Ford's CNC English Wheel(tmLJ)

Looking at the wreckage afterwards, I was struck by one thing: The hull was a hydroplaning catamaran with a solid sheet between the hulls, so scooped-up air has no way to escape. I bet the newer boats have a big opening between the hulls, to reduce the lift.

This is also the same shape as used for the tiny sliders (that carry read and write heads) in a disk drive. The sliders fly a few millionths of an inch above the spinning disk surface, held up by aerodynamic forces, and held down by the spring force of the arm to which the slider is glued. The slider is moving at about 100 mph with respect to the disk surface at the outside track.

Joe Gwinn

The boat actually was a three-point hydroplane, and the surface between the front sponsons is part of what made them fast, by providing lift from the air between them. It's a creepy feeling, and it's just as much a factor in much smaller hydros.

They used to be much more deadly. It the mid and late '60s, they were killing one or two thunderboat drivers per year. Four died in 1966. There were only about a dozen of those boats in the whole world.

Big improvements have been made since.

Ed Huntress

And racing engines. That's what those reverse-cone exhausts on racing motorcycles are all about. Particularly on two-strokes, the reflected wave takes the fresh fuel/air that is drawn through the combustion chamber and out the exhaust, and crams it back into the cylinder. It produces a big extra wallop of power but only in an extremely narrow rpm range. Thus, smaller Honda race bikes even back in the '60s had 12 speed gearboxes. I think that one of the 2-stroke Yamahas had 14 speeds.

Yeah, but then you'd just have drag strips and Bonneville.

The downforce is impressive. At 200 mph, a F1 or Indycar produces over

5,000 lb. of downforce. A F1 car weighs less than 1,500 lb. So it could, in a pinch, ride upside-down on an overhead track.

I saw it in one of my classes, too.

jsw

I wonder what those deflectors are attached to. And if they contain swinging weights. If the deflectors are just rigid metal attached to the edge of the deck, I don't see how it would work. There are many patents on dampers and the like to cause flutter vibrations to damp out.

The last video may cause fear of flying.

Joe Gwinn

Hmm. I didn't realize that those fancy cone exhausts were function, versus pretty. But, yes, this is exactly the same phenomena.

I have a contrary war story: In the 1970s in Baltimore I knew a fellow that raced gussied up Lotus sports cars. His problem was that the Lotus cars were smaller than the 'Vettes, and got no respect, and he mused that if he could make the Lotus louder, respect would follow. I ventured that replacing the exhaust system with an exponential horn would maximize the voice, over all engine speeds. He liked the idea and built one, to good effect (I never heard before or after).

So long as nobody loses their nerve.

Also see

Joe Gwinn

My uncle was one of the co-inventors of cone extractors ("megaphones"), back in the early 1930s. Apparently several people got the same idea at the same time. He was racing model hydroplanes. (He also was the primary mechanic on Fleur de Lis, a 50-foot rum runner from Keyport, NJ that had three Liberty aircraft engines and could outrun any Coast Guard chase boat, but that's another story. )

On four-strokes, they're usually open-ended and depend on a reflected rarified wave. On two-strokes, they've often had a plate with a smaller hole in the middle, or a shorter reversed cone on the end, reflecting a compressed wave.

They both wind up cramming a compressed wave, but the open-ended ones are a half-wavelength longer or shorter. I think.

Baltimore, eh? Did he ever race at the SCCA track at Vineland? It's not there anymore, but I think it was still going through the '70s.

I was in the North Jersey chapter so I probably didn't know him, but maybe...

mmm....creepy. The sailplane gives me a start. It looks like a Diamont, which I was supposed to fly once upon a time (I flew a Schleicher K6 and a Schweizer 1-26), but we ran out of time that day. Maybe I'm glad.

[snip]

Got any patent numbers and/or names?

Now that radar is common, people build one-use submarines for transport from South America.

Could be, but I don't recall.

I more recall a local track, but I bet he went to Vineland from time to time. I no longer know his name.

Airplanes are normally designed so they cannot go fast enough to cause flutter. But there are many coupling modes, many having a blood price:

Joe Gwinn

No, and I never had any luck looking for it. Even Fleur de Lis, which was famous out here and was written up in a book on indigenous New Jersey boats published by Rutgers, doesn't seem to show up online.

I read a history of those pipes once, included in a book on racing engines, and there are points in there that I know are wrong, because I saw several of those engines from the '30s, built by different people. So it appears to be one of those things that got lost in history.

Wikipedia's entry on "expansion chambers" (same thing) really misses the boat: "Expansion chambers were invented and successfully manufactured by Limbach, a German engineer, in 1938, to economize fuel in two stroke engines." By 1938, they were being used on most of the model hydroplanes raced at the higher levels.

I remember the crash, and the other Electra crash the following year. I was 11. It was scary.