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The de Havilland Comet changed aviation for good

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Re: The de Havilland Comet changed aviation for good

#51

Post by woodandsteel »

pjc50 wrote: post #39
Aloha wrote: post #33

Earlier quoted context omitted.

I've often argued that the root cause for loss of empire, was the best and brightest of a generation was left on Flanders fields. The best and brightest of the ruling class at the time was simple used up as cannon fodder, its also the cause for the decline of the aristocracy too.

And this was why postwar Germany lost its scientific and technical advantage and is now a ruined backwater - wait, no. Germany not only lost technicians and an aristocracy in WW1 and 2 but murdered those of its Jewish population that were not able to escape. Survivors defected to the US like Von Braun. The loss of empire was after WW2 not WW1, and partly due to the US insisting (Suez) and partly because it became mor…

>The postwar British disease was labour relations, which were handled far better in Germany with worker representatives at board level.

Interesting, UK went socialist after WWII while Germany went social democratic. I wonder what made the difference. Perhaps part of the answer is that the aristocracy retained more power in the UK? I have read that socialism in the UK was supported by the aristocracy as a way to keep control of the economy, but I am not sure if that is correct. Also, Germany was under US occupation for a number of years, I would suppose that made a difference, since the US is quite anti-socialist.

Re: The de Havilland Comet changed aviation for good

#52

Post by woodandsteel »

cdegroot wrote: post #10

My biggest "surprise" always is how little we have progressed if you just look at how the planes look and how fast they fly (6h11m NY->London in 1958, that's pretty much what they do today, not?). It seems like the airline industry got a lot of stuff just right the first time and since then just has been doing performance tweaks (where I take "performance" to be very broad to include things like safety, economy, ...)…

This is common in many areas of technology. There is a phase of rapid technological development, then it reaches the fundamental limits of the technology, and from then on it is all refinements.

For instance take a look at liquid-fueled rockets. The first one was built by Goddard in the 1930's, they advanced rapidly with the German V-2 and then the Soviet and American military and space programs, reaching a peak with the Saturn V that has not been exceeded to this day.

Re: The de Havilland Comet changed aviation for good

#53

Post by WalterBright »

dingaling wrote: post #35
WalterBright wrote: post #24

The corner of a square hole in a flat plate has 4x the stress of the surrounding material. It's called a "stress riser". If you look at a concrete slab with such an inside corner, there's usually a crack there. Boeing solved the problem by using rounded windows, and riveting on a forged doubler around the window frame. The skin was also organized so a crack will not propagate far. The success of the latter has shown…

> Boeing solved the problem by using rounded windows, and riveting on a forged doubler around the window frame. Boeing was by no means the first to use radiused windows in pressurised airliners; the Avro Tudor was doing so in 1946 and there may well have been earlier examples. Conversely the Boeing Stratoliner was flying with square windows in the early 1940s and didn't suffer fatigue failures, nor did the later DC-6…

> Avro Tudor

Curiously, this did not extend to the cockpit windows:

http://smg.photobucket.com/user/Coridano/media/TB01.jpg.html

suggesting that stress cracking was not the reason they did it. (There are other reasons for round windows - such as portholes on ships which are easier to make a seal.)

The 707 shows a more radiused corner for the cockpit windows.

Re: The de Havilland Comet changed aviation for good

#54

Post by nradov »

spaceflunky wrote: post #32
Animats wrote: post #19

Earlier quoted context omitted.

A little slower today, for fuel economy. Going supersonic uses 3x the fuel. That's what killed the Concorde.

This is the real reason. The 757 could cruise at Mach 0.8, but it's a lot less efficient at that speed. The 757 use to make the SFO-JFK route in a little under 5 hours, these days most flights make it in just under 6 (a 20% increase in time to save fuel). Air travel is technically capable of big improvements, but economics don't work out.

Nonstop SFO-JFK flights are 5:35 to 5:48. But this isn't all due to flying slower. Airlines have increased their scheduled flight times to improve their on-time arrival statistics. So if there are no delays then they actually arrive early.

Re: The de Havilland Comet changed aviation for good

#55

Post by rodgerd »

pjc50 wrote: post #39
Aloha wrote: post #33

Earlier quoted context omitted.

I've often argued that the root cause for loss of empire, was the best and brightest of a generation was left on Flanders fields. The best and brightest of the ruling class at the time was simple used up as cannon fodder, its also the cause for the decline of the aristocracy too.

And this was why postwar Germany lost its scientific and technical advantage and is now a ruined backwater - wait, no. Germany not only lost technicians and an aristocracy in WW1 and 2 but murdered those of its Jewish population that were not able to escape. Survivors defected to the US like Von Braun. The loss of empire was after WW2 not WW1, and partly due to the US insisting (Suez) and partly because it became mor…

I recommend Len Deighton's well-researched _Blood, Sweat, and Folly_ for a view of the disasterous management of the war effort - that the same people would mis-manage the peace isn't surprising.

Re: The de Havilland Comet changed aviation for good

#56

Post by pjc50 »

woodandsteel wrote: post #51
pjc50 wrote: post #39

Earlier quoted context omitted.

And this was why postwar Germany lost its scientific and technical advantage and is now a ruined backwater - wait, no. Germany not only lost technicians and an aristocracy in WW1 and 2 but murdered those of its Jewish population that were not able to escape. Survivors defected to the US like Von Braun. The loss of empire was after WW2 not WW1, and partly due to the US insisting (Suez) and partly because it became mor…

>The postwar British disease was labour relations, which were handled far better in Germany with worker representatives at board level. Interesting, UK went socialist after WWII while Germany went social democratic. I wonder what made the difference. Perhaps part of the answer is that the aristocracy retained more power in the UK? I have read that socialism in the UK was supported by the aristocracy as a way to keep…

"Socialist" is almost a useless label these days, it's used to mean too many things that the US doesn't like.

It's true that some of the aristocracy (e.g. Tony Benn) supported Labour and some very left-wing politics. But that was a small part of the whole. What is true is the Fabian Society proposing incrementalist socialism as an antidote to revolutionary socialism - a way for the aristocracy to keep their heads.

The UK nationalised a lot of industries after the war but then failed to run them effectively. After a few decades of this the Thatcherite response was to just privatise everything and give up on trying any form of state management. This leaves us in the bizarre situation where Germany, France, the Netherlands etc have state-owned rail companies running UK railways recieving UK subsidy.

Re: The de Havilland Comet changed aviation for good

#57

Post by RugnirViking »

WalterBright wrote: post #40
dingaling wrote: post #35

Earlier quoted context omitted.

> Boeing solved the problem by using rounded windows, and riveting on a forged doubler around the window frame. Boeing was by no means the first to use radiused windows in pressurised airliners; the Avro Tudor was doing so in 1946 and there may well have been earlier examples. Conversely the Boeing Stratoliner was flying with square windows in the early 1940s and didn't suffer fatigue failures, nor did the later DC-6…

Fatigue failure was poorly understood at the time. It still is incompletely understood, but much better models have been constructed to predict it. Fatigue damage goes up as the cube of the load, and the Comet was pressurized at 35,000 feet rather than 20,000 for the Stratoliner, meaning much more load.

I assume I am wrong on this, but surely if it pressurized to 35000 feet, then that would be less load? As they pressurized it to that it would be closer to the air at its altitude?

Re: The de Havilland Comet changed aviation for good

#58

Post by WalterBright »

RugnirViking wrote: post #57
WalterBright wrote: post #40

Earlier quoted context omitted.

Fatigue failure was poorly understood at the time. It still is incompletely understood, but much better models have been constructed to predict it. Fatigue damage goes up as the cube of the load, and the Comet was pressurized at 35,000 feet rather than 20,000 for the Stratoliner, meaning much more load.

I assume I am wrong on this, but surely if it pressurized to 35000 feet, then that would be less load? As they pressurized it to that it would be closer to the air at its altitude?

The cabin pressure inside is 10,000 feet, the air pressure outside is 35,000 feet, making for more of a pressure differential than at 20,000 feet altitude.

Re: The de Havilland Comet changed aviation for good

#59

Post by slededit »

lostlogin wrote: post #29
ak217 wrote: post #14

Earlier quoted context omitted.

In 1958, the cost of a ticket was about 4x what it is today (adjusted for inflation but not earnings growth), flying was at least 20x less safe in terms of fatal crashes per departure, and consumed at least 4x more fuel per passenger-mile. Those are some impressive performance tweaks.

Those of us with legs suffer at least 4x more - The price has been at least partly compensated for by cramming more people in.

A first class ticket is about double the cost and has the traditional leg room. If you can live with only half the cost of the 1950s then its an option.

Re: The de Havilland Comet changed aviation for good

#60

Post by frenchman_in_ny »

cromulent wrote: post #11
cdegroot wrote: post #10

My biggest "surprise" always is how little we have progressed if you just look at how the planes look and how fast they fly (6h11m NY->London in 1958, that's pretty much what they do today, not?). It seems like the airline industry got a lot of stuff just right the first time and since then just has been doing performance tweaks (where I take "performance" to be very broad to include things like safety, economy, ...)…

It's down to the laws of physics. They still fly at around 80% of the speed of sound, as that is close to the so-called "coffin corner". https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)

It's unrelated to the coffin corner.

Planes in the ~80s were flying NYLondon faster than today -- the fuel savings generated by flying slower are what is driving the decision.

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