In 1938. He said that. It seems a little . . . odd. Although no odder than attempting to make the argument that technological change is coming to a halt right now. Don't we live in an era of ever-accelerating technical change, catapulting down the runway?
So that's an experimental gunpowder catapult launch of a Vickers Virginia in 1931.
In case you didn't get a good enough look at it in the video, here's another view of a Vickers Virginia.
Replacing the Vickers Vimy in 1924, the Wikipedia article says that some of the 124 Virginias produced in the 1920s were still in "front line service" in 1938. It appears to have been predeceased, if anything, by the 97 bomber-freighter-transport variants of Victorias and Valentias. It also says that the Virginia was "somewhat accident-prone, 81 being lost in service."
You say "accident-prone," I say "widow-maker." Not the plane I'd choose for experiments in catapult-assisted takeoffs. That being said, the job of a "heavy" bomber is to carry more bombs, further, and one of the best ways of doing that is to increase the all-up-weight so that it can carry more fuel and bombs. Catapults are a means to that end. Below the fold, I'm going to talk about the goofy, goofy ways, that people tried to do that in the 1930s so that there could be commercial air service across the Atlantic, and reach for a comparison with the frustratingly long and sorry story of the introduction of colour television.
It's a comparison that, I think, has some relevance to the problem of technological innovation and seculary stagnation. Specifically, I am going to compare and contrast a couple of relevant developments in an attempt to show that what's important is not "research and development" taken in isolation, but the broad shoulders of the state, carrying the economy forward, where and when it is willing to be the investor of last resort. Once the research and development problems that could be solved without the state, were solved, all that was left was . . Well. All that's left is everything that still needs to be done in 1939.
And that's why Alvin Hansen was actually right!
After the jump, some kind of hand gesture in the direction of trying to make the point.