier seas is the origin of the term?

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#86

Post by HPsquared »

banannaise wrote: post #73
HPsquared wrote: post #54

Earlier quoted context omitted.

Standby PCU sounds like a control system. Was that a cause or effect of the event?

The PCU in this context is the part that moves the rudder. PCU issues were common on the 737 in the 90s[0] although that's... probably?... not relevant here. [0] https://en.wikipedia.org/wiki/Boeing_737_rudder_issues

Exactly, rudder control issues could trigger or exacerbate Dutch roll. Loss of yaw damper control, in other words (yaw damper actuates the rudder).

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#87

Post by jader201 »

tjpnz wrote: post #20
blakesterz wrote: post #4

"Dutch Roll is a coupled out of phase movement of the aircraft as result of weakened directional stability (provided by the vertical tail and rudder), in which the aircraft oscillates around its vertical as well as longitudinal axis (coupled yaw and roll)." That sounds pretty scary. I wonder why it wasn't bigger news when it happened last month?

Here's a video demonstrating it: https://youtu.be/Zmjam1evDD4

I feel like “roll” is a bad word for what’s happening here. In my brain, when I hear “roll”, I’m thinking a 360 degree rotation in either the vertical or horizontal axis (or both).

This is far from that (even in the real life footage linked in the sibling comments). This is more like a “Dutch wobble” or “tilt”.

But I’m not an aviator, so what do I know.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#88

Post by cwillu »

kcplate wrote: post #68
doctor_eval wrote: post #56

Earlier quoted context omitted.

It’s being downvoted because it’s technically incorrect. They are describing a Dutch Oven.

Uh yes, they were being sarcastic. Once again…the humorless HN strikes. Sheesh.

If the joke was worth making, the joke was worth suffering the downvotes. Have some courage in your convictions, and most importantly: don't whine about it.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#90

Post by bowsamic »

afavour wrote: post #84
amarant wrote: post #25

It kinda bothers me that airlines are still placing orders for new Boeing airplanes. Taking delivery of old orders is one thing, since they can't really back out of those, but placing new orders implies that some level of trust remains for this company, and I just don't see how that makes any sense at all?

Such is the state of the airline business/capitalism. There are basically only two manufacturers: Boeing and Airbus. The airlines place orders years in advance and if you cancel a Boeing order now you’re a) out of a lot of money and b) joining the back of the line with Airbus. The simple reality is that the airlines (and their shareholders) consider a) and b) to be greater risks than the safety record of Boeing plane…

Yeah, Airbus is extremely backed up with orders
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