
German students win hyperloop competition, reaching 200 mph - rmason
https://www.theverge.com/2017/8/28/16213348/hyperloop-pod-competition-spacex-warr-elon-musk
======
atroyn
Important to note, the WARR team doesn't receive any funding or direct support
from the university - not even professors or Ph.D's.

This is a 100% student created and run initiative

~~~
_Codemonkeyism
Is WARR the cart in the image? Why does it have all those logos?

~~~
bluejekyll
If that is the WARR vehicle, the GP doesn't mention not getting sponsors, just
that the University didn't directly support it.

Though, I wonder where they built this and worked on it. My guess would be
that they had lab space provided by the school.

~~~
turbinerneiter
There is lab space provided by university (we find it very weird that you call
it school).

The main point is that the WARR teams (Hyperloop, space elevator, deep space
concepts, rockets and satellites [I'm in the sat group]) are student teams.
Some Ph.D students are involved, too, but the point is that we decide what we
do. The teamleader is a student. The ideas are from the students.

The University, in the form of the chairs (Astronautics and Propulsion) are
partners and friends, but we are in charge of what we do.

WARR is actually older than the Universities Astronautics chair.

(btw, high to all WARRians on hackernews)

~~~
hsod
In America, "school" is a generic term for any kind of educational institution

~~~
jlebar
Well, but we Americans also say "where did you go to school?" meaning, in most
adult contexts, what other English speakers mean when they say "where did you
attend university?"

I agree it's a weird synecdoche, although, English is full of them if you
look.
[https://en.wikipedia.org/wiki/Synecdoche#Examples](https://en.wikipedia.org/wiki/Synecdoche#Examples)

~~~
King-Aaron
To be fair, America seems to change up a lot of conventional English, haha :P

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Robotbeat
It should be noted the California bullet train is planned to run at 220mph for
its fastest leg, so this is within spitting distance already.

If you pump the (vast majority of the) air out, no reason you couldn't get
supersonic. That's much faster than any non-rocket-propelled train has ever
gone.

The fastest train in service is around 270mph, more experimental maglevs have
reached 375mph. Supersonic is 767mph, so over twice the fastest maglev.

~~~
bluejekyll
> If you pump the (vast majority of the) air out, no reason you couldn't get
> supersonic.

Doesn't this sound like a maintenance nightmare? I'm not clear on a couple of
things. What happens when the vacuum fails? What happens to passengers if the
seal fails on the vehicle, and then all the air is sucked into the vacuum?
Maintaining long tunnels is by itself hard, but it seems like maintaining long
tunnels that also need to maintain a vacuum would be that much more complex.

I don't see much discussion on this aspect of the hyperloop.

~~~
mabbo
> What happens to passengers if the seal fails on the vehicle, and then all
> the air is sucked into the vacuum?

I fly a lot for work. Every week, someone gives me a demonstration of what to
do when this happens.

~~~
mikeash
Unfortunately, that won't work. Oxygen masks only work up to a certain
altitude, which is roughly the altitude where airliners cruise. At pressures
lower than that, even pure oxygen isn't enough to sustain you.

You don't die instantaneously when exposed to vacuum, although it is pretty
quick. I wonder if it would be possible to repressurize the tube (by blowing a
big hole in it?) within 15 seconds or so.

~~~
namlem
The hyperlink won't be a vacuum. It's just a low air pressure chamber. The
plan has never been to maintain a vacuum since that's too difficult at such
large scales.

~~~
mikeash
Hyperloop is planned to run at roughly 0.1% of sea level air pressure. For the
purposes of a discussion about human survival in the event of pressurization
failure, that's effectively a vacuum.

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Animats
The WARR sled runs on, and is propelled by, wheels.[1] It's not flying on an
air cushion, which was the original Hyperloop concept. Nor is it a maglev,
like Hyperloop One.[2] (That's a vactrain.)

[1] [http://hyperloop.warr.de/pod-ii/](http://hyperloop.warr.de/pod-ii/) [2]
[https://hyperloop-one.com/blog/how-and-why-were-
levitating](https://hyperloop-one.com/blog/how-and-why-were-levitating)

~~~
kaffeemitsahne
So originally they wanted to have an air cushion, inside a vacuum enclosure?

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nbanks
Yes. The Hyperloop concept Musk published in 2013 [1] was based on a partial
vacuum with air cushions like a plane flying at 40,000 feet rather than a
satellite zooming through space.

[1]
[http://www.spacex.com/sites/spacex/files/hyperloop_alpha-201...](http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf)

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Robotbeat
By the way, the only reason commercial air travel can go at transonic speeds
(670mph) efficiently is because it's at near vacuum, i.e. at high altitude,
just like Hyperloop.

That's also why conventional or maglev non-vacuum trains won't ever travel as
fast as passenger air travel cruise speed. It takes a stupendous amount of
energy to travel that fast near sea level. Even a lot of supersonic fighter
jets can only reach supersonic speeds at high altitude.

The whole advantage of hyperloop (and vacuum-trains) is you're bringing that
high altitude air down to near sea level. The other things are implementation
details.

This is why hyperloops will fairly quickly eclipse other train speed records,
currently 375mph for maglev.

Just a FYI, the Hyperloop One pod recently reached 192mph, so this student pod
bested them (although the student pod is much smaller and the student
competition hyperloop track is much longer, so the Hyperloop One pod must've
been higher performance).

~~~
jacquesm
Air pressure at 10 km altitude is about 30% or so of sea level, it is much
less but definitely not near vacuum.

If it were a near vacuum any airplane would stall...

~~~
Robotbeat
747 max altitude is 45,100ft, or 16% sea level.

At Concorde's cruise altitude of 18000m, it's just 8% of sea level. Of course,
Concorde had to fly very fast to keep from stalling. U2 spy plane has the same
problem at 21,000ft, 5% sea level pressure. It's nearly stalled while
cruising. I wouldn't call that "definitely not near vacuum." Still higher
planes, one at 100,000 ft, have flown (NASA's Helios), 1% atm. Near Mars
pressures, definitely near vacuum. (as much as this term is subjective)

Hyperloop One plans an altitude equivalent of about 200,000 ft, or about 0.16%
sea level pressure.

~~~
jacquesm
Seen any Concordes lately? The last time I saw one it was sitting on a static
display looking very good but going nowhere.

Concorde is not a representative sample of passenger air travel, neither is a
U2 spy plane nor is Helios.

What Hyperloop One plans is not relevant, what they will manage to achieve is
and there is _no way_ that they will manage to run that network at 0.16% of
sea level pressure.

The whole hyperloop discussion would benefit from an injection of some solid
engineering principles, the linked article is a nice example of what can be
done and even if they won a competition has nothing to do with the hyperloop
concept as presented originally, the vast majority of the original engineering
challenges still stands.

~~~
Robotbeat
"Seen any Concordes lately?"

Nevertheless, that was the genesis of the Hyperloop idea. Musk mentioned
Concordes as an example.

And you can't (realistically) have supersonic passenger travel without
traveling at similar altitudes (or altitude equivalent pressure) because it
uses too much energy. I think you're missing this key point: transonic
(670mph) or supersonic speed travel requires low or near-vacuum pressures to
work efficiently. Other aspects of hyperloop (or related ideas) are
implementation details. Power losses scale with drag which scales with air
density. And to the degree that Concorde failed because it was too
inefficient, having an even lower operating pressure should address that as
well.

"Concorde is not a representative sample of passenger air travel" It is, along
with the Soviet jet, the /only/ sample of supersonic passenger air travel.

I don't see any solid engineering analysis in your comment, by the way, just
assertions that this or that cannot be done.

~~~
jacquesm
The general idea here is not that something can not be done in principle or
not but that it will be hard to do it _economically_. Little details like
radius-of-turn, g-forces imparted on passengers, cost of maintaining
infrastructure and so on are important.

Elon Musk so far has done spectacularly well at re-doing stuff that was
already done in principle - other than the re-use of rockets, which is very
impressive and a serious source of headache for SpaceX competitors. To create
a whole new class of transportation from scratch is a different kind of
challenge. I wish him well, it is just that these mere matters of engineering
are hard and long distance travel is mercilessly dictated by economics. Hence
my reference to Concorde, which worked well but was not competitive in the
longer haul. So if you are looking for engineering reasons you will not get
those from me.

For now Hyperloop does not exist, we will see if it gets done in the next
decade. Or two. And once it has been done whether or not it can be operated
profitably.

~~~
Robotbeat
By this standard only way to satisfy your question of whether it can be done
_economically_ is if it already is being done, and being done en masse.
There's no point in discussing any future technology if this is the standard,
as there's no way this can be satisfied except in hindsight.

This sort of absurd standard of discussion is super common on the Internet and
highly boring as it leaves zero room for actual insight or analysis, as
everything that isn't already far in the rearview mirror is dismissed as
"unconvincing."

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sillysaurus3
Holy moly that's fast.
[https://twitter.com/elonmusk/status/902039243601485824](https://twitter.com/elonmusk/status/902039243601485824)

Can you imagine traveling that way?

Sorry for the fluff comment, but wow!

~~~
mason55
> _Can you imagine traveling that way?_

Plenty of people can imagine it because they travel that way every day. Trains
all over Asia and Europe reach those speeds and faster.

~~~
yorwba
Maybe I have been taking the wrong trains (in Germany), but 200 mph (321 km/h)
seems plenty fast to me.

That's higher than the maximum speed of most of Deutsche Bahn's high-speed
trains: [https://en.wikipedia.org/wiki/Intercity-
Express](https://en.wikipedia.org/wiki/Intercity-Express)

Even those that can go faster than 300 km/h tend to do so only on very short
legs, because they need long straight stretches to stay on track and have to
accelerate/decelerate at the ends as well.

~~~
adrianN
Hyperloops would also have those constraints on track layout.

~~~
stevep98
I think this is another reason why musk is getting into tunneling. Reducing
the cost of tunnels lets you place the hyperloop track in a more optimal
location.

~~~
convolvatron
would you still use a steel containment pipe? poured cement seems like it
would be cheaper, but every example I've seen develops cracks and starts
letting in water.

------
tveita
Details on the winning pod: [http://hyperloop.warr.de/pod-
ii/](http://hyperloop.warr.de/pod-ii/)

IIUC it accelerates using a wheel pressed towards the track, powered by an
electric engine... no fancy magnets or fans and air cushions.

It's cool, but it doesn't look a lot like the original Hyperloop white paper.

e: from the competition rules at
[http://www.spacex.com/sites/spacex/files/2016_0831_hyperloop...](http://www.spacex.com/sites/spacex/files/2016_0831_hyperloop_competition_ii_rules.pdf),
it looks like they were at least using an evacuated tube.

~~~
giarc
>It's cool, but it doesn't look a lot like the original Hyperloop white paper.

That's the first thing I noticed. This seems like a competition for fast
electric train.

~~~
lucideer
From my understanding, it seems the main concept behind Hyperloop is a "fast
electric train" in an evacuated tube.

Other design details from the original spec. don't seem as central to the
definition.

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Robotbeat
Musk made comments about traveling at up to 800mph in this 0.8 mile tube.

At constant acceleration, you'd have to have about 10 gees (each way) to reach
this speed in that short tunnel:

sqrt(2 * acceleration * distance) = speed

sqrt(2 * 100m/s^2 * 0.4mi)=358m/s = 800mph

[https://www.google.com/search?q=sqrt(2*100m/s^2*0.4mi)](https://www.google.com/search?q=sqrt\(2*100m/s^2*0.4mi\))

To accelerate at 100m/s^2 at the end when you're at 358m/s requires about
35.8kW/kg, which is /insane/. You'd need some sort of active cooling to get
that to work. (Water flashed to vapor? Liquid nitrogen?)

So you'd probably have a really high acceleration at first (as fast as the
sled could handle, maybe 100g?) and really hard deceleration at the end in
order to reduce required electric motor specific power. Might be tough to do
all that with a single motor, so you probably need either gearing or a two-
stage design, with a larger low-speed, extreme acceleration stage pushing a
lighter high speed moderate acceleration stage. I don't know if two stage
designs are allowed, but it'd certainly help in this competition.

