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Comment by InTheArena | Hacker News Reader

Near criminally stupid though. Not only did they have issues with two separate control surfaces, a unplanned stall and a safety violation on takeoff, they did all of these things for a marketing piece establishing the plane was safe. This at a time where metal fatigue and structural load was not well understood, as the Europeans where finding out as their planes decompressed explosively midair.

There was a 747-SP that went supersonic by accident and was only saved by the crew deploying the landing gear to slow the plane down. He amount of damage was non trivial.

Someone will probably jump all over the critics of Douglas and point out Boeing’s Tex Johnson’s barrel row. 1) that was not endorsed by the company and 2) was a neutral G maneuver. 3) the company appropriately freaked and told him never to do that again.

We have occupational safety and standards operating procedures for a reason.

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Since when is voluntary experimentation on a test rig, under controlled circumstances, criminally stupid? It’s not like this was a passenger flight.

It would warrant criticism if the pilot tried it without informing the crew prior to takeoff. All participants entered into the activity with an understanding that they were risking their lives.

These people did it because they enjoyed the challenge, not to score points with corporate overlords or jockey for a raise and a promotion. The marketing angle was simply to provide cost justification and demonstrate that a perceptible reward would be earned with the risk undertaken.

That's a optimistic reading of the article. The article states it was for marketing reasons, and also states that they had several plan threating outcomes that were not planned for.

If it where in the context of understanding the plane's behavior at trans-sonic speeds, I can understand it, but that is not really given as a justification.

> This at a time where metal fatigue and structural load was not well understood

You're mixing up problems that are completely irrelevant to the issue. Fatigue is only an issue in high load cycles (typically over 10^6) which means that it becomes a problem only after years of significant commercial operations.

Running a prototype is, obviously, not the case.

Moreover, structures designed to meet fatigue requirements are designed so that ultimate load is far higher than operational loads (over 5 or 10 times), and ultimate loads are covered by their own design scenario.

Fatigue and ultimate loads only cause problems when aged structures (i.e., planes that were well used and reaching their design life) are subjected to loads close to their ultimate load. That may lead structures to fail when subjected to loads that, although higher than typical operational loads, are far from the expected limit strength.

Here's an example of a retired C130 being used in firefighting missions that gets its wings to break off mid-flight.

https://www.youtube.com/watch?v=PK49QALNj-0

Running a prototype is, obviously, not the case.

We know that now. They didn't know that then. Remember, this was well less then 5 years after the de Haviland Comet's started falling out of the air because they used square windows instead of ovals, and metal fatigue at the corners of the windows were resulting in massively more rapid wear cycles then projected.

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