Subject:
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Re: A very fast TGV
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Newsgroups:
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lugnet.trains
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Date:
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Wed, 2 Nov 2005 11:33:20 GMT
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Viewed:
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2051 times
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Hello,
I would like to comment a bit on the speed calculation for the TGV. BTW a very
impressive TGV release by Xavier Viallefont.
In fact we should apply the scale factor to estimate the speed of Lego trains
and compare to the "real world". To ease calculations I'll assume that Lego
train scale is 1/45... ok ok we could discuss this value quite a lot, but it is
just for sake of discussion :).
Lets put it in simple words: one meter for a minifig is 1/45 meter for us. If it
takes one second for us to walk one meter (3.6 km/h), then a minifig would also
take one second to walk 1/45 meter (it has legs 45 times smaller than ours).
This would be 3.6 km/h for the minifig world, but only 45 times less in our
world which is 45 times bigger in dimensions (but not in time, here's the
trick...).
In lugnet.trains, Alban NANTY wrote:
[...]
> > How fast can you make the train go around the corners?
>
> Humm... unfortunatly very slow! :-)
> As for the real TGV, this train doesn't like curve with little curve radius.
> That's why you can see the train slow down just before the corner.
> Xavier (the designer of this MOC, who is not me) was able to try this speed
> because we had a very long straight line (around 51 baseplate 32x32, which
> represents approximatly 13 meters). On the video you can see that the train
> cover the 13 meters distance in approximatly 4 seconds, so the average speed of
> this train (including acceleration and decceleration) was 13/4 = 3.25 m/s = 11.7
> km/h
[...]
Alban's measurements are very interesting because we can use it to estimate the
speed of this TGV in a minifig world. In other words: at what speed would a
minifig see the TGV passing by? If the Lego TGV runs at 11.7 km/h in our real
world, then it runs 11.7 x 45 = 526.5 km/h in the minifig world. This is too
much for a real scaled down TGV :) BTW it is very close to the real speed
maximum ever recorded for a TGV, it was 515.3 km/h in 1991 by the "TGV
Atlantique", precisely that blue one which Xavier modelled in Lego.
To go further on that discussion, the commercial speed of present TGV is 280
km/h, which would give an apparent speed of 280 / 45 = 6.2 km/h on the Lego
layout. If we assume that motor speed is proportional to applied voltage (which
is true only within reasonable limits :) mechanical frictions, burnout...), then
22 Volts applied to produce a scaled speed of 526.5 km/h should be reduced by
280 / 526.5 = 53% to reach a real scaled TGV's commercial speed. Then applying
about 11-12 Volts to the Lego train motor would be enough to reach the real
commercial speed for the TGV on the Lego layout. I guess the Lego train motor
would stand this overvoltage quite easily for few minutes. But I doubt it would
negociate the curves peacefully :)
In addition, we can use this estimation to deduce the voltage to be applied for
other train types in the Lego world. A freight train runs at 80-100km/h (in
France at least), which needs about 3 to 4 Volts to the train motor. This is
between the first and second level of the yellow whell on the classical Lego 9V
speed regulator.
A train for travellers runs at 140-160km/h (also in France at least), which
needs between 6 and 7 Volts, no more.
Hope you enjoyed this funny development. Only meant to let you dream at the
minifig life :)
Philippe "frogleap" Label, FreeLUG member (too) :)
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Message has 1 Reply:
 | | Re: A very fast TGV
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| (...) it seems to me that it's 300, at least for the "Duplex" version. This (URL) source> talk about 300 also for "Atlantique" and "Réseau" versions. Concerning the number of trailers, TGVs are mainly 8 cars configuration (about 200m lenght), and (...) (19 years ago, 2-Nov-05, to lugnet.trains, FTX)
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Message is in Reply To:
| | Re: A very fast TGV
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| (...) On the video the train had 3 cars and 2 locos but the whole MOC was designed with 5 cars and 2 locos. The real TGV is always compound of 8 cars (and 2 locos) numbered 1 to 8, but usually between Paris and Lyon, there are 2 TGV trains fixed (...) (19 years ago, 31-Oct-05, to lugnet.trains)
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