Hyperloop

HYPERLOOP

The Hyperloop

• A concept for a fifth mode of transport after planes, trains, cars and boats.• Cheaper, faster, less environmental footprint.• Inflection point of about 1500 km after which air

travel becomes faster and cheaper.

Elon Musk

Founder of PayPal, SpaceX, Tesla, SolarCity.

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong".

-Clarke’s First Law

The Concept• Low pressure tube with capsules that move back and forth

throughout the length of the tube.• Accelerated via a linear magnetic accelerator.• Supported on a cushion of air.• Proposed route from Los Angeles to San Fransisco (approx. 560 km).• To be covered in just 35 minutes, with capsules leaving end stations

every 2 minutes.

The Hyperloop

Air Hockey Table

ConcordeRail Gun

The Concorde Part

The Concorde Part• Streamlined shape reduces drag.• Low pressure in the tube (100 Pa) reduces drag further.

Problem of Choked Air Flow• Kantrowitz limit gives the top speed for a given tube to pod area ratio,

above which flow will be choked.• Build up of air in front of capsule and subsequent increase in resistance.

• Fan and compressor in the front compresses this air and routes it to the rear via a bypass tunnel.

• This air expands in the nozzle at the back, also providing additional thrust.

The Rail Gun Part

The Rail Gun Part

• Magnetic linear accelerators present at various locations – rotor on the capsule, stator fixed to the tube.• Route divided into sections with speeds of 300 mph,

555 mph, 760 mph.• Maximum linear acceleration of 1g achieved while

accelerating from 300 to 760 mph. • Smaller turning radius implies a lower speed, such

that centripetal acceleration is not more than 0.5g.

The Air Hockey Table Part

The Air Hockey Table Part

• Part of the compressed air is rerouted to air bearings.• Known as external pressure (EP) bearing and effective

when capsule is stationary or moving at very high speeds.

• Each ski is integrated into a mechanical suspension.• 28 such air bearing skis.• Additional lift is provided aerodynamically – front edge

is higher than the rear edge (at an angle of 0.05º).• Viscous interactions generate pressure differential to

provide lift.

Advantages

• Safe • Fast • Low cost • Immune to weather• Energy saving • Sustainably self-powering • Resistant to earthquakes • Not disruptive to those along the route

Major Concerns

• In some parts, total acceleration experienced by the passenger will be more than 1g, taking the resultant of linear and centripetal acceleration. • Commercial aircrafts accelerate at approximately 0.25g,

roller coasters at (4-6)g.• Uneven shear stress markings were seen on the outside

of the capsule body during simulation.• Suggestion: Air bearings on top of the pod to improve

stability and help the pod stay balanced.

Thank You!

References• http://www.spacex.com/sites/spacex/files/hyperloop_alpha-

20130812.pdf• http://www.teslamotors.com/blog/hyperloop• http://science.howstuffworks.com/rail-gun1.htm• http://www.gizmag.com/hyperloop-musk-analysis/28672/• http://www.economist.com/blogs/economist-explains/

2013/08/economist-explains-12• http://www.businessweek.com/articles/2013-09-18/elon-

musks-hyperloop-will-work-says-some-very-smart-software