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it is a great joy to ride the TGV Atlantique. As it approaches it's maximum legal speed on the run to Irun,-- around 380 KPH

380 km/h? Surely that is a typo? The TGV Atlantique sets have a regular top speed of 300 km/h, and certainly wouldn't be allowed to run faster than 330 km/h under any other circumstance than a test, what's more, 380 km/h would be really at or beyond the physically possible without modifications. Maybe your cruise with the Cessna was against the wind?


*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Sat May 26th, 2007 at 10:39:03 AM EST
[ Parent ]
Well, yes and no. You're right--280 was what I meant to write, but turns out that is actually too slow.
I checked my logs, and though they contain nothing to show our actual ground speed at the exact time we went to Dijon, I found the date and flight plan, and we were probably cruise climbing to an assigned altitude, so our speed was less-- yes. About 160 knots, I would guess- or 270 kph or so. And good old wikipedia and some phone calls show the run was certified to 300 KPH at the time. Do the trains actually run that fast on revenue runs? My friend says sometimes yes. Depending on traffic, and on temperature, and on arcane stuff beyond my ken, to do with catenary sag and temperature. If that's true--then the train would easily outrun us. Which it did. More than once. I asked him if they ever pushed it. He slithered around the answer. However,

My son (who was about 13 at the time) and I used to pass the time on the Atlantique run to Spain- Irun- timing the kilometer markers, and waiting for the dance. We found we could tell the speed of the train quite well by the motion. 12 seconds per kilometer was 300 kilometers per hour. We knew we were really rolling when it would start to snake, and get down to 10--which it did, occasionally, no matter what they say.
Yes!!
What was the Chuck Berry lyric?

Good lord, I see spots!
The lines in the road--they just look like dots!

 

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by geezer in Paris (risico at wanadoo(flypoop)fr) on Mon May 28th, 2007 at 08:46:10 AM EST
[ Parent ]
certified to 300 KPH at the time. Do the trains actually run that fast on revenue runs?

Yes, but not on the whole stretch, not even the whole high-speed stretch (from the outskirts of Paris to Tours). Acceleration beyond 200 km/h is not so good, and moderate hills or bifurcations may cause slowdowns. The fastest Massy-St. Pierre des Corps trains cover 206.9 km in 49 minutes = 253.3 km/h on average.

We knew we were really rolling when it would start to snake, and get down to 10--which it did, occasionally, no matter what they say.

I still strongly doubt it. First, even ignoring the signalling system, going more than permitted speed +10% (that is, the top speed of type tests) would mean going into uncharted territory and thus will get you fired. But it can't come to this because there is an automated system that brakes down the train when it exceeds permitted speed by some amount, whatever the train driver does. At the top speed of 300 km/h, this is at 315 km/h, at which one kilometre is 11.4 seconds. If your trip was in the last three years, there is an outside possibility that you travelled on a train that for some reason (big lateness? special in-service trials?) had an allowed speed of 320 km/h, and superseded it to reach 335 km/h, still 10.75 seconds.

I suspect human error in clocking: a combination of differing time to look at the clock and the 1 second imprecision. At these speeds, it's better to clock times for 2-3 km.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Tue May 29th, 2007 at 06:31:49 AM EST
[ Parent ]

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