13yo Invents a Better Hyperloop - It's still a STUPID IDEA

[Fungus]

What is the cost of pumping all the air out of a tunnel hundreds or thousands of kms long and the machinery to do it?

Nobody's talking about pumping all the air out of the tube, just some percentage of it. Enough removed to reduce drag, enough left over for the engines to work.

ie. Some amount of air is needed inside the tube. The exact amount needed is still being tested and figured out via all these prototypes that people are building.

Your question is impossible to answer right now because the difference in cost/difficulty between removing 90%, 95% ... 99% of the air is orders of magnitude.

It may be that maximum efficiency is with only 80% removed, nobody's sure yet. 80% is a lot easier/cheaper than even 99% vacuum.

[StillTrying]

How are the trains and passengers going to get into and out of the 80% vacuum.

[EEVblog]

I doubt that Virgin for example had a team of crack engineers thoroughly investigate the feasibility and odds of success before they invested. Nor did the Saudi Arabian government.

Funny that you avoid to mention SNCF

I'm supposed to be impressed by a rail company investing in Hyperloop?
Talk to Colas about how their world leading expertise in roads helped Wattway. I do believe the worlds "total failure" apply.
https://www.sciencealert.com/the-world-s-first-solar-road-has-turned-out-to-be-a-disappointing-failure

[Fungus]

How are the trains and passengers going to get into and out of the 80% vacuum.

Through an airlock? 

PS: You know that people would die of asphyxiation in today's commercial aircraft if they didn't pressurize them, right?

[StillTrying]

Through an airlock? 

Well that sounds easy enough.

[GeorgeOfTheJungle]

Make that two airlocks. One for the tunnel another one for the capsule.

[Fungus]

Make that two airlocks. One for the tunnel another one for the capsule.

One would assume that:
a) You walk into the capsule normally
b) The capsule closes its doors
c) The capsule goes through an airlock

One airlock, no space suit needed.

(If this ever gets as far as carrying people...)

[GeorgeOfTheJungle]

Sorry but no. One for the tunnel another one for the capsule, that's two. If not, please define airlock.

[StillTrying]

One airlock will be 2 doors, with enough space between the 2 doors for the train.

This one shows the airlock, it has to hold back around 120 tons.
https://interestingengineering.com/virgin-hyperloop-one-sets-new-speed-record-at-240mph

[GeorgeOfTheJungle]

Ok. So if the airlock is (I've had to look it up) "a compartment with controlled pressure and parallel sets of doors, to permit movement between areas at different pressures." it's even worse than I thought yet, because you then need three or more perfectly air tight vacuum proof doors: one (at least) in the capsule and two to seal the compartment in the tunnel. Great!

Edit:
The opening in the tunnel to access the capsule's door needs yet another door, so => four minimum.

[Altair8800]

In the Hyper-loop alpha white paper they mention 100 Pa (Pascals) of pressure.  Air pressure at Sea Level is 101325 Pa (pascals) or 1 Atm (Atmosphere, depreciated unit).

Also in the Hyper-loop alpha white paper they mention "equivalent  to  flying above  150,000  feet  altitude"

Which equates 140 Pa (and is close to 100 Pa)

https://www.wolframalpha.com/input/?i=air+pressure+at+150%2C000++feet++

This is very close to 99.9% vacuum

Source: SpaceX Hyperloop Alpha White Paper

Just  as  aircraft  climb  to  high  altitudes  to  travel  through  less  dense  air, Hyperloop encloses the capsules in a reduced pressure tube. The pressure of air in  Hyperloop  is  about  1/6  the  pressure  of  the  atmosphere  on  Mars.  This  is  an operating  pressure  of 100  Pascals,  which reduces  the  drag  force  of  the  air  by 1,000  times  relative  to  sea  level  conditions  and  would  be  equivalent  to  flying above  150,000  feet  altitude. A  hard  vacuum  is  avoided  as  vacuums  are expensive  and  difficult  to  maintain  compared  with  low  pressure  solutions. Despite  the  low  pressure,  aerodynamic  challenges  must  still  be  addressed. These  include  managing  the  formation  of  shock  waves  when  the  speed  of  the capsule  approaches  the  speed  of  sound, and  the  air  resistance  increases sharply.  Close  to  the  cities  where  more  turns  must  be  navigated,  capsules travel at a lower speed. This reduces the accelerations felt by the passengers, and  also  reduces  power  requirements  for  the  capsule.  The  capsules  travel  at 760 mph (1,220 kph, Mach 0.99 at 68 ºF or 20 ºC).

[ogden]

Funny that you avoid to mention SNCF

I'm supposed to be impressed by a rail company investing in Hyperloop?

Highly unlikely. You are so preopinionated about just everything related to Hyperloop. Funny that you removed GE Ventures from quote

[Fungus]

In the Hyper-loop alpha white paper they mention 100 Pa (Pascals) of pressure.  Air pressure at Sea Level is 101325 Pa (pascals) or 1 Atm (Atmosphere, depreciated unit).

When was that?

Goal posts can move.

(and already have...)

[Altair8800]

In the Hyper-loop alpha white paper they mention 100 Pa (Pascals) of pressure.  Air pressure at Sea Level is 101325 Pa (pascals) or 1 Atm (Atmosphere, depreciated unit).

When was that?

Goal posts can move.

(and already have...)

The Hyperloop Alpha white paper is dated 16 Aug 2013.

Also in it is mention of 1/6 atmosphere of Mars which is 1/6*(660 Pa) = 110 Pa (which is again close to the 100 Pa stated).
https://www.wolframalpha.com/input/?i=air+pressure+on+mars

Understand things/goalposts can change.  But this is all I have specifics wise...

You said goal post can change and have already have...  Can you give a source and/or specifics?

[Fungus]

You said goal post can change and have already have...  Can you give a source and/or specifics?

The only long-term goal is to get a train through a tube at high speed. Nothing else is fixed.

The system used by the team I was on requires a bit of air in the tube for propulsion. It sucks air into the front of the train and shoves it out the back to make it move. We estimated a 30% saving in air-removal costs because of this.

[GeorgeOfTheJungle]

Reinventing the turbofans... great!

[Fungus]

Reinventing the turbofans... great!

What's the problem? 

[nctnico]

Here  just "off the top of my head", are some examples of large investments which never achieved any return to the investors:-

Gas Turbine cars.
Nuclear powered merchant ships (only four were ever built, & only one is still in service).
Nuclear powered Aircraft.
Nuclear powered cars.
Modern Airships
Modern Steamcar
Flying car

No doubt with a bit of searching, I can find many more!

OK, of this seven, two of them were principally government funded, but that leaves five that apparently sane investors poured money into.

The interesting thing is that, much like Hyperloop, none of them were unattainable, given enough money & time, but the problems piled up until they became overwhelming.

That is something of all times. Leonardo Da Vinci came up with this in 1493 but he didn't had the materials to make it work.

It is only since a short period of time we can build stuff like this:

[GeorgeOfTheJungle]

And... ? Elon invented the drones too?

[Bud]

It is only since a short period of time we can build stuff like this:

So now you have all the materials. Why dont you build one using Leo's drawings. Is it because it still will not fly?

[Fungus]

And... ? Elon invented the drones too?

No, but think of how long it took drones to go from 'expensive!' to '$19.99'.

The only real engineering problem of Hyperloop is "low pressure". If somebody solves that or comes up with a way to not need such low pressures then it's game-on.

[ogden]

So now you have all the materials. Why dont you build one using Leo's drawings. Is it because it still will not fly?

Electric vehicles are "reinvented" nowadays. Why do you think they do not look like this?

[Bud]

What is different in your example? The car shape ( appearance)? That old vehicle *Worked* and used the same principles to propell. Leo' s machine did not fly and will not fly  since it was using a different idea about the propellant force. None of the new nanomaterials will make it fly.

[Fungus]

Leo' s machine did not fly and will not fly

So? You can bet he'd have figured out the need for a tail rotor after a single prototype, etc.

Also: Most of his drawings had deliberate flaws in them, eg. this one:


Would that have moved anywhere if you built one? No.

Do you think he didn't know that...?

[ogden]

What is different in your example?

Message. - That not only materials but engineering is different today.

Leo' s machine did not fly and will not fly  since it was using a different idea about the propellant force. None of the new nanomaterials will make it fly.

Leo's machine did not fly. Similar machines that are built using modern materials and engineering do fly indeed:
https://en.wikipedia.org/wiki/Helicopter