Can some aerospace wind tunnel expert do a brief, simplified calculation of the power required to create a 900kph air flow in a 1800km (i.e. 1hr each way) loop tunnel/tube, say 10m in diameter?
Lets assume we have the tube (or tunnnel). Perhaps this power alone sheds light on the cost viability.
I'm still having visions of Nikola Tesla's declined years.
I think that is a fair call but you should probably wait until we find out just what the idea is.
In my opinion Nicola Tesla's induction motor was the greatest idea of the 20th century.
His later propositions not so much so and I think a valuable lesson.
this technology will require less power than creating a vacuum and you can easier seperate the tube into sections than the vacuum tube
I still believe in www.swiss-metro.ch! Underground and therefore hard to be attacked by stupid types like terrorists!
Can Elon convince Jerry Brown to hold off on His Bakersfield to Fresno
multi billion dollar slow speed train for a couple of weeks then?
How much friction heat will 900kph air create in the tube? How will this be dissipated along 1800 km? How is the speed of the moving air maintained? See friction previously mentioned. How can this be protected from sabotage? Lots of issues to deal with but I do like the concept.
It must be nice to have the chutzpa to put together these ideas and then use crowd-sourced ideas to refine them. Call it open source, call it democratic input but, at the end of it all, the guy with bulging chequing account is Mr. Musk. Maybe he will see his way clear to reward the people whose ideas have been capitalized on.
In the long-haul (no pun) it will be good to reduce take-off and landing numbers, particularly at hub airports. The amount of spent fuel blown into the air by jetliners is mind boggling. Same goes for transport ships but that's another horizon.
The Dyson company did a lot of the needed work with airflow induction.
Commercial maglev trains already exist so Elon is just using the effects to create synergies of near frictionless weight carrying and waveform surfing and a Push Pull effect of traveling with the wind as you have near zero wind resistance if you are traveling at near the same speed.
I doubt the train's front or rear will have a sharp aerodynamic profile.
Kudo's to Elon Musk keep on KISS ing!
That's what the Russians and British thought too... :[
Finally someone with both the vision and, moreover, the drive to make it work. Gather the right energetic and positive people around you; Negativity is for the slow minded and lazy. I envision Hyperloops criss-crossing the country and eventually the world. The Moon and Mars cities as well?
From the "what could possibly go wrong department": remember the standard movie scene where a train is headed for a broken/missing track? They engage the brakes, and it stops just in time, with a few yards of train hanging over the edge. Now, will these trains have some sort of (single use?) emergency braking system? Will deploying it require replacing the track, or just the brakes?
On the compensation for ideas: If you contribute an idea, the proper reward is a line in the credits. Financial rewards are for those who put their own hard earned cash on the line for such a project.
I think it is a pipe dream. The reason I think that is because Mr Musk is going to open source the idea. If he could make it work he would not need to do that.
I read the open sourcing as a way to gracefully bail out of a project that has proven to be impossible on paper.
Paul van Dinther
re; Daryl McDougall
Nikola Tesla went from being possibly the world's greatest genius to a crank. I hope something similar has not happened to Elon Musk.
There are always reasons why something could not/would not work. Some people see them as an excuse to do nothing. Others see them as a challenge to be overcome.
By Open Sourcing the concept, surley he opens the idea up to a WORLD of minds so that any obsitcles present on paper, can be tackled on a global scale until at last, a working solution is found.
Once upon a time, if someone had said "Let's go to another country", the answer would have been "Dont be silly! Have you any idea how far that is to swim?"
Envision "pumping stations" placed strategically along the loop, each with a pair of motor/gear driven turbofans (similar to huge jet engines, but non-fueled) all 'pumping' air while running at speeds approaching 10,000 RPM.
As you can imagine, there'd be one helluva vacuum on the intake side, and a similarly hellish amount of "push" coming out the exit of each fan. And these stations, once online and up to speed, could be expected to duct several TONS of air per second around a 'closed' loop, renewing said mass with outside air to attemperate mechanical and friction heat.
Car speed can be controlled by modulating the amount of bypass air (and mag lift) to gradually bring an 'injected' unit up to speed - and similarly to slow it down at the other end, prior to shunting it off to the station stop.
A more sophisticated system would have two parallel sets of loops, one atop the other. The lower 9m diameter loop would be maintained at a 'moderate' air movement velocity, with the upper 6m diameter loop accelerated to full velocity. At various points along the way, cars could be shunted between loops for a number of reasons, incl. traffic control, mechanical problems, and station stop/starts.
And a few dedicated bio-fuel cogen plants (40+MW each) would ensure a decent amount of barely subsonic mass flow cranking night & day.
Passenger safety, cabin environment, graduated g-forces, and other ergonomic considerations may prove to be the real challenges however. So let's see what the guy has to say.
Any system that uses air to accelerate an object through a column of air at rest or nearly at rest is subject to the extreme energy requirements of moving down a closed (or nearly closed) tube at or above the speed of sound.
The distance is 355 miles between SF and LA calling for an average speed of about 700 mph to achieve the about 30 minute transit. The peak speed must be at or above the speed of sound at sea level.
If the actual time was on the order of 40 to 45 minutes the air based transit is more likely and affordable.
The motion of flight within a tube is a well characterized process and is certainly well suited to short distance transport applications.
People care about time not speed 1 hour is the right time for a trip, whether its from LA to SF or SF to NY (indeed 1 hr. from Seattle to Rio de Janero). Understanding this it is easy to see that there is a place for Hyperloop and Terraspan in the over all transport of people and freight on our continent and hemisphere. Just as there is a place for cars, helicopters, small jets and Dreamliners.
Who says you need a complete vacuum?
Perhaps a lead/lag system combined with mag propulsion and levitation will work fine and the friction will be low enough without having to consume too much energy.
Overhead, a vacuum draws air at a distance forward of the train. While underneath, ports open up with a little lag.
(similar to how an motor has a rotating magnetic field with alternating poles that pull from in front and push from behind.)
In fact, a set of accumulator and vacuum tanks which are charged by pistons may be more efficient than losses that would be experienced by blades.
Educated guess here, but if a vacuum is ideal, wouldn't it make sense to at least fill the loop with a lighter than air gas to lower friction? Pure Nitrogen is all I can think if that might be easy to produce/cost effective/safe'ish - but would it make that much difference?
I think a tube of 10m in diameter would be too large to get a 900 kph flow at reasonable costs.
Assuming a 1,8m diameter, you would require an air flow of around 2,3 million cubic meter per hour (55 Mm3/d) to obtain a 900 kph air flow in the tunnel.
Producing such a flow is manageable: it is common practice with the turbines used in the natural gas pipeline business.
I guess a few dozen kW would be enough to steer the turbine. That's a lot, but keep in mind that high-speed trains are fitted such as TGV with 9 kW engines for 500 passengers.
But then you still need some more energy (which is not so easy to estimate)
for the propulsion, as the capsule is not pushed forward by the pressure difference between the back and the front of the capsule, but rather by the magnetic drive.
for the levitation through air cushion, some more compression will be required, the amount depending on the characteristcs of the air jets on the inside of the tube.
Well I meant MW, not kW, sorry. Assuming 1 bar air pressure in and out of the turbine we would require approx. 120 MW of power.