Hyperloop Alpha Intro
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- Table 1. Crew capsule weight and cost breakdown Vehicle Component Cost ($) Weight (kg)
- Table 2. Cargo and crew capsule weight and cost breakdown Vehicle Component Cost ($) Weight (kg)
- Figure 13. Typical vacuum pump speed for functional pressure range.
- Figure 14. Hyperloop capsule in tube cutaway with attached solar arrays.
- 4.2.2. Tube Construction
- 4.2.3. Pylons and Tunnels
- Figure 15. First mode shape of Hyperloop at 2.71Hz (magnified x1500).
- Figure 18. Maximum principal stress at 1g Inertia in X (psi) (magnified x10).
- Figure 20. Maximum shear stress at 1g Inertia in X (psi) (magnified x10). 4.2.4. Station Construction
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4.1.5. Onboard Power The passenger capsule power system includes an estimated 5,500 lb (2,500 kg) of batteries to power the capsule systems in addition to the compressor motor (using 3,400 lb or 1,500 kg of the batteries) and coolant. The battery, motor, and electronic components cost is estimated to be near $150,000 per capsule in addition to the cost of the suspension system. The passenger plus vehicle capsule power system includes an estimated 12,100 lb (5,500 kg) of batteries to power capsule systems in addition to the compressor motor (using 8,900 lb or 4,000 kg of the batteries) and coolant. The battery, motor and electronic components cost is estimated to be near $200,000 per capsule in addition to the cost of the suspension system.
In order to propel the vehicle at the required travel speed, an advanced linear motor system is being developed to accelerate the capsule above 760 mph (1,220 kph) at a maximum of 1g for comfort. The moving motor element (rotor) will be located on the vehicle for weight savings and power requirements while the tube will incorporate the stationary motor element (stator) which powers the vehicle. More details can be found in the section 4.3.
The overall propulsion system weight attached to the capsule is expected to be near 2,900 lb (1,300 kg) including the support and emergency braking system. The overall cost of the system is targeted to be no more than $125,000. This brings the total capsule weight near 33,000 lb (15,000 kg) including passenger and luggage weight. Hyperloop Passenger Plus Vehicle Capsule The overall propulsion system weight attached to the capsule is expected to be near 3,500 lb (1,600 kg) including the support and emergency braking system. The overall cost of the system is targeted to be no more than $150,000. This Page 23
brings the total capsule weight near 57,000 lb (26,000) kg including passenger, luggage, and vehicle weight.
The overall cost of the Hyperloop passenger capsule version (Table 1) is expected to be under $1.35 million USD including manufacturing and assembly cost. With 40 capsules required for the expected demand, the total cost of capsules for the Hyperloop system should be no more than $54 million USD or approximately 1% of the total budget. Although the overall cost of the project would be higher, we have also detailed the expected cost of a larger capsule (Table 2) which could carry not only passengers but cargo and cars/SUVs as well. The frontal area of the capsule would have to be increased to 43 ft 2 (4 m
2 ) and the tube diameter would be increased to 10 ft 10 in. (3.3 m).
Capsule Structure & Doors: $ 245,000 3100 Interior & Seats: $ 255,000 2500
Propulsion System: $ 75,000 700 Suspension & Air Bearings: $ 200,000 1000
Batteries, Motor & Coolant: $ 150,000 2500 Air Compressor: $ 275,000 1800
Emergency Braking: $ 50,000 600 General Assembly: $ 100,000 N/A
Passengers & Luggage: N/A
2800
Total/Capsule: $ 1,350,000 15000 Total for Hyperloop: $ 54,000,000
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Table 2. Cargo and crew capsule weight and cost breakdown Vehicle Component Cost ($) Weight (kg)
Capsule Structure & Doors: $ 275,000 3500
Interior & Seats: $ 185,000 2700 Propulsion System: $ 80,000 800
Suspension & Air Bearings: $ 265,000 1300 Batteries, Motor & Coolant: $ 200,000 5500
Air Compressor: $ 300,000 2500 Emergency Braking: $ 70,000 800
General Assembly: $ 150,000 N/A Passengers & Luggage: N/A 1400
Car & Cargo: N/A
7500
Total/Capsule: $ 1,525,000 26000 Total for Hyperloop: $ 61,000,000
The main Hyperloop route consists of a partially evacuated cylindrical tube that connects the Los Angeles and San Francisco stations in a closed loop system (Figure 2). The tube is specifically sized for optimal air flow around the capsule improving performance and energy consumption at the expected travel speed. The expected pressure inside the tube will be maintained around 0.015 psi (100 Pa, 0.75 torr), which is about 1/6 the pressure on Mars or 1/1000 the pressure on Earth. This low pressure minimizes the drag force on the capsule while maintaining the relative ease of pumping out the air from the tube. The efficiency of industrial vacuum pumps decreases exponentially as the pressure is reduced (Figure 13), so further benefits from reducing tube pressure would be offset by increased pumping complexity.
In order to minimize cost of the Hyperloop tube, it will be elevated on pillars which greatly reduce the footprint required on the ground and the size of the construction area required. Thanks to the small pillar footprint and by
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maintaining the route as close as possible to currently operated highways, the amount of land required for the Hyperloop is minimized. More details are available for the route in section 4.4. The Hyperloop travel journey will feel very smooth since the capsule will be guided directly on the inner surface of the tube via the use of air bearings and suspension; this also prevents the need for costly tracks. The capsule will bank off the walls and include a control system for smooth returns to nominal capsule location from banking as well. Some specific sections of the tube will incorporate the stationary motor element (stator) which will locally guide and accelerate (or decelerate) the capsule. More details are available for the propulsion system in section 4.3. Between linear motor stations, the capsule will glide with little drag via air bearings.
The geometry of the tube depends on the choice of either the passenger version of Hyperloop or the passenger plus vehicles version of Hyperloop. In either case, if the speed of the air passing through the gaps accelerates to supersonic velocities, then shock waves form. These waves limit how much air can actually get out of the way of the capsule, building up a column of air in front of its nose and increasing drag until the air pressure builds up significantly in front of the capsule.
With the increased drag and additional mass of air to push, the power requirements for the capsule increase significantly. It is therefore very important to avoid shock wave formation around the capsule by careful selection of the capsule/tube area ratio. This ensures sufficient mass air flow around and through the capsule at all operating speeds. Any air that cannot pass around the annulus between the capsule and tube is bypassed using the onboard compressor in each capsule. Page 26
Passenger Hyperloop Tube The inner diameter of the tube is optimized to be 7 ft 4 in. (2.23 m) which is small enough to keep material cost low while large enough to provide some alleviation of choked air flow around the capsule. The tube cross-sectional area is 42.2 ft 2 (3.91 m 2 ) giving a capsule/tube area ratio of 36% or a diameter ratio of 60%.
It is critical to the aerodynamics of the capsule to keep this ratio as large as possible, even though the pressure in the tube is extremely low. As the capsule moves through the tube, it must displace its own volume of air, in a loosely similar way to a boat in water. The displacement of the air is constricted by the walls of the tube, which makes it accelerate to squeeze through the gaps. Any flow not displaced must be ingested by the onboard compressor of each capsule, which increases power requirements. The closed loop tube will be mounted side-by-side on elevated pillars as seen in Figure 5. The surface above the tubes will be lined with solar panels to provide the required system energy. This represents a possible area of 14 ft (4.25 m) wide for more than 350 miles (563 km) of tube length. With an expected solar panel energy production of 0.015 hp/ft 2 (120 W/m 2 ), we can expect the system to produce a maximum of 382,000 hp (285 MW) at peak solar activity. This would actually be more energy than needed for the Hyperloop system and the detailed power requirements will be described in section 4.3.
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Passenger Plus Vehicle Hyperloop Tube The inner diameter of the tube is optimized to be 10 ft 10 in. (3.30 m), larger than the passenger version to accommodate the larger capsule. The tube cross- sectional area is 92.1 ft 2 (8.55 m
2 ) giving a capsule/tube area ratio of 47% or a diameter ratio of 68%. The closed passenger plus vehicle Hyperloop tube will be mounted side-by-side in the same manner as the passenger version as seen in Figure 5. The surface above the tubes will be lined with solar panels to provide the required system energy. This represents a possible area of 22 ft (6.6 m) wide for more than 350 miles (563 km) of tube length. With an expected solar panel energy production of 0.015 hp/ft 2 (120W/m 2 ), we can expect the system to produce a maximum of 598,000 hp (446 MW) at peak solar activity. This would actually be more energy than needed for the passenger plus vehicle Hyperloop system and the specific power requirements will be detailed in section 4.3.
The stations are isolated from the main tube as much as possible in order to limit air leaks into the system. In addition, isolated branches and stations off the main tubes could be built to access some towns along the way between Los Angeles and San Francisco. Vacuum pumps will run continuously at various locations along the length of the tube to maintain the required pressure despite any possible leaks through the joints and stations. The expected cost of all required vacuum pumps is expected to be no more than $10 million USD. 4.2.2. Tube Construction In order to keep cost to a minimum, a uniform thickness steel tube reinforced with stringers was selected as the material of choice for the inner diameter tube. Tube sections would be pre-fabricated and installed between pillar supports spaced 100 ft (30 m) on average, varying slightly depending on location. This relatively short span allows keeping tube material cost and deflection to a minimum. The steel construction allows simple welding processes to join different tube sections together. A specifically designed cleaning and boring machine will make it possible to surface finish the inside of the tube and welded joints for a better gliding surface. In addition, safety emergency exits and pressurization ports will be added in key locations along the length of the tube. Passenger Hyperloop Tube A tube wall thickness between 0.8 and 0.9 in. (20 to 23 mm) is necessary to provide sufficient strength for the load cases considered in this study. These cases included, but were not limited to, pressure differential, bending and Page 28
buckling between pillars, loading due to the capsule weight and acceleration, as well as seismic considerations. The cost of the tube is expected to be less than $650 million USD, including pre-fabricated tube sections with stringer reinforcements and emergency exits. The support pillars and joints which will be detailed in section 4.2.3. Passenger Plus Vehicle Hyperloop Tube The tube wall thickness for the larger tube would be between 0.9 and 1.0 in (23 to 25 mm). Tube cost calculations were also made for the larger diameter tube which would allow usage of the cargo and vehicle capsule in addition to the passenger capsule. In this case, the cost of the tube is expected to be less than $1.2 billion USD. Since the spacing between pillars would not change and the pillars are more expensive than the tube, the overall cost increase is kept to a minimum. 4.2.3. Pylons and Tunnels The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquakes. In addition, the pillar to tube connection nominal position will be adjustable vertically and laterally to ensure proper alignment despite possible ground settling. These minimally constrained pillars to tube joints will also allow a smoother ride. Specially designed slip joints at stations will be able to take any tube length variance due to thermal expansion. This is an ideal location for the thermal expansion joints as the speed is much lower nearby the stations. It thus allows the tube to be smooth and welded along the high speed gliding middle section. The spacing of the Hyperloop pillars retaining the tube is critical to achieve the design objective of the tube structure. The average spacing is 100 ft (30 m), which means there will be roughly 25,000 pillars supporting both Hyperloop tubes and overhead solar panels. The pillars will be 20 ft (6 m) tall whenever possible but may vary in height in hilly areas or where obstacles are in the way. Also, in some key areas, the spacing will have to vary in order to pass over roads or other obstacles. Small spacing between each support reduces the deflection of the tube keeping the capsule steadier and the journey more enjoyable. In addition, reduced spacing has increased resistance to seismic loading as well as the lateral acceleration of the capsule. Due to the sheer quantity of pillars required, reinforced concrete was selected as the construction material due to its very low cost per volume. In some short areas, tunneling may be required to avoid going over mountains and to keep the route as straight as possible. The cost for the pillar construction and tube joints is anticipated to be no more than $2.55 billion USD for the passenger version tube and $3.15 billion USD for the passenger plus vehicle version tube.
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The expected cost for the tunneling is expected to be no more than $600 million USD for the smaller diameter tube and near $700 million USD for the larger diameter tube. Structural simulations (Figure 15 through Figure 20) have demonstrated the capability of the Hyperloop to withstand atmospheric pressure, tube weight, earthquakes, winds, etc. Dampers will be incorporated between the pylons and tubes to isolate movements in the ground from the tubes.
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4.2.4. Station Construction Hyperloop stations are intended to be minimalist but practical with a boarding process and layout much simpler than airports. Due to the short travel time and frequent departures, it is envisaged that there will be a continual flow of passengers through each Hyperloop station, in contrast to the pulsed situation at airports which leads to lines and delays. Safety and security are paramount, and so security checks will still be made in a similar fashion as TSA does for the airport. The process could be greatly streamlined to reduce wait time and maintain a more continuous passenger flow.
All ticketing and baggage tracking for the Hyperloop will be handled electronically, negating the need for printing boarding passes and luggage labels. Since Hyperloop travel time is very short, the main usage is more for commuting than for vacations. There would be a luggage limit of 2 bags per person, for no more than 110 lb (50 kg) in total. Luggage would be stowed in a separate compartment at the rear of the capsule, in a way comparable to the overhead bins on passenger aircraft. This luggage compartment can be removed from the capsule, so that the process of stowing and retrieving luggage can be undertaken separately from embarking or disembarking the capsule’s passenger cabin. In addition, Hyperloop staff will take care of loading and unloading passenger luggage in order to maximize efficiency. The transit area at a Hyperloop terminal would be a large open area with two large airlocks signifying the entry and exit points for the capsules. An arriving capsule would enter the incoming airlock, where the pressure is equalized with Page 33
the station, before being released into the transit area. The doors of the capsule would open allowing the passengers to disembark. The luggage pod would be quickly unloaded by the Hyperloop staff or separated from the capsule so that baggage retrieval would not interfere with the capsule turnaround. Once vacated, the capsule would be rotated on a turntable, and aligned for re- entry into the Hyperloop tube. The departing passengers, and their pre-loaded luggage pod, would then enter the capsule. A Hyperloop attendant would next perform a safety check of the seat belt of each passenger before the capsule is cleared for departure. At this point the capsule would then be moved forward into the exit airlock, where the pressure is lowered to the operating level of the Hyperloop, and then sent on its way. Note that loading and unloading would occur in parallel with up to three capsules at a given station at any time. The expected cost for each station is around $125 million for a total of $250 million USD initially. 4.2.5. Cost The overall cost of the tube, pillars, vacuum pumps and stations is thus expected to be around $4.06 billion USD for the passenger version of the Hyperloop. This does not include the cost of the propulsion linear motors or solar panels. The tube represents approximately 70% of the total budget. The larger 10 ft 10 in. (3.3 m) tube would allow the cargo and vehicle capsules to fit at a total cost including the tube, pillars, vacuum pumps, and stations around $5.31 billion USD. This minimal cost increase would allow a much more versatile Hyperloop system.
The propulsion system has the following basic requirements: 1.
speed travel in urban areas. 2.
Maintain the capsule at 300 mph (480 kph) as necessary, including during ascents over the mountains surrounding Los Angeles and San Francisco. 3.
at the beginning of the long coasting section along the I-5 corridor. 4.
To decelerate the capsule back to 300 mph (480 kph) at the end of the I- 5 corridor. The Hyperloop as a whole is projected to consume an average of 28,000 hp (21 MW). This includes the power needed to make up for propulsion motor efficiency (including elevation changes), aerodynamic drag, charging the batteries to power on-board compressors, and vacuum pumps to keep the tube evacuated. A solar array covering the entire Hyperloop is large enough to
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provide an annual average of 76,000 hp (57 MW), significantly more than the Hyperloop requires. Since the peak powers of accelerating and decelerating capsules are up to 3 times the average power, the power architecture includes a battery array at each accelerator. These arrays provide storage of excess power during non- peak periods that can be used during periods of peak usage. Power from the grid is needed only when solar power is not available. This section details a large linear accelerator, capable of the 300 to 760 mph (480 to 1,220 kph) acceleration at 1G. Smaller accelerators appropriate for urban areas and ascending mountain ranges can be scaled down from this system.
The Hyperloop uses a linear induction motor to accelerate and decelerate the capsule. This provides several important benefits over a permanent magnet motor:
Lower material cost – the rotor can be a simple aluminum shape, and does not require rare-earth elements.
Smaller capsule dimensions. The lateral forces exerted by the stator on the rotor though low at 0.9 lb f /ft (13 N/m) are inherently stabilizing. This simplifies the problem of keeping the rotor aligned in the air gap. |